diff --git a/plugins/calendar/calendar.php b/plugins/calendar/calendar.php
index af579578..8e031a41 100644
--- a/plugins/calendar/calendar.php
+++ b/plugins/calendar/calendar.php
@@ -1,4017 +1,4014 @@
 <?php
 
 /**
  * Calendar plugin for Roundcube webmail
  *
  * @author Lazlo Westerhof <hello@lazlo.me>
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2010, Lazlo Westerhof <hello@lazlo.me>
  * Copyright (C) 2014-2015, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 #[AllowDynamicProperties]
 class calendar extends rcube_plugin
 {
     const FREEBUSY_UNKNOWN   = 0;
     const FREEBUSY_FREE      = 1;
     const FREEBUSY_BUSY      = 2;
     const FREEBUSY_TENTATIVE = 3;
     const FREEBUSY_OOF       = 4;
 
     const SESSION_KEY = 'calendar_temp';
 
     public $task = '?(?!logout).*';
     public $rc;
     public $lib;
     public $resources_dir;
     public $home;  // declare public to be used in other classes
     public $urlbase;
     public $timezone;
     public $timezone_offset;
     public $gmt_offset;
     public $dst_active;
     public $ui;
 
     public $defaults = [
         'calendar_default_view' => "agendaWeek",
         'calendar_timeslots'    => 2,
         'calendar_work_start'   => 6,
         'calendar_work_end'     => 18,
         'calendar_agenda_range' => 60,
         'calendar_show_weekno'  => 0,
         'calendar_first_day'    => 1,
         'calendar_first_hour'   => 6,
         'calendar_time_format'  => null,
         'calendar_event_coloring'      => 0,
         'calendar_time_indicator'      => true,
         'calendar_allow_invite_shared' => false,
         'calendar_itip_send_option'    => 3,
         'calendar_itip_after_action'   => 0,
     ];
 
     // These are implemented with __get()
     //  private $ical;
     //  private $itip;
     //  private $driver;
 
 
     /**
      * Plugin initialization.
      */
     function init()
     {
         $this->rc = rcube::get_instance();
 
         $this->register_task('calendar', 'calendar');
 
         // load calendar configuration
         $this->load_config();
 
         // catch iTIP confirmation requests that don're require a valid session
         if ($this->rc->action == 'attend' && !empty($_REQUEST['_t'])) {
             $this->add_hook('startup', [$this, 'itip_attend_response']);
         }
         else if ($this->rc->action == 'feed' && !empty($_REQUEST['_cal'])) {
             $this->add_hook('startup', [$this, 'ical_feed_export']);
         }
         else if ($this->rc->task != 'login') {
             // default startup routine
             $this->add_hook('startup', [$this, 'startup']);
         }
 
         $this->add_hook('user_delete', [$this, 'user_delete']);
     }
 
     /**
      * Setup basic plugin environment and UI
      */
     protected function setup()
     {
         $this->require_plugin('libcalendaring');
         $this->require_plugin('libkolab');
 
         require $this->home . '/lib/calendar_ui.php';
 
         // load localizations
         $this->add_texts('localization/', $this->rc->task == 'calendar' && (!$this->rc->action || $this->rc->action == 'print'));
 
         $this->lib             = libcalendaring::get_instance();
         $this->timezone        = $this->lib->timezone;
         $this->gmt_offset      = $this->lib->gmt_offset;
         $this->dst_active      = $this->lib->dst_active;
         $this->timezone_offset = $this->gmt_offset / 3600 - $this->dst_active;
         $this->ui              = new calendar_ui($this);
     }
 
     /**
      * Startup hook
      */
     public function startup($args)
     {
         // the calendar module can be enabled/disabled by the kolab_auth plugin
         if ($this->rc->config->get('calendar_disabled', false)
             || !$this->rc->config->get('calendar_enabled', true)
         ) {
             return;
         }
 
         $this->setup();
 
         // load Calendar user interface
         if (!$this->rc->output->ajax_call
             && (empty($this->rc->output->env['framed']) || $args['action'] == 'preview')
         ) {
             $this->ui->init();
 
             // settings are required in (almost) every GUI step
             if ($args['action'] != 'attend') {
                 $this->rc->output->set_env('calendar_settings', $this->load_settings());
             }
 
             // A hack to replace "Edit/Share Calendar" label with "Edit calendar", for CalDAV driver
             if ($args['task'] == 'calendar' && $this->rc->config->get('calendar_driver', 'database') === 'caldav') {
                 $merge = ['calendar.editcalendar' => $this->gettext('edcalendar')];
                 $this->rc->load_language(null, [], $merge);
                 $this->rc->output->command('add_label', $merge);
             }
         }
 
         if ($args['task'] == 'calendar' && $args['action'] != 'save-pref') {
             if ($args['action'] != 'upload') {
                 $this->load_driver();
             }
 
             // register calendar actions
             $this->register_action('index', [$this, 'calendar_view']);
             $this->register_action('event', [$this, 'event_action']);
             $this->register_action('calendar', [$this, 'calendar_action']);
             $this->register_action('count', [$this, 'count_events']);
             $this->register_action('load_events', [$this, 'load_events']);
             $this->register_action('export_events', [$this, 'export_events']);
             $this->register_action('import_events', [$this, 'import_events']);
             $this->register_action('upload', [$this, 'attachment_upload']);
             $this->register_action('get-attachment', [$this, 'attachment_get']);
             $this->register_action('freebusy-status', [$this, 'freebusy_status']);
             $this->register_action('freebusy-times', [$this, 'freebusy_times']);
             $this->register_action('randomdata', [$this, 'generate_randomdata']);
             $this->register_action('print', [$this,'print_view']);
             $this->register_action('mailimportitip', [$this, 'mail_import_itip']);
             $this->register_action('mailimportattach', [$this, 'mail_import_attachment']);
             $this->register_action('dialog-ui', [$this, 'mail_message2event']);
             $this->register_action('check-recent', [$this, 'check_recent']);
             $this->register_action('itip-status', [$this, 'event_itip_status']);
             $this->register_action('itip-remove', [$this, 'event_itip_remove']);
             $this->register_action('itip-decline-reply', [$this, 'mail_itip_decline_reply']);
             $this->register_action('itip-delegate', [$this, 'mail_itip_delegate']);
             $this->register_action('resources-list', [$this, 'resources_list']);
             $this->register_action('resources-owner', [$this, 'resources_owner']);
             $this->register_action('resources-calendar', [$this, 'resources_calendar']);
             $this->register_action('resources-autocomplete', [$this, 'resources_autocomplete']);
             $this->register_action('talk-room-create', [$this, 'talk_room_create']);
 
             $this->add_hook('refresh', [$this, 'refresh']);
 
             // remove undo information...
             if (!empty($_SESSION['calendar_event_undo'])) {
                 $undo = $_SESSION['calendar_event_undo'];
                 // ...after timeout
                 $undo_time = $this->rc->config->get('undo_timeout', 0);
                 if ($undo['ts'] < time() - $undo_time) {
                     $this->rc->session->remove('calendar_event_undo');
                     // @TODO: do EXPUNGE on kolab objects?
                 }
             }
         }
         else if ($args['task'] == 'settings') {
             // add hooks for Calendar settings
             $this->add_hook('preferences_sections_list', [$this, 'preferences_sections_list']);
             $this->add_hook('preferences_list', [$this, 'preferences_list']);
             $this->add_hook('preferences_save', [$this, 'preferences_save']);
         }
         else if ($args['task'] == 'mail') {
             // hooks to catch event invitations on incoming mails
             if ($args['action'] == 'show' || $args['action'] == 'preview') {
                 $this->add_hook('template_object_messagebody', [$this, 'mail_messagebody_html']);
             }
 
             // add 'Create event' item to message menu
             if ($this->api->output->type == 'html' && (empty($_GET['_rel']) || $_GET['_rel'] != 'event')) {
                 $this->api->output->add_label('calendar.createfrommail');
                 $this->api->add_content(
                     html::tag('li', ['role' => 'menuitem'],
                         $this->api->output->button([
                             'command'  => 'calendar-create-from-mail',
                             'label'    => 'calendar.createfrommail',
                             'type'     => 'link',
                             'classact' => 'icon calendarlink active',
                             'class'    => 'icon calendarlink disabled',
                             'innerclass' => 'icon calendar',
                         ])
                     ),
                     'messagemenu'
                 );
             }
 
             $this->add_hook('messages_list', [$this, 'mail_messages_list']);
             $this->add_hook('message_compose', [$this, 'mail_message_compose']);
         }
         else if ($args['task'] == 'addressbook') {
             if ($this->rc->config->get('calendar_contact_birthdays')) {
                 $this->add_hook('contact_update', [$this, 'contact_update']);
                 $this->add_hook('contact_create', [$this, 'contact_update']);
             }
         }
 
         // add hooks to display alarms
         $this->add_hook('pending_alarms', [$this, 'pending_alarms']);
         $this->add_hook('dismiss_alarms', [$this, 'dismiss_alarms']);
     }
 
     /**
      * Helper method to load the backend driver according to local config
      */
     private function load_driver()
     {
         if (!empty($this->driver)) {
             return;
         }
 
         $driver_name = $this->rc->config->get('calendar_driver', 'database');
         $driver_class = $driver_name . '_driver';
 
         require_once $this->home . '/drivers/calendar_driver.php';
         require_once $this->home . '/drivers/' . $driver_name . '/' . $driver_class . '.php';
 
         $this->driver = new $driver_class($this);
 
         if ($this->driver->undelete) {
             $this->driver->undelete = $this->rc->config->get('undo_timeout', 0) > 0;
         }
     }
 
     /**
      * Load iTIP functions
      */
     private function load_itip()
     {
         if (empty($this->itip)) {
             require_once $this->home . '/lib/calendar_itip.php';
 
             $this->itip = new calendar_itip($this);
 
             if ($this->rc->config->get('kolab_invitation_calendars')) {
                 $this->itip->set_rsvp_actions(['accepted','tentative','declined','delegated','needs-action']);
             }
         }
 
         return $this->itip;
     }
 
     /**
      * Load iCalendar functions
      */
     public function get_ical()
     {
         if (empty($this->ical)) {
             $this->ical = libcalendaring::get_ical();
         }
 
         return $this->ical;
     }
 
     /**
      * Get properties of the calendar this user has specified as default
      */
     public function get_default_calendar($calendars = null)
     {
         if ($calendars === null) {
             $filter    = calendar_driver::FILTER_PERSONAL | calendar_driver::FILTER_WRITEABLE;
             $calendars = $this->driver->list_calendars($filter);
         }
 
         $default_id = $this->rc->config->get('calendar_default_calendar');
         $calendar   = !empty($calendars[$default_id]) ? $calendars[$default_id] : null;
         $first      = null;
 
         if (!$calendar) {
             foreach ($calendars as $cal) {
                 if (!empty($cal['default']) && $cal['editable']) {
                     $calendar = $cal;
                 }
                 if ($cal['editable']) {
                     $first = $cal;
                 }
             }
         }
 
         return $calendar ?: $first;
     }
 
     /**
      * Render the main calendar view from skin template
      */
     function calendar_view()
     {
         $this->rc->output->set_pagetitle($this->gettext('calendar'));
 
         // Add JS files to the page header
         $this->ui->addJS();
 
         $this->ui->init_templates();
         $this->rc->output->add_label('lowest','low','normal','high','highest','delete',
             'cancel','uploading','noemailwarning','close'
         );
 
         // initialize attendees autocompletion
         $this->rc->autocomplete_init();
 
         $this->rc->output->set_env('timezone', $this->timezone->getName());
         $this->rc->output->set_env('calendar_driver', $this->rc->config->get('calendar_driver'), false);
         $this->rc->output->set_env('calendar_resources', (bool)$this->rc->config->get('calendar_resources_driver'));
         $this->rc->output->set_env('identities-selector', $this->ui->identity_select([
                 'id'         => 'edit-identities-list',
                 'aria-label' => $this->gettext('roleorganizer'),
                 'class'      => 'form-control custom-select',
         ]));
 
         $view = rcube_utils::get_input_value('view', rcube_utils::INPUT_GPC);
         if (in_array($view, ['agendaWeek', 'agendaDay', 'month', 'list'])) {
             $this->rc->output->set_env('view', $view);
         }
 
         if ($date = rcube_utils::get_input_value('date', rcube_utils::INPUT_GPC)) {
             $this->rc->output->set_env('date', $date);
         }
 
         if ($msgref = rcube_utils::get_input_value('itip', rcube_utils::INPUT_GPC)) {
             $this->rc->output->set_env('itip_events', $this->itip_events($msgref));
         }
 
         $this->rc->output->send('calendar.calendar');
     }
 
     /**
      * Handler for preferences_sections_list hook.
      * Adds Calendar settings sections into preferences sections list.
      *
      * @param array Original parameters
      *
      * @return array Modified parameters
      */
     function preferences_sections_list($p)
     {
         $p['list']['calendar'] = [
             'id'      => 'calendar',
             'section' => $this->gettext('calendar'),
         ];
 
         return $p;
     }
 
     /**
      * Handler for preferences_list hook.
      * Adds options blocks into Calendar settings sections in Preferences.
      *
      * @param array Original parameters
      *
      * @return array Modified parameters
      */
     function preferences_list($p)
     {
         if ($p['section'] != 'calendar') {
             return $p;
         }
 
         $no_override = array_flip((array) $this->rc->config->get('dont_override'));
 
         $p['blocks']['view']['name'] = $this->gettext('mainoptions');
 
         if (!isset($no_override['calendar_default_view'])) {
             if (empty($p['current'])) {
                 $p['blocks']['view']['content'] = true;
                 return $p;
             }
 
             $field_id = 'rcmfd_default_view';
             $view = $this->rc->config->get('calendar_default_view', $this->defaults['calendar_default_view']);
 
             $select = new html_select(['name' => '_default_view', 'id' => $field_id]);
             $select->add($this->gettext('day'), "agendaDay");
             $select->add($this->gettext('week'), "agendaWeek");
             $select->add($this->gettext('month'), "month");
             $select->add($this->gettext('agenda'), "list");
 
             $p['blocks']['view']['options']['default_view'] = [
                 'title'   => html::label($field_id, rcube::Q($this->gettext('default_view'))),
                 'content' => $select->show($view == 'table' ? 'list' : $view),
             ];
         }
 
         if (!isset($no_override['calendar_timeslots'])) {
             if (empty($p['current'])) {
                 $p['blocks']['view']['content'] = true;
                 return $p;
             }
 
             $field_id  = 'rcmfd_timeslots';
             $choices   = ['1', '2', '3', '4', '6'];
             $timeslots = $this->rc->config->get('calendar_timeslots', $this->defaults['calendar_timeslots']);
 
             $select = new html_select(['name' => '_timeslots', 'id' => $field_id]);
             $select->add($choices, $choices);
 
             $p['blocks']['view']['options']['timeslots'] = [
                 'title' => html::label($field_id, rcube::Q($this->gettext('timeslots'))),
                 'content' => $select->show(strval($timeslots)),
             ];
         }
 
         if (!isset($no_override['calendar_first_day'])) {
             if (empty($p['current'])) {
                 $p['blocks']['view']['content'] = true;
                 return $p;
             }
 
             $field_id  = 'rcmfd_firstday';
             $first_day = $this->rc->config->get('calendar_first_day', $this->defaults['calendar_first_day']);
 
             $select = new html_select(['name' => '_first_day', 'id' => $field_id]);
             $select->add($this->gettext('sunday'), '0');
             $select->add($this->gettext('monday'), '1');
             $select->add($this->gettext('tuesday'), '2');
             $select->add($this->gettext('wednesday'), '3');
             $select->add($this->gettext('thursday'), '4');
             $select->add($this->gettext('friday'), '5');
             $select->add($this->gettext('saturday'), '6');
 
             $p['blocks']['view']['options']['first_day'] = [
                 'title'   => html::label($field_id, rcube::Q($this->gettext('first_day'))),
                 'content' => $select->show(strval($first_day)),
             ];
         }
 
         if (!isset($no_override['calendar_first_hour'])) {
             if (empty($p['current'])) {
                 $p['blocks']['view']['content'] = true;
                 return $p;
             }
 
             $first_hour  = $this->rc->config->get('calendar_first_hour', $this->defaults['calendar_first_hour']);
             $time_format = $this->rc->config->get('calendar_time_format', $this->defaults['calendar_time_format']);
             $time_format = $this->rc->config->get('time_format', libcalendaring::to_php_date_format($time_format));
             $field_id    = 'rcmfd_firsthour';
 
             $select_hours = new html_select(['name' => '_first_hour', 'id' => $field_id]);
             for ($h = 0; $h < 24; $h++) {
                 $select_hours->add(date($time_format, mktime($h, 0, 0)), $h);
             }
 
             $p['blocks']['view']['options']['first_hour'] = [
                 'title'   => html::label($field_id, rcube::Q($this->gettext('first_hour'))),
                 'content' => $select_hours->show($first_hour),
             ];
         }
 
         if (!isset($no_override['calendar_work_start'])) {
             if (empty($p['current'])) {
                 $p['blocks']['view']['content'] = true;
                 return $p;
             }
 
             $field_id   = 'rcmfd_workstart';
             $work_start = $this->rc->config->get('calendar_work_start', $this->defaults['calendar_work_start']);
             $work_end   = $this->rc->config->get('calendar_work_end', $this->defaults['calendar_work_end']);
 
             $p['blocks']['view']['options']['workinghours'] = [
                 'title'   => html::label($field_id, rcube::Q($this->gettext('workinghours'))),
                 'content' => html::div('input-group',
                     $select_hours->show($work_start, ['name' => '_work_start', 'id' => $field_id])
                     . html::span('input-group-append input-group-prepend', html::span('input-group-text',' &mdash; '))
                     . $select_hours->show($work_end, ['name' => '_work_end', 'id' => $field_id])
                 )
             ];
         }
 
         if (!isset($no_override['calendar_event_coloring'])) {
             if (empty($p['current'])) {
                 $p['blocks']['view']['content'] = true;
                 return $p;
             }
 
             $field_id = 'rcmfd_coloring';
             $mode     = $this->rc->config->get('calendar_event_coloring', $this->defaults['calendar_event_coloring']);
 
             $select_colors = new html_select(['name' => '_event_coloring', 'id' => $field_id]);
             $select_colors->add($this->gettext('coloringmode0'), 0);
             $select_colors->add($this->gettext('coloringmode1'), 1);
             $select_colors->add($this->gettext('coloringmode2'), 2);
             $select_colors->add($this->gettext('coloringmode3'), 3);
 
             $p['blocks']['view']['options']['eventcolors'] = [
                 'title'   => html::label($field_id, rcube::Q($this->gettext('eventcoloring'))),
                 'content' => $select_colors->show($mode),
             ];
         }
 
         // loading driver is expensive, don't do it if not needed
         $this->load_driver();
 
         if (!isset($no_override['calendar_default_alarm_type']) || !isset($no_override['calendar_default_alarm_offset'])) {
             if (empty($p['current'])) {
                 $p['blocks']['view']['content'] = true;
                 return $p;
             }
 
             $alarm_type = $alarm_offset = '';
 
             if (!isset($no_override['calendar_default_alarm_type'])) {
                 $field_id    = 'rcmfd_alarm';
                 $select_type = new html_select(['name' => '_alarm_type', 'id' => $field_id]);
                 $select_type->add($this->gettext('none'), '');
 
                 foreach ($this->driver->alarm_types as $type) {
                     $select_type->add($this->rc->gettext(strtolower("alarm{$type}option"), 'libcalendaring'), $type);
                 }
 
                 $alarm_type = $select_type->show($this->rc->config->get('calendar_default_alarm_type', ''));
             }
 
             if (!isset($no_override['calendar_default_alarm_offset'])) {
                 $field_id      = 'rcmfd_alarm';
                 $input_value   = new html_inputfield(['name' => '_alarm_value', 'id' => $field_id . 'value', 'size' => 3]);
                 $select_offset = new html_select(['name' => '_alarm_offset', 'id' => $field_id . 'offset']);
 
                 foreach (['-M','-H','-D','+M','+H','+D'] as $trigger) {
                     $select_offset->add($this->rc->gettext('trigger' . $trigger, 'libcalendaring'), $trigger);
                 }
 
                 $preset = libcalendaring::parse_alarm_value($this->rc->config->get('calendar_default_alarm_offset', '-15M'));
                 $alarm_offset = $input_value->show($preset[0]) . ' ' . $select_offset->show($preset[1]);
             }
 
             $p['blocks']['view']['options']['alarmtype'] = [
                 'title'   => html::label($field_id, rcube::Q($this->gettext('defaultalarmtype'))),
                 'content' => html::div('input-group', $alarm_type . ' ' . $alarm_offset),
             ];
         }
 
         if (!isset($no_override['calendar_default_calendar'])) {
             if (empty($p['current'])) {
                 $p['blocks']['view']['content'] = true;
                 return $p;
             }
 
             // default calendar selection
             $field_id   = 'rcmfd_default_calendar';
             $filter     = calendar_driver::FILTER_PERSONAL | calendar_driver::FILTER_ACTIVE | calendar_driver::FILTER_INSERTABLE;
             $select_cal = new html_select(['name' => '_default_calendar', 'id' => $field_id, 'is_escaped' => true]);
 
             $default_calendar = null;
             foreach ((array) $this->driver->list_calendars($filter) as $id => $prop) {
                 $select_cal->add($prop['name'], strval($id));
                 if (!empty($prop['default'])) {
                     $default_calendar = $id;
                 }
             }
 
             $p['blocks']['view']['options']['defaultcalendar'] = [
                 'title'   => html::label($field_id, rcube::Q($this->gettext('defaultcalendar'))),
                 'content' => $select_cal->show($this->rc->config->get('calendar_default_calendar', $default_calendar)),
             ];
         }
 
         if (!isset($no_override['calendar_show_weekno'])) {
             if (empty($p['current'])) {
                 $p['blocks']['view']['content'] = true;
                 return $p;
             }
 
             $field_id   = 'rcmfd_show_weekno';
             $select = new html_select(['name' => '_show_weekno', 'id' => $field_id]);
             $select->add($this->gettext('weeknonone'), -1);
             $select->add($this->gettext('weeknodatepicker'), 0);
             $select->add($this->gettext('weeknoall'), 1);
 
             $p['blocks']['view']['options']['show_weekno'] = [
                 'title'   => html::label($field_id, rcube::Q($this->gettext('showweekno'))),
                 'content' => $select->show(intval($this->rc->config->get('calendar_show_weekno'))),
             ];
         }
 
         $p['blocks']['itip']['name'] = $this->gettext('itipoptions');
 
         // Invitations handling
         if (!isset($no_override['calendar_itip_after_action'])) {
             if (empty($p['current'])) {
                 $p['blocks']['itip']['content'] = true;
                 return $p;
             }
 
             $field_id = 'rcmfd_after_action';
             $select   = new html_select([
                     'name'     => '_after_action',
                     'id'       => $field_id,
                     'onchange' => "\$('#{$field_id}_select')[this.value == 4 ? 'show' : 'hide']()"
             ]);
 
             $select->add($this->gettext('afternothing'), '');
             $select->add($this->gettext('aftertrash'), 1);
             $select->add($this->gettext('afterdelete'), 2);
             $select->add($this->gettext('afterflagdeleted'), 3);
             $select->add($this->gettext('aftermoveto'), 4);
 
             $val    = $this->rc->config->get('calendar_itip_after_action', $this->defaults['calendar_itip_after_action']);
             $folder = null;
 
             if ($val !== null && $val !== '' && !is_int($val)) {
                 $folder = $val;
                 $val    = 4;
             }
 
             $folders = $this->rc->folder_selector([
                     'id'            => $field_id . '_select',
                     'name'          => '_after_action_folder',
                     'maxlength'     => 30,
                     'folder_filter' => 'mail',
                     'folder_rights' => 'w',
                     'style'         => $val !== 4 ? 'display:none' : '',
             ]);
 
             $p['blocks']['itip']['options']['after_action'] = [
                 'title'   => html::label($field_id, rcube::Q($this->gettext('afteraction'))),
                 'content' => html::div(
                     'input-group input-group-combo',
                     $select->show($val) . $folders->show($folder)
                 ),
             ];
         }
 
         // category definitions
         if (empty($this->driver->nocategories) && !isset($no_override['calendar_categories'])) {
             $p['blocks']['categories']['name'] = $this->gettext('categories');
 
             if (empty($p['current'])) {
                 $p['blocks']['categories']['content'] = true;
                 return $p;
             }
 
             $categories      = (array) $this->driver->list_categories();
             $categories_list = '';
 
             foreach ($categories as $name => $color) {
                 $key = md5($name);
                 $field_class = 'rcmfd_category_' . str_replace(' ', '_', $name);
                 $category_remove = html::span('input-group-append',
                     html::a([
                             'class'   => 'button icon delete input-group-text',
                             'onclick' => '$(this).parent().parent().remove()',
                             'title'   => $this->gettext('remove_category'),
                             'href'    => '#rcmfd_new_category',
                         ],
                         html::span('inner', $this->gettext('delete'))
                     )
                 );
 
                 $category_name  = new html_inputfield(array('name' => "_categories[$key]", 'class' => $field_class, 'size' => 30, 'disabled' => $this->driver->categoriesimmutable));
                 $category_color = new html_inputfield(array('name' => "_colors[$key]", 'class' => "$field_class colors", 'size' => 6));
                 $hidden         = '';
 
                 if (!empty($this->driver->categoriesimmutable)) {
                     $hidden =  html::tag('input', ['type' => 'hidden', 'name' => "_categories[$key]", 'value' => $name]);
                 }
 
                 $categories_list .= $hidden
                     . html::div('input-group', $category_name->show($name) . $category_color->show($color) . $category_remove);
             }
 
             $p['blocks']['categories']['options']['category_' . $name] = [
                 'content' => html::div(['id' => 'calendarcategories'], $categories_list),
             ];
 
             $field_id = 'rcmfd_new_category';
             $new_category = new html_inputfield(['name' => '_new_category', 'id' => $field_id, 'size' => 30]);
             $add_category = html::span('input-group-append',
                 html::a(
                     [
                         'type'    => 'button',
                         'class'   => 'button create input-group-text',
                         'title'   => $this->gettext('add_category'),
                         'onclick' => 'rcube_calendar_add_category()',
                         'href'    => '#rcmfd_new_category',
                     ],
                     html::span('inner', $this->gettext('add_category'))
                 )
             );
 
             $p['blocks']['categories']['options']['categories'] = [
                 'content' => html::div('input-group', $new_category->show('') . $add_category),
             ];
 
             $this->rc->output->add_label('delete', 'calendar.remove_category');
             $this->rc->output->add_script('
 function rcube_calendar_add_category() {
     var name = $("#rcmfd_new_category").val();
     if (name.length) {
         var button_label = rcmail.gettext("calendar.remove_category");
         var input = $("<input>").attr({type: "text", name: "_categories[]", size: 30, "class": "form-control"}).val(name);
         var color = $("<input>").attr({type: "text", name: "_colors[]", size: 6, "class": "colors form-control"}).val("000000");
         var button = $("<a>").attr({"class": "button icon delete input-group-text", title: button_label, href: "#rcmfd_new_category"})
             .click(function() { $(this).parent().parent().remove(); })
             .append($("<span>").addClass("inner").text(rcmail.gettext("delete")));
 
         $("<div>").addClass("input-group").append(input).append(color).append($("<span class=\'input-group-append\'>").append(button))
             .appendTo("#calendarcategories");
         color.minicolors(rcmail.env.minicolors_config || {});
         $("#rcmfd_new_category").val("");
     }
 }',
                 'foot'
             );
 
             $this->rc->output->add_script('
 $("#rcmfd_new_category").keypress(function(event) {
     if (event.which == 13) {
         rcube_calendar_add_category();
         event.preventDefault();
     }
 });',
                 'docready'
             );
 
             // load miniColors js/css files
             jqueryui::miniColors();
         }
 
         // virtual birthdays calendar
         if (!isset($no_override['calendar_contact_birthdays'])) {
             $p['blocks']['birthdays']['name'] = $this->gettext('birthdayscalendar');
 
             if (empty($p['current'])) {
                 $p['blocks']['birthdays']['content'] = true;
                 return $p;
             }
 
             $field_id = 'rcmfd_contact_birthdays';
             $input    = new html_checkbox([
                     'name'    => '_contact_birthdays',
                     'id'      => $field_id,
                     'value'   => 1,
                     'onclick' => '$(".calendar_birthday_props").prop("disabled",!this.checked)'
             ]);
 
             $p['blocks']['birthdays']['options']['contact_birthdays'] = [
                 'title'   => html::label($field_id, $this->gettext('displaybirthdayscalendar')),
                 'content' => $input->show($this->rc->config->get('calendar_contact_birthdays') ? 1 : 0),
             ];
 
             $input_attrib = [
                 'class'    => 'calendar_birthday_props',
                 'disabled' => !$this->rc->config->get('calendar_contact_birthdays'),
             ];
 
             $sources  = [];
             $checkbox = new html_checkbox(['name' => '_birthday_adressbooks[]'] + $input_attrib);
 
             foreach ($this->rc->get_address_sources(false, true) as $source) {
                 // Roundcube >= 1.5, Ignore Collected Recipients and Trusted Senders sources
                 if ((defined('rcube_addressbook::TYPE_RECIPIENT') && $source['id'] == (string) rcube_addressbook::TYPE_RECIPIENT)
                     || (defined('rcube_addressbook::TYPE_TRUSTED_SENDER') && $source['id'] == (string) rcube_addressbook::TYPE_TRUSTED_SENDER)
                 ) {
                     continue;
                 }
 
                 $active = in_array($source['id'], (array) $this->rc->config->get('calendar_birthday_adressbooks')) ? $source['id'] : '';
                 $sources[] = html::tag('li', null,
                     html::label(null,
                         $checkbox->show($active, ['value' => $source['id']])
                         . rcube::Q(!empty($source['realname']) ? $source['realname'] : $source['name'])
                     )
                 );
             }
 
             $p['blocks']['birthdays']['options']['birthday_adressbooks'] = [
                 'title'   => rcube::Q($this->gettext('birthdayscalendarsources')),
                 'content' => html::tag('ul', 'proplist', implode("\n", $sources)),
             ];
 
             $field_id = 'rcmfd_birthdays_alarm';
             $select_type = new html_select(['name' => '_birthdays_alarm_type', 'id' => $field_id] + $input_attrib);
             $select_type->add($this->gettext('none'), '');
 
             foreach ($this->driver->alarm_types as $type) {
                 $select_type->add($this->rc->gettext(strtolower("alarm{$type}option"), 'libcalendaring'), $type);
             }
 
             $input_value   = new html_inputfield(['name' => '_birthdays_alarm_value', 'id' => $field_id . 'value', 'size' => 3] + $input_attrib);
             $select_offset = new html_select(['name' => '_birthdays_alarm_offset', 'id' => $field_id . 'offset'] + $input_attrib);
 
             foreach (['-M','-H','-D'] as $trigger) {
                 $select_offset->add($this->rc->gettext('trigger' . $trigger, 'libcalendaring'), $trigger);
             }
 
             $preset      = libcalendaring::parse_alarm_value($this->rc->config->get('calendar_birthdays_alarm_offset', '-1D'));
             $preset_type = $this->rc->config->get('calendar_birthdays_alarm_type', '');
 
             $p['blocks']['birthdays']['options']['birthdays_alarmoffset'] = [
                 'title'   => html::label($field_id, rcube::Q($this->gettext('showalarms'))),
                 'content' => html::div('input-group',
                     $select_type->show($preset_type)
                     . $input_value->show($preset[0]) . ' ' . $select_offset->show($preset[1])
                 ),
             ];
         }
 
         return $p;
     }
 
     /**
      * Handler for preferences_save hook.
      * Executed on Calendar settings form submit.
      *
      * @param array Original parameters
      *
      * @return array Modified parameters
      */
     function preferences_save($p)
     {
         if ($p['section'] == 'calendar') {
             $this->load_driver();
 
             // compose default alarm preset value
             $alarm_offset  = rcube_utils::get_input_value('_alarm_offset', rcube_utils::INPUT_POST);
             $alarm_value   = rcube_utils::get_input_value('_alarm_value', rcube_utils::INPUT_POST);
             $default_alarm = $alarm_offset[0] . intval($alarm_value) . $alarm_offset[1];
 
             $birthdays_alarm_offset = rcube_utils::get_input_value('_birthdays_alarm_offset', rcube_utils::INPUT_POST);
             $birthdays_alarm_value  = rcube_utils::get_input_value('_birthdays_alarm_value', rcube_utils::INPUT_POST);
             $birthdays_alarm_value  = $birthdays_alarm_offset[0] . intval($birthdays_alarm_value) . $birthdays_alarm_offset[1];
 
             $p['prefs'] = [
                 'calendar_default_view' => rcube_utils::get_input_value('_default_view', rcube_utils::INPUT_POST),
                 'calendar_timeslots'    => intval(rcube_utils::get_input_value('_timeslots', rcube_utils::INPUT_POST)),
                 'calendar_first_day'    => intval(rcube_utils::get_input_value('_first_day', rcube_utils::INPUT_POST)),
                 'calendar_first_hour'   => intval(rcube_utils::get_input_value('_first_hour', rcube_utils::INPUT_POST)),
                 'calendar_work_start'   => intval(rcube_utils::get_input_value('_work_start', rcube_utils::INPUT_POST)),
                 'calendar_work_end'     => intval(rcube_utils::get_input_value('_work_end', rcube_utils::INPUT_POST)),
                 'calendar_show_weekno'  => intval(rcube_utils::get_input_value('_show_weekno', rcube_utils::INPUT_POST)),
                 'calendar_event_coloring'       => intval(rcube_utils::get_input_value('_event_coloring', rcube_utils::INPUT_POST)),
                 'calendar_default_alarm_type'   => rcube_utils::get_input_value('_alarm_type', rcube_utils::INPUT_POST),
                 'calendar_default_alarm_offset' => $default_alarm,
                 'calendar_default_calendar'     => rcube_utils::get_input_value('_default_calendar', rcube_utils::INPUT_POST),
                 'calendar_date_format'          => null,  // clear previously saved values
                 'calendar_time_format'          => null,
                 'calendar_contact_birthdays'      => (bool) rcube_utils::get_input_value('_contact_birthdays', rcube_utils::INPUT_POST),
                 'calendar_birthday_adressbooks'   => (array) rcube_utils::get_input_value('_birthday_adressbooks', rcube_utils::INPUT_POST),
                 'calendar_birthdays_alarm_type'   => rcube_utils::get_input_value('_birthdays_alarm_type', rcube_utils::INPUT_POST),
                 'calendar_birthdays_alarm_offset' => $birthdays_alarm_value ?: null,
                 'calendar_itip_after_action'      => intval(rcube_utils::get_input_value('_after_action', rcube_utils::INPUT_POST)),
             ];
 
             if ($p['prefs']['calendar_itip_after_action'] == 4) {
                 $p['prefs']['calendar_itip_after_action'] = rcube_utils::get_input_value('_after_action_folder', rcube_utils::INPUT_POST, true);
             }
 
             // categories
             if (empty($this->driver->nocategories)) {
                 $old_categories = $new_categories = [];
 
                 foreach ($this->driver->list_categories() as $name => $color) {
                     $old_categories[md5($name)] = $name;
                 }
 
                 $categories = (array) rcube_utils::get_input_value('_categories', rcube_utils::INPUT_POST);
                 $colors     = (array) rcube_utils::get_input_value('_colors', rcube_utils::INPUT_POST);
 
                 foreach ($categories as $key => $name) {
                     if (!isset($colors[$key])) {
                         continue;
                     }
 
                     $color = preg_replace('/^#/', '', strval($colors[$key]));
 
                     // rename categories in existing events -> driver's job
                     if (!empty($old_categories[$key])) {
                         $oldname = $old_categories[$key];
                         $this->driver->replace_category($oldname, $name, $color);
                         unset($old_categories[$key]);
                     }
                     else {
                         $this->driver->add_category($name, $color);
                     }
 
                     $new_categories[$name] = $color;
                 }
 
                 // these old categories have been removed, alter events accordingly -> driver's job
                 foreach ((array) $old_categories as $key => $name) {
                     $this->driver->remove_category($name);
                 }
 
                 $p['prefs']['calendar_categories'] = $new_categories;
             }
         }
 
         return $p;
     }
 
     /**
      * Dispatcher for calendar actions initiated by the client
      */
     function calendar_action()
     {
         $action  = rcube_utils::get_input_value('action', rcube_utils::INPUT_GPC);
         $cal     = rcube_utils::get_input_value('c', rcube_utils::INPUT_GPC);
         $success = false;
         $reload  = false;
 
         if (isset($cal['showalarms'])) {
             $cal['showalarms'] = intval($cal['showalarms']);
         }
 
         switch ($action) {
         case "form-new":
         case "form-edit":
             echo $this->ui->calendar_editform($action, $cal);
             exit;
 
         case "new":
             $success = $this->driver->create_calendar($cal);
             $reload  = true;
             break;
 
         case "edit":
             $success = $this->driver->edit_calendar($cal);
             $reload  = true;
             break;
 
         case "delete":
             if ($success = $this->driver->delete_calendar($cal)) {
                 $this->rc->output->command('plugin.destroy_source', ['id' => $cal['id']]);
             }
             break;
 
         case "subscribe":
             if (!$this->driver->subscribe_calendar($cal)) {
                 $this->rc->output->show_message($this->gettext('errorsaving'), 'error');
             }
             else {
                 $calendars = $this->driver->list_calendars();
                 $calendar  = !empty($calendars[$cal['id']]) ? $calendars[$cal['id']] : null;
 
                 // find parent folder and check if it's a "user calendar"
                 // if it's also activated we need to refresh it (#5340)
                 while (!empty($calendar['parent'])) {
                     if (isset($calendars[$calendar['parent']])) {
                         $calendar = $calendars[$calendar['parent']];
                     }
                     else {
                         break;
                     }
                 }
 
                 if ($calendar && $calendar['id'] != $cal['id']
                     && !empty($calendar['active'])
                     && $calendar['group'] == "other user"
                 ) {
                     $this->rc->output->command('plugin.refresh_source', $calendar['id']);
                 }
             }
             return;
 
         case "search":
             $results    = [];
             $color_mode = $this->rc->config->get('calendar_event_coloring', $this->defaults['calendar_event_coloring']);
             $query      = rcube_utils::get_input_value('q', rcube_utils::INPUT_GPC);
             $source     = rcube_utils::get_input_value('source', rcube_utils::INPUT_GPC);
 
             foreach ((array) $this->driver->search_calendars($query, $source) as $id => $prop) {
                 $editname = $prop['editname'];
                 unset($prop['editname']);  // force full name to be displayed
                 $prop['active'] = false;
 
                 // let the UI generate HTML and CSS representation for this calendar
                 $html = $this->ui->calendar_list_item($id, $prop, $jsenv);
                 $cal  = $jsenv[$id];
                 $cal['editname'] = $editname;
                 $cal['html']     = $html;
 
                 if (!empty($prop['color'])) {
                     $cal['css'] = $this->ui->calendar_css_classes($id, $prop, $color_mode);
                 }
 
                 $results[] = $cal;
             }
 
             // report more results available
             if (!empty($this->driver->search_more_results)) {
                 $this->rc->output->show_message('autocompletemore', 'notice');
             }
 
             $reqid = rcube_utils::get_input_value('_reqid', rcube_utils::INPUT_GPC);
             $this->rc->output->command('multi_thread_http_response', $results, $reqid);
             return;
         }
 
         if ($success) {
             $this->rc->output->show_message('successfullysaved', 'confirmation');
         }
         else {
             $error_msg = $this->gettext('errorsaving');
             if (!empty($this->driver->last_error)) {
                 $error_msg .= ': ' . $this->driver->last_error;
             }
             $this->rc->output->show_message($error_msg, 'error');
         }
 
         $this->rc->output->command('plugin.unlock_saving');
 
         if ($success && $reload) {
             $this->rc->output->command('plugin.reload_view');
         }
     }
 
     /**
      * Dispatcher for event actions initiated by the client
      */
     function event_action()
     {
         $action  = rcube_utils::get_input_value('action', rcube_utils::INPUT_GPC);
         $event   = rcube_utils::get_input_value('e', rcube_utils::INPUT_POST, true);
         $success = $reload = $got_msg = false;
         $old     = null;
 
         // read old event data in order to find changes
         if ((!empty($event['_notify']) || !empty($event['_decline'])) && $action != 'new') {
             $old = $this->driver->get_event($event);
 
             // load main event if savemode is 'all' or if deleting 'future' events
             if (!empty($old['recurrence_id'])
                 && !empty($event['_savemode'])
                 && ($event['_savemode'] == 'all' || ($event['_savemode'] == 'future' && $action == 'remove' && empty($event['_decline'])))
             ) {
                 $old['id'] = $old['recurrence_id'];
                 $old = $this->driver->get_event($old);
             }
         }
 
         switch ($action) {
         case "new":
             // create UID for new event
             $event['uid'] = $this->generate_uid();
             if (!$this->write_preprocess($event, $action)) {
                 $got_msg = true;
             }
             else if ($success = $this->driver->new_event($event)) {
                 $event['id']        = $event['uid'];
                 $event['_savemode'] = 'all';
 
                 $this->cleanup_event($event);
                 $this->event_save_success($event, null, $action, true);
                 $this->talk_room_update($event);
             }
 
             $reload = $success && !empty($event['recurrence']) ? 2 : 1;
             break;
 
         case "edit":
             if (!$this->write_preprocess($event, $action)) {
                 $got_msg = true;
             }
             else if ($success = $this->driver->edit_event($event)) {
                 $this->cleanup_event($event);
                 $this->event_save_success($event, $old, $action, $success);
                 $this->talk_room_update($event);
             }
 
             $reload = $success && (!empty($event['recurrence']) || !empty($event['_savemode']) || !empty($event['_fromcalendar'])) ? 2 : 1;
             break;
 
         case "resize":
             if (!$this->write_preprocess($event, $action)) {
                 $got_msg = true;
             }
             else if ($success = $this->driver->resize_event($event)) {
                 $this->event_save_success($event, $old, $action, $success);
             }
 
             $reload = !empty($event['_savemode']) ? 2 : 1;
             break;
 
         case "move":
             if (!$this->write_preprocess($event, $action)) {
                 $got_msg = true;
             }
             else if ($success = $this->driver->move_event($event)) {
                 $this->event_save_success($event, $old, $action, $success);
             }
 
             $reload = $success && !empty($event['_savemode']) ? 2 : 1;
             break;
 
         case "remove":
             // remove previous deletes
             $undo_time = $this->driver->undelete ? $this->rc->config->get('undo_timeout', 0) : 0;
 
             // search for event if only UID is given
             if (!isset($event['calendar']) && !empty($event['uid'])) {
                 if (!($event = $this->driver->get_event($event, calendar_driver::FILTER_WRITEABLE))) {
                     break;
                 }
                 $undo_time = 0;
             }
 
             // Note: the driver is responsible for setting $_SESSION['calendar_event_undo']
             //       containing 'ts' and 'data' elements
             $success = $this->driver->remove_event($event, $undo_time < 1);
             $reload = (!$success || !empty($event['_savemode'])) ? 2 : 1;
 
             if ($undo_time > 0 && $success) {
                 // display message with Undo link.
                 $onclick = sprintf("%s.http_request('event', 'action=undo', %s.display_message('', 'loading'))",
                     rcmail_output::JS_OBJECT_NAME,
                     rcmail_output::JS_OBJECT_NAME
                 );
                 $msg = html::span(null, $this->gettext('successremoval'))
                     . ' ' . html::a(['onclick' => $onclick], $this->gettext('undo'));
 
                 $this->rc->output->show_message($msg, 'confirmation', null, true, $undo_time);
                 $got_msg = true;
             }
             else if ($success) {
                 $this->rc->output->show_message('calendar.successremoval', 'confirmation');
                 $got_msg = true;
             }
 
             // send cancellation for the main event
             if (isset($event['_savemode']) && $event['_savemode'] == 'all') {
                 unset($old['_instance'], $old['recurrence_date'], $old['recurrence_id']);
             }
             // send an update for the main event's recurrence rule instead of a cancellation message
             else if (isset($event['_savemode']) && $event['_savemode'] == 'future' && !is_bool($success)) {
                 $event['_savemode'] = 'all';  // force event_save_success() to load master event
                 $action  = 'edit';
                 $success = true;
             }
 
             // send iTIP reply that participant has declined the event
             if ($success && !empty($event['_decline'])) {
                 $emails    = $this->get_user_emails();
                 $organizer = null;
 
                 foreach ($old['attendees'] as $i => $attendee) {
                     if ($attendee['role'] == 'ORGANIZER') {
                         $organizer = $attendee;
                     }
                     else if (!empty($attendee['email']) && in_array(strtolower($attendee['email']), $emails)) {
                         $old['attendees'][$i]['status'] = 'DECLINED';
                         $reply_sender = $attendee['email'];
                     }
                 }
 
                 if ($event['_savemode'] == 'future' && $event['id'] != $old['id']) {
                     $old['thisandfuture'] = true;
                 }
 
                 $itip = $this->load_itip();
                 $itip->set_sender_email($reply_sender);
 
                 if ($organizer && $itip->send_itip_message($old, 'REPLY', $organizer, 'itipsubjectdeclined', 'itipmailbodydeclined')) {
                     $mailto = !empty($organizer['name']) ? $organizer['name'] : $organizer['email'];
                     $msg    = $this->gettext(['name' => 'sentresponseto', 'vars' => ['mailto' => $mailto]]);
 
                     $this->rc->output->command('display_message', $msg, 'confirmation');
                 }
                 else {
                     $this->rc->output->command('display_message', $this->gettext('itipresponseerror'), 'error');
                 }
             }
             else if ($success) {
                 $this->event_save_success($event, $old, $action, $success);
             }
 
             break;
 
         case "undo":
             // Restore deleted event
             if (!empty($_SESSION['calendar_event_undo']['data'])) {
                 $event   = $_SESSION['calendar_event_undo']['data'];
                 $success = $this->driver->restore_event($event);
             }
 
             if ($success) {
                 $this->rc->session->remove('calendar_event_undo');
                 $this->rc->output->show_message('calendar.successrestore', 'confirmation');
                 $got_msg = true;
                 $reload  = 2;
             }
 
             break;
 
         case "rsvp":
             $itip_sending  = $this->rc->config->get('calendar_itip_send_option', $this->defaults['calendar_itip_send_option']);
             $status        = rcube_utils::get_input_value('status', rcube_utils::INPUT_POST);
             $attendees     = rcube_utils::get_input_value('attendees', rcube_utils::INPUT_POST);
             $reply_comment = $event['comment'];
 
             $this->write_preprocess($event, 'edit');
             $ev = $this->driver->get_event($event);
             $ev['attendees'] = $event['attendees'];
             $ev['free_busy'] = $event['free_busy'];
             $ev['_savemode'] = $event['_savemode'];
             $ev['comment']   = $reply_comment;
 
             // send invitation to delegatee + add it as attendee
             if ($status == 'delegated' && !empty($event['to'])) {
                 $itip = $this->load_itip();
                 if ($itip->delegate_to($ev, $event['to'], !empty($event['rsvp']), $attendees)) {
                     $this->rc->output->show_message('calendar.itipsendsuccess', 'confirmation');
                     $noreply = false;
                 }
             }
 
             $event = $ev;
 
             // compose a list of attendees affected by this change
             $updated_attendees = array_filter(array_map(function($j) use ($event) {
                     return $event['attendees'][$j];
                 },
                 $attendees
             ));
 
             if ($success = $this->driver->edit_rsvp($event, $status, $updated_attendees)) {
                 $noreply = rcube_utils::get_input_value('noreply', rcube_utils::INPUT_GPC);
                 $noreply = intval($noreply) || $status == 'needs-action' || $itip_sending === 0;
                 $reload  = $event['calendar'] != $ev['calendar'] || !empty($event['recurrence']) ? 2 : 1;
                 $emails  = $this->get_user_emails();
                 $ownedResourceEmails = $this->owned_resources_emails();
                 $organizer = null;
                 $resourceConfirmation = false;
 
                 foreach ($event['attendees'] as $i => $attendee) {
                     if ($attendee['role'] == 'ORGANIZER') {
                         $organizer = $attendee;
                     }
                     else if (!empty($attendee['email']) && in_array_nocase($attendee['email'], $emails)) {
                         $reply_sender = $attendee['email'];
                     }
                     else if (!empty($attendee['cutype']) && $attendee['cutype'] == 'RESOURCE' && !empty($attendee['email']) && in_array_nocase($attendee['email'], $ownedResourceEmails)) {
                         $resourceConfirmation = true;
                         // Note on behalf of which resource this update is going to be sent out
                         $event['_resource'] = $attendee['email'];
                     }
                 }
 
                 if (!$noreply) {
                     $itip = $this->load_itip();
                     $itip->set_sender_email($reply_sender);
                     $event['thisandfuture'] = $event['_savemode'] == 'future';
                     $bodytextprefix = $resourceConfirmation ? 'itipmailbodyresource' : 'itipmailbody';
 
                     if ($organizer && $itip->send_itip_message($event, 'REPLY', $organizer, 'itipsubject' . $status, $bodytextprefix . $status)) {
                         $mailto = !empty($organizer['name']) ? $organizer['name'] : $organizer['email'];
                         $msg    = $this->gettext(['name' => 'sentresponseto', 'vars' => ['mailto' => $mailto]]);
 
                         $this->rc->output->command('display_message', $msg, 'confirmation');
                     }
                     else {
                         $this->rc->output->command('display_message', $this->gettext('itipresponseerror'), 'error');
                     }
                 }
 
                 // refresh all calendars
                 if ($event['calendar'] != $ev['calendar']) {
                     $this->rc->output->command('plugin.refresh_calendar', ['source' => null, 'refetch' => true]);
                     $reload = 0;
                 }
             }
 
             break;
 
         case "dismiss":
             $event['ids'] = explode(',', $event['id']);
             $plugin  = $this->rc->plugins->exec_hook('dismiss_alarms', $event);
             $success = $plugin['success'];
 
             foreach ($event['ids'] as $id) {
                 if (strpos($id, 'cal:') === 0) {
                     $success |= $this->driver->dismiss_alarm(substr($id, 4), $event['snooze']);
                 }
             }
 
             break;
 
         case "changelog":
             $data = $this->driver->get_event_changelog($event);
             if (is_array($data) && !empty($data)) {
                 $lib = $this->lib;
                 $dtformat = $this->rc->config->get('date_format') . ' ' . $this->rc->config->get('time_format');
                 array_walk($data, function(&$change) use ($lib, $dtformat) {
                     if (!empty($change['date'])) {
                         $dt = $lib->adjust_timezone($change['date']);
 
                         if ($dt instanceof DateTimeInterface) {
                             $change['date'] = $this->rc->format_date($dt, $dtformat, false);
                         }
                     }
                 });
 
                 $this->rc->output->command('plugin.render_event_changelog', $data);
             }
             else {
                 $this->rc->output->command('plugin.render_event_changelog', false);
             }
 
             $got_msg = true;
             $reload  = false;
 
             break;
 
         case "diff":
             $data = $this->driver->get_event_diff($event, $event['rev1'], $event['rev2']);
             if (is_array($data)) {
                 // convert some properties, similar to self::_client_event()
                 $lib = $this->lib;
                 array_walk($data['changes'], function(&$change, $i) use ($event, $lib) {
                     // convert date cols
                     foreach (['start', 'end', 'created', 'changed'] as $col) {
                         if ($change['property'] == $col) {
                             $change['old'] = $lib->adjust_timezone($change['old'], strlen($change['old']) == 10)->format('c');
                             $change['new'] = $lib->adjust_timezone($change['new'], strlen($change['new']) == 10)->format('c');
                         }
                     }
                     // create textual representation for alarms and recurrence
                     if ($change['property'] == 'alarms') {
                         if (is_array($change['old'])) {
                             $change['old_'] = libcalendaring::alarm_text($change['old']);
                         }
                         if (is_array($change['new'])) {
                             $change['new_'] = libcalendaring::alarm_text(array_merge((array)$change['old'], $change['new']));
                         }
                     }
                     if ($change['property'] == 'recurrence') {
                         if (is_array($change['old'])) {
                             $change['old_'] = $lib->recurrence_text($change['old']);
                         }
                         if (is_array($change['new'])) {
                             $change['new_'] = $lib->recurrence_text(array_merge((array)$change['old'], $change['new']));
                         }
                     }
                     if ($change['property'] == 'attachments') {
                         if (is_array($change['old'])) {
                             $change['old']['classname'] = rcube_utils::file2class($change['old']['mimetype'], $change['old']['name']);
                         }
                         if (is_array($change['new'])) {
                             $change['new']['classname'] = rcube_utils::file2class($change['new']['mimetype'], $change['new']['name']);
                         }
                     }
                     // compute a nice diff of description texts
                     if ($change['property'] == 'description') {
                         $change['diff_'] = libkolab::html_diff($change['old'], $change['new']);
                     }
                 });
 
                 $this->rc->output->command('plugin.event_show_diff', $data);
             }
             else {
                 $this->rc->output->command('display_message', $this->gettext('objectdiffnotavailable'), 'error');
             }
 
             $got_msg = true;
             $reload  = false;
 
             break;
 
         case "show":
             if ($event = $this->driver->get_event_revison($event, $event['rev'])) {
                 $this->rc->output->command('plugin.event_show_revision', $this->_client_event($event));
             }
             else {
                 $this->rc->output->command('display_message', $this->gettext('objectnotfound'), 'error');
             }
 
             $got_msg = true;
             $reload  = false;
             break;
 
         case "restore":
             if ($success = $this->driver->restore_event_revision($event, $event['rev'])) {
                 $_event = $this->driver->get_event($event);
                 $reload = $_event['recurrence'] ? 2 : 1;
                 $msg = $this->gettext(['name' => 'objectrestoresuccess', 'vars' => ['rev' => $event['rev']]]);
                 $this->rc->output->command('display_message', $msg, 'confirmation');
                 $this->rc->output->command('plugin.close_history_dialog');
             }
             else {
                 $this->rc->output->command('display_message', $this->gettext('objectrestoreerror'), 'error');
                 $reload = 0;
             }
 
             $got_msg = true;
             break;
         }
 
         // show confirmation/error message
         if (!$got_msg) {
             if ($success) {
                 $this->rc->output->show_message('successfullysaved', 'confirmation');
             }
             else {
                 $this->rc->output->show_message('calendar.errorsaving', 'error');
             }
         }
 
         // unlock client
         $this->rc->output->command('plugin.unlock_saving', $success);
 
         // update event object on the client or trigger a complete refresh if too complicated
         if ($reload && empty($_REQUEST['_framed'])) {
             $args = ['source' => $event['calendar']];
             if ($reload > 1) {
                 $args['refetch'] = true;
             }
             else if ($success && $action != 'remove') {
                 $args['update'] = $this->_client_event($this->driver->get_event($event), true);
             }
             $this->rc->output->command('plugin.refresh_calendar', $args);
         }
     }
 
     /**
      * Helper method sending iTip notifications after successful event updates
      */
     private function event_save_success(&$event, $old, $action, $success)
     {
         // $success is a new event ID
         if ($success !== true) {
             // send update notification on the main event
             if (!empty($event['_savemode']) && $event['_savemode'] == 'future' && !empty($event['_notify'])
                 && !empty($old['attendees']) && !empty($old['recurrence_id'])
             ) {
                 $master = $this->driver->get_event(['id' => $old['recurrence_id'], 'calendar' => $old['calendar']], 0, true);
                 unset($master['_instance'], $master['recurrence_date']);
 
                 $sent = $this->notify_attendees($master, null, $action, $event['_comment'], false);
                 if ($sent < 0) {
                     $this->rc->output->show_message('calendar.errornotifying', 'error');
                 }
 
                 $event['attendees'] = $master['attendees'];  // this tricks us into the next if clause
             }
 
             // delete old reference if saved as new
             if (!empty($event['_savemode']) && ($event['_savemode'] == 'future' || $event['_savemode'] == 'new')) {
                 $old = null;
             }
 
             $event['id']        = $success;
             $event['_savemode'] = 'all';
         }
 
         // send out notifications
         if (!empty($event['_notify']) && (!empty($event['attendees']) || !empty($old['attendees']))) {
             $_savemode = $event['_savemode'] ?? null;
 
             // send notification for the main event when savemode is 'all'
             if ($action != 'remove' && $_savemode == 'all'
                 && (!empty($event['recurrence_id']) || !empty($old['recurrence_id']) || ($old && $old['id'] != $event['id']))
             ) {
                 if (!empty($event['recurrence_id'])) {
                     $event['id'] = $event['recurrence_id'];
                 }
                 else if (!empty($old['recurrence_id'])) {
                     $event['id'] = $old['recurrence_id'];
                 }
                 else {
                     $event['id'] = $old['id'];
                 }
                 $event = $this->driver->get_event($event, 0, true);
                 unset($event['_instance'], $event['recurrence_date']);
             }
             else {
                 // make sure we have the complete record
                 $event = $action == 'remove' ? $old : $this->driver->get_event($event, 0, true);
             }
 
             $event['_savemode'] = $_savemode;
 
             if ($old) {
                 $old['thisandfuture'] = $_savemode == 'future';
             }
 
             // only notify if data really changed (TODO: do diff check on client already)
             if (!$old || $action == 'remove' || self::event_diff($event, $old)) {
                 $comment = isset($event['_comment']) ? $event['_comment'] : null;
                 $sent    = $this->notify_attendees($event, $old, $action, $comment);
 
                 if ($sent > 0) {
                     $this->rc->output->show_message('calendar.itipsendsuccess', 'confirmation');
                 }
                 else if ($sent < 0) {
                     $this->rc->output->show_message('calendar.errornotifying', 'error');
                 }
             }
         }
     }
 
     /**
      * Handler for load-requests from fullcalendar
      * This will return pure JSON formatted output
      */
     function load_events()
     {
         $start  = $this->input_timestamp('start', rcube_utils::INPUT_GET);
         $end    = $this->input_timestamp('end', rcube_utils::INPUT_GET);
         $query  = rcube_utils::get_input_value('q', rcube_utils::INPUT_GET);
         $source = rcube_utils::get_input_value('source', rcube_utils::INPUT_GET);
 
         $events = $this->driver->load_events($start, $end, $query, $source);
         echo $this->encode($events, !empty($query));
         exit;
     }
 
     /**
      * Handler for requests fetching event counts for calendars
      */
     public function count_events()
     {
         // don't update session on these requests (avoiding race conditions)
         $this->rc->session->nowrite = true;
 
         $start  = rcube_utils::get_input_value('start', rcube_utils::INPUT_GET);
         $source = rcube_utils::get_input_value('source', rcube_utils::INPUT_GET);
         $end    = rcube_utils::get_input_value('end', rcube_utils::INPUT_GET);
 
         if (!$start) {
             $start = new DateTime('today 00:00:00', $this->timezone);
             $start = $start->format('U');
         }
 
         $counts = $this->driver->count_events($source, $start, $end);
 
         $this->rc->output->command('plugin.update_counts', ['counts' => $counts]);
     }
 
     /**
      * Load event data from an iTip message attachment
      */
     public function itip_events($msgref)
     {
         $path = explode('/', $msgref);
         $msg  = array_pop($path);
         $mbox = join('/', $path);
         list($uid, $mime_id) = explode('#', $msg);
         $events = [];
 
         if ($event = $this->lib->mail_get_itip_object($mbox, $uid, $mime_id, 'event')) {
             $partstat = 'NEEDS-ACTION';
 
             $event['id']        = $event['uid'];
             $event['temporary'] = true;
             $event['readonly']  = true;
             $event['calendar']  = '--invitation--itip';
             $event['className'] = 'fc-invitation-' . strtolower($partstat);
             $event['_mbox']     = $mbox;
             $event['_uid']      = $uid;
             $event['_part']     = $mime_id;
 
             $events[] = $this->_client_event($event, true);
 
             // add recurring instances
             if (!empty($event['recurrence'])) {
                 // Some installations can't handle all occurrences (aborting the request w/o an error in log)
                 $freq = !empty($event['recurrence']['FREQ']) ? $event['recurrence']['FREQ'] : null;
                 $end  = clone $event['start'];
                 $end->add(new DateInterval($freq == 'DAILY' ? 'P1Y' : 'P10Y'));
 
                 foreach ($this->driver->get_recurring_events($event, $event['start'], $end) as $recurring) {
                     $recurring['temporary'] = true;
                     $recurring['readonly']  = true;
                     $recurring['calendar']  = '--invitation--itip';
 
                     $events[] = $this->_client_event($recurring, true);
                 }
             }
         }
 
         return $events;
     }
 
     /**
      * Handler for keep-alive requests
      * This will check for updated data in active calendars and sync them to the client
      */
     public function refresh($attr)
     {
         // refresh the entire calendar every 10th time to also sync deleted events
         if (rand(0, 10) == 10) {
             $this->rc->output->command('plugin.refresh_calendar', ['refetch' => true]);
             return;
         }
 
         $counts = [];
 
         foreach ($this->driver->list_calendars(calendar_driver::FILTER_ACTIVE) as $cal) {
             $events = $this->driver->load_events(
                 rcube_utils::get_input_value('start', rcube_utils::INPUT_GPC),
                 rcube_utils::get_input_value('end', rcube_utils::INPUT_GPC),
                 rcube_utils::get_input_value('q', rcube_utils::INPUT_GPC),
                 $cal['id'],
                 1,
                 $attr['last']
             );
 
             foreach ($events as $event) {
                 $this->rc->output->command(
                     'plugin.refresh_calendar',
                     ['source' => $cal['id'], 'update' => $this->_client_event($event)]
                 );
             }
 
             // refresh count for this calendar
             if (!empty($cal['counts'])) {
                 $today = new DateTime('today 00:00:00', $this->timezone);
                 $counts += $this->driver->count_events($cal['id'], $today->format('U'));
             }
         }
 
         if (!empty($counts)) {
             $this->rc->output->command('plugin.update_counts', ['counts' => $counts]);
         }
     }
 
     /**
      * Handler for pending_alarms plugin hook triggered by the calendar module on keep-alive requests.
      * This will check for pending notifications and pass them to the client
      */
     public function pending_alarms($p)
     {
         $this->load_driver();
 
         $time = !empty($p['time']) ? $p['time'] : time();
 
         if ($alarms = $this->driver->pending_alarms($time)) {
             foreach ($alarms as $alarm) {
                 $alarm['id'] = 'cal:' . $alarm['id'];  // prefix ID with cal:
                 $p['alarms'][] = $alarm;
             }
         }
 
         // get alarms for birthdays calendar
         if (
             $this->rc->config->get('calendar_contact_birthdays')
             && $this->rc->config->get('calendar_birthdays_alarm_type') == 'DISPLAY'
         ) {
             $cache = $this->rc->get_cache('calendar.birthdayalarms', 'db');
 
             foreach ($this->driver->load_birthday_events($time, $time + 86400 * 60) as $e) {
                 $alarm = libcalendaring::get_next_alarm($e);
 
                 // overwrite alarm time with snooze value (or null if dismissed)
                 if ($dismissed = $cache->get($e['id'])) {
                     $alarm['time'] = $dismissed['notifyat'];
                 }
 
                 // add to list if alarm is set
                 if ($alarm && !empty($alarm['time']) && $alarm['time'] <= $time) {
                     $e['id']       = 'cal:bday:' . $e['id'];
                     $e['notifyat'] = $alarm['time'];
                     $p['alarms'][] = $e;
                 }
             }
         }
 
         return $p;
     }
 
     /**
      * Handler for alarm dismiss hook triggered by libcalendaring
      */
     public function dismiss_alarms($p)
     {
         $this->load_driver();
 
         foreach ((array) $p['ids'] as $id) {
             if (strpos($id, 'cal:bday:') === 0) {
                 $p['success'] |= $this->driver->dismiss_birthday_alarm(substr($id, 9), $p['snooze']);
             }
             else if (strpos($id, 'cal:') === 0) {
                 $p['success'] |= $this->driver->dismiss_alarm(substr($id, 4), $p['snooze']);
             }
         }
 
         return $p;
     }
 
     /**
      * Handler for check-recent requests which are accidentally sent to calendar
      */
     function check_recent()
     {
         // NOP
         $this->rc->output->send();
     }
 
     /**
      * Hook triggered when a contact is saved
      */
     function contact_update($p)
     {
         // clear birthdays calendar cache
         if (!empty($p['record']['birthday'])) {
             $cache = $this->rc->get_cache('calendar.birthdays', 'db');
             $cache->remove();
         }
     }
 
     /**
      *
      */
     function import_events()
     {
         // Upload progress update
         if (!empty($_GET['_progress'])) {
             $this->rc->upload_progress();
         }
 
         @set_time_limit(0);
 
         // process uploaded file if there is no error
         $err = $_FILES['_data']['error'];
 
         if (!$err && !empty($_FILES['_data']['tmp_name'])) {
             $calendar   = rcube_utils::get_input_value('calendar', rcube_utils::INPUT_GPC);
             $rangestart = !empty($_REQUEST['_range']) ? date_create("now -" . intval($_REQUEST['_range']) . " months") : 0;
 
             // extract zip file
             if ($_FILES['_data']['type'] == 'application/zip') {
                 $count = 0;
                 if (class_exists('ZipArchive', false)) {
                     $zip = new ZipArchive();
                     if ($zip->open($_FILES['_data']['tmp_name'])) {
                         $randname = uniqid('zip-' . session_id(), true);
                         $tmpdir = slashify($this->rc->config->get('temp_dir', sys_get_temp_dir())) . $randname;
                         mkdir($tmpdir, 0700);
 
                         // extract each ical file from the archive and import it
                         for ($i = 0; $i < $zip->numFiles; $i++) {
                             $filename = $zip->getNameIndex($i);
                             if (preg_match('/\.ics$/i', $filename)) {
                                 $tmpfile = $tmpdir . '/' . basename($filename);
                                 if (copy('zip://' . $_FILES['_data']['tmp_name'] . '#'.$filename, $tmpfile)) {
                                     $count += $this->import_from_file($tmpfile, $calendar, $rangestart, $errors);
                                     unlink($tmpfile);
                                 }
                             }
                         }
 
                         rmdir($tmpdir);
                         $zip->close();
                     }
                     else {
                         $errors = 1;
                         $msg = 'Failed to open zip file.';
                     }
                 }
                 else {
                     $errors = 1;
                     $msg = 'Zip files are not supported for import.';
                 }
             }
             else {
                 // attempt to import teh uploaded file directly
                 $count = $this->import_from_file($_FILES['_data']['tmp_name'], $calendar, $rangestart, $errors);
             }
 
             if ($count) {
                 $this->rc->output->command('display_message', $this->gettext(['name' => 'importsuccess', 'vars' => ['nr' => $count]]), 'confirmation');
                 $this->rc->output->command('plugin.import_success', ['source' => $calendar, 'refetch' => true]);
             }
             else if (!$errors) {
                 $this->rc->output->command('display_message', $this->gettext('importnone'), 'notice');
                 $this->rc->output->command('plugin.import_success', ['source' => $calendar]);
             }
             else {
                 $this->rc->output->command('plugin.import_error', ['message' => $this->gettext('importerror') . ($msg ? ': ' . $msg : '')]);
             }
         }
         else {
             if ($err == UPLOAD_ERR_INI_SIZE || $err == UPLOAD_ERR_FORM_SIZE) {
                 $max = $this->rc->show_bytes(parse_bytes(ini_get('upload_max_filesize')));
                 $msg = $this->rc->gettext(['name' => 'filesizeerror', 'vars' => ['size' => $max]]);
             }
             else {
                 $msg = $this->rc->gettext('fileuploaderror');
             }
 
             $this->rc->output->command('plugin.import_error', ['message' => $msg]);
         }
 
         $this->rc->output->send('iframe');
     }
 
     /**
      * Helper function to parse and import a single .ics file
      */
     private function import_from_file($filepath, $calendar, $rangestart, &$errors)
     {
         $user_email = $this->rc->user->get_username();
         $ical       = $this->get_ical();
         $errors     = !$ical->fopen($filepath);
 
         $count = $i = 0;
 
         foreach ($ical as $event) {
             // keep the browser connection alive on long import jobs
             if (++$i > 100 && $i % 100 == 0) {
                 echo "<!-- -->";
                 ob_flush();
             }
 
             // TODO: correctly handle recurring events which start before $rangestart
             if ($rangestart && $event['end'] < $rangestart
                 && (empty($event['recurrence']) || (!empty($event['recurrence']['until']) && $event['recurrence']['until'] < $rangestart))
             ) {
                 continue;
             }
 
             $event['_owner']   = $user_email;
             $event['calendar'] = $calendar;
 
             if ($this->driver->new_event($event)) {
                 $count++;
             }
             else {
                 $errors++;
             }
         }
 
         return $count;
     }
 
     /**
      * Construct the ics file for exporting events to iCalendar format;
      */
     function export_events($terminate = true)
     {
         $start       = rcube_utils::get_input_value('start', rcube_utils::INPUT_GET);
         $end         = rcube_utils::get_input_value('end', rcube_utils::INPUT_GET);
         $event_id    = rcube_utils::get_input_value('id', rcube_utils::INPUT_GET);
         $attachments = rcube_utils::get_input_value('attachments', rcube_utils::INPUT_GET);
         $calid       = rcube_utils::get_input_value('source', rcube_utils::INPUT_GET);
 
         if (!isset($start)) {
             $start = 'today -1 year';
         }
         if (!is_numeric($start)) {
             $start = strtotime($start . ' 00:00:00');
         }
         if (!$end) {
             $end = 'today +10 years';
         }
         if (!is_numeric($end)) {
             $end = strtotime($end . ' 23:59:59');
         }
 
         $filename  = $calid;
         $calendars = $this->driver->list_calendars();
         $events    = [];
 
         if (!empty($calendars[$calid])) {
             $filename = !empty($calendars[$calid]['name']) ? $calendars[$calid]['name'] : $calid;
             $filename = asciiwords(html_entity_decode($filename));  // to 7bit ascii
 
             if (!empty($event_id)) {
                 if ($event = $this->driver->get_event(['calendar' => $calid, 'id' => $event_id], 0, true)) {
                     if (!empty($event['recurrence_id'])) {
                         $event = $this->driver->get_event(['calendar' => $calid, 'id' => $event['recurrence_id']], 0, true);
                     }
 
                     $events   = [$event];
                     $filename = asciiwords($event['title']);
 
                     if (empty($filename)) {
                         $filename = 'event';
                     }
                 }
             }
             else {
                 $events = $this->driver->load_events($start, $end, null, $calid, 0);
                 if (empty($filename)) {
                     $filename = $calid;
                 }
             }
         }
 
         header("Content-Type: text/calendar");
         header("Content-Disposition: inline; filename=".$filename.'.ics');
 
         $this->get_ical()->export($events, '', true, $attachments ? [$this->driver, 'get_attachment_body'] : null);
 
         if ($terminate) {
             exit;
         }
     }
 
     /**
      * Handler for iCal feed requests
      */
     function ical_feed_export()
     {
         $session_exists = !empty($_SESSION['user_id']);
 
         // process HTTP auth info
         if (!empty($_SERVER['PHP_AUTH_USER']) && isset($_SERVER['PHP_AUTH_PW'])) {
             $_POST['_user'] = $_SERVER['PHP_AUTH_USER']; // used for rcmail::autoselect_host()
             $auth = $this->rc->plugins->exec_hook('authenticate', [
                 'host' => $this->rc->autoselect_host(),
                 'user' => trim($_SERVER['PHP_AUTH_USER']),
                 'pass' => $_SERVER['PHP_AUTH_PW'],
                 'cookiecheck' => true,
                 'valid'       => true,
             ]);
 
             if ($auth['valid'] && !$auth['abort']) {
                 $this->rc->login($auth['user'], $auth['pass'], $auth['host']);
             }
         }
 
         // require HTTP auth
         if (empty($_SESSION['user_id'])) {
             header('WWW-Authenticate: Basic realm="Kolab Calendar"');
             header('HTTP/1.0 401 Unauthorized');
             exit;
         }
 
         // decode calendar feed hash
         $format  = 'ics';
         $calhash = rcube_utils::get_input_value('_cal', rcube_utils::INPUT_GET);
 
         if (preg_match(($suff_regex = '/\.([a-z0-9]{3,5})$/i'), $calhash, $m)) {
             $format  = strtolower($m[1]);
             $calhash = preg_replace($suff_regex, '', $calhash);
         }
 
         if (!strpos($calhash, ':')) {
             $calhash = base64_decode($calhash);
         }
 
         list($user, $_GET['source']) = explode(':', $calhash, 2);
 
         // sanity check user
         if ($this->rc->user->get_username() == $user) {
             $this->setup();
             $this->load_driver();
             $this->export_events(false);
         }
         else {
             header('HTTP/1.0 404 Not Found');
         }
 
         // don't save session data
         if (!$session_exists) {
             session_destroy();
         }
 
         exit;
     }
 
     /**
      *
      */
     function load_settings()
     {
         $this->lib->load_settings();
         $this->defaults += $this->lib->defaults;
 
         $settings = [];
 
         // configuration
         $settings['default_view']     = (string) $this->rc->config->get('calendar_default_view', $this->defaults['calendar_default_view']);
         $settings['timeslots']        = (int) $this->rc->config->get('calendar_timeslots', $this->defaults['calendar_timeslots']);
         $settings['first_day']        = (int) $this->rc->config->get('calendar_first_day', $this->defaults['calendar_first_day']);
         $settings['first_hour']       = (int) $this->rc->config->get('calendar_first_hour', $this->defaults['calendar_first_hour']);
         $settings['work_start']       = (int) $this->rc->config->get('calendar_work_start', $this->defaults['calendar_work_start']);
         $settings['work_end']         = (int) $this->rc->config->get('calendar_work_end', $this->defaults['calendar_work_end']);
         $settings['agenda_range']     = (int) $this->rc->config->get('calendar_agenda_range', $this->defaults['calendar_agenda_range']);
         $settings['event_coloring']   = (int) $this->rc->config->get('calendar_event_coloring', $this->defaults['calendar_event_coloring']);
         $settings['time_indicator']   = (int) $this->rc->config->get('calendar_time_indicator', $this->defaults['calendar_time_indicator']);
         $settings['invite_shared']    = (int) $this->rc->config->get('calendar_allow_invite_shared', $this->defaults['calendar_allow_invite_shared']);
         $settings['itip_notify']      = (int) $this->rc->config->get('calendar_itip_send_option', $this->defaults['calendar_itip_send_option']);
         $settings['show_weekno']      = (int) $this->rc->config->get('calendar_show_weekno', $this->defaults['calendar_show_weekno']);
         $settings['default_calendar'] = $this->rc->config->get('calendar_default_calendar');
         $settings['invitation_calendars'] = (bool) $this->rc->config->get('kolab_invitation_calendars', false);
 
         // 'table' view has been replaced by 'list' view
         if ($settings['default_view'] == 'table') {
             $settings['default_view'] = 'list';
         }
 
         // get user identity to create default attendee
         if ($this->ui->screen == 'calendar') {
             foreach ($this->rc->user->list_emails() as $rec) {
                 if (empty($identity)) {
                     $identity = $rec;
                 }
 
                 $identity['emails'][] = $rec['email'];
                 $settings['identities'][$rec['identity_id']] = $rec['email'];
             }
 
             $identity['emails'][] = $this->rc->user->get_username();
             $identity['ownedResources'] = $this->owned_resources_emails();
             $settings['identity'] = [
                 'name'   => $identity['name'],
                 'email'  => strtolower($identity['email']),
                 'emails' => ';' . strtolower(join(';', $identity['emails'])),
                 'ownedResources' => ';' . strtolower(join(';', $identity['ownedResources']))
             ];
         }
 
         // freebusy token authentication URL
         if (($url = $this->rc->config->get('calendar_freebusy_session_auth_url'))
             && ($uniqueid = $this->rc->config->get('kolab_uniqueid'))
         ) {
             if ($url === true) {
                 $url = '/freebusy';
             }
             $url = rtrim(rcube_utils::resolve_url($url), '/ ');
             $url .= '/' . urlencode($this->rc->get_user_name());
             $url .= '/' . urlencode($uniqueid);
 
             $settings['freebusy_url'] = $url;
         }
 
         return $settings;
     }
 
     /**
      * Encode events as JSON
      *
      * @param array Events as array
      * @param bool  Add CSS class names according to calendar and categories
      *
      * @return string JSON encoded events
      */
     function encode($events, $addcss = false)
     {
         $json = [];
         foreach ($events as $event) {
             $json[] = $this->_client_event($event, $addcss);
         }
         return rcube_output::json_serialize($json);
     }
 
     /**
      * Convert an event object to be used on the client
      */
     private function _client_event($event, $addcss = false)
     {
         // compose a human readable strings for alarms_text and recurrence_text
         if (!empty($event['valarms'])) {
             $event['alarms_text'] = libcalendaring::alarms_text($event['valarms']);
             $event['valarms'] = libcalendaring::to_client_alarms($event['valarms']);
         }
 
         if (!empty($event['recurrence'])) {
             $event['recurrence_text'] = $this->lib->recurrence_text($event['recurrence']);
             $event['recurrence'] = $this->lib->to_client_recurrence($event['recurrence'], $event['allday']);
             unset($event['recurrence_date']);
         }
 
         if (!empty($event['attachments'])) {
             foreach ($event['attachments'] as $k => $attachment) {
                 $event['attachments'][$k]['classname'] = rcube_utils::file2class($attachment['mimetype'], $attachment['name']);
 
                 unset($event['attachments'][$k]['data'], $event['attachments'][$k]['content']);
 
                 if (empty($attachment['id'])) {
                     $event['attachments'][$k]['id'] = $k;
                 }
             }
         }
 
         // convert link URIs references into structs
         if (array_key_exists('links', $event)) {
             foreach ((array) $event['links'] as $i => $link) {
                 if (strpos($link, 'imap://') === 0 && ($msgref = $this->driver->get_message_reference($link))) {
                     $event['links'][$i] = $msgref;
                 }
             }
         }
 
         // check for organizer in attendees list
         $organizer = null;
         foreach ((array) $event['attendees'] as $i => $attendee) {
             if ($attendee['role'] == 'ORGANIZER') {
                 $organizer = $attendee;
             }
             if (!empty($attendee['status']) && $attendee['status'] == 'DELEGATED' && empty($attendee['rsvp'])) {
                 $event['attendees'][$i]['noreply'] = true;
             }
             else {
                 unset($event['attendees'][$i]['noreply']);
             }
         }
 
         if ($organizer === null && !empty($event['organizer'])) {
             $organizer = $event['organizer'];
             $organizer['role'] = 'ORGANIZER';
             if (!is_array($event['attendees'])) {
                 $event['attendees'] = [$organizer];
             }
         }
 
         // Convert HTML description into plain text
         if ($this->is_html($event)) {
             $h2t = new rcube_html2text($event['description'], false, true, 0);
             $event['description'] = trim($h2t->get_text());
         }
 
         // mapping url => vurl, allday => allDay because of the fullcalendar client script
         $event['vurl']   = $event['url'] ?? null;
         $event['allDay'] = !empty($event['allday']);
         unset($event['url']);
         unset($event['allday']);
 
         $event['className'] = !empty($event['className']) ? explode(' ', $event['className']) : [];
 
         if ($event['allDay']) {
             $event['end'] = $event['end']->add(new DateInterval('P1D'));
         }
 
         if (!empty($_GET['mode']) && $_GET['mode'] == 'print') {
             $event['editable'] = false;
         }
 
         return [
             '_id'     => $event['calendar'] . ':' . $event['id'],  // unique identifier for fullcalendar
             'start'   => $this->lib->adjust_timezone($event['start'], $event['allDay'])->format('c'),
             'end'     => $this->lib->adjust_timezone($event['end'], $event['allDay'])->format('c'),
             // 'changed' might be empty for event recurrences (Bug #2185)
             'changed' => !empty($event['changed']) ? $this->lib->adjust_timezone($event['changed'])->format('c') : null,
             'created' => !empty($event['created']) ? $this->lib->adjust_timezone($event['created'])->format('c') : null,
             'title'       => strval($event['title'] ?? null),
             'description' => strval($event['description'] ?? null),
             'location'    => strval($event['location'] ?? null),
         ] + $event;
     }
 
     /**
      * Generate a unique identifier for an event
      */
     public function generate_uid()
     {
         return strtoupper(md5(time() . uniqid(rand())) . '-' . substr(md5($this->rc->user->get_username()), 0, 16));
     }
 
     /**
      * TEMPORARY: generate random event data for testing
      * Create events by opening http://<roundcubeurl>/?_task=calendar&_action=randomdata&_num=500&_date=2014-08-01&_dev=120
      */
     public function generate_randomdata()
     {
         @set_time_limit(0);
 
         $num   = !empty($_REQUEST['_num']) ? intval($_REQUEST['_num']) : 100;
         $date  = !empty($_REQUEST['_date']) ? $_REQUEST['_date'] : 'now';
         $dev   = !empty($_REQUEST['_dev']) ? $_REQUEST['_dev'] : 30;
         $cats  = array_keys($this->driver->list_categories());
         $cals  = $this->driver->list_calendars(calendar_driver::FILTER_ACTIVE);
         $count = 0;
 
         while ($count++ < $num) {
             $spread   = intval($dev) * 86400; // days
             $refdate  = strtotime($date);
             $start    = round(($refdate + rand(-$spread, $spread)) / 600) * 600;
             $duration = round(rand(30, 360) / 30) * 30 * 60;
             $allday   = rand(0,20) > 18;
             $alarm    = rand(-30,12) * 5;
             $fb       = rand(0,2);
 
             if (date('G', $start) > 23) {
                 $start -= 3600;
             }
 
             if ($allday) {
                 $start    = strtotime(date('Y-m-d 00:00:00', $start));
                 $duration = 86399;
             }
 
             $title = '';
             $len = rand(2, 12);
             $words = explode(" ", "The Hough transform is named after Paul Hough who patented the method in 1962."
                 . " It is a technique which can be used to isolate features of a particular shape within an image."
                 . " Because it requires that the desired features be specified in some parametric form, the classical"
                 . " Hough transform is most commonly used for the de- tection of regular curves such as lines, circles,"
                 . " ellipses, etc. A generalized Hough transform can be employed in applications where a simple"
                 . " analytic description of a feature(s) is not possible. Due to the computational complexity of"
                 . " the generalized Hough algorithm, we restrict the main focus of this discussion to the classical"
                 . " Hough transform. Despite its domain restrictions, the classical Hough transform (hereafter"
                 . " referred to without the classical prefix ) retains many applications, as most manufac- tured"
                 . " parts (and many anatomical parts investigated in medical imagery) contain feature boundaries"
                 . " which can be described by regular curves. The main advantage of the Hough transform technique"
                 . " is that it is tolerant of gaps in feature boundary descriptions and is relatively unaffected"
                 . " by image noise.");
             // $chars = "!# abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ 1234567890";
             for ($i = 0; $i < $len; $i++) {
                 $title .= $words[rand(0,count($words)-1)] . " ";
             }
 
             $this->driver->new_event([
                 'uid'        => $this->generate_uid(),
                 'start'      => new DateTime('@'.$start),
                 'end'        => new DateTime('@'.($start + $duration)),
                 'allday'     => $allday,
                 'title'      => rtrim($title),
                 'free_busy'  => $fb == 2 ? 'outofoffice' : ($fb ? 'busy' : 'free'),
                 'categories' => $cats[array_rand($cats)],
                 'calendar'   => array_rand($cals),
                 'alarms'     => $alarm > 0 ? "-{$alarm}M:DISPLAY" : '',
                 'priority'   => rand(0,9),
             ]);
         }
 
         $this->rc->output->redirect('');
     }
 
     /**
      * Handler for attachments upload
      */
     public function attachment_upload()
     {
         $handler = new kolab_attachments_handler();
         $handler->attachment_upload(self::SESSION_KEY, 'cal-');
     }
 
     /**
      * Handler for attachments download/displaying
      */
     public function attachment_get()
     {
         $handler = new kolab_attachments_handler();
 
         // show loading page
         if (!empty($_GET['_preload'])) {
             return $handler->attachment_loading_page();
         }
 
         $event_id = rcube_utils::get_input_value('_event', rcube_utils::INPUT_GPC);
         $calendar = rcube_utils::get_input_value('_cal', rcube_utils::INPUT_GPC);
         $id       = rcube_utils::get_input_value('_id', rcube_utils::INPUT_GPC);
         $rev      = rcube_utils::get_input_value('_rev', rcube_utils::INPUT_GPC);
 
         $event = ['id' => $event_id, 'calendar' => $calendar, 'rev' => $rev];
 
         if ($calendar == '--invitation--itip') {
             $uid  = rcube_utils::get_input_value('_uid', rcube_utils::INPUT_GPC);
             $part = rcube_utils::get_input_value('_part', rcube_utils::INPUT_GPC);
             $mbox = rcube_utils::get_input_value('_mbox', rcube_utils::INPUT_GPC);
 
             $event      = $this->lib->mail_get_itip_object($mbox, $uid, $part, 'event');
             $attachment = $event['attachments'][$id];
             $attachment['body'] = &$attachment['data'];
         }
         else {
             $attachment = $this->driver->get_attachment($id, $event);
         }
 
         // show part page
         if (!empty($_GET['_frame'])) {
             $handler->attachment_page($attachment);
         }
         // deliver attachment content
         else if ($attachment) {
             if ($calendar != '--invitation--itip') {
                 $attachment['body'] = $this->driver->get_attachment_body($id, $event);
             }
 
             $handler->attachment_get($attachment);
         }
 
         // if we arrive here, the requested part was not found
         header('HTTP/1.1 404 Not Found');
         exit;
     }
 
     /**
      * Determine whether the given event description is HTML formatted
      */
     private function is_html($event)
     {
           // check for opening and closing <html> or <body> tags
         return !empty($event['description'])
             && preg_match('/<(html|body)(\s+[a-z]|>)/', $event['description'], $m)
             && strpos($event['description'], '</'.$m[1].'>') > 0;
     }
 
     /**
      * Prepares new/edited event properties before save
      */
     private function write_preprocess(&$event, $action)
     {
         // Remove double timezone specification (T2313)
         $event['start'] = preg_replace('/\s*\(.*\)/', '', $event['start']);
         $event['end']   = preg_replace('/\s*\(.*\)/', '', $event['end']);
 
         // convert dates into DateTime objects in user's current timezone
         $event['start']  = new DateTime($event['start'], $this->timezone);
         $event['end']    = new DateTime($event['end'], $this->timezone);
         $event['allday'] = !empty($event['allDay']);
         unset($event['allDay']);
 
         // start/end is all we need for 'move' action (#1480)
         if ($action == 'move') {
             return true;
         }
 
         // convert the submitted recurrence settings
         if (!empty($event['recurrence'])) {
             $event['recurrence'] = $this->lib->from_client_recurrence($event['recurrence'], $event['start']);
 
             // align start date with the first occurrence
             if (!empty($event['recurrence']) && !empty($event['syncstart'])
                 && (empty($event['_savemode']) || $event['_savemode'] == 'all')
             ) {
                 $next = $this->find_first_occurrence($event);
 
                 if (!$next) {
                     $this->rc->output->show_message('calendar.recurrenceerror', 'error');
                     return false;
                 }
                 else if ($event['start'] != $next) {
                     $diff = $event['start']->diff($event['end'], true);
 
                     $event['start'] = $next;
                     $event['end']   = clone $next;
                     $event['end']->add($diff);
                 }
             }
         }
 
         // convert the submitted alarm values
         if (!empty($event['valarms'])) {
             $event['valarms'] = libcalendaring::from_client_alarms($event['valarms']);
         }
 
         $eventid = 'cal-' . (!empty($event['id']) ? $event['id'] : 'new');
         $handler = new kolab_attachments_handler();
         $event['attachments'] = $handler->attachments_set(self::SESSION_KEY, $eventid, $event['attachments'] ?? []);
 
         // convert link references into simple URIs
         if (array_key_exists('links', $event)) {
             $event['links'] = array_map(function($link) {
                     return is_array($link) ? $link['uri'] : strval($link);
                 },
                 (array) $event['links']
             );
         }
 
         // check for organizer in attendees
         if ($action == 'new' || $action == 'edit') {
             if (empty($event['attendees'])) {
                 $event['attendees'] = [];
             }
 
             $emails = $this->get_user_emails();
             $organizer = $owner = false;
 
             foreach ((array) $event['attendees'] as $i => $attendee) {
                 if ($attendee['role'] == 'ORGANIZER') {
                     $organizer = $i;
                 }
                 if (!empty($attendee['email']) && in_array(strtolower($attendee['email']), $emails)) {
                     $owner = $i;
                 }
                 if (!isset($attendee['rsvp'])) {
                     $event['attendees'][$i]['rsvp'] = true;
                 }
                 else if (is_string($attendee['rsvp'])) {
                     $event['attendees'][$i]['rsvp'] = $attendee['rsvp'] == 'true' || $attendee['rsvp'] == '1';
                 }
             }
 
             if (!empty($event['_identity'])) {
                 $identity = $this->rc->user->get_identity($event['_identity']);
             }
 
             // set new organizer identity
             if ($organizer !== false && !empty($identity)) {
                 $event['attendees'][$organizer]['name']  = $identity['name'];
                 $event['attendees'][$organizer]['email'] = $identity['email'];
             }
             // set owner as organizer if yet missing
             else if ($organizer === false && $owner !== false) {
                 $event['attendees'][$owner]['role'] = 'ORGANIZER';
                 unset($event['attendees'][$owner]['rsvp']);
             }
             // fallback to the selected identity
             else if ($organizer === false && !empty($identity)) {
                 $event['attendees'][] = [
                     'role'  => 'ORGANIZER',
                     'name'  => $identity['name'],
                     'email' => $identity['email'],
                 ];
             }
         }
 
         // mapping url => vurl because of the fullcalendar client script
         if (array_key_exists('vurl', $event)) {
             $event['url'] = $event['vurl'];
             unset($event['vurl']);
         }
 
         return true;
     }
 
     /**
      * Releases some resources after successful event save
      */
     private function cleanup_event(&$event)
     {
         $handler = new kolab_attachments_handler();
         $handler->attachments_cleanup(self::SESSION_KEY);
     }
 
     /**
      * Send out an invitation/notification to all event attendees
      */
     private function notify_attendees($event, $old, $action = 'edit', $comment = null, $rsvp = null)
     {
         $is_cancelled = $action == 'remove'
             || (!empty($event['status']) && $event['status'] == 'CANCELLED' && ($old['status'] ?? '') != $event['status']);
 
         $event['cancelled'] = $is_cancelled;
 
         if ($rsvp === null) {
             $rsvp = !$old || ($event['sequence'] ?? 0) > ($old['sequence'] ?? 0);
         }
 
         $itip        = $this->load_itip();
         $emails      = $this->get_user_emails();
         $itip_notify = (int) $this->rc->config->get('calendar_itip_send_option', $this->defaults['calendar_itip_send_option']);
 
         // add comment to the iTip attachment
         $event['comment'] = $comment;
 
         // set a valid recurrence-id if this is a recurrence instance
         libcalendaring::identify_recurrence_instance($event);
 
         // compose multipart message using PEAR:Mail_Mime
         $method  = $action == 'remove' ? 'CANCEL' : 'REQUEST';
         $message = $itip->compose_itip_message($event, $method, $rsvp);
 
         // list existing attendees from $old event
         $old_attendees = [];
         if (!empty($old['attendees'])) {
             foreach ((array) $old['attendees'] as $attendee) {
                 $old_attendees[] = $attendee['email'];
             }
         }
 
         // send to every attendee
         $sent    = 0;
         $current = [];
         foreach ((array) $event['attendees'] as $attendee) {
             // skip myself for obvious reasons
             if (empty($attendee['email']) || in_array(strtolower($attendee['email']), $emails)) {
                 continue;
             }
 
             $current[] = strtolower($attendee['email']);
 
             // skip if notification is disabled for this attendee
             if (!empty($attendee['noreply']) && $itip_notify & 2) {
                 continue;
             }
 
             // skip if this attendee has delegated and set RSVP=FALSE
             if ($attendee['status'] == 'DELEGATED' && $attendee['rsvp'] === false) {
                 continue;
             }
 
             // which template to use for mail text
             $is_new   = !in_array($attendee['email'], $old_attendees);
             $is_rsvp  = $is_new || $event['sequence'] > $old['sequence'];
             $bodytext = $is_cancelled ? 'eventcancelmailbody' : ($is_new ? 'invitationmailbody' : 'eventupdatemailbody');
             $subject  = $is_cancelled ? 'eventcancelsubject'  : ($is_new ? 'invitationsubject' : ($event['title'] ? 'eventupdatesubject' : 'eventupdatesubjectempty'));
 
             $event['comment'] = $comment;
 
             // finally send the message
             if ($itip->send_itip_message($event, $method, $attendee, $subject, $bodytext, $message, $is_rsvp)) {
                 $sent++;
             }
             else {
                 $sent = -100;
             }
         }
 
         // TODO: on change of a recurring (main) event, also send updates to differing attendess of recurrence exceptions
 
         // send CANCEL message to removed attendees
         if (!empty($old['attendees'])) {
             foreach ($old['attendees'] as $attendee) {
                 if ($attendee['role'] == 'ORGANIZER'
                     || empty($attendee['email'])
                     || in_array(strtolower($attendee['email']), $current)
                 ) {
                     continue;
                 }
 
                 $vevent = $old;
                 $vevent['cancelled'] = $is_cancelled;
                 $vevent['attendees'] = [$attendee];
                 $vevent['comment']   = $comment;
 
                 if ($itip->send_itip_message($vevent, 'CANCEL', $attendee, 'eventcancelsubject', 'eventcancelmailbody')) {
                     $sent++;
                 }
                 else {
                     $sent = -100;
                 }
             }
         }
 
         return $sent;
     }
 
     /**
      * Echo simple free/busy status text for the given user and time range
      */
     public function freebusy_status()
     {
         $email = rcube_utils::get_input_value('email', rcube_utils::INPUT_GPC);
         $start = $this->input_timestamp('start', rcube_utils::INPUT_GPC);
         $end   = $this->input_timestamp('end', rcube_utils::INPUT_GPC);
 
         if (!$start) $start = time();
         if (!$end) $end = $start + 3600;
 
         $status = 'UNKNOWN';
         $fbtypemap = [
             calendar::FREEBUSY_UNKNOWN   => 'UNKNOWN',
             calendar::FREEBUSY_FREE      => 'FREE',
             calendar::FREEBUSY_BUSY      => 'BUSY',
             calendar::FREEBUSY_TENTATIVE => 'TENTATIVE',
             calendar::FREEBUSY_OOF       => 'OUT-OF-OFFICE'
         ];
 
         // if the backend has free-busy information
         $fblist = $this->driver->get_freebusy_list($email, $start, $end);
 
         if (is_array($fblist)) {
             $status = 'FREE';
 
             foreach ($fblist as $slot) {
                 list($from, $to, $type) = $slot;
                 if ($from < $end && $to > $start) {
                     $status = isset($type) && !empty($fbtypemap[$type]) ? $fbtypemap[$type] : 'BUSY';
                     break;
                 }
             }
         }
 
         // let this information be cached for 5min
         $this->rc->output->future_expire_header(300);
 
         echo $status;
         exit;
     }
 
     /**
      * Return a list of free/busy time slots within the given period
      * Echo data in JSON encoding
      */
     public function freebusy_times()
     {
         $email = rcube_utils::get_input_value('email', rcube_utils::INPUT_GPC);
         $start = $this->input_timestamp('start', rcube_utils::INPUT_GPC);
         $end   = $this->input_timestamp('end', rcube_utils::INPUT_GPC);
         $interval  = intval(rcube_utils::get_input_value('interval', rcube_utils::INPUT_GPC));
         $strformat = $interval > 60 ? 'Ymd' : 'YmdHis';
 
         if (!$start) $start = time();
         if (!$end)   $end = $start + 86400 * 30;
         if (!$interval) $interval = 60;  // 1 hour
 
-        if (!$dte) {
-            $dts = new DateTime('@'.$start);
-            $dts->setTimezone($this->timezone);
-        }
-
         $fblist = $this->driver->get_freebusy_list($email, $start, $end);
         $slots  = '';
 
         // prepare freebusy list before use (for better performance)
         if (is_array($fblist)) {
             foreach ($fblist as $idx => $slot) {
                 list($from, $to, ) = $slot;
 
                 // check for possible all-day times
                 if (gmdate('His', $from) == '000000' && gmdate('His', $to) == '235959') {
                     // shift into the user's timezone for sane matching
                     $fblist[$idx][0] -= $this->gmt_offset;
                     $fblist[$idx][1] -= $this->gmt_offset;
                 }
             }
         }
 
         // build a list from $start till $end with blocks representing the fb-status
         for ($s = 0, $t = $start; $t <= $end; $s++) {
             $t_end = $t + $interval * 60;
             $dt = new DateTime('@'.$t);
             $dt->setTimezone($this->timezone);
 
             // determine attendee's status
             if (is_array($fblist)) {
                 $status = self::FREEBUSY_FREE;
 
                 foreach ($fblist as $slot) {
                     list($from, $to, $type) = $slot;
 
                     if ($from < $t_end && $to > $t) {
                         $status = isset($type) ? $type : self::FREEBUSY_BUSY;
                         if ($status == self::FREEBUSY_BUSY) {
                             // can't get any worse :-)
                             break;
                         }
                     }
                 }
             }
             else {
                 $status = self::FREEBUSY_UNKNOWN;
             }
 
             // use most compact format, assume $status is one digit/character
             $slots .= $status;
             $t = $t_end;
         }
 
-        $dte = new DateTime('@'.$t_end);
+        $dts = new DateTime('@' . $start);
+        $dts->setTimezone($this->timezone);
+        $dte = new DateTime('@' . $t_end);
         $dte->setTimezone($this->timezone);
 
         // let this information be cached for 5min
         $this->rc->output->future_expire_header(300);
 
         echo rcube_output::json_serialize([
             'email' => $email,
             'start' => $dts->format('c'),
             'end'   => $dte->format('c'),
             'interval' => $interval,
             'slots' => $slots,
         ]);
         exit;
     }
 
     /**
      * Handler for printing calendars
      */
     public function print_view()
     {
         $title = $this->gettext('print');
 
         $view = rcube_utils::get_input_value('view', rcube_utils::INPUT_GPC);
         if (!in_array($view, ['agendaWeek', 'agendaDay', 'month', 'list'])) {
             $view = 'agendaDay';
         }
 
         $this->rc->output->set_env('view', $view);
 
         if ($date = rcube_utils::get_input_value('date', rcube_utils::INPUT_GPC)) {
             $this->rc->output->set_env('date', $date);
         }
 
         if ($range = rcube_utils::get_input_value('range', rcube_utils::INPUT_GPC)) {
             $this->rc->output->set_env('listRange', intval($range));
         }
 
         if ($search = rcube_utils::get_input_value('search', rcube_utils::INPUT_GPC)) {
             $this->rc->output->set_env('search', $search);
             $title .= ' "' . $search . '"';
         }
 
         // Add JS to the page
         $this->ui->addJS();
 
         $this->register_handler('plugin.calendar_css', [$this->ui, 'calendar_css']);
         $this->register_handler('plugin.calendar_list', [$this->ui, 'calendar_list']);
 
         $this->rc->output->set_pagetitle($title);
         $this->rc->output->send('calendar.print');
     }
 
     /**
      * Compare two event objects and return differing properties
      *
      * @param array Event A
      * @param array Event B
      *
      * @return array List of differing event properties
      */
     public static function event_diff($a, $b)
     {
         $diff   = [];
         $ignore = ['changed' => 1, 'attachments' => 1];
 
         foreach (array_unique(array_merge(array_keys($a), array_keys($b))) as $key) {
             if (empty($ignore[$key]) && $key[0] != '_') {
                 $av = isset($a[$key]) ? $a[$key] : null;
                 $bv = isset($b[$key]) ? $b[$key] : null;
 
                 if ($av != $bv) {
                     $diff[] = $key;
                 }
             }
         }
 
         // only compare number of attachments
         $ac = !empty($a['attachments']) ? count($a['attachments']) : 0;
         $bc = !empty($b['attachments']) ? count($b['attachments']) : 0;
 
         if ($ac != $bc) {
             $diff[] = 'attachments';
         }
 
         return $diff;
     }
 
     /**
      * Update attendee properties on the given event object
      *
      * @param array The event object to be altered
      * @param array List of hash arrays each represeting an updated/added attendee
      */
     public static function merge_attendee_data(&$event, $attendees, $removed = null)
     {
         if (!empty($attendees) && !is_array($attendees[0])) {
             $attendees = [$attendees];
         }
 
         foreach ($attendees as $attendee) {
             $found = false;
 
             foreach ($event['attendees'] as $i => $candidate) {
                 if ($candidate['email'] == $attendee['email']) {
                     $event['attendees'][$i] = $attendee;
                     $found = true;
                     break;
                 }
             }
 
             if (!$found) {
                 $event['attendees'][] = $attendee;
             }
         }
 
         // filter out removed attendees
         if (!empty($removed)) {
             $event['attendees'] = array_filter($event['attendees'], function($attendee) use ($removed) {
                 return !in_array($attendee['email'], $removed);
             });
         }
     }
 
     /****  Resource management functions  ****/
 
     /**
      * Getter for the configured implementation of the resource directory interface
      */
     private function resources_directory()
     {
         if (!empty($this->resources_dir)) {
             return $this->resources_dir;
         }
 
         if ($driver_name = $this->rc->config->get('calendar_resources_driver')) {
             $driver_class = 'resources_driver_' . $driver_name;
 
             require_once $this->home . '/drivers/resources_driver.php';
             require_once $this->home . '/drivers/' . $driver_name . '/' . $driver_class . '.php';
 
             $this->resources_dir = new $driver_class($this);
         }
 
         return $this->resources_dir;
     }
 
     /**
      * Handler for resoruce autocompletion requests
      */
     public function resources_autocomplete()
     {
         $search  = rcube_utils::get_input_value('_search', rcube_utils::INPUT_GPC, true);
         $sid     = rcube_utils::get_input_value('_reqid', rcube_utils::INPUT_GPC);
         $maxnum  = (int)$this->rc->config->get('autocomplete_max', 15);
         $results = [];
 
         if ($directory = $this->resources_directory()) {
             foreach ($directory->load_resources($search, $maxnum) as $rec) {
                 $results[]  = [
                     'name'  => $rec['name'],
                     'email' => $rec['email'],
                     'type'  => $rec['_type'],
                 ];
             }
         }
 
         $this->rc->output->command('ksearch_query_results', $results, $search, $sid);
         $this->rc->output->send();
     }
 
     /**
      * Handler for load-requests for resource data
      */
     function resources_list()
     {
         $data = [];
 
         if ($directory = $this->resources_directory()) {
             foreach ($directory->load_resources() as $rec) {
                 $data[] = $rec;
             }
         }
 
         $this->rc->output->command('plugin.resource_data', $data);
         $this->rc->output->send();
     }
 
     /**
      * Handler for requests loading resource owner information
      */
     function resources_owner()
     {
         if ($directory = $this->resources_directory()) {
             $id   = rcube_utils::get_input_value('_id', rcube_utils::INPUT_GPC);
             $data = $directory->get_resource_owner($id);
         }
 
         $this->rc->output->command('plugin.resource_owner', $data);
         $this->rc->output->send();
     }
 
     /**
      * Deliver event data for a resource's calendar
      */
     function resources_calendar()
     {
         $events = [];
 
         if ($directory = $this->resources_directory()) {
             $id    = rcube_utils::get_input_value('_id', rcube_utils::INPUT_GPC);
             $start = $this->input_timestamp('start', rcube_utils::INPUT_GET);
             $end   = $this->input_timestamp('end', rcube_utils::INPUT_GET);
 
             $events = $directory->get_resource_calendar($id, $start, $end);
         }
 
         echo $this->encode($events);
         exit;
     }
 
     /**
      * List email addressed of owned resources
      */
     private function owned_resources_emails()
     {
         $results = [];
         if ($directory = $this->resources_directory()) {
             foreach ($directory->load_resources($_SESSION['kolab_dn'], 5000, 'owner') as $rec) {
                 $results[] = $rec['email'];
             }
         }
         return $results;
     }
 
 
     /****  Event invitation plugin hooks ****/
 
     /**
      * Find an event in user calendars
      */
     protected function find_event($event, &$mode)
     {
         $this->load_driver();
 
         // We search for writeable calendars in personal namespace by default
         $mode   = calendar_driver::FILTER_WRITEABLE | calendar_driver::FILTER_PERSONAL;
         $result = $this->driver->get_event($event, $mode);
         // ... now check shared folders if not found
         if (!$result) {
             $result = $this->driver->get_event($event, calendar_driver::FILTER_WRITEABLE | calendar_driver::FILTER_SHARED);
             if ($result) {
                 $mode |= calendar_driver::FILTER_SHARED;
             }
         }
 
         return $result;
     }
 
     /**
      * Handler for calendar/itip-status requests
      */
     function event_itip_status()
     {
         $data = rcube_utils::get_input_value('data', rcube_utils::INPUT_POST, true);
 
         $this->load_driver();
 
         // find local copy of the referenced event (in personal namespace)
         $existing  = $this->find_event($data, $mode);
         $is_shared = $mode & calendar_driver::FILTER_SHARED;
         $itip      = $this->load_itip();
         $response  = $itip->get_itip_status($data, $existing);
 
         // get a list of writeable calendars to save new events to
         if (
             (!$existing || $is_shared)
             && empty($data['nosave'])
             && ($response['action'] == 'rsvp' || $response['action'] == 'import')
         ) {
             $calendars       = $this->driver->list_calendars($mode);
             $calendar_select = new html_select([
                 'name'       => 'calendar',
                 'id'         => 'itip-saveto',
                 'is_escaped' => true,
                 'class'      => 'form-control custom-select'
             ]);
 
             $calendar_select->add('--', '');
             $numcals = 0;
             foreach ($calendars as $calendar) {
                 if (!empty($calendar['editable'])) {
                     $calendar_select->add($calendar['name'], $calendar['id']);
                     $numcals++;
                 }
             }
             if ($numcals < 1) {
                 $calendar_select = null;
             }
         }
 
         if (!empty($calendar_select)) {
             $default_calendar   = $this->get_default_calendar($calendars);
             $response['select'] = html::span('folder-select', $this->gettext('saveincalendar')
                 . '&nbsp;'
                 . $calendar_select->show($is_shared ? $existing['calendar'] : $default_calendar['id'])
             );
         }
         else if (!empty($data['nosave'])) {
             $response['select'] = html::tag('input', ['type' => 'hidden', 'name' => 'calendar', 'id' => 'itip-saveto', 'value' => '']);
         }
 
         // render small agenda view for the respective day
         if ($data['method'] == 'REQUEST' && !empty($data['date']) && $response['action'] == 'rsvp') {
             $event_start = rcube_utils::anytodatetime($data['date']);
             $day_start   = new Datetime(gmdate('Y-m-d 00:00', $data['date']), $this->lib->timezone);
             $day_end     = new Datetime(gmdate('Y-m-d 23:59', $data['date']), $this->lib->timezone);
 
             // get events on that day from the user's personal calendars
             $calendars = $this->driver->list_calendars(calendar_driver::FILTER_PERSONAL);
             $events    = $this->driver->load_events($day_start->format('U'), $day_end->format('U'), null, array_keys($calendars));
 
             usort($events, function($a, $b) { return $a['start'] > $b['start'] ? 1 : -1; });
 
             $before = $after = [];
             foreach ($events as $event) {
                 // TODO: skip events with free_busy == 'free' ?
                 if ($event['uid'] == $data['uid']
                     || $event['end'] < $day_start || $event['start'] > $day_end
                     || $event['status'] == 'CANCELLED'
                     || (!empty($event['className']) && strpos($event['className'], 'declined') !== false)
                 ) {
                     continue;
                 }
 
                 if ($event['start'] < $event_start) {
                     $before[] = $this->mail_agenda_event_row($event);
                 }
                 else {
                     $after[] = $this->mail_agenda_event_row($event);
                 }
             }
 
             $response['append'] = [
                 'selector' => '.calendar-agenda-preview',
                 'replacements' => [
                     '%before%' => !empty($before) ? join("\n", array_slice($before,  -3)) : html::div('event-row no-event', $this->gettext('noearlierevents')),
                     '%after%'  => !empty($after)  ? join("\n", array_slice($after, 0, 3)) : html::div('event-row no-event', $this->gettext('nolaterevents')),
                 ],
             ];
         }
 
         $this->rc->output->command('plugin.update_itip_object_status', $response);
     }
 
     /**
      * Handler for calendar/itip-remove requests
      */
     function event_itip_remove()
     {
         $uid      = rcube_utils::get_input_value('uid', rcube_utils::INPUT_POST);
         $instance = rcube_utils::get_input_value('_instance', rcube_utils::INPUT_POST);
         $savemode = rcube_utils::get_input_value('_savemode', rcube_utils::INPUT_POST);
         $listmode = calendar_driver::FILTER_WRITEABLE | calendar_driver::FILTER_PERSONAL;
         $success  = false;
 
         // search for event if only UID is given
         if ($event = $this->driver->get_event(['uid' => $uid, '_instance' => $instance], $listmode)) {
             $event['_savemode'] = $savemode;
             $success = $this->driver->remove_event($event, true);
         }
 
         if ($success) {
             $this->rc->output->show_message('calendar.successremoval', 'confirmation');
         }
         else {
             $this->rc->output->show_message('calendar.errorsaving', 'error');
         }
     }
 
     /**
      * Handler for URLs that allow an invitee to respond on his invitation mail
      */
     public function itip_attend_response($p)
     {
         $this->setup();
 
         if ($p['action'] == 'attend') {
             $this->ui->init();
 
             $this->rc->output->set_env('task', 'calendar');  // override some env vars
             $this->rc->output->set_env('refresh_interval', 0);
             $this->rc->output->set_pagetitle($this->gettext('calendar'));
 
             $itip  = $this->load_itip();
             $token = rcube_utils::get_input_value('_t', rcube_utils::INPUT_GPC);
 
             // read event info stored under the given token
             if ($invitation = $itip->get_invitation($token)) {
                 $this->token = $token;
                 $this->event = $invitation['event'];
 
                 // show message about cancellation
                 if (!empty($invitation['cancelled'])) {
                     $this->invitestatus = html::div('rsvp-status declined', $itip->gettext('eventcancelled'));
                 }
                 // save submitted RSVP status
                 else if (!empty($_POST['rsvp'])) {
                     $status = null;
                     foreach (['accepted', 'tentative', 'declined'] as $method) {
                         if ($_POST['rsvp'] == $itip->gettext('itip' . $method)) {
                             $status = $method;
                             break;
                         }
                     }
 
                     // send itip reply to organizer
                     $invitation['event']['comment'] = rcube_utils::get_input_value('_comment', rcube_utils::INPUT_POST);
                     if ($status && $itip->update_invitation($invitation, $invitation['attendee'], strtoupper($status))) {
                         $this->invitestatus = html::div('rsvp-status ' . strtolower($status), $itip->gettext('youhave'.strtolower($status)));
                     }
                     else {
                         $this->rc->output->command('display_message', $this->gettext('errorsaving'), 'error', -1);
                     }
 
                     // if user is logged in...
                     // FIXME: we should really consider removing this functionality
                     //        it's confusing that it creates/updates an event only for logged-in user
                     //        what if the logged-in user is not the same as the attendee?
                     if ($this->rc->user->ID) {
                         $this->load_driver();
 
                         $invitation = $itip->get_invitation($token);
                         $existing   = $this->driver->get_event($this->event);
 
                         // save the event to his/her default calendar if not yet present
                         if (!$existing && ($calendar = $this->get_default_calendar())) {
                             $invitation['event']['calendar'] = $calendar['id'];
                             if ($this->driver->new_event($invitation['event'])) {
                                 $msg = $this->gettext(['name' => 'importedsuccessfully', 'vars' => ['calendar' => $calendar['name']]]);
                                 $this->rc->output->command('display_message', $msg, 'confirmation');
                             }
                             else {
                                 $this->rc->output->command('display_message', $this->gettext('errorimportingevent'), 'error');
                             }
                         }
                         else if ($existing
                             && ($this->event['sequence'] >= $existing['sequence']
                                 || $this->event['changed'] >= $existing['changed'])
                             && ($calendar = $this->driver->get_calendar($existing['calendar']))
                         ) {
                             $this->event       = $invitation['event'];
                             $this->event['id'] = $existing['id'];
 
                             unset($this->event['comment']);
 
                             // merge attendees status
                             // e.g. preserve my participant status for regular updates
                             $this->lib->merge_attendees($this->event, $existing, $status);
 
                             // update attachments list
                             $event['deleted_attachments'] = true;
 
                             // show me as free when declined (#1670)
                             if ($status == 'declined') {
                                 $this->event['free_busy'] = 'free';
                             }
 
                             if ($this->driver->edit_event($this->event)) {
                                 $msg = $this->gettext(['name' => 'updatedsuccessfully', 'vars' => ['calendar' => $calendar->get_name()]]);
                                 $this->rc->output->command('display_message', $msg, 'confirmation');
                             }
                             else {
                                 $this->rc->output->command('display_message', $this->gettext('errorimportingevent'), 'error');
                             }
                         }
                     }
                 }
 
                 $this->register_handler('plugin.event_inviteform', [$this, 'itip_event_inviteform']);
                 $this->register_handler('plugin.event_invitebox', [$this->ui, 'event_invitebox']);
 
                 if (empty($this->invitestatus)) {
                     $this->itip->set_rsvp_actions(['accepted', 'tentative', 'declined']);
                     $this->register_handler('plugin.event_rsvp_buttons', [$this->ui, 'event_rsvp_buttons']);
                 }
 
                 $this->rc->output->set_pagetitle($itip->gettext('itipinvitation') . ' ' . $this->event['title']);
             }
             else {
                 $this->rc->output->command('display_message', $this->gettext('itipinvalidrequest'), 'error', -1);
             }
 
             $this->rc->output->send('calendar.itipattend');
         }
     }
 
     /**
      *
      */
     public function itip_event_inviteform($attrib)
     {
         $hidden = new html_hiddenfield(['name' => "_t", 'value' => $this->token]);
 
         return html::tag('form', [
                 'action' => $this->rc->url(['task' => 'calendar', 'action' => 'attend']),
                 'method' => 'post',
                 'noclose' => true
             ] + $attrib
         ) . $hidden->show();
     }
 
     /**
      *
      */
     private function mail_agenda_event_row($event, $class = '')
     {
         if (!empty($event['allday'])) {
             $time = $this->gettext('all-day');
         }
         else {
             $start = is_object($event['start']) ? clone $event['start'] : $event['start'];
             $end = is_object($event['end']) ? clone $event['end'] : $event['end'];
 
             $time = $this->rc->format_date($start, $this->rc->config->get('time_format'))
                 . ' - ' . $this->rc->format_date($end, $this->rc->config->get('time_format'));
         }
 
         return html::div(rtrim('event-row ' . ($class ?: $event['className'])),
             html::span('event-date', $time)
             . html::span('event-title', rcube::Q($event['title']))
         );
     }
 
     /**
      *
      */
     public function mail_messages_list($p)
     {
         if (!empty($p['cols']) && in_array('attachment', (array) $p['cols']) && !empty($p['messages'])) {
             foreach ($p['messages'] as $header) {
                 $part = new StdClass;
                 $part->mimetype = $header->ctype;
 
                 if (libcalendaring::part_is_vcalendar($part)) {
                     $header->list_flags['attachmentClass'] = 'ical';
                 }
                 else if (in_array($header->ctype, ['multipart/alternative', 'multipart/mixed'])) {
                     // TODO: fetch bodystructure and search for ical parts. Maybe too expensive?
                     if (!empty($header->structure) && !empty($header->structure->parts)) {
                         foreach ($header->structure->parts as $part) {
                             if (libcalendaring::part_is_vcalendar($part)
                                 && !empty($part->ctype_parameters['method'])
                             ) {
                                 $header->list_flags['attachmentClass'] = 'ical';
                                 break;
                             }
                         }
                     }
                 }
             }
         }
     }
 
     /**
      * Add UI element to copy event invitations or updates to the calendar
      */
     public function mail_messagebody_html($p)
     {
         // load iCalendar functions (if necessary)
         if (!empty($this->lib->ical_parts)) {
             $this->get_ical();
             $this->load_itip();
         }
 
         $html = '';
         $has_events = false;
         $ical_objects = $this->lib->get_mail_ical_objects();
 
         // show a box for every event in the file
         foreach ($ical_objects as $idx => $event) {
             if ($event['_type'] != 'event') {
                 // skip non-event objects (#2928)
                 continue;
             }
 
             $has_events = true;
 
             // get prepared inline UI for this event object
             if ($ical_objects->method) {
                 $append   = '';
                 $date_str = $this->rc->format_date(clone $event['start'], $this->rc->config->get('date_format'), empty($event['start']->_dateonly));
                 $date     = new DateTime($event['start']->format('Y-m-d') . ' 12:00:00', new DateTimeZone('UTC'));
 
                 // prepare a small agenda preview to be filled with actual event data on async request
                 if ($ical_objects->method == 'REQUEST') {
                     $append = html::div('calendar-agenda-preview',
                         html::tag('h3', 'preview-title', $this->gettext('agenda') . ' ' . html::span('date', $date_str))
                         . '%before%' . $this->mail_agenda_event_row($event, 'current') . '%after%'
                     );
                 }
 
                 $html .= html::div('calendar-invitebox invitebox boxinformation',
                     $this->itip->mail_itip_inline_ui(
                         $event,
                         $ical_objects->method,
                         $ical_objects->mime_id . ':' . $idx,
                         'calendar',
                         rcube_utils::anytodatetime($ical_objects->message_date),
                         $this->rc->url(['task' => 'calendar']) . '&view=agendaDay&date=' . $date->format('U')
                     ) . $append
                 );
             }
 
             // limit listing
             if ($idx >= 3) {
                 break;
             }
         }
 
         // prepend event boxes to message body
         if ($html) {
             $this->ui->init();
             $p['content'] = $html . $p['content'];
             $this->rc->output->add_label('calendar.savingdata','calendar.deleteventconfirm','calendar.declinedeleteconfirm');
         }
 
         // add "Save to calendar" button into attachment menu
         if ($has_events) {
             $this->add_button([
                     'id'         => 'attachmentsavecal',
                     'name'       => 'attachmentsavecal',
                     'type'       => 'link',
                     'wrapper'    => 'li',
                     'command'    => 'attachment-save-calendar',
                     'class'      => 'icon calendarlink disabled',
                     'classact'   => 'icon calendarlink active',
                     'innerclass' => 'icon calendar',
                     'label'      => 'calendar.savetocalendar',
                 ],
                 'attachmentmenu'
             );
         }
 
         return $p;
     }
 
     /**
      * Handler for POST request to import an event attached to a mail message
      */
     public function mail_import_itip()
     {
         $itip_sending = $this->rc->config->get('calendar_itip_send_option', $this->defaults['calendar_itip_send_option']);
 
         $uid     = rcube_utils::get_input_value('_uid', rcube_utils::INPUT_POST);
         $mbox    = rcube_utils::get_input_value('_mbox', rcube_utils::INPUT_POST);
         $mime_id = rcube_utils::get_input_value('_part', rcube_utils::INPUT_POST);
         $status  = rcube_utils::get_input_value('_status', rcube_utils::INPUT_POST);
         $delete  = intval(rcube_utils::get_input_value('_del', rcube_utils::INPUT_POST));
         $noreply = intval(rcube_utils::get_input_value('_noreply', rcube_utils::INPUT_POST));
         $noreply = $noreply || $status == 'needs-action' || $itip_sending === 0;
         $instance = rcube_utils::get_input_value('_instance', rcube_utils::INPUT_POST);
         $savemode = rcube_utils::get_input_value('_savemode', rcube_utils::INPUT_POST);
         $comment  = rcube_utils::get_input_value('_comment', rcube_utils::INPUT_POST);
 
         $error_msg = $this->gettext('errorimportingevent');
         $success   = false;
         $deleted   = false;
 
         if ($status == 'delegated') {
             $to = rcube_utils::get_input_value('_to', rcube_utils::INPUT_POST, true);
             $delegates = rcube_mime::decode_address_list($to, 1, false);
             $delegate  = reset($delegates);
 
             if (empty($delegate) || empty($delegate['mailto'])) {
                 $this->rc->output->command('display_message', $this->rc->gettext('libcalendaring.delegateinvalidaddress'), 'error');
                 return;
             }
         }
 
         // successfully parsed events?
         if ($event = $this->lib->mail_get_itip_object($mbox, $uid, $mime_id, 'event')) {
             // forward iTip request to delegatee
             if (!empty($delegate)) {
                 $rsvpme = rcube_utils::get_input_value('_rsvp', rcube_utils::INPUT_POST);
                 $itip   = $this->load_itip();
 
                 $event['comment'] = $comment;
 
                 if ($itip->delegate_to($event, $delegate, !empty($rsvpme))) {
                     $this->rc->output->show_message('calendar.itipsendsuccess', 'confirmation');
                 }
                 else {
                     $this->rc->output->command('display_message', $this->gettext('itipresponseerror'), 'error');
                 }
 
                 unset($event['comment']);
 
                 // the delegator is set to non-participant, thus save as non-blocking
                 $event['free_busy'] = 'free';
             }
 
             $mode = calendar_driver::FILTER_PERSONAL
                 | calendar_driver::FILTER_SHARED
                 | calendar_driver::FILTER_WRITEABLE;
 
             // find writeable calendar to store event
             $cal_id    = rcube_utils::get_input_value('_folder', rcube_utils::INPUT_POST);
             $dontsave  = $cal_id === '' && $event['_method'] == 'REQUEST';
             $calendars = $this->driver->list_calendars($mode);
             $calendar  = isset($calendars[$cal_id]) ? $calendars[$cal_id] : null;
 
             // select default calendar except user explicitly selected 'none'
             if (!$calendar && !$dontsave) {
                 $calendar = $this->get_default_calendar($calendars);
             }
 
             $metadata = [
                 'uid'       => $event['uid'],
                 '_instance' => isset($event['_instance']) ? $event['_instance'] : null,
                 'changed'   => is_object($event['changed']) ? $event['changed']->format('U') : 0,
                 'sequence'  => intval($event['sequence']),
                 'fallback'  => strtoupper($status),
                 'method'    => $event['_method'],
                 'task'      => 'calendar',
             ];
 
             // update my attendee status according to submitted method
             if (!empty($status)) {
                 $organizer = null;
                 $emails = $this->get_user_emails();
                 foreach ($event['attendees'] as $i => $attendee) {
                     if ($attendee['role'] == 'ORGANIZER') {
                         $organizer = $attendee;
                     }
                     else if (!empty($attendee['email']) && in_array(strtolower($attendee['email']), $emails)) {
                         $event['attendees'][$i]['status'] = strtoupper($status);
                         if (!in_array($event['attendees'][$i]['status'], ['NEEDS-ACTION', 'DELEGATED'])) {
                             $event['attendees'][$i]['rsvp'] = false;  // unset RSVP attribute
                         }
 
                         $metadata['attendee'] = $attendee['email'];
                         $metadata['rsvp']     = $attendee['role'] != 'NON-PARTICIPANT';
 
                         $reply_sender   = $attendee['email'];
                         $event_attendee = $attendee;
                     }
                 }
 
                 // add attendee with this user's default identity if not listed
                 if (!$reply_sender) {
                     $sender_identity = $this->rc->user->list_emails(true);
                     $event['attendees'][] = [
                         'name'   => $sender_identity['name'],
                         'email'  => $sender_identity['email'],
                         'role'   => 'OPT-PARTICIPANT',
                         'status' => strtoupper($status),
                     ];
                     $metadata['attendee'] = $sender_identity['email'];
                 }
             }
 
             // save to calendar
             if ($calendar && !empty($calendar['editable'])) {
                 // check for existing event with the same UID
                 $existing = $this->find_event($event, $mode);
 
                 // we'll create a new copy if user decided to change the calendar
                 if ($existing && $cal_id && $calendar && $calendar['id'] != $existing['calendar']) {
                     $existing = null;
                 }
 
                 if ($existing) {
                     $calendar = $calendars[$existing['calendar']];
 
                     // forward savemode for correct updates of recurring events
                     $existing['_savemode'] = $savemode ?: (!empty($event['_savemode']) ? $event['_savemode'] : null);
 
                     // only update attendee status
                     if ($event['_method'] == 'REPLY') {
                         $existing_attendee_index  = -1;
 
                         $event_attendee   = null;
                         $update_attendees = [];
 
                         if ($attendee = $this->itip->find_reply_attendee($event)) {
                             $event_attendee       = $attendee;
                             $update_attendees[]   = $attendee;
                             $metadata['fallback'] = $attendee['status'];
                             $metadata['attendee'] = $attendee['email'];
                             $metadata['rsvp']     = !empty($attendee['rsvp']) || $attendee['role'] != 'NON-PARTICIPANT';
 
                             $existing_attendee_emails = [];
 
                             // Find the attendee to update
                             foreach ($existing['attendees'] as $i => $existing_attendee) {
                                 $existing_attendee_emails[] = $existing_attendee['email'];
                                 if ($this->itip->compare_email($existing_attendee['email'], $attendee['email'])) {
                                     $existing_attendee_index = $i;
                                 }
                             }
 
                             if ($attendee['status'] == 'DELEGATED') {
                                 //Also find and copy the delegatee
                                 $delegatee_email = $attendee['email'];
                                 $delegatees = array_filter($event['attendees'], function($attendee) use ($delegatee_email){ return $attendee['role'] != 'ORGANIZER' && $this->itip->compare_email($attendee['delegated-from'], $delegatee_email); });
 
                                 if ($delegatee = $this->itip->find_attendee_by_email($event['attendees'], 'delegated-from', $attendee['email'])) {
                                     $update_attendees[] = $delegatee;
                                     if (!in_array_nocase($delegatee['email'], $existing_attendee_emails)) {
                                         $existing['attendees'][] = $delegated_attendee;
                                     }
                                 }
                             }
                         }
 
                         // if delegatee has declined, set delegator's RSVP=True
                         if ($event_attendee
                             && $event_attendee['status'] == 'DECLINED'
                             && !empty($event_attendee['delegated-from'])
                         ) {
                             foreach ($existing['attendees'] as $i => $attendee) {
                                 if ($attendee['email'] == $event_attendee['delegated-from']) {
                                     $existing['attendees'][$i]['rsvp'] = true;
                                     break;
                                 }
                             }
                         }
 
                         // found matching attendee entry in both existing and new events
                         if ($existing_attendee_index >= 0 && $event_attendee) {
                             $existing['attendees'][$existing_attendee_index] = $event_attendee;
                             $success = $this->driver->update_attendees($existing, $update_attendees);
                         }
                         // update the entire attendees block
                         else if (
                             ($event['sequence'] >= $existing['sequence'] || $event['changed'] >= $existing['changed'])
                             && $event_attendee
                         ) {
                             $existing['attendees'][] = $event_attendee;
                             $success = $this->driver->update_attendees($existing, $update_attendees);
                         }
                         else if (!$event_attendee) {
                             $error_msg = $this->gettext('errorunknownattendee');
                         }
                         else {
                             $error_msg = $this->gettext('newerversionexists');
                         }
                     }
                     // delete the event when declined (#1670)
                     else if ($status == 'declined' && $delete) {
                         $deleted = $this->driver->remove_event($existing, true);
                         $success = true;
                     }
                     // import the (newer) event
                     else if ($event['sequence'] >= $existing['sequence'] || $event['changed'] >= $existing['changed']) {
                         $event['id']       = $existing['id'];
                         $event['calendar'] = $existing['calendar'];
 
                         // merge attendees status
                         // e.g. preserve my participant status for regular updates
                         $this->lib->merge_attendees($event, $existing, $status);
 
                         // set status=CANCELLED on CANCEL messages
                         if ($event['_method'] == 'CANCEL') {
                             $event['status'] = 'CANCELLED';
                         }
 
                         // update attachments list, allow attachments update only on REQUEST (#5342)
                         if ($event['_method'] == 'REQUEST') {
                             $event['deleted_attachments'] = true;
                         }
                         else {
                             unset($event['attachments']);
                         }
 
                         // show me as free when declined (#1670)
                         if ($status == 'declined'
                             || (!empty($event['status']) && $event['status'] == 'CANCELLED')
                             || $event_attendee['role'] == 'NON-PARTICIPANT'
                         ) {
                             $event['free_busy'] = 'free';
                         }
 
                         $success = $this->driver->edit_event($event);
                     }
                     else if (!empty($status)) {
                         $existing['attendees'] = $event['attendees'];
                         if ($status == 'declined' || $event_attendee['role'] == 'NON-PARTICIPANT') {
                             // show me as free when declined (#1670)
                             $existing['free_busy'] = 'free';
                         }
                         $success = $this->driver->edit_event($existing);
                     }
                     else {
                         $error_msg = $this->gettext('newerversionexists');
                     }
                 }
                 else if (!$existing && ($status != 'declined' || $this->rc->config->get('kolab_invitation_calendars'))) {
                     if ($status == 'declined'
                         || $event['status'] == 'CANCELLED'
                         || $event_attendee['role'] == 'NON-PARTICIPANT'
                     ) {
                         $event['free_busy'] = 'free';
                     }
 
                     // if the RSVP reply only refers to a single instance:
                     // store unmodified master event with current instance as exception
                     if (!empty($instance) && !empty($savemode) && $savemode != 'all') {
                         $master = $this->lib->mail_get_itip_object($mbox, $uid, $mime_id, 'event');
                         if ($master['recurrence'] && empty($master['_instance'])) {
                             // compute recurring events until this instance's date
                             if ($recurrence_date = rcube_utils::anytodatetime($instance, $master['start']->getTimezone())) {
                                 $recurrence_date->setTime(23,59,59);
 
                                 foreach ($this->driver->get_recurring_events($master, $master['start'], $recurrence_date) as $recurring) {
                                     if ($recurring['_instance'] == $instance) {
                                         // copy attendees block with my partstat to exception
                                         $recurring['attendees'] = $event['attendees'];
                                         $master['recurrence']['EXCEPTIONS'][] = $recurring;
                                         $event = $recurring;  // set reference for iTip reply
                                         break;
                                     }
                                 }
 
                                 $master['calendar'] = $event['calendar'] = $calendar['id'];
                                 $success = $this->driver->new_event($master);
                             }
                             else {
                                 $master = null;
                             }
                         }
                         else {
                             $master = null;
                         }
                     }
 
                     // save to the selected/default calendar
                     if (!$master) {
                         $event['calendar'] = $calendar['id'];
                         $success = $this->driver->new_event($event);
                     }
                 }
                 else if ($status == 'declined') {
                     $error_msg = null;
                 }
             }
             else if ($status == 'declined' || $dontsave) {
                 $error_msg = null;
             }
             else {
                 $error_msg = $this->gettext('nowritecalendarfound');
             }
         }
 
         if ($success) {
             if ($event['_method'] == 'REPLY') {
                 $message = 'attendeupdateesuccess';
             }
             else {
                 $message = $deleted ? 'successremoval' : ($existing ? 'updatedsuccessfully' : 'importedsuccessfully');
             }
 
             $msg = $this->gettext(['name' => $message, 'vars' => ['calendar' => $calendar['name']]]);
             $this->rc->output->command('display_message', $msg, 'confirmation');
         }
 
         if ($success || $dontsave) {
             $metadata['calendar'] = isset($event['calendar']) ? $event['calendar'] : null;
             $metadata['nosave']   = $dontsave;
             $metadata['rsvp']     = !empty($metadata['rsvp']);
 
             $metadata['after_action'] = $this->rc->config->get('calendar_itip_after_action', $this->defaults['calendar_itip_after_action']);
             $this->rc->output->command('plugin.itip_message_processed', $metadata);
             $error_msg = null;
         }
         else if ($error_msg) {
             $this->rc->output->command('display_message', $error_msg, 'error');
         }
 
         // send iTip reply
         if ($event['_method'] == 'REQUEST' && !empty($organizer) && !$noreply
             && !in_array(strtolower($organizer['email']), $emails) && !$error_msg
         ) {
             $event['comment'] = $comment;
             $itip = $this->load_itip();
             $itip->set_sender_email($reply_sender);
 
             if ($itip->send_itip_message($event, 'REPLY', $organizer, 'itipsubject' . $status, 'itipmailbody' . $status)) {
                 $mailto = $organizer['name'] ? $organizer['name'] : $organizer['email'];
                 $msg    = $this->gettext(['name' => 'sentresponseto', 'vars' => ['mailto' => $mailto]]);
                 $this->rc->output->command('display_message', $msg, 'confirmation');
             }
             else {
                 $this->rc->output->command('display_message', $this->gettext('itipresponseerror'), 'error');
             }
         }
 
         $this->rc->output->send();
     }
 
     /**
      * Handler for calendar/itip-remove requests
      */
     function mail_itip_decline_reply()
     {
         $uid     = rcube_utils::get_input_value('_uid', rcube_utils::INPUT_POST);
         $mbox    = rcube_utils::get_input_value('_mbox', rcube_utils::INPUT_POST);
         $mime_id = rcube_utils::get_input_value('_part', rcube_utils::INPUT_POST);
 
         if (($event = $this->lib->mail_get_itip_object($mbox, $uid, $mime_id, 'event'))
             && $event['_method'] == 'REPLY'
         ) {
             $event['comment'] = rcube_utils::get_input_value('_comment', rcube_utils::INPUT_POST);
 
             foreach ($event['attendees'] as $_attendee) {
                 if ($_attendee['role'] != 'ORGANIZER') {
                     $attendee = $_attendee;
                     break;
                 }
             }
 
             $itip = $this->load_itip();
 
             if ($itip->send_itip_message($event, 'CANCEL', $attendee, 'itipsubjectcancel', 'itipmailbodycancel')) {
                 $mailto = !empty($attendee['name']) ? $attendee['name'] : $attendee['email'];
                 $msg    = $this->gettext(['name' => 'sentresponseto', 'vars' => ['mailto' => $mailto]]);
                 $this->rc->output->command('display_message', $msg, 'confirmation');
             }
             else {
                 $this->rc->output->command('display_message', $this->gettext('itipresponseerror'), 'error');
             }
         }
         else {
             $this->rc->output->command('display_message', $this->gettext('itipresponseerror'), 'error');
         }
     }
 
     /**
      * Handler for calendar/itip-delegate requests
      */
     function mail_itip_delegate()
     {
         // forward request to mail_import_itip() with the right status
         $_POST['_status'] = $_REQUEST['_status'] = 'delegated';
         $this->mail_import_itip();
     }
 
     /**
      * Import the full payload from a mail message attachment
      */
     public function mail_import_attachment()
     {
         $uid     = rcube_utils::get_input_value('_uid', rcube_utils::INPUT_POST);
         $mbox    = rcube_utils::get_input_value('_mbox', rcube_utils::INPUT_POST);
         $mime_id = rcube_utils::get_input_value('_part', rcube_utils::INPUT_POST);
         $charset = RCUBE_CHARSET;
 
         // establish imap connection
         $imap = $this->rc->get_storage();
         $imap->set_folder($mbox);
 
         if ($uid && $mime_id) {
             $part = $imap->get_message_part($uid, $mime_id);
             // $headers = $imap->get_message_headers($uid);
 
             if ($part) {
                 if (!empty($part->ctype_parameters['charset'])) {
                     $charset = $part->ctype_parameters['charset'];
                 }
                 $events = $this->get_ical()->import($part, $charset);
             }
         }
 
         $success = $existing = 0;
 
         if (!empty($events)) {
             // find writeable calendar to store event
             $cal_id = !empty($_REQUEST['_calendar']) ? rcube_utils::get_input_value('_calendar', rcube_utils::INPUT_POST) : null;
             $calendars = $this->driver->list_calendars(calendar_driver::FILTER_PERSONAL);
 
             foreach ($events as $event) {
                 // save to calendar
                 $calendar = !empty($calendars[$cal_id]) ? $calendars[$cal_id] : $this->get_default_calendar();
                 if ($calendar && $calendar['editable'] && $event['_type'] == 'event') {
                     $event['calendar'] = $calendar['id'];
 
                     if (!$this->driver->get_event($event['uid'], calendar_driver::FILTER_WRITEABLE)) {
                         $success += (bool)$this->driver->new_event($event);
                     }
                     else {
                         $existing++;
                     }
                 }
             }
         }
 
         if ($success) {
             $msg = $this->gettext(['name' => 'importsuccess', 'vars' => ['nr' => $success]]);
             $this->rc->output->command('display_message', $msg, 'confirmation');
         }
         else if ($existing) {
             $this->rc->output->command('display_message', $this->gettext('importwarningexists'), 'warning');
         }
         else {
             $this->rc->output->command('display_message', $this->gettext('errorimportingevent'), 'error');
         }
     }
 
     /**
      * Read email message and return contents for a new event based on that message
      */
     public function mail_message2event()
     {
         $this->ui->init();
         $this->ui->addJS();
         $this->ui->init_templates();
         $this->ui->calendar_list([], true); // set env['calendars']
 
         $uid   = rcube_utils::get_input_value('_uid', rcube_utils::INPUT_GET);
         $mbox  = rcube_utils::get_input_value('_mbox', rcube_utils::INPUT_GET);
         $event = [];
 
         // establish imap connection
         $imap    = $this->rc->get_storage();
         $message = new rcube_message($uid, $mbox);
 
         if ($message->headers) {
             $event['title']       = trim($message->subject);
             $event['description'] = trim($message->first_text_part());
 
             $this->load_driver();
 
             // add a reference to the email message
             if ($msgref = $this->driver->get_message_reference($message->headers, $mbox)) {
                 $event['links'] = [$msgref];
             }
             // copy mail attachments to event
             else if (!empty($message->attachments) && !empty($this->driver->attachments)) {
                 $handler = new kolab_attachments_handler();
                 $event['attachments'] = $handler->copy_mail_attachments(self::SESSION_KEY, 'cal-', $message);
             }
 
             $this->rc->output->set_env('event_prop', $event);
         }
         else {
             $this->rc->output->command('display_message', $this->gettext('messageopenerror'), 'error');
         }
 
         $this->rc->output->send('calendar.dialog');
     }
 
     /**
      * Handler for the 'message_compose' plugin hook. This will check for
      * a compose parameter 'calendar_event' and create an attachment with the
      * referenced event in iCal format
      */
     public function mail_message_compose($args)
     {
         // set the submitted event ID as attachment
         if (!empty($args['param']['calendar_event'])) {
             $this->load_driver();
 
             list($cal, $id) = explode(':', $args['param']['calendar_event'], 2);
 
             if ($event = $this->driver->get_event(['id' => $id, 'calendar' => $cal])) {
                 $filename = asciiwords($event['title']);
                 if (empty($filename)) {
                     $filename = 'event';
                 }
 
                 // save ics to a temp file and register as attachment
                 $tmp_path = tempnam($this->rc->config->get('temp_dir'), 'rcmAttmntCal');
                 $export   = $this->get_ical()->export([$event], '', false, [$this->driver, 'get_attachment_body']);
 
                 file_put_contents($tmp_path, $export);
 
                 $args['attachments'][] = [
                     'path'     => $tmp_path,
                     'name'     => $filename . '.ics',
                     'mimetype' => 'text/calendar',
                     'size'     => filesize($tmp_path),
                 ];
                 $args['param']['subject'] = $event['title'];
             }
         }
 
         return $args;
     }
 
     /**
      * Create a Nextcould Talk room
      */
     public function talk_room_create()
     {
         require_once __DIR__ . '/lib/calendar_nextcloud_api.php';
 
         $api = new calendar_nextcloud_api();
 
         $name = (string) rcube_utils::get_input_value('_name', rcube_utils::INPUT_POST);
 
         $room_url = $api->talk_room_create($name);
 
         if ($room_url) {
             $this->rc->output->command('plugin.talk_room_created', ['url' => $room_url]);
         }
         else {
             $this->rc->output->command('display_message', $this->gettext('talkroomcreateerror'), 'error');
         }
     }
 
     /**
      * Update a Nextcould Talk room
      */
     public function talk_room_update($event)
     {
         // If a room is assigned to the event...
         if (
             ($talk_url = $this->rc->config->get('calendar_nextcloud_url'))
             && isset($event['attendees'])
             && !empty($event['location'])
             && strpos($event['location'], unslashify($talk_url) . '/call/') === 0
         ) {
             $participants = [];
             $organizer = null;
 
             // ollect participants' and organizer's email addresses
             foreach ($event['attendees'] as $attendee) {
                 if (!empty($attendee['email'])) {
                     if ($attendee['role'] == 'ORGANIZER') {
                         $organizer = $attendee['email'];
                     }
                     else if ($attendee['cutype'] == 'INDIVIDUAL') {
                         $participants[] = $attendee['email'];
                     }
                 }
             }
 
             // If the event is owned by the current user update the room
             if ($organizer && in_array($organizer, $this->get_user_emails())) {
                 require_once __DIR__ . '/lib/calendar_nextcloud_api.php';
 
                 $api = new calendar_nextcloud_api();
 
                 $api->talk_room_update($event['location'], $participants);
             }
         }
     }
 
     /**
      * Get a list of email addresses of the current user (from login and identities)
      */
     public function get_user_emails()
     {
         return $this->lib->get_user_emails();
     }
 
     /**
      * Build an absolute URL with the given parameters
      */
     public function get_url($param = [])
     {
         $param += ['task' => 'calendar'];
         return $this->rc->url($param, true, true);
     }
 
     public function ical_feed_hash($source)
     {
         return base64_encode($this->rc->user->get_username() . ':' . $source);
     }
 
     /**
      * Handler for user_delete plugin hook
      */
     public function user_delete($args)
     {
          // delete itipinvitations entries related to this user
          $db = $this->rc->get_dbh();
          $table_itipinvitations = $db->table_name('itipinvitations', true);
 
          $db->query("DELETE FROM $table_itipinvitations WHERE `user_id` = ?", $args['user']->ID);
 
         $this->setup();
         $this->load_driver();
 
         return $this->driver->user_delete($args);
     }
 
     /**
      * Find first occurrence of a recurring event excluding start date
      *
      * @param array $event Event data (with 'start' and 'recurrence')
      *
      * @return DateTime Date of the first occurrence
      */
     public function find_first_occurrence($event)
     {
         // Make sure libkolab/libcalendaring plugins are loaded
         $this->load_driver();
 
         $driver_name = $this->rc->config->get('calendar_driver', 'database');
 
         // Use kolabcalendaring/kolabformat to compute recurring events only with the Kolab driver
         if ($driver_name == 'kolab' && class_exists('kolabformat') && class_exists('kolabcalendaring')
             && class_exists('kolab_date_recurrence')
         ) {
             $object = kolab_format::factory('event', 3.0);
             $object->set($event);
 
             $recurrence = new kolab_date_recurrence($object);
         }
         else {
             // fallback to libcalendaring recurrence implementation
             $recurrence = new libcalendaring_recurrence($this->lib, $event);
         }
 
         return $recurrence->first_occurrence();
     }
 
     /**
      * Get date-time input from UI and convert to unix timestamp
      */
     protected function input_timestamp($name, $type)
     {
         $ts = rcube_utils::get_input_value($name, $type);
 
         if ($ts && (!is_numeric($ts) || strpos($ts, 'T'))) {
             $ts = new DateTime($ts, $this->timezone);
             $ts = $ts->getTimestamp();
         }
 
         return $ts;
     }
 
     /**
      * Magic getter for public access to protected members
      */
     public function __get($name)
     {
         switch ($name) {
         case 'ical':
             return $this->get_ical();
 
         case 'itip':
             return $this->load_itip();
 
         case 'driver':
             $this->load_driver();
             return $this->driver;
         }
 
         return null;
     }
 }
diff --git a/plugins/kolab_addressbook/drivers/carddav/carddav_contacts.php b/plugins/kolab_addressbook/drivers/carddav/carddav_contacts.php
index b815064c..bbffb6ef 100644
--- a/plugins/kolab_addressbook/drivers/carddav/carddav_contacts.php
+++ b/plugins/kolab_addressbook/drivers/carddav/carddav_contacts.php
@@ -1,1271 +1,1272 @@
 <?php
 
 /**
  * Backend class for a custom address book using CardDAV service.
  *
  * This part of the Roundcube+Kolab integration and connects the
  * rcube_addressbook interface with the kolab_storage_dav wrapper from libkolab
  *
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  * @author Aleksander Machniak <machniak@apheleia-it.chm>
  *
  * Copyright (C) 2011-2022, Kolab Systems AG <contact@apheleia-it.ch>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  *
  * @see rcube_addressbook
  */
 class carddav_contacts extends rcube_addressbook
 {
     public $primary_key = 'ID';
     public $rights   = 'lrs';
     public $readonly = true;
     public $undelete = false;
     public $groups   = true;
 
     public $coltypes = [
         'name'         => ['limit' => 1],
         'firstname'    => ['limit' => 1],
         'surname'      => ['limit' => 1],
         'middlename'   => ['limit' => 1],
         'prefix'       => ['limit' => 1],
         'suffix'       => ['limit' => 1],
         'nickname'     => ['limit' => 1],
         'jobtitle'     => ['limit' => 1],
         'organization' => ['limit' => 1],
         'department'   => ['limit' => 1],
         'email'        => ['subtypes' => ['home','work','other']],
         'phone'        => [],
         'address'      => ['subtypes' => ['home','work','office']],
         'website'      => ['subtypes' => ['homepage','blog']],
         'im'           => ['subtypes' => null],
         'gender'       => ['limit' => 1],
         'birthday'     => ['limit' => 1],
         'anniversary'  => ['limit' => 1],
         'manager'      => ['limit' => null],
         'assistant'    => ['limit' => null],
         'spouse'       => ['limit' => 1],
         'notes'        => ['limit' => 1],
         'photo'        => ['limit' => 1],
     ];
 
     public $vcard_map = [
     //    'profession'     => 'X-PROFESSION',
     //    'officelocation' => 'X-OFFICE-LOCATION',
     //    'initials'       => 'X-INITIALS',
     //    'children'       => 'X-CHILDREN',
     //    'freebusyurl'    => 'X-FREEBUSY-URL',
     //    'pgppublickey'   => 'KEY',
         'uid'            => 'UID',
     ];
 
     /**
      * List of date type fields
      */
     public $date_cols = ['birthday', 'anniversary'];
 
     public $fulltext_cols  = ['name', 'firstname', 'surname', 'middlename', 'email'];
 
     private $gid;
     private $storage;
     private $dataset;
     private $sortindex;
     private $contacts;
     private $distlists;
     private $groupmembers;
     private $filter;
     private $result;
     private $namespace;
     private $action;
 
     // list of fields used for searching in "All fields" mode
     private $search_fields = [
         'name',
         'firstname',
         'surname',
         'middlename',
         'prefix',
         'suffix',
         'nickname',
         'jobtitle',
         'organization',
         'department',
         'email',
         'phone',
         'address',
 //        'profession',
         'manager',
         'assistant',
         'spouse',
 //        'children',
         'notes',
     ];
 
 
     /**
      * Object constructor
      */
     public function __construct($dav_folder = null)
     {
         $this->storage = $dav_folder;
         $this->ready   = !empty($this->storage);
 
         // Set readonly and rights flags according to folder permissions
         if ($this->ready) {
             if ($this->storage->get_owner() == $_SESSION['username']) {
                 $this->readonly = false;
                 $this->rights = 'lrswikxtea';
             }
             else {
                 $rights = $this->storage->get_myrights();
                 if ($rights && !PEAR::isError($rights)) {
                     $this->rights = $rights;
                     if (strpos($rights, 'i') !== false && strpos($rights, 't') !== false) {
                         $this->readonly = false;
                     }
                 }
             }
         }
 
         $this->action = rcube::get_instance()->action;
     }
 
     /**
      * Getter for the address book name to be displayed
      *
      * @return string Name of this address book
      */
     public function get_name()
     {
         return $this->storage->get_name();
     }
 
     /**
      * Wrapper for kolab_storage_folder::get_foldername()
      */
     public function get_foldername()
     {
         return $this->storage->get_foldername();
     }
 
     /**
      * Getter for the folder name
      *
      * @return string Name of the folder
      */
     public function get_realname()
     {
         return $this->get_name();
     }
 
     /**
      * Getter for the name of the namespace to which the IMAP folder belongs
      *
      * @return string Name of the namespace (personal, other, shared)
      */
     public function get_namespace()
     {
         if ($this->namespace === null && $this->ready) {
             $this->namespace = $this->storage->get_namespace();
         }
 
         return $this->namespace;
     }
 
     /**
      * Getter for parent folder path
      *
      * @return string Full path to parent folder
      */
     public function get_parent()
     {
         return $this->storage->get_parent();
     }
 
     /**
      * Check subscription status of this folder
      *
      * @return boolean True if subscribed, false if not
      */
     public function is_subscribed()
     {
         return true;
     }
 
     /**
      * Compose an URL for CardDAV access to this address book (if configured)
      */
     public function get_carddav_url()
     {
 /*
         $rcmail = rcmail::get_instance();
         if ($template = $rcmail->config->get('kolab_addressbook_carddav_url', null)) {
             return strtr($template, [
                     '%h' => $_SERVER['HTTP_HOST'],
                     '%u' => urlencode($rcmail->get_user_name()),
                     '%i' => urlencode($this->storage->get_uid()),
                     '%n' => urlencode($this->imap_folder),
             ]);
         }
 */
         return false;
     }
 
     /**
      * Setter for the current group
      */
     public function set_group($gid)
     {
         $this->gid = $gid;
     }
 
     /**
      * Save a search string for future listings
      *
      * @param mixed Search params to use in listing method, obtained by get_search_set()
      */
     public function set_search_set($filter)
     {
         $this->filter = $filter;
     }
 
     /**
      * Getter for saved search properties
      *
      * @return mixed Search properties used by this class
      */
     public function get_search_set()
     {
         return $this->filter;
     }
 
     /**
      * Reset saved results and search parameters
      */
     public function reset()
     {
         $this->result = null;
         $this->filter = null;
     }
 
     /**
      * List all active contact groups of this source
      *
      * @param string Optional search string to match group name
      * @param int    Search mode. Sum of self::SEARCH_*
      *
      * @return array Indexed list of contact groups, each a hash array
      */
     function list_groups($search = null, $mode = 0)
     {
         $this->_fetch_groups();
         $groups = [];
 
         foreach ((array)$this->distlists as $group) {
             if (!$search || strstr(mb_strtolower($group['name']), mb_strtolower($search))) {
                 $groups[$group['ID']] = ['ID' => $group['ID'], 'name' => $group['name']];
             }
         }
 
         // sort groups by name
         uasort($groups, function($a, $b) { return strcoll($a['name'], $b['name']); });
 
         return array_values($groups);
     }
 
     /**
      * List the current set of contact records
      *
      * @param array List of cols to show
      * @param int   Only return this number of records, use negative values for tail
      * @param bool  True to skip the count query (select only)
      *
      * @return array Indexed list of contact records, each a hash array
      */
     public function list_records($cols = null, $subset = 0, $nocount = false)
     {
         $this->result = new rcube_result_set(0, ($this->list_page-1) * $this->page_size);
 
         $fetch_all = false;
         $fast_mode = !empty($cols) && is_array($cols);
 
         // list member of the selected group
         if ($this->gid) {
             $this->_fetch_groups();
 
             $this->sortindex = [];
             $this->contacts  = [];
             $local_sortindex = [];
             $uids            = [];
 
             // get members with email specified
             foreach ((array)$this->distlists[$this->gid]['member'] as $member) {
                 // skip member that don't match the search filter
                 if (!empty($this->filter['ids']) && array_search($member['ID'], $this->filter['ids']) === false) {
                     continue;
                 }
 
                 if (!empty($member['uid'])) {
                     $uids[] = $member['uid'];
                 }
                 else if (!empty($member['email'])) {
                     $this->contacts[$member['ID']] = $member;
                     $local_sortindex[$member['ID']] = $this->_sort_string($member);
                     $fetch_all = true;
                 }
             }
 
             // get members by UID
             if (!empty($uids)) {
                 $this->_fetch_contacts($query = [['uid', '=', $uids]], $fetch_all ? false : count($uids), $fast_mode);
                 $this->sortindex = array_merge($this->sortindex, $local_sortindex);
             }
         }
         else if (isset($this->filter['ids']) && is_array($this->filter['ids'])) {
             $ids = $this->filter['ids'];
             if (count($ids)) {
                 $uids = array_map([$this, 'id2uid'], $this->filter['ids']);
                 $this->_fetch_contacts($query = [['uid', '=', $uids]], count($ids), $fast_mode);
             }
         }
         else {
             $this->_fetch_contacts($query = 'contact', true, $fast_mode);
         }
 
         if ($fetch_all) {
             // sort results (index only)
             asort($this->sortindex, SORT_LOCALE_STRING);
             $ids = array_keys($this->sortindex);
 
             // fill contact data into the current result set
             $this->result->count = count($ids);
             $start_row = $subset < 0 ? $this->result->first + $this->page_size + $subset : $this->result->first;
             $last_row = min($subset != 0 ? $start_row + abs($subset) : $this->result->first + $this->page_size, $this->result->count);
 
             for ($i = $start_row; $i < $last_row; $i++) {
                 if (array_key_exists($i, $ids)) {
                     $idx = $ids[$i];
                     $this->result->add($this->contacts[$idx] ?: $this->_to_rcube_contact($this->dataset[$idx]));
                 }
             }
         }
         else if (!empty($this->dataset)) {
             // get all records count, skip the query if possible
             if (!isset($query) || count($this->dataset) < $this->page_size) {
                 $this->result->count = count($this->dataset) + $this->page_size * ($this->list_page - 1);
             }
             else {
                 $this->result->count = $this->storage->count($query);
             }
 
             $start_row = $subset < 0 ? $this->page_size + $subset : 0;
             $last_row  = min($subset != 0 ? $start_row + abs($subset) : $this->page_size, $this->result->count);
 
             for ($i = $start_row; $i < $last_row; $i++) {
                 $this->result->add($this->_to_rcube_contact($this->dataset[$i]));
             }
         }
 
         return $this->result;
     }
 
     /**
      * Search records
      *
      * @param mixed $fields   The field name of array of field names to search in
      * @param mixed $value    Search value (or array of values when $fields is array)
      * @param int   $mode     Matching mode:
      *                        0 - partial (*abc*),
      *                        1 - strict (=),
      *                        2 - prefix (abc*)
      *                        4 - include groups (if supported)
      * @param bool  $select   True if results are requested, False if count only
      * @param bool  $nocount  True to skip the count query (select only)
      * @param array $required List of fields that cannot be empty
      *
      * @return rcube_result_set List of contact records and 'count' value
      */
     public function search($fields, $value, $mode = 0, $select = true, $nocount = false, $required = [])
     {
         // search by ID
         if ($fields == $this->primary_key) {
             $ids    = !is_array($value) ? explode(',', $value) : $value;
             $result = new rcube_result_set();
 
             foreach ($ids as $id) {
                 if ($rec = $this->get_record($id, true)) {
                     $result->add($rec);
                     $result->count++;
                 }
             }
             return $result;
         }
         else if ($fields == '*') {
             $fields = $this->search_fields;
         }
 
         if (!is_array($fields)) {
             $fields = [$fields];
         }
         if (!is_array($required) && !empty($required)) {
             $required = [$required];
         }
 
         // advanced search
         if (is_array($value)) {
             $advanced = true;
             $value = array_map('mb_strtolower', $value);
         }
         else {
             $value = mb_strtolower($value);
         }
 
         $scount = count($fields);
         // build key name regexp
         $regexp = '/^(' . implode('|', $fields) . ')(?:.*)$/';
 
         // pass query to storage if only indexed cols are involved
         // NOTE: this is only some rough pre-filtering but probably includes false positives
         $squery = $this->_search_query($fields, $value, $mode);
 
         // add magic selector to select contacts with birthday dates only
         if (in_array('birthday', $required)) {
             $squery[] = ['tags', '=', 'x-has-birthday'];
         }
 
         $squery[] = ['type', '=', 'contact'];
 
         // get all/matching records
         $this->_fetch_contacts($squery);
 
         // save searching conditions
         $this->filter = ['fields' => $fields, 'value' => $value, 'mode' => $mode, 'ids' => []];
 
         // search by iterating over all records in dataset
         foreach ($this->dataset as $record) {
             $contact = $this->_to_rcube_contact($record);
             $id = $contact['ID'];
 
             // check if current contact has required values, otherwise skip it
             if ($required) {
                 foreach ($required as $f) {
                     // required field might be 'email', but contact might contain 'email:home'
                     if (!($v = rcube_addressbook::get_col_values($f, $contact, true)) || empty($v)) {
                         continue 2;
                     }
                 }
             }
 
             $found    = [];
             $contents = '';
 
             foreach (preg_grep($regexp, array_keys($contact)) as $col) {
                 $pos     = strpos($col, ':');
                 $colname = $pos ? substr($col, 0, $pos) : $col;
 
                 foreach ((array)$contact[$col] as $val) {
-                    if ($advanced) {
+                    if (!empty($advanced)) {
                         $found[$colname] = $this->compare_search_value($colname, $val, $value[array_search($colname, $fields)], $mode);
                     }
                     else {
                         $contents .= ' ' . join(' ', (array)$val);
                     }
                 }
             }
 
             // compare matches
-            if (($advanced && count($found) >= $scount) ||
-                (!$advanced && rcube_utils::words_match(mb_strtolower($contents), $value))) {
+            if ((!empty($advanced) && count($found) >= $scount)
+                || (empty($advanced) && rcube_utils::words_match(mb_strtolower($contents), $value))
+            ) {
                 $this->filter['ids'][] = $id;
             }
         }
 
         // dummy result with contacts count
         if (!$select) {
             return new rcube_result_set(count($this->filter['ids']), ($this->list_page-1) * $this->page_size);
         }
 
         // list records (now limited by $this->filter)
         return $this->list_records();
     }
 
     /**
      * Refresh saved search results after data has changed
      */
     public function refresh_search()
     {
         if ($this->filter) {
             $this->search($this->filter['fields'], $this->filter['value'], $this->filter['mode']);
         }
 
         return $this->get_search_set();
     }
 
     /**
      * Count number of available contacts in database
      *
      * @return rcube_result_set Result set with values for 'count' and 'first'
      */
     public function count()
     {
         if ($this->gid) {
             $this->_fetch_groups();
             $count = count($this->distlists[$this->gid]['member']);
         }
         else if (is_array($this->filter['ids'])) {
             $count = count($this->filter['ids']);
         }
         else {
             $count = $this->storage->count('contact');
         }
 
         return new rcube_result_set($count, ($this->list_page-1) * $this->page_size);
     }
 
     /**
      * Return the last result set
      *
      * @return rcube_result_set Current result set or NULL if nothing selected yet
      */
     public function get_result()
     {
         return $this->result;
     }
 
     /**
      * Get a specific contact record
      *
      * @param mixed Record identifier(s)
      * @param bool  True to return record as associative array, otherwise a result set is returned
      *
      * @return mixed Result object with all record fields or False if not found
      */
     public function get_record($id, $assoc = false)
     {
         $rec = null;
         $uid = $this->id2uid($id);
         $rev = rcube_utils::get_input_value('_rev', rcube_utils::INPUT_GPC);
 
         if (strpos($uid, 'mailto:') === 0) {
             $this->_fetch_groups(true);
             $rec = $this->contacts[$id];
             $this->readonly = true;  // set source to read-only
         }
 /*
         else if (!empty($rev)) {
             $rcmail = rcube::get_instance();
             $plugin = $rcmail->plugins->get_plugin('kolab_addressbook');
             if ($plugin && ($object = $plugin->get_revision($id, kolab_storage::id_encode($this->imap_folder), $rev))) {
                 $rec = $this->_to_rcube_contact($object);
                 $rec['rev'] = $rev;
             }
             $this->readonly = true;  // set source to read-only
         }
 */
         else if ($object = $this->storage->get_object($uid)) {
             $rec = $this->_to_rcube_contact($object);
         }
 
         if ($rec) {
             $this->result = new rcube_result_set(1);
             $this->result->add($rec);
             return $assoc ? $rec : $this->result;
         }
 
         return false;
     }
 
     /**
      * Get group assignments of a specific contact record
      *
      * @param mixed Record identifier
      *
      * @return array List of assigned groups as ID=>Name pairs
      */
     public function get_record_groups($id)
     {
         $out = [];
         $this->_fetch_groups();
 
         if (!empty($this->groupmembers[$id])) {
             foreach ((array) $this->groupmembers[$id] as $gid) {
                 if (!empty($this->distlists[$gid])) {
                     $group = $this->distlists[$gid];
                     $out[$gid] = $group['name'];
                 }
             }
         }
 
         return $out;
     }
 
     /**
      * Create a new contact record
      *
      * @param array Associative array with save data
      *  Keys:   Field name with optional section in the form FIELD:SECTION
      *  Values: Field value. Can be either a string or an array of strings for multiple values
      * @param bool  True to check for duplicates first
      *
      * @return mixed The created record ID on success, False on error
      */
     public function insert($save_data, $check = false)
     {
         if (!is_array($save_data)) {
             return false;
         }
 
         $insert_id = $existing = false;
 
         // check for existing records by e-mail comparison
         if ($check) {
             foreach ($this->get_col_values('email', $save_data, true) as $email) {
                 if (($res = $this->search('email', $email, true, false)) && $res->count) {
                     $existing = true;
                     break;
                 }
             }
         }
 
         if (!$existing) {
             // Unset contact ID (e.g. when copying/moving from another addressbook)
             unset($save_data['ID'], $save_data['uid'], $save_data['_type']);
 
             // generate new Kolab contact item
             $object = $this->_from_rcube_contact($save_data);
             $saved  = $this->storage->save($object, 'contact');
 
             if (!$saved) {
                 rcube::raise_error([
                         'code' => 600, 'file' => __FILE__, 'line' => __LINE__,
                         'message' => "Error saving contact object to CardDAV server"
                     ],
                     true, false);
             }
             else {
                 $insert_id = $object['uid'];
             }
         }
 
         return $insert_id;
     }
 
     /**
      * Update a specific contact record
      *
      * @param mixed Record identifier
      * @param array Associative array with save data
      *  Keys:   Field name with optional section in the form FIELD:SECTION
      *  Values: Field value. Can be either a string or an array of strings for multiple values
      *
      * @return bool True on success, False on error
      */
     public function update($id, $save_data)
     {
         $updated = false;
         if ($old = $this->storage->get_object($this->id2uid($id))) {
             $object = $this->_from_rcube_contact($save_data, $old);
 
             if (!$this->storage->save($object, 'contact', $old['uid'])) {
                 rcube::raise_error([
                         'code' => 600, 'file' => __FILE__, 'line' => __LINE__,
                         'message' => "Error saving contact object to CardDAV server"
                     ],
                     true, false
                 );
             }
             else {
                 $updated = true;
 
                 // TODO: update data in groups this contact is member of
             }
         }
 
         return $updated;
     }
 
     /**
      * Mark one or more contact records as deleted
      *
      * @param array Record identifiers
      * @param bool  Remove record(s) irreversible (mark as deleted otherwise)
      *
      * @return int Number of records deleted
      */
     public function delete($ids, $force = true)
     {
         $this->_fetch_groups();
 
         if (!is_array($ids)) {
             $ids = explode(',', $ids);
         }
 
         $count = 0;
         foreach ($ids as $id) {
             if ($uid = $this->id2uid($id)) {
                 $is_mailto = strpos($uid, 'mailto:') === 0;
                 $deleted = $is_mailto || $this->storage->delete($uid, $force);
 
                 if (!$deleted) {
                     rcube::raise_error([
                             'code' => 600, 'file' => __FILE__, 'line' => __LINE__,
                             'message' => "Error deleting a contact object $uid from the CardDAV server"
                         ],
                         true, false
                     );
                 }
                 else {
                     // remove from distribution lists
                     foreach ((array) $this->groupmembers[$id] as $gid) {
                         if (!$is_mailto || $gid == $this->gid) {
                             $this->remove_from_group($gid, $id);
                         }
                     }
 
                     // clear internal cache
                     unset($this->groupmembers[$id]);
                     $count++;
                 }
             }
         }
 
         return $count;
     }
 
     /**
      * Undelete one or more contact records.
      * Only possible just after delete (see 2nd argument of delete() method).
      *
      * @param array Record identifiers
      *
      * @return int Number of records restored
      */
     public function undelete($ids)
     {
         if (!is_array($ids)) {
             $ids = explode(',', $ids);
         }
 
         $count = 0;
         foreach ($ids as $id) {
             $uid = $this->id2uid($id);
             if ($this->storage->undelete($uid)) {
                 $count++;
             }
             else {
                 rcube::raise_error([
                         'code' => 600, 'file' => __FILE__, 'line' => __LINE__,
                         'message' => "Error undeleting a contact object $uid from the CardDav server"
                     ],
                     true, false
                 );
             }
         }
 
         return $count;
     }
 
     /**
      * Remove all records from the database
      *
      * @param bool $with_groups Remove also groups
      */
     public function delete_all($with_groups = false)
     {
         if ($this->storage->delete_all()) {
             $this->contacts  = [];
             $this->sortindex = [];
             $this->dataset   = null;
             $this->result    = null;
         }
     }
 
     /**
      * Close connection to source
      * Called on script shutdown
      */
     public function close()
     {
         // NOP
     }
 
     /**
      * Create a contact group with the given name
      *
      * @param string The group name
      *
      * @return mixed False on error, array with record props in success
      */
     function create_group($name)
     {
         $this->_fetch_groups();
 
         $rcube = rcube::get_instance();
 
         $list = [
             'uid'    => strtoupper(md5(time() . uniqid(rand())) . '-' . substr(md5($rcube->user->get_username()), 0, 16)),
             'name'   => $name,
             'kind'   => 'group',
             'member' => [],
         ];
 
         $saved = $this->storage->save($list, 'contact');
 
         if (!$saved) {
             rcube::raise_error([
                     'code' => 600, 'file' => __FILE__, 'line' => __LINE__,
                     'message' => "Error saving a contact group to CardDAV server"
                 ],
                 true, false
             );
 
             return false;
         }
 
         $id = $this->uid2id($list['uid']);
 
         $this->distlists[$id] = $list;
 
         return ['id' => $id, 'name' => $name];
     }
 
     /**
      * Delete the given group and all linked group members
      *
      * @param string Group identifier
      *
      * @return bool True on success, false if no data was changed
      */
     function delete_group($gid)
     {
         $this->_fetch_groups();
 
         $list = $this->distlists[$gid];
 
         if (!$list) {
             return false;
         }
 
         $deleted = $this->storage->delete($list['uid']);
 
         if (!$deleted) {
             rcube::raise_error([
                     'code' => 600, 'file' => __FILE__, 'line' => __LINE__,
                     'message' => "Error deleting a contact group from the CardDAV server"
                 ],
                 true, false
             );
         }
 
         return $deleted;
     }
 
     /**
      * Rename a specific contact group
      *
      * @param string Group identifier
      * @param string New name to set for this group
      * @param string New group identifier (if changed, otherwise don't set)
      *
      * @return string|false New name on success, false if no data was changed
      */
     function rename_group($gid, $newname, &$newid)
     {
         $this->_fetch_groups();
 
         $list = $this->distlists[$gid];
 
         if (!$list) {
             return false;
         }
 
         if ($newname === $list['name']) {
             return $newname;
         }
 
         $list['name'] = $newname;
         $saved = $this->storage->save($list, 'contact', $list['uid']);
 
         if (!$saved) {
             rcube::raise_error([
                     'code' => 600, 'file' => __FILE__, 'line' => __LINE__,
                     'message' => "Error saving a contact group to CardDAV server"
                 ],
                 true, false
             );
 
             return false;
         }
 
         return $newname;
     }
 
     /**
      * Add the given contact records the a certain group
      *
      * @param string Group identifier
      * @param array  List of contact identifiers to be added
      *
      * @return int Number of contacts added
      */
     function add_to_group($gid, $ids)
     {
         if (!is_array($ids)) {
             $ids = explode(',', $ids);
         }
 
         $this->_fetch_groups(true);
 
         $list = $this->distlists[$gid];
 
         if (!$list) {
             return 0;
         }
 
         $added  = 0;
         $uids   = [];
         $exists = [];
 
         foreach ((array) $list['member'] as $member) {
             $exists[] = $member['ID'];
         }
 
         // substract existing assignments from list
         $ids = array_unique(array_diff($ids, $exists));
 
         // add mailto: members
         foreach ($ids as $contact_id) {
             $uid = $this->id2uid($contact_id);
             if (strpos($uid, 'mailto:') === 0 && ($contact = $this->contacts[$contact_id])) {
                 $list['member'][] = [
                     'email' => $contact['email'],
                     'name'  => $contact['name'],
                 ];
                 $this->groupmembers[$contact_id][] = $gid;
                 $added++;
             }
             else {
                 $uids[$uid] = $contact_id;
             }
         }
 
         // add members with UID
         if (!empty($uids)) {
             foreach ($uids as $uid => $contact_id) {
                 $list['member'][] = ['uid' => $uid];
                 $this->groupmembers[$contact_id][] = $gid;
                 $added++;
             }
         }
 
         if ($added) {
             $saved = $this->storage->save($list, 'contact', $list['uid']);
         }
         else {
             $saved = true;
         }
 
         if (!$saved) {
             rcube::raise_error([
                     'code' => 600, 'file' => __FILE__, 'line' => __LINE__,
                     'message' => "Error saving a contact-group to CardDAV server"
                 ],
                 true, false
             );
 
             $added = false;
             $this->set_error(self::ERROR_SAVING, 'errorsaving');
         }
         else {
             $this->distlists[$gid] = $list;
         }
 
         return $added;
     }
 
     /**
      * Remove the given contact records from a certain group
      *
      * @param string Group identifier
      * @param array  List of contact identifiers to be removed
      *
      * @return bool
      */
     function remove_from_group($gid, $ids)
     {
         $this->_fetch_groups();
 
         $list = $this->distlists[$gid];
 
         if (!$list) {
             return false;
         }
 
         if (!is_array($ids)) {
             $ids = explode(',', $ids);
         }
 
         $new_member = [];
         foreach ((array) $list['member'] as $member) {
             if (!in_array($member['ID'], $ids)) {
                 $new_member[] = $member;
             }
         }
 
         // write distribution list back to server
         $list['member'] = $new_member;
         $saved = $this->storage->save($list, 'contact', $list['uid']);
 
         if (!$saved) {
             rcube::raise_error([
                     'code' => 600, 'file' => __FILE__, 'line' => __LINE__,
                     'message' => "Error saving a contact group to CardDAV server"
                 ],
                 true, false
             );
         }
         else {
             // remove group assigments in local cache
             foreach ($ids as $id) {
                 $j = array_search($gid, $this->groupmembers[$id]);
                 unset($this->groupmembers[$id][$j]);
             }
 
             $this->distlists[$gid] = $list;
 
             return true;
         }
 
         return false;
     }
 
     /**
      * Check the given data before saving.
      * If input not valid, the message to display can be fetched using get_error()
      *
      * @param array Associative array with contact data to save
      * @param bool  Attempt to fix/complete data automatically
      *
      * @return bool True if input is valid, False if not.
      */
     public function validate(&$save_data, $autofix = false)
     {
         // validate e-mail addresses
         $valid = parent::validate($save_data);
 
         // require at least one e-mail address if there's no name
         // (syntax check is already done)
         if ($valid) {
             if (!strlen($save_data['name'])
                 && !strlen($save_data['organization'])
                 && !array_filter($this->get_col_values('email', $save_data, true))
             ) {
                 $this->set_error('warning', 'kolab_addressbook.noemailnamewarning');
                 $valid = false;
             }
         }
 
         return $valid;
     }
 
     /**
      * Query storage layer and store records in private member var
      */
     private function _fetch_contacts($query = [], $limit = false, $fast_mode = false)
     {
         if (!isset($this->dataset) || !empty($query)) {
             if ($limit) {
                 $size = is_int($limit) && $limit < $this->page_size ? $limit : $this->page_size;
                 $this->storage->set_order_and_limit($this->_sort_columns(), $size, ($this->list_page-1) * $this->page_size);
             }
 
             $this->sortindex = [];
             $this->dataset   = $this->storage->select($query, $fast_mode);
 
             foreach ($this->dataset as $idx => $record) {
                 $contact = $this->_to_rcube_contact($record);
                 $this->sortindex[$idx] = $this->_sort_string($contact);
             }
         }
     }
 
     /**
      * Extract a string for sorting from the given contact record
      */
     private function _sort_string($rec)
     {
         $str = '';
 
         switch ($this->sort_col) {
         case 'name':
             $str = ($rec['name'] ?? '') . ($rec['prefix'] ?? '');
         case 'firstname':
             $str .= ($rec['firstname'] ?? '') . ($rec['middlename'] ?? '') . ($rec['surname'] ?? '');
             break;
 
         case 'surname':
             $str = ($rec['surname'] ?? '') . ($rec['firstname'] ?? '') . ($rec['middlename'] ?? '');
             break;
 
         default:
             $str = $rec[$this->sort_col] ?? '';
             break;
         }
 
         if (!empty($rec['email'])) {
             $str .= is_array($rec['email']) ? $rec['email'][0] : $rec['email'];
         }
 
         return mb_strtolower($str);
     }
 
     /**
      * Return the cache table columns to order by
      */
     private function _sort_columns()
     {
         $sortcols = [];
 
         switch ($this->sort_col) {
         case 'name':
             $sortcols[] = 'name';
 
         case 'firstname':
             $sortcols[] = 'firstname';
             break;
 
         case 'surname':
             $sortcols[] = 'surname';
             break;
         }
 
         $sortcols[] = 'email';
         return $sortcols;
     }
 
     /**
      * Read contact groups from server
      */
     private function _fetch_groups($with_contacts = false)
     {
         if (!isset($this->distlists)) {
             $this->distlists = $this->groupmembers = [];
 
             // Set order (and LIMIT to skip the count(*) select)
             $this->storage->set_order_and_limit(['name'], 200, 0);
 
             foreach ($this->storage->select('group', true) as $record) {
                 $record['ID'] = $this->uid2id($record['uid']);
                 foreach ((array)$record['member'] as $i => $member) {
                     $mid = $this->uid2id($member['uid'] ? $member['uid'] : 'mailto:' . $member['email']);
                     $record['member'][$i]['ID'] = $mid;
                     $record['member'][$i]['readonly'] = empty($member['uid']);
                     $this->groupmembers[$mid][] = $record['ID'];
 
                     if ($with_contacts && empty($member['uid'])) {
                         $this->contacts[$mid] = $record['member'][$i];
                     }
                 }
 
                 $this->distlists[$record['ID']] = $record;
             }
 
             $this->storage->set_order_and_limit($this->_sort_columns(), null, 0);
         }
     }
 
     /**
      * Encode object UID into a safe identifier
      */
     public function uid2id($uid)
     {
         return rtrim(strtr(base64_encode($uid), '+/', '-_'), '=');
     }
 
     /**
      * Convert Roundcube object identifier back into the original UID
      */
     public function id2uid($id)
     {
         return base64_decode(str_pad(strtr($id, '-_', '+/'), strlen($id) % 4, '=', STR_PAD_RIGHT));
     }
 
     /**
      * Build SQL query for fulltext matches
      */
     private function _search_query($fields, $value, $mode)
     {
         $query = [];
         $cols  = [];
 
         $cols = array_intersect($fields, $this->fulltext_cols);
 
         if (count($cols)) {
             if ($mode & rcube_addressbook::SEARCH_STRICT) {
                 $prefix = '^'; $suffix = '$';
             }
             else if ($mode & rcube_addressbook::SEARCH_PREFIX) {
                 $prefix = '^'; $suffix = '';
             }
             else {
                 $prefix = ''; $suffix = '';
             }
 
             $search_string = is_array($value) ? join(' ', $value) : $value;
             foreach (rcube_utils::normalize_string($search_string, true) as $word) {
                 $query[] = ['words', 'LIKE', $prefix . $word . $suffix];
             }
         }
 
         return $query;
     }
 
     /**
      * Map fields from internal Kolab_Format to Roundcube contact format
      */
     private function _to_rcube_contact($record)
     {
         $record['ID'] = $this->uid2id($record['uid']);
 
         // remove empty fields
         $record = array_filter($record);
 
         // Set _type for proper icon on the list
         $record['_type'] = 'person';
 
         return $record;
     }
 
     /**
      * Map fields from Roundcube format to internal kolab_format_contact properties
      */
     private function _from_rcube_contact($contact, $old = [])
     {
         if (empty($contact['uid']) && !empty($contact['ID'])) {
             $contact['uid'] = $this->id2uid($contact['ID']);
         }
         else if (empty($contact['uid']) && !empty($old['uid'])) {
             $contact['uid'] = $old['uid'];
         }
         else if (empty($contact['uid'])) {
             $rcube = rcube::get_instance();
             $contact['uid'] = strtoupper(md5(time() . uniqid(rand())) . '-' . substr(md5($rcube->user->get_username()), 0, 16));
         }
 
         // When importing contacts 'vcard' data might be added, we don't need it (Bug #1711)
         unset($contact['vcard']);
 
         return $contact;
     }
 }
diff --git a/plugins/libkolab/config.inc.php.dist b/plugins/libkolab/config.inc.php.dist
index 9801af37..ca8a769e 100644
--- a/plugins/libkolab/config.inc.php.dist
+++ b/plugins/libkolab/config.inc.php.dist
@@ -1,87 +1,90 @@
 <?php
 
 /* Configuration for libkolab */
 
 // Enable caching of Kolab objects in local database
 $config['kolab_cache'] = true;
 
 // Specify format version to write Kolab objects (must be a string value!)
 $config['kolab_format_version']  = '3.0';
 
 // Optional override of the URL to read and trigger Free/Busy information of Kolab users
 // Defaults to /freebusy or https://<imap-server->/freebusy
+// Note that we add <email>.ifb path automatically, with optional query parameeters.
+// You can prevent addition of path by specifying an URL with %u variable, e.g.
+// "https://dav.domain.tld/freebusy/user/%u" (works with Cyrus v3 Freebusy service).
 $config['kolab_freebusy_server'] = null;
 
 // Enables listing of only subscribed folders. This e.g. will limit
 // folders in calendar view or available addressbooks
 $config['kolab_use_subscriptions'] = false;
 
 // List any of 'personal','shared','other' namespaces to be excluded from groupware folder listing
 // example: array('other');
 $config['kolab_skip_namespace'] = null;
 
 // Enables the use of displayname folder annotations as introduced in KEP:?
 // for displaying resource folder names (experimental!)
 $config['kolab_custom_display_names'] = false;
 
 // Configuration of HTTP requests.
 // See http://pear.php.net/manual/en/package.http.http-request2.config.php
 // for list of supported configuration options (array keys)
 $config['kolab_http_request'] = array();
 
 // When kolab_cache is enabled Roundcube's messages cache will be redundant
 // when working on kolab folders. Here we can:
 // 3 - bypass only indexes, but use messages cache
 // 2 - bypass both messages and indexes cache
 // 1 - bypass only messages, but use index cache
 $config['kolab_messages_cache_bypass'] = 0;
 
 // These event properties contribute to a significant revision to the calendar component
 // and if changed will increment the sequence number relevant for scheduling according to RFC 5545
 $config['kolab_event_scheduling_properties'] = array('start', 'end', 'allday', 'recurrence', 'location', 'status', 'cancelled');
 
 // These task properties contribute to a significant revision to the calendar component
 // and if changed will increment the sequence number relevant for scheduling according to RFC 5545
 $config['kolab_task_scheduling_properties'] = array('start', 'due', 'summary', 'status');
 
 // LDAP directory to find avilable users for folder sharing.
 // Either contains an array with LDAP addressbook configuration or refers to entry in $config['ldap_public'].
 // If not specified, the configuraton from 'kolab_auth_addressbook' will be used.
 // Should be provided for multi-domain setups with placeholders like %dc, %d, %u, %fu or %dn.
 $config['kolab_users_directory'] = null;
 
 // Filter to be used for resolving user folders in LDAP.
 // Defaults to the 'kolab_auth_filter' configuration option.
 $config['kolab_users_filter'] = '(&(objectclass=kolabInetOrgPerson)(|(uid=%u)(mail=%fu)))';
 
 // Which property of the LDAP user record to use for user folder mapping in IMAP.
 // Defaults to the 'kolab_auth_login' configuration option.
 $config['kolab_users_id_attrib'] = null;
 
 // Use these attributes when searching users in LDAP
 $config['kolab_users_search_attrib'] = array('cn','mail','alias');
 
 // Which property of the LDAP user record to use as a display name.
 // Defaults to the 'kolab_auth_name' configuration option.
 $config['kolab_users_name_field'] = null;
 
 // Type of cache for uid-to-user map. Supported: 'db', 'apc', 'memcache' and 'memcached'.
 // Note: This stores only other user folder identifier to user attributes map.
 $config['kolab_users_cache'] = null;
 
 // lifetime of shared folder mapping cache
 // possible units: s, m, h, d, w
 $config['kolab_users_cache_ttl'] = '10d';
 
 // JSON-RPC endpoint configuration of the Bonnie web service providing historic data for groupware objects
 $config['kolab_bonnie_api'] = null;
 /*
 $config['kolab_bonnie_api'] = array(
     'uri'    => 'https://<kolab-hostname>:8080/api/rpc',
     'user'   => 'webclient',
     'pass'   => 'Welcome2KolabSystems',
     'secret' => '8431f191707fffffff00000000cccc',
     'debug'  => true,   // logs requests/responses to <log-dir>/bonnie
     'timeout' => 30,
 );
 */
diff --git a/plugins/libkolab/lib/kolab_storage.php b/plugins/libkolab/lib/kolab_storage.php
index 795a4319..6d9db480 100644
--- a/plugins/libkolab/lib/kolab_storage.php
+++ b/plugins/libkolab/lib/kolab_storage.php
@@ -1,1795 +1,1810 @@
 <?php
 
 /**
  * Kolab storage class providing static methods to access groupware objects on a Kolab server.
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  * @author Aleksander Machniak <machniak@kolabsys.com>
  *
  * Copyright (C) 2012-2014, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 class kolab_storage
 {
     const CTYPE_KEY         = '/shared/vendor/kolab/folder-type';
     const CTYPE_KEY_PRIVATE = '/private/vendor/kolab/folder-type';
     const COLOR_KEY_SHARED  = '/shared/vendor/kolab/color';
     const COLOR_KEY_PRIVATE = '/private/vendor/kolab/color';
     const NAME_KEY_SHARED   = '/shared/vendor/kolab/displayname';
     const NAME_KEY_PRIVATE  = '/private/vendor/kolab/displayname';
     const UID_KEY_SHARED    = '/shared/vendor/kolab/uniqueid';
     const UID_KEY_CYRUS     = '/shared/vendor/cmu/cyrus-imapd/uniqueid';
 
     const ERROR_IMAP_CONN      = 1;
     const ERROR_CACHE_DB       = 2;
     const ERROR_NO_PERMISSION  = 3;
     const ERROR_INVALID_FOLDER = 4;
 
     public static $version = '3.0';
     public static $last_error;
     public static $encode_ids = false;
 
     private static $ready = false;
     private static $with_tempsubs = true;
     private static $subscriptions;
     private static $ldapcache = array();
     private static $ldap = array();
     private static $states;
     private static $config;
     private static $imap;
 
 
     // Default folder names
     private static $default_folders = array(
         'event'         => 'Calendar',
         'contact'       => 'Contacts',
         'task'          => 'Tasks',
         'note'          => 'Notes',
         'file'          => 'Files',
         'configuration' => 'Configuration',
         'journal'       => 'Journal',
         'mail.inbox'       => 'INBOX',
         'mail.drafts'      => 'Drafts',
         'mail.sentitems'   => 'Sent',
         'mail.wastebasket' => 'Trash',
         'mail.outbox'      => 'Outbox',
         'mail.junkemail'   => 'Junk',
     );
 
 
     /**
      * Setup the environment needed by the libs
      */
     public static function setup()
     {
         if (self::$ready)
             return true;
 
         $rcmail = rcube::get_instance();
         self::$config  = $rcmail->config;
         self::$version = strval($rcmail->config->get('kolab_format_version', self::$version));
         self::$imap    = $rcmail->get_storage();
         self::$ready   = class_exists('kolabformat') &&
             (self::$imap->get_capability('METADATA') || self::$imap->get_capability('ANNOTATEMORE') || self::$imap->get_capability('ANNOTATEMORE2'));
 
         if (self::$ready) {
             // do nothing
         }
         else if (!class_exists('kolabformat')) {
             rcube::raise_error(array(
                 'code' => 900, 'type' => 'php',
                 'message' => "required kolabformat module not found"
             ), true);
         }
         else if (self::$imap->get_error_code()) {
             rcube::raise_error(array(
                 'code' => 900, 'type' => 'php', 'message' => "IMAP error"
             ), true);
         }
 
         // adjust some configurable settings
         if ($event_scheduling_prop = $rcmail->config->get('kolab_event_scheduling_properties', null)) {
             kolab_format_event::$scheduling_properties = (array)$event_scheduling_prop;
         }
         // adjust some configurable settings
         if ($task_scheduling_prop = $rcmail->config->get('kolab_task_scheduling_properties', null)) {
             kolab_format_task::$scheduling_properties = (array)$task_scheduling_prop;
         }
 
         return self::$ready;
     }
 
     /**
      * Initializes LDAP object to resolve Kolab users
      *
      * @param string $name Name of the configuration option with LDAP config
      */
     public static function ldap($name = 'kolab_users_directory')
     {
         self::setup();
 
         $config = self::$config->get($name);
 
         if (empty($config)) {
             $name   = 'kolab_auth_addressbook';
             $config = self::$config->get($name);
         }
 
         if (self::$ldap[$name]) {
             return self::$ldap[$name];
         }
 
         if (!is_array($config)) {
             $ldap_config = (array)self::$config->get('ldap_public');
             $config = $ldap_config[$config];
         }
 
         if (empty($config)) {
             return null;
         }
 
         $ldap = new kolab_ldap($config);
 
         // overwrite filter option
         if ($filter = self::$config->get('kolab_users_filter')) {
             self::$config->set('kolab_auth_filter', $filter);
         }
 
         $user_field = $user_attrib = self::$config->get('kolab_users_id_attrib');
 
         // Fallback to kolab_auth_login, which is not attribute, but field name
         if (!$user_field && ($user_field = self::$config->get('kolab_auth_login', 'email'))) {
             $user_attrib = $config['fieldmap'][$user_field];
         }
 
         if ($user_field && $user_attrib) {
             $ldap->extend_fieldmap(array($user_field => $user_attrib));
         }
 
         self::$ldap[$name] = $ldap;
 
         return $ldap;
     }
 
     /**
      * Get a list of storage folders for the given data type
      *
      * @param string Data type to list folders for (contact,distribution-list,event,task,note)
      * @param boolean Enable to return subscribed folders only (null to use configured subscription mode)
      *
      * @return array List of Kolab_Folder objects (folder names in UTF7-IMAP)
      */
     public static function get_folders($type, $subscribed = null)
     {
         $folders = $folderdata = array();
 
         if (self::setup()) {
             foreach ((array)self::list_folders('', '*', $type, $subscribed, $folderdata) as $foldername) {
                 $folders[$foldername] = new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
             }
         }
 
         return $folders;
     }
 
     /**
      * Getter for the storage folder for the given type
      *
      * @param string Data type to list folders for (contact,distribution-list,event,task,note)
      * @return object kolab_storage_folder  The folder object
      */
     public static function get_default_folder($type)
     {
         if (self::setup()) {
             foreach ((array)self::list_folders('', '*', $type . '.default', false, $folderdata) as $foldername) {
                 return new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
             }
         }
 
         return null;
     }
 
     /**
      * Getter for a specific storage folder
      *
      * @param string IMAP folder to access (UTF7-IMAP)
      * @param string Expected folder type
      *
      * @return object kolab_storage_folder  The folder object
      */
     public static function get_folder($folder, $type = null)
     {
         return self::setup() ? new kolab_storage_folder($folder, $type) : null;
     }
 
     /**
      * Getter for a single Kolab object, identified by its UID.
      * This will search all folders storing objects of the given type.
      *
      * @param string Object UID
      * @param string Object type (contact,event,task,journal,file,note,configuration)
      * @return array The Kolab object represented as hash array or false if not found
      */
     public static function get_object($uid, $type)
     {
         self::setup();
         $folder = null;
         foreach ((array)self::list_folders('', '*', $type, null, $folderdata) as $foldername) {
             if (!$folder)
                 $folder = new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
             else
                 $folder->set_folder($foldername, $type, $folderdata[$foldername]);
 
             if ($object = $folder->get_object($uid))
                 return $object;
         }
 
         return false;
     }
 
     /**
      * Execute cross-folder searches with the given query.
      *
      * @param array  Pseudo-SQL query as list of filter parameter triplets
      * @param string Folder type (contact,event,task,journal,file,note,configuration)
      * @param int    Expected number of records or limit (for performance reasons)
      *
      * @return array List of Kolab data objects (each represented as hash array)
      * @see kolab_storage_format::select()
      */
     public static function select($query, $type, $limit = null)
     {
         self::setup();
         $folder = null;
         $result = array();
 
         foreach ((array)self::list_folders('', '*', $type, null, $folderdata) as $foldername) {
             $folder = new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
 
             if ($limit) {
                 $folder->set_order_and_limit(null, $limit);
             }
 
             foreach ($folder->select($query) as $object) {
                 $result[] = $object;
             }
         }
 
         return $result;
     }
 
     /**
      * Returns Free-busy server URL
      */
     public static function get_freebusy_server()
     {
-        self::setup();
+        $rcmail = rcube::get_instance();
 
         $url = 'https://' . $_SESSION['imap_host'] . '/freebusy';
-        $url = self::$config->get('kolab_freebusy_server', $url);
+        $url = $rcmail->config->get('kolab_freebusy_server', $url);
         $url = rcube_utils::resolve_url($url);
 
         return unslashify($url);
     }
 
     /**
      * Compose an URL to query the free/busy status for the given user
      *
      * @param string Email address of the user to get free/busy data for
      * @param object DateTime Start of the query range (optional)
      * @param object DateTime End of the query range (optional)
      *
      * @return string Fully qualified URL to query free/busy data
      */
     public static function get_freebusy_url($email, $start = null, $end = null)
     {
         $query = '';
         $param = array();
         $utc = new \DateTimeZone('UTC');
 
+        // https://www.calconnect.org/pubdocs/CD0903%20Freebusy%20Read%20URL.pdf
+
         if ($start instanceof \DateTime) {
             $start->setTimezone($utc);
-            $param['dtstart'] = $start->format('Ymd\THis\Z');
+            $param['start'] = $param['dtstart'] = $start->format('Ymd\THis\Z');
         }
+
         if ($end instanceof \DateTime) {
             $end->setTimezone($utc);
-            $param['dtend'] = $end->format('Ymd\THis\Z');
+            $param['end'] = $param['dtend'] = $end->format('Ymd\THis\Z');
         }
+
         if (!empty($param)) {
             $query = '?' . http_build_query($param);
         }
 
-        return self::get_freebusy_server() . '/' . $email . '.ifb' . $query;
+        $url = self::get_freebusy_server();
+
+        if (strpos($url, '%u')) {
+            // Expected configured full URL, just replace the %u variable
+            // Note: Cyrus v3 Free-Busy service does not use .ifb extension
+            $url = str_replace('%u', rawurlencode($email), $url);
+        }
+        else {
+            $url .= '/' . $email . '.ifb';
+        }
+
+        return $url . $query;
     }
 
     /**
      * Creates folder ID from folder name
      *
      * @param string  $folder Folder name (UTF7-IMAP)
      * @param boolean $enc    Use lossless encoding
      * @return string Folder ID string
      */
     public static function folder_id($folder, $enc = null)
     {
         return $enc == true || ($enc === null && self::$encode_ids) ?
             self::id_encode($folder) :
             asciiwords(strtr($folder, '/.-', '___'));
     }
 
     /**
      * Encode the given ID to a safe ascii representation
      *
      * @param string $id Arbitrary identifier string
      *
      * @return string Ascii representation
      */
     public static function id_encode($id)
     {
         return rtrim(strtr(base64_encode($id), '+/', '-_'), '=');
     }
 
     /**
      * Convert the given identifier back to it's raw value
      *
      * @param string $id Ascii identifier
      * @return string Raw identifier string
      */
     public static function id_decode($id)
     {
       return base64_decode(str_pad(strtr($id, '-_', '+/'), strlen($id) % 4, '=', STR_PAD_RIGHT));
     }
 
     /**
      * Return the (first) path of the requested IMAP namespace
      *
      * @param string  Namespace name (personal, shared, other)
      * @return string IMAP root path for that namespace
      */
     public static function namespace_root($name)
     {
         self::setup();
 
         foreach ((array)self::$imap->get_namespace($name) as $paths) {
             if (strlen($paths[0]) > 1) {
                 return $paths[0];
             }
         }
 
         return '';
     }
 
     /**
      * Deletes IMAP folder
      *
      * @param string $name Folder name (UTF7-IMAP)
      *
      * @return bool True on success, false on failure
      */
     public static function folder_delete($name)
     {
         // clear cached entries first
         if ($folder = self::get_folder($name))
             $folder->cache->purge();
 
         $rcmail = rcube::get_instance();
         $plugin = $rcmail->plugins->exec_hook('folder_delete', array('name' => $name));
 
         $success = self::$imap->delete_folder($name);
         self::$last_error = self::$imap->get_error_str();
 
         return $success;
     }
 
     /**
      * Creates IMAP folder
      *
      * @param string $name       Folder name (UTF7-IMAP)
      * @param string $type       Folder type
      * @param bool   $subscribed Sets folder subscription
      * @param bool   $active     Sets folder state (client-side subscription)
      *
      * @return bool True on success, false on failure
      */
     public static function folder_create($name, $type = null, $subscribed = false, $active = false)
     {
         self::setup();
 
         $rcmail = rcube::get_instance();
         $plugin = $rcmail->plugins->exec_hook('folder_create', array('record' => array(
             'name' => $name,
             'subscribe' => $subscribed,
         )));
 
         if ($saved = self::$imap->create_folder($name, $subscribed)) {
             // set metadata for folder type
             if ($type) {
                 $saved = self::set_folder_type($name, $type);
 
                 // revert if metadata could not be set
                 if (!$saved) {
                     self::$imap->delete_folder($name);
                 }
                 // activate folder
                 else if ($active) {
                     self::set_state($name, true);
                 }
             }
         }
 
         if ($saved) {
             return true;
         }
 
         self::$last_error = self::$imap->get_error_str();
         return false;
     }
 
     /**
      * Renames IMAP folder
      *
      * @param string $oldname Old folder name (UTF7-IMAP)
      * @param string $newname New folder name (UTF7-IMAP)
      *
      * @return bool True on success, false on failure
      */
     public static function folder_rename($oldname, $newname)
     {
         self::setup();
 
         $rcmail = rcube::get_instance();
         $plugin = $rcmail->plugins->exec_hook('folder_rename', array(
             'oldname' => $oldname, 'newname' => $newname));
 
         $oldfolder = self::get_folder($oldname);
         $active    = self::folder_is_active($oldname);
         $success   = self::$imap->rename_folder($oldname, $newname);
         self::$last_error = self::$imap->get_error_str();
 
         // pass active state to new folder name
         if ($success && $active) {
             self::set_state($oldname, false);
             self::set_state($newname, true);
         }
 
         // assign existing cache entries to new resource uri
         if ($success && $oldfolder) {
             $oldfolder->cache->rename($newname);
         }
 
         return $success;
     }
 
     /**
      * Rename or Create a new IMAP folder.
      *
      * Does additional checks for permissions and folder name restrictions
      *
      * @param array &$prop Hash array with folder properties and metadata
      *  - name:       Folder name
      *  - oldname:    Old folder name when changed
      *  - parent:     Parent folder to create the new one in
      *  - type:       Folder type to create
      *  - subscribed: Subscribed flag (IMAP subscription)
      *  - active:     Activation flag (client-side subscription)
      *
      * @return string|false New folder name or False on failure
      *
      * @see self::set_folder_props() for list of other properties
      */
     public static function folder_update(&$prop)
     {
         self::setup();
 
         $folder    = rcube_charset::convert($prop['name'], RCUBE_CHARSET, 'UTF7-IMAP');
         $oldfolder = $prop['oldname']; // UTF7
         $parent    = $prop['parent']; // UTF7
         $delimiter = self::$imap->get_hierarchy_delimiter();
 
         if (strlen($oldfolder)) {
             $options = self::$imap->folder_info($oldfolder);
         }
 
         if (!empty($options) && ($options['norename'] || $options['protected'])) {
         }
         // sanity checks (from steps/settings/save_folder.inc)
         else if (!strlen($folder)) {
             self::$last_error = 'cannotbeempty';
             return false;
         }
         else if (strlen($folder) > 128) {
             self::$last_error = 'nametoolong';
             return false;
         }
         else {
             // these characters are problematic e.g. when used in LIST/LSUB
             foreach (array($delimiter, '%', '*') as $char) {
                 if (strpos($folder, $char) !== false) {
                     self::$last_error = 'forbiddencharacter';
                     return false;
                 }
             }
         }
 
         if (!empty($options) && ($options['protected'] || $options['norename'])) {
             $folder = $oldfolder;
         }
         else if (strlen($parent)) {
             $folder = $parent . $delimiter . $folder;
         }
         else {
             // add namespace prefix (when needed)
             $folder = self::$imap->mod_folder($folder, 'in');
         }
 
         // Check access rights to the parent folder
         if (strlen($parent) && (!strlen($oldfolder) || $oldfolder != $folder)) {
             $parent_opts = self::$imap->folder_info($parent);
             if ($parent_opts['namespace'] != 'personal'
                 && (empty($parent_opts['rights']) || !preg_match('/[ck]/', implode($parent_opts['rights'])))
             ) {
                 self::$last_error = 'No permission to create folder';
                 return false;
             }
         }
 
         // update the folder name
         if (strlen($oldfolder)) {
             if ($oldfolder != $folder) {
                 $result = self::folder_rename($oldfolder, $folder);
             }
             else {
                 $result = true;
             }
         }
         // create new folder
         else {
             $result = self::folder_create($folder, $prop['type'], $prop['subscribed'], $prop['active']);
         }
 
         if ($result) {
             self::set_folder_props($folder, $prop);
         }
 
         return $result ? $folder : false;
     }
 
     /**
      * Getter for human-readable name of Kolab object (folder)
      * with kolab_custom_display_names support.
      * See http://wiki.kolab.org/UI-Concepts/Folder-Listing for reference
      *
      * @param string $folder    IMAP folder name (UTF7-IMAP)
      * @param string $folder_ns Will be set to namespace name of the folder
      *
      * @return string Name of the folder-object
      */
     public static function object_name($folder, &$folder_ns=null)
     {
         // find custom display name in folder METADATA
         if ($name = self::custom_displayname($folder)) {
             return $name;
         }
 
         return self::object_prettyname($folder, $folder_ns);
     }
 
     /**
      * Get custom display name (saved in metadata) for the given folder
      */
     public static function custom_displayname($folder)
     {
         static $_metadata;
 
         // find custom display name in folder METADATA
         if (self::$config->get('kolab_custom_display_names', true) && self::setup()) {
             if ($_metadata !== null) {
                 $metadata = $_metadata;
             }
             else {
                 // For performance reasons ask for all folders, it will be cached as one cache entry
                 $metadata = self::$imap->get_metadata("*", array(self::NAME_KEY_PRIVATE, self::NAME_KEY_SHARED));
 
                 // If cache is disabled store result in memory
                 if (!self::$config->get('imap_cache')) {
                     $_metadata = $metadata;
                 }
             }
 
             if ($data = $metadata[$folder]) {
                 if (($name = $data[self::NAME_KEY_PRIVATE]) || ($name = $data[self::NAME_KEY_SHARED])) {
                     return $name;
                 }
             }
         }
 
         return false;
     }
 
     /**
      * Getter for human-readable name of Kolab object (folder)
      * See http://wiki.kolab.org/UI-Concepts/Folder-Listing for reference
      *
      * @param string $folder    IMAP folder name (UTF7-IMAP)
      * @param string $folder_ns Will be set to namespace name of the folder
      *
      * @return string Name of the folder-object
      */
     public static function object_prettyname($folder, &$folder_ns=null)
     {
         self::setup();
 
         $found     = false;
         $namespace = self::$imap->get_namespace();
 
         if (!empty($namespace['shared'])) {
             foreach ($namespace['shared'] as $ns) {
                 if (strlen($ns[0]) && strpos($folder, $ns[0]) === 0) {
                     $prefix = '';
                     $folder = substr($folder, strlen($ns[0]));
                     $delim  = $ns[1];
                     $found  = true;
                     $folder_ns = 'shared';
                     break;
                 }
             }
         }
 
         if (!$found && !empty($namespace['other'])) {
             foreach ($namespace['other'] as $ns) {
                 if (strlen($ns[0]) && strpos($folder, $ns[0]) === 0) {
                     // remove namespace prefix and extract username
                     $folder = substr($folder, strlen($ns[0]));
                     $delim  = $ns[1];
 
                     // get username part and map it to user name
                     $pos = strpos($folder, $delim);
                     $fid = $pos ? substr($folder, 0, $pos) : $folder;
 
                     if ($user = self::folder_id2user($fid, true)) {
                         $fid = str_replace($delim, '', $user);
                     }
 
                     $prefix = "($fid)";
                     $folder = $pos ? substr($folder, $pos + 1) : '';
                     $found  = true;
                     $folder_ns = 'other';
                     break;
                 }
             }
         }
 
         if (!$found && !empty($namespace['personal'])) {
             foreach ($namespace['personal'] as $ns) {
                 if (strlen($ns[0]) && strpos($folder, $ns[0]) === 0) {
                     // remove namespace prefix
                     $folder = substr($folder, strlen($ns[0]));
                     $prefix = '';
                     $delim  = $ns[1];
                     $found  = true;
                     break;
                 }
             }
         }
 
         if (empty($delim))
             $delim = self::$imap->get_hierarchy_delimiter();
 
         $folder = rcube_charset::convert($folder, 'UTF7-IMAP');
         $folder = html::quote($folder);
         $folder = str_replace(html::quote($delim), ' &raquo; ', $folder);
 
         if ($prefix)
             $folder = html::quote($prefix) . ($folder !== '' ? ' ' . $folder : '');
 
         if (!$folder_ns)
             $folder_ns = 'personal';
 
         return $folder;
     }
 
     /**
      * Helper method to generate a truncated folder name to display.
      * Note: $origname is a string returned by self::object_name()
      */
     public static function folder_displayname($origname, &$names)
     {
         $name = $origname;
 
         // find folder prefix to truncate
         for ($i = count($names)-1; $i >= 0; $i--) {
             if (strpos($name, $names[$i] . ' &raquo; ') === 0) {
                 $length = strlen($names[$i] . ' &raquo; ');
                 $prefix = substr($name, 0, $length);
                 $count  = count(explode(' &raquo; ', $prefix));
                 $diff   = 1;
 
                 // check if prefix folder is in other users namespace
                 for ($n = count($names)-1; $n >= 0; $n--) {
                     if (strpos($prefix, '(' . $names[$n] . ') ') === 0) {
                         $diff = 0;
                         break;
                     }
                 }
 
                 $name = str_repeat('&nbsp;&nbsp;&nbsp;', $count - $diff) . '&raquo; ' . substr($name, $length);
                 break;
             }
             // other users namespace and parent folder exists
             else if (strpos($name, '(' . $names[$i] . ') ') === 0) {
                 $length = strlen('(' . $names[$i] . ') ');
                 $prefix = substr($name, 0, $length);
                 $count  = count(explode(' &raquo; ', $prefix));
                 $name   = str_repeat('&nbsp;&nbsp;&nbsp;', $count) . '&raquo; ' . substr($name, $length);
                 break;
             }
         }
 
         $names[] = $origname;
 
         return $name;
     }
 
     /**
      * Creates a SELECT field with folders list
      *
      * @param string $type    Folder type
      * @param array  $attrs   SELECT field attributes (e.g. name)
      * @param string $current The name of current folder (to skip it)
      *
      * @return html_select SELECT object
      */
     public static function folder_selector($type, $attrs, $current = '')
     {
         // get all folders of specified type (sorted)
         $folders = self::get_folders($type, true);
 
         $delim = self::$imap->get_hierarchy_delimiter();
         $names = array();
         $len   = strlen($current);
 
         if ($len && ($rpos = strrpos($current, $delim))) {
             $parent = substr($current, 0, $rpos);
             $p_len  = strlen($parent);
         }
 
         // Filter folders list
         foreach ($folders as $c_folder) {
             $name = $c_folder->name;
 
             // skip current folder and it's subfolders
             if ($len) {
                 if ($name == $current) {
                     // Make sure parent folder is listed (might be skipped e.g. if it's namespace root)
                     if ($p_len && !isset($names[$parent])) {
                         $names[$parent] = self::object_name($parent);
                     }
                     continue;
                 }
                 if (strpos($name, $current.$delim) === 0) {
                     continue;
                 }
             }
 
             // always show the parent of current folder
             if ($p_len && $name == $parent) {
             }
             // skip folders where user have no rights to create subfolders
             else if ($c_folder->get_owner() != $_SESSION['username']) {
                 $rights = $c_folder->get_myrights();
                 if (!preg_match('/[ck]/', $rights)) {
                     continue;
                 }
             }
 
             $names[$name] = $c_folder->get_name();
         }
 
         // Build SELECT field of parent folder
         $attrs['is_escaped'] = true;
         $select = new html_select($attrs);
         $select->add('---', '');
 
         $listnames = array();
         foreach (array_keys($names) as $imap_name) {
             $name = $origname = $names[$imap_name];
 
             // find folder prefix to truncate
             for ($i = count($listnames)-1; $i >= 0; $i--) {
                 if (strpos($name, $listnames[$i].' &raquo; ') === 0) {
                     $length = strlen($listnames[$i].' &raquo; ');
                     $prefix = substr($name, 0, $length);
                     $count  = count(explode(' &raquo; ', $prefix));
                     $name   = str_repeat('&nbsp;&nbsp;', $count-1) . '&raquo; ' . substr($name, $length);
                     break;
                 }
             }
 
             $listnames[] = $origname;
             $select->add($name, $imap_name);
         }
 
         return $select;
     }
 
     /**
      * Returns a list of folder names
      *
      * @param string  Optional root folder
      * @param string  Optional name pattern
      * @param string  Data type to list folders for (contact,event,task,journal,file,note,mail,configuration)
      * @param boolean Enable to return subscribed folders only (null to use configured subscription mode)
      * @param array   Will be filled with folder-types data
      *
      * @return array List of folders
      */
     public static function list_folders($root = '', $mbox = '*', $filter = null, $subscribed = null, &$folderdata = array())
     {
         if (!self::setup()) {
             return null;
         }
 
         // use IMAP subscriptions
         if ($subscribed === null && self::$config->get('kolab_use_subscriptions')) {
             $subscribed = true;
         }
 
         if (!$filter) {
             // Get ALL folders list, standard way
             if ($subscribed) {
                 $folders = self::_imap_list_subscribed($root, $mbox, $filter);
             }
             else {
                 $folders = self::_imap_list_folders($root, $mbox);
             }
 
             return $folders;
         }
         $prefix = $root . $mbox;
         $regexp = '/^' . preg_quote($filter, '/') . '(\..+)?$/';
 
         // get folders types for all folders
         $folderdata = self::folders_typedata($prefix);
 
         if (!is_array($folderdata)) {
             return array();
         }
 
         // If we only want groupware folders and don't care about the subscription state,
         // then the metadata will already contain all folder names and we can avoid the LIST below.
         if (!$subscribed && $filter != 'mail' && $prefix == '*') {
             foreach ($folderdata as $folder => $type) {
                 if (!preg_match($regexp, $type)) {
                     unset($folderdata[$folder]);
                 }
             }
 
             return self::$imap->sort_folder_list(array_keys($folderdata), true);
         }
 
         // Get folders list
         if ($subscribed) {
             $folders = self::_imap_list_subscribed($root, $mbox, $filter);
         }
         else {
             $folders = self::_imap_list_folders($root, $mbox);
         }
 
         // In case of an error, return empty list (?)
         if (!is_array($folders)) {
             return array();
         }
 
         // Filter folders list
         foreach ($folders as $idx => $folder) {
             $type = $folderdata[$folder];
 
             if ($filter == 'mail' && empty($type)) {
                 continue;
             }
             if (empty($type) || !preg_match($regexp, $type)) {
                 unset($folders[$idx]);
             }
         }
 
         return $folders;
     }
 
     /**
      * Wrapper for rcube_imap::list_folders() with optional post-filtering
      */
     protected static function _imap_list_folders($root, $mbox)
     {
         $postfilter = null;
 
         // compose a post-filter expression for the excluded namespaces
         if ($root . $mbox == '*' && ($skip_ns = self::$config->get('kolab_skip_namespace'))) {
             $excludes = array();
             foreach ((array)$skip_ns as $ns) {
                 if ($ns_root = self::namespace_root($ns)) {
                     $excludes[] = $ns_root;
                 }
             }
 
             if (count($excludes)) {
                 $postfilter = '!^(' . join(')|(', array_map('preg_quote', $excludes)) . ')!';
             }
         }
 
         // use normal LIST command to return all folders, it's fast enough
         $folders = self::$imap->list_folders($root, $mbox, null, null, !empty($postfilter));
 
         if (!empty($postfilter)) {
             $folders = array_filter($folders, function($folder) use ($postfilter) { return !preg_match($postfilter, $folder); });
             $folders = self::$imap->sort_folder_list($folders);
         }
 
         return $folders;
     }
 
     /**
      * Wrapper for rcube_imap::list_folders_subscribed()
      * with support for temporarily subscribed folders
      */
     protected static function _imap_list_subscribed($root, $mbox, $filter = null)
     {
         $folders = self::$imap->list_folders_subscribed($root, $mbox);
 
         // add temporarily subscribed folders
         if ($filter != 'mail' && self::$with_tempsubs && is_array($_SESSION['kolab_subscribed_folders'])) {
             $folders = array_unique(array_merge($folders, $_SESSION['kolab_subscribed_folders']));
         }
 
         return $folders;
     }
 
     /**
      * Search for shared or otherwise not listed groupware folders the user has access
      *
      * @param string Folder type of folders to search for
      * @param string Search string
      * @param array  Namespace(s) to exclude results from
      *
      * @return array List of matching kolab_storage_folder objects
      */
     public static function search_folders($type, $query, $exclude_ns = array())
     {
         if (!self::setup()) {
             return array();
         }
 
         $folders = array();
         $query = str_replace('*', '', $query);
 
         // find unsubscribed IMAP folders of the given type
         foreach ((array)self::list_folders('', '*', $type, false, $folderdata) as $foldername) {
             // FIXME: only consider the last part of the folder path for searching?
             $realname = strtolower(rcube_charset::convert($foldername, 'UTF7-IMAP'));
             if (($query == '' || strpos($realname, $query) !== false) &&
                 !self::folder_is_subscribed($foldername, true) &&
                 !in_array(self::$imap->folder_namespace($foldername), (array)$exclude_ns)
               ) {
                 $folders[] = new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
             }
         }
 
         return $folders;
     }
 
     /**
      * Sort the given list of kolab folders by namespace/name
      *
      * @param array List of kolab_storage_folder objects
      * @return array Sorted list of folders
      */
     public static function sort_folders($folders)
     {
         $pad     = '  ';
         $out     = array();
         $nsnames = array('personal' => array(), 'shared' => array(), 'other' => array());
 
         foreach ($folders as $folder) {
             $_folders[$folder->name] = $folder;
             $ns = $folder->get_namespace();
             $nsnames[$ns][$folder->name] = strtolower(html_entity_decode($folder->get_name(), ENT_COMPAT, RCUBE_CHARSET)) . $pad;  // decode &raquo;
         }
 
         // $folders is a result of get_folders() we can assume folders were already sorted
         foreach (array_keys($nsnames) as $ns) {
             asort($nsnames[$ns], SORT_LOCALE_STRING);
             foreach (array_keys($nsnames[$ns]) as $utf7name) {
                 $out[] = $_folders[$utf7name];
             }
         }
 
         return $out;
     }
 
     /**
      * Check the folder tree and add the missing parents as virtual folders
      *
      * @param array $folders Folders list
      * @param object $tree   Reference to the root node of the folder tree
      *
      * @return array Flat folders list
      */
     public static function folder_hierarchy($folders, &$tree = null)
     {
         if (!self::setup()) {
             return array();
         }
 
         $_folders = array();
         $delim    = self::$imap->get_hierarchy_delimiter();
         $other_ns = rtrim(self::namespace_root('other'), $delim);
         $tree     = new kolab_storage_folder_virtual('', '<root>', '');  // create tree root
         $refs     = array('' => $tree);
 
         foreach ($folders as $idx => $folder) {
             $path = explode($delim, $folder->name);
             array_pop($path);
             $folder->parent = join($delim, $path);
             $folder->children = array();  // reset list
 
             // skip top folders or ones with a custom displayname
             if (count($path) < 1 || kolab_storage::custom_displayname($folder->name)) {
                 $tree->children[] = $folder;
             }
             else {
                 $parents = array();
                 $depth = $folder->get_namespace() == 'personal' ? 1 : 2;
 
                 while (count($path) >= $depth && ($parent = join($delim, $path))) {
                     array_pop($path);
                     $parent_parent = join($delim, $path);
 
                     if (!$refs[$parent]) {
                         if ($folder->type && self::folder_type($parent) == $folder->type) {
                             $refs[$parent] = new kolab_storage_folder($parent, $folder->type, $folder->type);
                             $refs[$parent]->parent = $parent_parent;
                         }
                         else if ($parent_parent == $other_ns) {
                             $refs[$parent] = new kolab_storage_folder_user($parent, $parent_parent);
                         }
                         else {
                             $name = kolab_storage::object_name($parent);
                             $refs[$parent] = new kolab_storage_folder_virtual($parent, $name, $folder->get_namespace(), $parent_parent);
                         }
                         $parents[] = $refs[$parent];
                     }
                 }
 
                 if (!empty($parents)) {
                     $parents = array_reverse($parents);
                     foreach ($parents as $parent) {
                         $parent_node = $refs[$parent->parent] ?: $tree;
                         $parent_node->children[] = $parent;
                         $_folders[] = $parent;
                     }
                 }
 
                 $parent_node = $refs[$folder->parent] ?: $tree;
                 $parent_node->children[] = $folder;
             }
 
             $refs[$folder->name] = $folder;
             $_folders[] = $folder;
             unset($folders[$idx]);
         }
 
         return $_folders;
     }
 
     /**
      * Returns folder types indexed by folder name
      *
      * @param string $prefix Folder prefix (Default '*' for all folders)
      *
      * @return array|bool List of folders, False on failure
      */
     public static function folders_typedata($prefix = '*')
     {
         if (!self::setup()) {
             return false;
         }
 
         $type_keys = array(self::CTYPE_KEY, self::CTYPE_KEY_PRIVATE);
 
         // fetch metadata from *some* folders only
         if (($prefix == '*' || $prefix == '') && ($skip_ns = self::$config->get('kolab_skip_namespace'))) {
             $delimiter = self::$imap->get_hierarchy_delimiter();
             $folderdata = $blacklist = array();
             foreach ((array)$skip_ns as $ns) {
                 if ($ns_root = rtrim(self::namespace_root($ns), $delimiter)) {
                     $blacklist[] = $ns_root;
                 }
             }
             foreach (array('personal','other','shared') as $ns) {
                 if (!in_array($ns, (array)$skip_ns)) {
                     $ns_root = rtrim(self::namespace_root($ns), $delimiter);
 
                     // list top-level folders and their childs one by one
                     // GETMETADATA "%" doesn't list shared or other namespace folders but "*" would
                     if ($ns_root == '') {
                         foreach ((array)self::$imap->get_metadata('%', $type_keys) as $folder => $metadata) {
                             if (!in_array($folder, $blacklist)) {
                                 $folderdata[$folder] = $metadata;
                                 $opts = self::$imap->folder_attributes($folder);
                                 if (!in_array('\\HasNoChildren', $opts) && ($data = self::$imap->get_metadata($folder.$delimiter.'*', $type_keys))) {
                                     $folderdata += $data;
                                 }
                             }
                         }
                     }
                     else if ($data = self::$imap->get_metadata($ns_root.$delimiter.'*', $type_keys)) {
                         $folderdata += $data;
                     }
                 }
             }
         }
         else {
             $folderdata = self::$imap->get_metadata($prefix, $type_keys);
         }
 
         if (!is_array($folderdata)) {
             return false;
         }
 
         return array_map(array('kolab_storage', 'folder_select_metadata'), $folderdata);
     }
 
     /**
      * Callback for array_map to select the correct annotation value
      */
     public static function folder_select_metadata($types)
     {
         if (!empty($types[self::CTYPE_KEY_PRIVATE])) {
             return $types[self::CTYPE_KEY_PRIVATE];
         }
         else if (!empty($types[self::CTYPE_KEY])) {
             list($ctype, ) = explode('.', $types[self::CTYPE_KEY]);
             return $ctype;
         }
         return null;
     }
 
     /**
      * Returns type of IMAP folder
      *
      * @param string $folder Folder name (UTF7-IMAP)
      *
      * @return string Folder type
      */
     public static function folder_type($folder)
     {
         self::setup();
 
         $metadata = self::$imap->get_metadata($folder, array(self::CTYPE_KEY, self::CTYPE_KEY_PRIVATE));
 
         if (!is_array($metadata)) {
             return null;
         }
 
         if (!empty($metadata[$folder])) {
             return self::folder_select_metadata($metadata[$folder]);
         }
 
         return 'mail';
     }
 
     /**
      * Sets folder content-type.
      *
      * @param string $folder Folder name
      * @param string $type   Content type
      *
      * @return boolean True on success
      */
     public static function set_folder_type($folder, $type='mail')
     {
         self::setup();
 
         list($ctype, $subtype) = explode('.', $type);
 
         $success = self::$imap->set_metadata($folder, array(self::CTYPE_KEY => $ctype, self::CTYPE_KEY_PRIVATE => $subtype ? $type : null));
 
         if (!$success)  // fallback: only set private annotation
             $success |= self::$imap->set_metadata($folder, array(self::CTYPE_KEY_PRIVATE => $type));
 
         return $success;
     }
 
     /**
      * Check subscription status of this folder
      *
      * @param string $folder Folder name
      * @param boolean $temp  Include temporary/session subscriptions
      *
      * @return boolean True if subscribed, false if not
      */
     public static function folder_is_subscribed($folder, $temp = false)
     {
         if (self::$subscriptions === null) {
             self::setup();
             self::$with_tempsubs = false;
             self::$subscriptions = self::$imap->list_folders_subscribed();
             self::$with_tempsubs = true;
         }
 
         return in_array($folder, self::$subscriptions) ||
             ($temp && in_array($folder, (array)$_SESSION['kolab_subscribed_folders']));
     }
 
     /**
      * Change subscription status of this folder
      *
      * @param string $folder Folder name
      * @param boolean $temp  Only subscribe temporarily for the current session
      *
      * @return True on success, false on error
      */
     public static function folder_subscribe($folder, $temp = false)
     {
         self::setup();
 
         // temporary/session subscription
         if ($temp) {
             if (self::folder_is_subscribed($folder)) {
                 return true;
             }
             else if (!is_array($_SESSION['kolab_subscribed_folders']) || !in_array($folder, $_SESSION['kolab_subscribed_folders'])) {
                 $_SESSION['kolab_subscribed_folders'][] = $folder;
                 return true;
             }
         }
         else if (self::$imap->subscribe($folder)) {
             self::$subscriptions = null;
             return true;
         }
 
         return false;
     }
 
     /**
      * Change subscription status of this folder
      *
      * @param string $folder Folder name
      * @param boolean $temp  Only remove temporary subscription
      *
      * @return True on success, false on error
      */
     public static function folder_unsubscribe($folder, $temp = false)
     {
         self::setup();
 
         // temporary/session subscription
         if ($temp) {
             if (is_array($_SESSION['kolab_subscribed_folders']) && ($i = array_search($folder, $_SESSION['kolab_subscribed_folders'])) !== false) {
                 unset($_SESSION['kolab_subscribed_folders'][$i]);
             }
             return true;
         }
         else if (self::$imap->unsubscribe($folder)) {
             self::$subscriptions = null;
             return true;
         }
 
         return false;
     }
 
     /**
      * Check activation status of this folder
      *
      * @param string $folder Folder name
      *
      * @return boolean True if active, false if not
      */
     public static function folder_is_active($folder)
     {
         $active_folders = self::get_states();
 
         return in_array($folder, $active_folders);
     }
 
     /**
      * Change activation status of this folder
      *
      * @param string $folder Folder name
      *
      * @return True on success, false on error
      */
     public static function folder_activate($folder)
     {
         // activation implies temporary subscription
         self::folder_subscribe($folder, true);
         return self::set_state($folder, true);
     }
 
     /**
      * Change activation status of this folder
      *
      * @param string $folder Folder name
      *
      * @return True on success, false on error
      */
     public static function folder_deactivate($folder)
     {
         // remove from temp subscriptions, really?
         self::folder_unsubscribe($folder, true);
 
         return self::set_state($folder, false);
     }
 
     /**
      * Return list of active folders
      */
     private static function get_states()
     {
         if (self::$states !== null) {
             return self::$states;
         }
 
         $rcube   = rcube::get_instance();
         $folders = $rcube->config->get('kolab_active_folders');
 
         if ($folders !== null) {
             self::$states = !empty($folders) ? explode('**', $folders) : array();
         }
         // for backward-compatibility copy server-side subscriptions to activation states
         else {
             self::setup();
             if (self::$subscriptions === null) {
                 self::$with_tempsubs = false;
                 self::$subscriptions = self::$imap->list_folders_subscribed();
                 self::$with_tempsubs = true;
             }
             self::$states = (array) self::$subscriptions;
             $folders = implode('**', self::$states);
             $rcube->user->save_prefs(array('kolab_active_folders' => $folders));
         }
 
         return self::$states;
     }
 
     /**
      * Update list of active folders
      */
     private static function set_state($folder, $state)
     {
         self::get_states();
 
         // update in-memory list
         $idx = array_search($folder, self::$states);
         if ($state && $idx === false) {
             self::$states[] = $folder;
         }
         else if (!$state && $idx !== false) {
             unset(self::$states[$idx]);
         }
 
         // update user preferences
         $folders = implode('**', self::$states);
 
         return rcube::get_instance()->user->save_prefs(array('kolab_active_folders' => $folders));
     }
 
     /**
      * Creates default folder of specified type
      * To be run when none of subscribed folders (of specified type) is found
      *
      * @param string $type  Folder type
      * @param string $props Folder properties (color, etc)
      *
      * @return string Folder name
      */
     public static function create_default_folder($type, $props = array())
     {
         if (!self::setup()) {
             return;
         }
 
         $folders = self::$imap->get_metadata('*', array(kolab_storage::CTYPE_KEY_PRIVATE));
 
         // from kolab_folders config
         $folder_type  = strpos($type, '.') ? str_replace('.', '_', $type) : $type . '_default';
         $default_name = self::$config->get('kolab_folders_' . $folder_type);
         $folder_type  = str_replace('_', '.', $folder_type);
 
         // check if we have any folder in personal namespace
         // folder(s) may exist but not subscribed
         foreach ((array)$folders as $f => $data) {
             if (strpos($data[self::CTYPE_KEY_PRIVATE], $type) === 0) {
                 $folder = $f;
                 break;
             }
         }
 
         if (!$folder) {
             if (!$default_name) {
                 $default_name = self::$default_folders[$type];
             }
 
             if (!$default_name) {
                 return;
             }
 
             $folder = rcube_charset::convert($default_name, RCUBE_CHARSET, 'UTF7-IMAP');
             $prefix = self::$imap->get_namespace('prefix');
 
             // add personal namespace prefix if needed
             if ($prefix && strpos($folder, $prefix) !== 0 && $folder != 'INBOX') {
                 $folder = $prefix . $folder;
             }
 
             if (!self::$imap->folder_exists($folder)) {
                 if (!self::$imap->create_folder($folder)) {
                     return;
                 }
             }
 
             self::set_folder_type($folder, $folder_type);
         }
 
         self::folder_subscribe($folder);
 
         if ($props['active']) {
             self::set_state($folder, true);
         }
 
         if (!empty($props)) {
             self::set_folder_props($folder, $props);
         }
 
         return $folder;
     }
 
     /**
      * Sets folder metadata properties
      *
      * @param string $folder Folder name
      * @param array  &$prop  Folder properties (color, displayname)
      */
     public static function set_folder_props($folder, &$prop)
     {
         if (!self::setup()) {
             return;
         }
 
         // TODO: also save 'showalarams' and other properties here
         $ns        = self::$imap->folder_namespace($folder);
         $supported = array(
             'color'       => array(self::COLOR_KEY_SHARED, self::COLOR_KEY_PRIVATE),
             'displayname' => array(self::NAME_KEY_SHARED, self::NAME_KEY_PRIVATE),
         );
 
         foreach ($supported as $key => $metakeys) {
             if (array_key_exists($key, $prop)) {
                 $meta_saved = false;
                 if ($ns == 'personal')  // save in shared namespace for personal folders
                     $meta_saved = self::$imap->set_metadata($folder, array($metakeys[0] => $prop[$key]));
                 if (!$meta_saved)    // try in private namespace
                     $meta_saved = self::$imap->set_metadata($folder, array($metakeys[1] => $prop[$key]));
                 if ($meta_saved)
                     unset($prop[$key]);  // unsetting will prevent fallback to local user prefs
             }
         }
     }
 
     /**
      * Search users in Kolab LDAP storage
      *
      * @param mixed   $query    Search value (or array of field => value pairs)
      * @param int     $mode     Matching mode: 0 - partial (*abc*), 1 - strict (=), 2 - prefix (abc*)
      * @param array   $required List of fields that shall ot be empty
      * @param int     $limit    Maximum number of records
      * @param int     $count    Returns the number of records found
      *
      * @return array List of users
      */
     public static function search_users($query, $mode = 1, $required = array(), $limit = 0, &$count = 0)
     {
         $query = str_replace('*', '', $query);
 
         // requires a working LDAP setup
         if (!strlen($query) || !($ldap = self::ldap())) {
             return array();
         }
 
         $root          = self::namespace_root('other');
         $user_attrib   = self::$config->get('kolab_users_id_attrib', self::$config->get('kolab_auth_login', 'mail'));
         $search_attrib = self::$config->get('kolab_users_search_attrib', array('cn','mail','alias'));
 
         // search users using the configured attributes
         $results = $ldap->dosearch($search_attrib, $query, $mode, $required, $limit, $count);
 
         // exclude myself
         if ($_SESSION['kolab_dn']) {
             unset($results[$_SESSION['kolab_dn']]);
         }
 
         // resolve to IMAP folder name
         array_walk($results, function(&$user, $dn) use ($root, $user_attrib) {
             list($localpart, ) = explode('@', $user[$user_attrib]);
             $user['kolabtargetfolder'] = $root . $localpart;
         });
 
         return $results;
     }
 
     /**
      * Returns a list of IMAP folders shared by the given user
      *
      * @param array   User entry from LDAP
      * @param string  Data type to list folders for (contact,event,task,journal,file,note,mail,configuration)
      * @param int     1 - subscribed folders only, 0 - all folders, 2 - all non-active
      * @param array   Will be filled with folder-types data
      *
      * @return array List of folders
      */
     public static function list_user_folders($user, $type, $subscribed = 0, &$folderdata = array())
     {
         self::setup();
 
         $folders = array();
 
         // use localpart of user attribute as root for folder listing
         $user_attrib = self::$config->get('kolab_users_id_attrib', self::$config->get('kolab_auth_login', 'mail'));
         if (!empty($user[$user_attrib])) {
             list($mbox) = explode('@', $user[$user_attrib]);
 
             $delimiter  = self::$imap->get_hierarchy_delimiter();
             $other_ns   = self::namespace_root('other');
             $prefix     = $other_ns . $mbox . $delimiter;
             $subscribed = (int) $subscribed;
             $subs       = $subscribed < 2 ? (bool) $subscribed : false;
             $folders    = self::list_folders($prefix, '*', $type, $subs, $folderdata);
 
             if ($subscribed === 2 && !empty($folders)) {
                 $active = self::get_states();
                 if (!empty($active)) {
                     $folders = array_diff($folders, $active);
                 }
             }
         }
 
         return $folders;
     }
 
     /**
      * Get a list of (virtual) top-level folders from the other users namespace
      *
      * @param string  Data type to list folders for (contact,event,task,journal,file,note,mail,configuration)
      * @param boolean Enable to return subscribed folders only (null to use configured subscription mode)
      *
      * @return array List of kolab_storage_folder_user objects
      */
     public static function get_user_folders($type, $subscribed)
     {
         $folders = $folderdata = array();
 
         if (self::setup()) {
             $delimiter = self::$imap->get_hierarchy_delimiter();
             $other_ns = rtrim(self::namespace_root('other'), $delimiter);
             $path_len = count(explode($delimiter, $other_ns));
 
             foreach ((array)self::list_folders($other_ns . $delimiter, '*', '', $subscribed) as $foldername) {
                 if ($foldername == 'INBOX')  // skip INBOX which is added by default
                     continue;
 
                 $path = explode($delimiter, $foldername);
 
                 // compare folder type if a subfolder is listed
                 if ($type && count($path) > $path_len + 1 && $type != self::folder_type($foldername)) {
                     continue;
                 }
 
                 // truncate folder path to top-level folders of the 'other' namespace
                 $foldername = join($delimiter, array_slice($path, 0, $path_len + 1));
 
                 if (!$folders[$foldername]) {
                     $folders[$foldername] = new kolab_storage_folder_user($foldername, $other_ns);
                 }
             }
 
             // for every (subscribed) user folder, list all (unsubscribed) subfolders
             foreach ($folders as $userfolder) {
                 foreach ((array)self::list_folders($userfolder->name . $delimiter, '*', $type, false, $folderdata) as $foldername) {
                     if (!$folders[$foldername]) {
                         $folders[$foldername] = new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
                         $userfolder->children[] = $folders[$foldername];
                     }
                 }
             }
         }
 
         return $folders;
     }
 
     /**
      * Handler for user_delete plugin hooks
      *
      * Remove all cache data from the local database related to the given user.
      */
     public static function delete_user_folders($args)
     {
         $db = rcmail::get_instance()->get_dbh();
         $prefix = 'imap://' . urlencode($args['username']) . '@' . $args['host'] . '/%';
         $db->query("DELETE FROM " . $db->table_name('kolab_folders', true) . " WHERE `resource` LIKE ?", $prefix);
 
     }
 
     /**
      * Get folder METADATA for all supported keys
      * Do this in one go for better caching performance
      */
     public static function folder_metadata($folder)
     {
         if (self::setup()) {
             $keys = array(
                 // For better performance we skip displayname here, see (self::custom_displayname())
                 // self::NAME_KEY_PRIVATE,
                 // self::NAME_KEY_SHARED,
                 self::CTYPE_KEY,
                 self::CTYPE_KEY_PRIVATE,
                 self::COLOR_KEY_PRIVATE,
                 self::COLOR_KEY_SHARED,
                 self::UID_KEY_SHARED,
                 self::UID_KEY_CYRUS,
             );
 
             $metadata = self::$imap->get_metadata($folder, $keys);
 
             return $metadata[$folder];
         }
     }
 
     /**
      * Get user attributes for specified other user (imap) folder identifier.
      *
      * @param string $folder_id Folder name w/o path (imap user identifier)
      * @param bool   $as_string Return configured display name attribute value
      *
      * @return array User attributes
      * @see self::ldap()
      */
     public static function folder_id2user($folder_id, $as_string = false)
     {
         static $domain, $cache, $name_attr;
 
         $rcube = rcube::get_instance();
 
         if ($domain === null) {
             list(, $domain) = explode('@', $rcube->get_user_name());
         }
 
         if ($name_attr === null) {
             $name_attr = (array) ($rcube->config->get('kolab_users_name_field', $rcube->config->get('kolab_auth_name')) ?: 'name');
         }
 
         $token = $folder_id;
         if ($domain && strpos($find, '@') === false) {
             $token .= '@' . $domain;
         }
 
         if ($cache === null) {
             $cache = $rcube->get_cache_shared('kolab_users') ?: false;
         }
 
         // use value cached in memory for repeated lookups
         if (!$cache && array_key_exists($token, self::$ldapcache)) {
             $user = self::$ldapcache[$token];
         }
 
         if (empty($user) && $cache) {
             $user = $cache->get($token);
         }
 
         if (empty($user) && ($ldap = self::ldap())) {
             $user = $ldap->get_user_record($token, $_SESSION['imap_host']);
 
             if (!empty($user)) {
                 $keys = array('displayname', 'name', 'mail'); // supported keys
                 $user = array_intersect_key($user, array_flip($keys));
 
                 if (!empty($user)) {
                     if ($cache) {
                         $cache->set($token, $user);
                     }
                     else {
                         self::$ldapcache[$token] = $user;
                     }
                 }
             }
         }
 
         if (!empty($user)) {
             if ($as_string) {
                 foreach ($name_attr as $attr) {
                     if ($display = $user[$attr]) {
                         break;
                     }
                 }
 
                 if (!$display) {
                     $display = $user['displayname'] ?: $user['name'];
                 }
 
                 if ($display && $display != $folder_id) {
                     $display = "$display ($folder_id)";
                 }
 
                 return $display;
             }
 
             return $user;
         }
     }
 
     /**
      * Chwala's 'folder_mod' hook handler for mapping other users folder names
      */
     public static function folder_mod($args)
     {
         static $roots;
 
         if ($roots === null) {
             self::setup();
             $roots = self::$imap->get_namespace('other');
         }
 
         // Note: We're working with UTF7-IMAP encoding here
 
         if ($args['dir'] == 'in') {
             foreach ((array) $roots as $root) {
                 if (strpos($args['folder'], $root[0]) === 0) {
                     // remove root and explode folder
                     $delim  = $root[1];
                     $folder = explode($delim, substr($args['folder'], strlen($root[0])));
                     // compare first (user) part with a regexp, it's supposed
                     // to look like this: "Doe, Jane (uid)", so we can extract the uid
                     // and replace the folder with it
                     if (preg_match('~^[^/]+ \(([^)]+)\)$~', $folder[0], $m)) {
                         $folder[0] = $m[1];
                         $args['folder'] = $root[0] . implode($delim, $folder);
                     }
 
                     break;
                 }
             }
         }
         else { // dir == 'out'
             foreach ((array) $roots as $root) {
                 if (strpos($args['folder'], $root[0]) === 0) {
                     // remove root and explode folder
                     $delim  = $root[1];
                     $folder = explode($delim, substr($args['folder'], strlen($root[0])));
 
                     // Replace uid with "Doe, Jane (uid)"
                     if ($user = self::folder_id2user($folder[0], true)) {
                         $user      = str_replace($delim, '', $user);
                         $folder[0] = rcube_charset::convert($user, RCUBE_CHARSET, 'UTF7-IMAP');
 
                         $args['folder'] = $root[0] . implode($delim, $folder);
                     }
 
                     break;
                 }
             }
         }
 
         return $args;
     }
 }
diff --git a/plugins/libkolab/libkolab.php b/plugins/libkolab/libkolab.php
index 5b0ecbbe..eb5b1c10 100644
--- a/plugins/libkolab/libkolab.php
+++ b/plugins/libkolab/libkolab.php
@@ -1,389 +1,392 @@
 <?php
 
 /**
  * Kolab core library
  *
  * Plugin to setup a basic environment for the interaction with a Kolab server.
  * Other Kolab-related plugins will depend on it and can use the library classes
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2012-2015, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 class libkolab extends rcube_plugin
 {
     static $http_requests = array();
     static $bonnie_api    = false;
 
     /**
      * Required startup method of a Roundcube plugin
      */
     public function init()
     {
         // load local config
         $this->load_config();
         $this->require_plugin('libcalendaring');
 
         // extend include path to load bundled lib classes
         $include_path = $this->home . '/lib' . PATH_SEPARATOR . ini_get('include_path');
         set_include_path($include_path);
 
         $this->add_hook('storage_init', array($this, 'storage_init'));
         $this->add_hook('storage_connect', array($this, 'storage_connect'));
         $this->add_hook('user_delete', array('kolab_storage', 'delete_user_folders'));
 
         // For Chwala
         $this->add_hook('folder_mod', array('kolab_storage', 'folder_mod'));
 
         $rcmail = rcube::get_instance();
         try {
             kolab_format::$timezone = new DateTimeZone($rcmail->config->get('timezone', 'GMT'));
         }
         catch (Exception $e) {
             rcube::raise_error($e, true);
             kolab_format::$timezone = new DateTimeZone('GMT');
         }
 
         $this->add_texts('localization/', false);
 
         if (!empty($rcmail->output->type) && $rcmail->output->type == 'html') {
             $rcmail->output->add_handler('libkolab.folder_search_form', array($this, 'folder_search_form'));
             $this->include_stylesheet($this->local_skin_path() . '/libkolab.css');
         }
 
         // embed scripts and templates for email message audit trail
         if ($rcmail->task == 'mail' && self::get_bonnie_api()) {
             if ($rcmail->output->type == 'html') {
                 $this->add_hook('render_page', array($this, 'bonnie_render_page'));
                 $this->include_script('libkolab.js');
 
                 // add 'Show history' item to message menu
                 $this->api->add_content(html::tag('li', array('role' => 'menuitem'),
                     $this->api->output->button(array(
                         'command'  => 'kolab-mail-history',
                         'label'    => 'libkolab.showhistory',
                         'type'     => 'link',
                         'classact' => 'icon history active',
                         'class'    => 'icon history disabled',
                         'innerclass' => 'icon history',
                     ))),
                     'messagemenu');
             }
 
             $this->register_action('plugin.message-changelog', array($this, 'message_changelog'));
         }
     }
 
     /**
      * Hook into IMAP FETCH HEADER.FIELDS command and request Kolab-specific headers
      */
     function storage_init($p)
     {
         $kolab_headers = 'X-KOLAB-TYPE X-KOLAB-MIME-VERSION MESSAGE-ID';
 
         if (!empty($p['fetch_headers'])) {
             $p['fetch_headers'] .= ' ' . $kolab_headers;
         }
         else {
             $p['fetch_headers'] = $kolab_headers;
         }
 
         return $p;
     }
 
     /**
      * Hook into IMAP connection to replace client identity
      */
     function storage_connect($p)
     {
         $client_name = 'Roundcube/Kolab';
 
         if (empty($p['ident'])) {
             $p['ident'] = array(
                 'name'    => $client_name,
                 'version' => RCUBE_VERSION,
 /*
                 'php'     => PHP_VERSION,
                 'os'      => PHP_OS,
                 'command' => $_SERVER['REQUEST_URI'],
 */
             );
         }
         else {
             $p['ident']['name'] = $client_name;
         }
 
         return $p;
     }
 
     /**
      * Getter for a singleton instance of the Bonnie API
      *
      * @return mixed kolab_bonnie_api instance if configured, false otherwise
      */
     public static function get_bonnie_api()
     {
         // get configuration for the Bonnie API
         if (!self::$bonnie_api && ($bonnie_config = rcube::get_instance()->config->get('kolab_bonnie_api', false))) {
             self::$bonnie_api = new kolab_bonnie_api($bonnie_config);
         }
 
         return self::$bonnie_api;
     }
 
     /**
      * Hook to append the message history dialog template to the mail view
      */
     function bonnie_render_page($p)
     {
         if (($p['template'] === 'mail' || $p['template'] === 'message') && !$p['kolab-audittrail']) {
             // append a template for the audit trail dialog
             $this->api->output->add_footer(
                 html::div(array('id' => 'mailmessagehistory',  'class' => 'uidialog', 'aria-hidden' => 'true', 'style' => 'display:none'),
                     self::object_changelog_table(array('class' => 'records-table changelog-table'))
                 )
             );
             $this->api->output->set_env('kolab_audit_trail', true);
             $p['kolab-audittrail'] = true;
         }
 
         return $p;
     }
 
     /**
      * Handler for message audit trail changelog requests
      */
     public function message_changelog()
     {
         if (!self::$bonnie_api) {
             return false;
         }
 
         $rcmail = rcube::get_instance();
         $msguid = rcube_utils::get_input_value('_uid', rcube_utils::INPUT_POST, true);
         $mailbox = rcube_utils::get_input_value('_mbox', rcube_utils::INPUT_POST);
 
         $result = $msguid && $mailbox ? self::$bonnie_api->changelog('mail', null, $mailbox, $msguid) : null;
         if (is_array($result)) {
             if (is_array($result['changes'])) {
                 $dtformat = $rcmail->config->get('date_format') . ' ' . $rcmail->config->get('time_format');
                 array_walk($result['changes'], function(&$change) use ($dtformat, $rcmail) {
                   if ($change['date']) {
                       $dt = rcube_utils::anytodatetime($change['date']);
                       if ($dt instanceof DateTimeInterface) {
                           $change['date'] = $rcmail->format_date($dt, $dtformat);
                       }
                   }
                 });
             }
             $this->api->output->command('plugin.message_render_changelog', $result['changes']);
         }
         else {
             $this->api->output->command('plugin.message_render_changelog', false);
         }
 
         $this->api->output->send();
     }
 
     /**
      * Wrapper function to load and initalize the HTTP_Request2 Object
      *
      * @param string|Net_Url2 Request URL
      * @param string          Request method ('OPTIONS','GET','HEAD','POST','PUT','DELETE','TRACE','CONNECT')
      * @param array           Configuration for this Request instance, that will be merged
      *                        with default configuration
      *
      * @return HTTP_Request2 Request object
      */
     public static function http_request($url = '', $method = 'GET', $config = array())
     {
         $rcube       = rcube::get_instance();
         $http_config = (array) $rcube->config->get('kolab_http_request');
 
         // deprecated configuration options
         if (empty($http_config)) {
             foreach (array('ssl_verify_peer', 'ssl_verify_host') as $option) {
                 $value = $rcube->config->get('kolab_' . $option, true);
                 if (is_bool($value)) {
                     $http_config[$option] = $value;
                 }
             }
         }
 
         if (!empty($config)) {
             $http_config = array_merge($http_config, $config);
         }
 
         // force CURL adapter, this allows to handle correctly
         // compressed responses with SplObserver registered (kolab_files) (#4507)
         $http_config['adapter'] = 'HTTP_Request2_Adapter_Curl';
 
         $key = md5(serialize($http_config));
 
-        if (!($request = self::$http_requests[$key])) {
+        if (!empty(self::$http_requests[$key])) {
+            $request = self::$http_requests[$key];
+        }
+        else {
             // load HTTP_Request2 (support both composer-installed and system-installed package)
             if (!class_exists('HTTP_Request2')) {
                 require_once 'HTTP/Request2.php';
             }
 
             try {
                 $request = new HTTP_Request2();
                 $request->setConfig($http_config);
             }
             catch (Exception $e) {
                 rcube::raise_error($e, true, true);
             }
 
             // proxy User-Agent string
             $request->setHeader('user-agent', $_SERVER['HTTP_USER_AGENT']);
 
             self::$http_requests[$key] = $request;
         }
 
         // cleanup
         try {
             $request->setBody('');
             $request->setUrl($url);
             $request->setMethod($method);
         }
         catch (Exception $e) {
             rcube::raise_error($e, true, true);
         }
 
         return $request;
     }
 
     /**
      * Table oultine for object changelog display
      */
     public static function object_changelog_table($attrib = array())
     {
         $rcube = rcube::get_instance();
         $attrib += array('domain' => 'libkolab');
 
         $table = new html_table(array('cols' => 5, 'border' => 0, 'cellspacing' => 0));
         $table->add_header('diff',      '');
         $table->add_header('revision',  $rcube->gettext('revision', $attrib['domain']));
         $table->add_header('date',      $rcube->gettext('date', $attrib['domain']));
         $table->add_header('user',      $rcube->gettext('user', $attrib['domain']));
         $table->add_header('operation', $rcube->gettext('operation', $attrib['domain']));
         $table->add_header('actions',   '&nbsp;');
 
         $rcube->output->add_label(
             'libkolab.showrevision',
             'libkolab.actionreceive',
             'libkolab.actionappend',
             'libkolab.actionmove',
             'libkolab.actiondelete',
             'libkolab.actionread',
             'libkolab.actionflagset',
             'libkolab.actionflagclear',
             'libkolab.objectchangelog',
             'libkolab.objectchangelognotavailable',
             'close'
         );
 
         return $table->show($attrib);
     }
 
     /**
      * Wrapper function for generating a html diff using the FineDiff class by Raymond Hill
      */
     public static function html_diff($from, $to, $is_html = null)
     {
         // auto-detect text/html format
         if ($is_html === null) {
             $from_html = (preg_match('/<(html|body)(\s+[a-z]|>)/', $from, $m) && strpos($from, '</'.$m[1].'>') > 0);
             $to_html   = (preg_match('/<(html|body)(\s+[a-z]|>)/', $to, $m) && strpos($to, '</'.$m[1].'>') > 0);
             $is_html   = $from_html || $to_html;
 
             // ensure both parts are of the same format
             if ($is_html && !$from_html) {
                 $converter = new rcube_text2html($from, false, array('wrap' => true));
                 $from = $converter->get_html();
             }
             if ($is_html && !$to_html) {
                 $converter = new rcube_text2html($to, false, array('wrap' => true));
                 $to = $converter->get_html();
             }
         }
 
         // compute diff from HTML
         if ($is_html) {
             include_once __dir__ . '/vendor/Caxy/HtmlDiff/Match.php';
             include_once __dir__ . '/vendor/Caxy/HtmlDiff/Operation.php';
             include_once __dir__ . '/vendor/Caxy/HtmlDiff/HtmlDiff.php';
 
             // replace data: urls with a transparent image to avoid memory problems
             $from = preg_replace('/src="data:image[^"]+/', 'src="data:image/gif;base64,R0lGODlhAQABAPAAAOjq6gAAACH/C1hNUCBEYXRhWE1QAT8AIfkEBQAAAAAsAAAAAAEAAQAAAgJEAQA7', $from);
             $to   = preg_replace('/src="data:image[^"]+/', 'src="data:image/gif;base64,R0lGODlhAQABAPAAAOjq6gAAACH/C1hNUCBEYXRhWE1QAT8AIfkEBQAAAAAsAAAAAAEAAQAAAgJEAQA7', $to);
 
             $diff = new Caxy\HtmlDiff\HtmlDiff($from, $to);
             $diffhtml = $diff->build();
 
             // remove empty inserts (from tables)
             return preg_replace('!<ins class="diff\w+">\s*</ins>!Uims', '', $diffhtml);
         }
         else {
             include_once __dir__ . '/vendor/finediff.php';
 
             $diff = new FineDiff($from, $to, FineDiff::$wordGranularity);
             return $diff->renderDiffToHTML();
         }
     }
 
     /**
      * Return a date() format string to render identifiers for recurrence instances
      *
      * @param array Hash array with event properties
      * @return string Format string
      */
     public static function recurrence_id_format($event)
     {
         return $event['allday'] ? 'Ymd' : 'Ymd\THis';
     }
 
     /**
      * Returns HTML code for folder search widget
      *
      * @param array $attrib Named parameters
      *
      * @return string HTML code for the gui object
      */
     public function folder_search_form($attrib)
     {
         $rcmail = rcube::get_instance();
         $attrib += array(
             'gui-object'    => false,
             'wrapper'       => true,
             'form-name'     => 'foldersearchform',
             'command'       => 'non-extsing-command',
             'reset-command' => 'non-existing-command',
         );
 
         if ($attrib['label-domain'] && !strpos($attrib['buttontitle'], '.')) {
             $attrib['buttontitle'] = $attrib['label-domain'] . '.' . $attrib['buttontitle'];
         }
 
         if ($attrib['buttontitle']) {
             $attrib['placeholder'] = $rcmail->gettext($attrib['buttontitle']);
         }
 
         return $rcmail->output->search_form($attrib);
     }
 }