diff --git a/plugins/calendar/calendar.php b/plugins/calendar/calendar.php
index 7d142233..b3855350 100644
--- a/plugins/calendar/calendar.php
+++ b/plugins/calendar/calendar.php
@@ -1,3360 +1,3380 @@
 <?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/>.
  */
 
 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 $ui;
 
   public $defaults = array(
     'calendar_default_view' => "agendaWeek",
     'calendar_timeslots'    => 2,
     'calendar_work_start'   => 6,
     'calendar_work_end'     => 18,
     'calendar_agenda_range' => 60,
     'calendar_agenda_sections' => 'smart',
     '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'])) {
       $this->add_hook('startup', array($this, 'itip_attend_response'));
     }
     else if ($this->rc->action == 'feed' && !empty($_REQUEST['_cal'])) {
       $this->add_hook('startup', array($this, 'ical_feed_export'));
     }
     else if ($this->rc->task != 'login') {
       // default startup routine
       $this->add_hook('startup', array($this, 'startup'));
     }
 
     $this->add_hook('user_delete', array($this, 'user_delete'));
   }
 
   /**
    * Setup basic plugin environment and UI
    */
   protected function setup()
   {
     $this->require_plugin('libcalendaring');
 
     $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;
 
     // load localizations
     $this->add_texts('localization/', $this->rc->task == 'calendar' && (!$this->rc->action || $this->rc->action == 'print'));
 
     require($this->home . '/lib/calendar_ui.php');
     $this->ui = new calendar_ui($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 (!$this->rc->output->ajax_call && (!$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());
     }
 
     if ($args['task'] == 'calendar' && $args['action'] != 'save-pref') {
       if ($args['action'] != 'upload') {
         $this->load_driver();
       }
 
       // register calendar actions
       $this->register_action('index', array($this, 'calendar_view'));
       $this->register_action('event', array($this, 'event_action'));
       $this->register_action('calendar', array($this, 'calendar_action'));
       $this->register_action('count', array($this, 'count_events'));
       $this->register_action('load_events', array($this, 'load_events'));
       $this->register_action('export_events', array($this, 'export_events'));
       $this->register_action('import_events', array($this, 'import_events'));
       $this->register_action('upload', array($this, 'attachment_upload'));
       $this->register_action('get-attachment', array($this, 'attachment_get'));
       $this->register_action('freebusy-status', array($this, 'freebusy_status'));
       $this->register_action('freebusy-times', array($this, 'freebusy_times'));
       $this->register_action('randomdata', array($this, 'generate_randomdata'));
       $this->register_action('print', array($this,'print_view'));
       $this->register_action('mailimportitip', array($this, 'mail_import_itip'));
       $this->register_action('mailimportattach', array($this, 'mail_import_attachment'));
       $this->register_action('mailtoevent', array($this, 'mail_message2event'));
       $this->register_action('inlineui', array($this, 'get_inline_ui'));
       $this->register_action('check-recent', array($this, 'check_recent'));
       $this->register_action('itip-status', array($this, 'event_itip_status'));
       $this->register_action('itip-remove', array($this, 'event_itip_remove'));
       $this->register_action('itip-decline-reply', array($this, 'mail_itip_decline_reply'));
       $this->register_action('itip-delegate', array($this, 'mail_itip_delegate'));
       $this->register_action('resources-list', array($this, 'resources_list'));
       $this->register_action('resources-owner', array($this, 'resources_owner'));
       $this->register_action('resources-calendar', array($this, 'resources_calendar'));
       $this->register_action('resources-autocomplete', array($this, 'resources_autocomplete'));
       $this->add_hook('refresh', array($this, 'refresh'));
 
       // remove undo information...
       if ($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
       $this->add_hook('preferences_sections_list', array($this, 'preferences_sections_list'));
       $this->add_hook('preferences_list', array($this, 'preferences_list'));
       $this->add_hook('preferences_save', array($this, 'preferences_save')); 
     }
     else if ($args['task'] == 'mail') {
       // hooks to catch event invitations on incoming mails
       if ($args['action'] == 'show' || $args['action'] == 'preview') {
         $this->add_hook('template_object_messagebody', array($this, 'mail_messagebody_html'));
       }
 
       // add 'Create event' item to message menu
       if ($this->api->output->type == 'html') {
         $this->api->add_content(html::tag('li', null, 
           $this->api->output->button(array(
             'command'  => 'calendar-create-from-mail',
             'label'    => 'calendar.createfrommail',
             'type'     => 'link',
             'classact' => 'icon calendarlink active',
             'class'    => 'icon calendarlink',
             'innerclass' => 'icon calendar',
           ))),
           'messagemenu');
 
         $this->api->output->add_label('calendar.createfrommail');
       }
 
       $this->add_hook('messages_list', array($this, 'mail_messages_list'));
       $this->add_hook('message_compose', array($this, 'mail_message_compose'));
     }
     else if ($args['task'] == 'addressbook') {
       if ($this->rc->config->get('calendar_contact_birthdays')) {
         $this->add_hook('contact_update', array($this, 'contact_update'));
         $this->add_hook('contact_create', array($this, 'contact_update'));
       }
     }
 
     // add hooks to display alarms
     $this->add_hook('pending_alarms', array($this, 'pending_alarms'));
     $this->add_hook('dismiss_alarms', array($this, 'dismiss_alarms'));
   }
 
   /**
    * Helper method to load the backend driver according to local config
    */
   private function load_driver()
   {
     if (is_object($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 (!$this->itip) {
       require_once($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(array('accepted','tentative','declined','delegated','needs-action'));
     }
 
     return $this->itip;
   }
 
   /**
    * Load iCalendar functions
    */
   public function get_ical()
   {
     if (!$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($sensitivity = null)
   {
     $default_id = $this->rc->config->get('calendar_default_calendar');
     $calendars = $this->driver->list_calendars(calendar_driver::FILTER_PERSONAL | calendar_driver::FILTER_WRITEABLE);
     $calendar = $calendars[$default_id] ?: null;
     if (!$calendar || $sensitivity) {
       foreach ($calendars as $cal) {
         if ($sensitivity && $cal['subtype'] == $sensitivity) {
           $calendar = $cal;
           break;
         }
         if ($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 CSS stylesheets to the page header
     $this->ui->addCSS();
 
     // 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');
     $this->rc->output->add_label('libcalendaring.itipaccepted','libcalendaring.itiptentative','libcalendaring.itipdeclined','libcalendaring.itipdelegated','libcalendaring.expandattendeegroup','libcalendaring.expandattendeegroupnodata');
 
     // 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('mscolors', jqueryui::get_color_values());
     $this->rc->output->set_env('identities-selector', $this->ui->identity_select(array('id' => 'edit-identities-list', 'aria-label' => $this->gettext('roleorganizer'))));
 
     $view = rcube_utils::get_input_value('view', rcube_utils::INPUT_GPC);
     if (in_array($view, array('agendaWeek', 'agendaDay', 'month', 'table')))
       $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'] = array(
       '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($no_override['calendar_default_view'])) {
       if (!$p['current']) {
         $p['blocks']['view']['content'] = true;
         return $p;
       }
 
       $field_id = 'rcmfd_default_view';
       $select = new html_select(array('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'), "table");
       $p['blocks']['view']['options']['default_view'] = array(
         'title' => html::label($field_id, rcube::Q($this->gettext('default_view'))),
         'content' => $select->show($this->rc->config->get('calendar_default_view', $this->defaults['calendar_default_view'])),
       );
     }
 
     if (!isset($no_override['calendar_timeslots'])) {
       if (!$p['current']) {
         $p['blocks']['view']['content'] = true;
         return $p;
       }
 
       $field_id = 'rcmfd_timeslot';
       $choices = array('1', '2', '3', '4', '6');
       $select = new html_select(array('name' => '_timeslots', 'id' => $field_id));
       $select->add($choices);
       $p['blocks']['view']['options']['timeslots'] = array(
         'title' => html::label($field_id, rcube::Q($this->gettext('timeslots'))),
         'content' => $select->show(strval($this->rc->config->get('calendar_timeslots', $this->defaults['calendar_timeslots']))),
       );
     }
 
     if (!isset($no_override['calendar_first_day'])) {
       if (!$p['current']) {
         $p['blocks']['view']['content'] = true;
         return $p;
       }
 
       $field_id = 'rcmfd_firstday';
       $select = new html_select(array('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');
       $p['blocks']['view']['options']['first_day'] = array(
         'title' => html::label($field_id, rcube::Q($this->gettext('first_day'))),
         'content' => $select->show(strval($this->rc->config->get('calendar_first_day', $this->defaults['calendar_first_day']))),
       );
     }
 
     if (!isset($no_override['calendar_first_hour'])) {
       if (!$p['current']) {
         $p['blocks']['view']['content'] = true;
         return $p;
       }
 
       $time_format = $this->rc->config->get('time_format', libcalendaring::to_php_date_format($this->rc->config->get('calendar_time_format', $this->defaults['calendar_time_format'])));
       $select_hours = new html_select();
       for ($h = 0; $h < 24; $h++)
         $select_hours->add(date($time_format, mktime($h, 0, 0)), $h);
 
       $field_id = 'rcmfd_firsthour';
       $p['blocks']['view']['options']['first_hour'] = array(
         'title' => html::label($field_id, rcube::Q($this->gettext('first_hour'))),
         'content' => $select_hours->show($this->rc->config->get('calendar_first_hour', $this->defaults['calendar_first_hour']), array('name' => '_first_hour', 'id' => $field_id)),
       );
     }
 
     if (!isset($no_override['calendar_work_start'])) {
       if (!$p['current']) {
         $p['blocks']['view']['content'] = true;
         return $p;
       }
 
       $field_id = 'rcmfd_workstart';
       $p['blocks']['view']['options']['workinghours'] = array(
         'title' => html::label($field_id, rcube::Q($this->gettext('workinghours'))),
         'content' => $select_hours->show($this->rc->config->get('calendar_work_start', $this->defaults['calendar_work_start']), array('name' => '_work_start', 'id' => $field_id)) .
         ' &mdash; ' . $select_hours->show($this->rc->config->get('calendar_work_end', $this->defaults['calendar_work_end']), array('name' => '_work_end', 'id' => $field_id)),
       );
     }
 
     if (!isset($no_override['calendar_event_coloring'])) {
       if (!$p['current']) {
         $p['blocks']['view']['content'] = true;
         return $p;
       }
 
       $field_id = 'rcmfd_coloring';
       $select_colors = new html_select(array('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);
 
       $p['blocks']['view']['options']['eventcolors'] = array(
         'title' => html::label($field_id . 'value', rcube::Q($this->gettext('eventcoloring'))),
         'content' => $select_colors->show($this->rc->config->get('calendar_event_coloring', $this->defaults['calendar_event_coloring'])),
       );
     }
 
     // loading driver is expensive, don't do it if not needed
     $this->load_driver();
 
     if (!isset($no_override['calendar_default_alarm_type'])) {
       if (!$p['current']) {
         $p['blocks']['view']['content'] = true;
         return $p;
       }
 
       $field_id = 'rcmfd_alarm';
       $select_type = new html_select(array('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);
 
       $p['blocks']['view']['options']['alarmtype'] = array(
         'title' => html::label($field_id, rcube::Q($this->gettext('defaultalarmtype'))),
         'content' => $select_type->show($this->rc->config->get('calendar_default_alarm_type', '')),
       );
     }
 
     if (!isset($no_override['calendar_default_alarm_offset'])) {
       if (!$p['current']) {
         $p['blocks']['view']['content'] = true;
         return $p;
       }
 
       $field_id = 'rcmfd_alarm';
       $input_value = new html_inputfield(array('name' => '_alarm_value', 'id' => $field_id . 'value', 'size' => 3));
       $select_offset = new html_select(array('name' => '_alarm_offset', 'id' => $field_id . 'offset'));
       foreach (array('-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'));
       $p['blocks']['view']['options']['alarmoffset'] = array(
         'title' => html::label($field_id . 'value', rcube::Q($this->gettext('defaultalarmoffset'))),
         'content' => $input_value->show($preset[0]) . ' ' . $select_offset->show($preset[1]),
       );
     }
 
     if (!isset($no_override['calendar_default_calendar'])) {
       if (!$p['current']) {
         $p['blocks']['view']['content'] = true;
         return $p;
       }
       // default calendar selection
       $field_id = 'rcmfd_default_calendar';
       $select_cal = new html_select(array('name' => '_default_calendar', 'id' => $field_id, 'is_escaped' => true));
       foreach ((array)$this->driver->list_calendars(calendar_driver::FILTER_PERSONAL | calendar_driver::FILTER_ACTIVE) as $id => $prop) {
         $select_cal->add($prop['name'], strval($id));
         if ($prop['default'])
           $default_calendar = $id;
       }
       $p['blocks']['view']['options']['defaultcalendar'] = array(
         'title' => html::label($field_id . 'value', rcube::Q($this->gettext('defaultcalendar'))),
         'content' => $select_cal->show($this->rc->config->get('calendar_default_calendar', $default_calendar)),
       );
     }
 
     $p['blocks']['itip']['name'] = $this->gettext('itipoptions');
 
     // Invitations handling
     if (!isset($no_override['calendar_itip_after_action'])) {
       if (!$p['current']) {
         $p['blocks']['itip']['content'] = true;
         return $p;
       }
 
       $field_id = 'rcmfd_after_action';
       $select   = new html_select(array('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', $this->defaults['calendar_itip_after_action']);
       if ($val !== null && $val !== '' && !is_int($val)) {
         $folder = $val;
         $val    = 4;
       }
 
       $folders = $this->rc->folder_selector(array(
           'id'            => $field_id . '_select',
           'name'          => '_after_action_folder',
           'maxlength'     => 30,
           'folder_filter' => 'mail',
           'folder_rights' => 'w',
           'style'         => $val !== 4 ? 'display:none' : '',
       ));
 
       $p['blocks']['itip']['options']['after_action'] = array(
         'title'   => html::label($field_id, rcube::Q($this->gettext('afteraction'))),
         'content' => $select->show($val) . $folders->show($folder),
       );
     }
 
     // category definitions
     if (!$this->driver->nocategories && !isset($no_override['calendar_categories'])) {
         $p['blocks']['categories']['name'] = $this->gettext('categories');
 
         if (!$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);
           $category_remove = new html_inputfield(array('type' => 'button', 'value' => 'X', 'class' => 'button', 'onclick' => '$(this).parent().remove()', 'title' => $this->gettext('remove_category')));
           $category_name  = new html_inputfield(array('name' => "_categories[$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 = $this->driver->categoriesimmutable ? html::tag('input', array('type' => 'hidden', 'name' => "_categories[$key]", 'value' => $name)) : '';
           $categories_list .= html::div(null, $hidden . $category_name->show($name) . '&nbsp;' . $category_color->show($color) . '&nbsp;' . $category_remove->show());
         }
 
         $p['blocks']['categories']['options']['category_' . $name] = array(
           'content' => html::div(array('id' => 'calendarcategories'), $categories_list),
         );
 
         $field_id = 'rcmfd_new_category';
         $new_category = new html_inputfield(array('name' => '_new_category', 'id' => $field_id, 'size' => 30));
         $add_category = new html_inputfield(array('type' => 'button', 'class' => 'button', 'value' => $this->gettext('add_category'),  'onclick' => "rcube_calendar_add_category()"));
         $p['blocks']['categories']['options']['categories'] = array(
           'content' => $new_category->show('') . '&nbsp;' . $add_category->show(),
         );
 
         $this->rc->output->add_script('function rcube_calendar_add_category(){
           var name = $("#rcmfd_new_category").val();
           if (name.length) {
             var input = $("<input>").attr("type", "text").attr("name", "_categories[]").attr("size", 30).val(name);
             var color = $("<input>").attr("type", "text").attr("name", "_colors[]").attr("size", 6).addClass("colors").val("000000");
             var button = $("<input>").attr("type", "button").attr("value", "X").addClass("button").click(function(){ $(this).parent().remove() });
             $("<div>").append(input).append("&nbsp;").append(color).append("&nbsp;").append(button).appendTo("#calendarcategories");
             color.miniColors({ colorValues:(rcmail.env.mscolors || []) });
             $("#rcmfd_new_category").val("");
           }
         }');
 
         $this->rc->output->add_script('$("#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 (!$p['current']) {
         $p['blocks']['birthdays']['content'] = true;
         return $p;
       }
 
       $field_id = 'rcmfd_contact_birthdays';
       $input    = new html_checkbox(array('name' => '_contact_birthdays', 'id' => $field_id, 'value' => 1, 'onclick' => '$(".calendar_birthday_props").prop("disabled",!this.checked)'));
 
       $p['blocks']['birthdays']['options']['contact_birthdays'] = array(
         'title'   => html::label($field_id, $this->gettext('displaybirthdayscalendar')),
         'content' => $input->show($this->rc->config->get('calendar_contact_birthdays')?1:0),
       );
 
       $input_attrib = array(
         'class' => 'calendar_birthday_props',
         'disabled' => !$this->rc->config->get('calendar_contact_birthdays'),
       );
 
       $sources = array();
       $checkbox = new html_checkbox(array('name' => '_birthday_adressbooks[]') + $input_attrib);
       foreach ($this->rc->get_address_sources(false, true) as $source) {
         $active = in_array($source['id'], (array)$this->rc->config->get('calendar_birthday_adressbooks', array())) ? $source['id'] : '';
         $sources[] = html::label(null, $checkbox->show($active, array('value' => $source['id'])) . '&nbsp;' . rcube::Q($source['realname'] ?: $source['name']));
       }
 
       $p['blocks']['birthdays']['options']['birthday_adressbooks'] = array(
         'title'   => rcube::Q($this->gettext('birthdayscalendarsources')),
         'content' => join(html::br(), $sources),
       );
 
       $field_id = 'rcmfd_birthdays_alarm';
       $select_type = new html_select(array('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(array('name' => '_birthdays_alarm_value', 'id' => $field_id . 'value', 'size' => 3) + $input_attrib);
       $select_offset = new html_select(array('name' => '_birthdays_alarm_offset', 'id' => $field_id . 'offset') + $input_attrib);
       foreach (array('-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'));
       $p['blocks']['birthdays']['options']['birthdays_alarmoffset'] = array(
         'title' => html::label($field_id . 'value', rcube::Q($this->gettext('showalarms'))),
         'content' => $select_type->show($this->rc->config->get('calendar_birthdays_alarm_type', '')) . ' ' . $input_value->show($preset[0]) . '&nbsp;' . $select_offset->show($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'] = array(
         '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_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'    => rcube_utils::get_input_value('_contact_birthdays', rcube_utils::INPUT_POST) ? true : false,
         '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 (!$this->driver->nocategories) {
         $old_categories = $new_categories = array();
         foreach ($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) {
           $color = preg_replace('/^#/', '', strval($colors[$key]));
 
           // rename categories in existing events -> driver's job
           if ($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)$old_categories[$key] 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 = $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', array('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  = $calendars[$cal['id']];
 
           // find parent folder and check if it's a "user calendar"
           // if it's also activated we need to refresh it (#5340)
           while ($calendar['parent']) {
             if (isset($calendars[$calendar['parent']]))
               $calendar = $calendars[$calendar['parent']];
             else
               break;
           }
 
           if ($calendar['id'] != $cal['id'] && $calendar['active'] && $calendar['group'] == "other user")
             $this->rc->output->command('plugin.refresh_source', $calendar['id']);
         }
         return;
       case "search":
         $results    = array();
         $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[] = $cal;
         }
         // report more results available
         if ($this->driver->search_more_results)
           $this->rc->output->show_message('autocompletemore', 'info');
 
         $this->rc->output->command('multi_thread_http_response', $results, rcube_utils::get_input_value('_reqid', rcube_utils::INPUT_GPC));
         return;
     }
     
     if ($success)
       $this->rc->output->show_message('successfullysaved', 'confirmation');
     else {
       $error_msg = $this->gettext('errorsaving') . ($this->driver->last_error ? ': ' . $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;
     
     // force notify if hidden + active
     if ((int)$this->rc->config->get('calendar_itip_send_option', $this->defaults['calendar_itip_send_option']) === 1)
       $event['_notify'] = 1;
 
     // read old event data in order to find changes
     if (($event['_notify'] || $event['_decline']) && $action != 'new') {
       $old = $this->driver->get_event($event);
 
       // load main event if savemode is 'all' or if deleting 'future' events
       if (($event['_savemode'] == 'all' || ($event['_savemode'] == 'future' && $action == 'remove' && !$event['_decline'])) && $old['recurrence_id']) {
         $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();
         $this->write_preprocess($event, $action);
         if ($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);
         }
         $reload = $success && $event['recurrence'] ? 2 : 1;
         break;
         
       case "edit":
         $this->write_preprocess($event, $action);
         if ($success = $this->driver->edit_event($event)) {
           $this->cleanup_event($event);
           $this->event_save_success($event, $old, $action, $success);
         }
         $reload = $success && ($event['recurrence'] || $event['_savemode'] || $event['_fromcalendar']) ? 2 : 1;
         break;
       
       case "resize":
         $this->write_preprocess($event, $action);
         if ($success = $this->driver->resize_event($event)) {
           $this->event_save_success($event, $old, $action, $success);
         }
         $reload = $event['_savemode'] ? 2 : 1;
         break;
       
       case "move":
         $this->write_preprocess($event, $action);
         if ($success = $this->driver->move_event($event)) {
           $this->event_save_success($event, $old, $action, $success);
         }
         $reload  = $success && $event['_savemode'] ? 2 : 1;
         break;
       
       case "remove":
         // remove previous deletes
         $undo_time = $this->driver->undelete ? $this->rc->config->get('undo_timeout', 0) : 0;
         $this->rc->session->remove('calendar_event_undo');
         
         // search for event if only UID is given
         if (!isset($event['calendar']) && $event['uid']) {
           if (!($event = $this->driver->get_event($event, calendar_driver::FILTER_WRITEABLE))) {
             break;
           }
           $undo_time = 0;
         }
 
         $success = $this->driver->remove_event($event, $undo_time < 1);
         $reload = (!$success || $event['_savemode']) ? 2 : 1;
 
         if ($undo_time > 0 && $success) {
           $_SESSION['calendar_event_undo'] = array('ts' => time(), 'data' => $event);
           // display message with Undo link.
           $msg = html::span(null, $this->gettext('successremoval'))
             . ' ' . html::a(array('onclick' => sprintf("%s.http_request('event', 'action=undo', %s.display_message('', 'loading'))",
               rcmail_output::JS_OBJECT_NAME, rcmail_output::JS_OBJECT_NAME)), $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 ($event['_savemode'] == 'all') {
           unset($old['_instance'], $old['recurrence_date'], $old['recurrence_id']);
         }
         // send an update for the main event's recurrence rule instead of a cancellation message
         else if ($event['_savemode'] == 'future' && $success !== false && $success !== true) {
           $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 && $event['_decline']) {
           $emails = $this->get_user_emails();
           foreach ($old['attendees'] as $i => $attendee) {
             if ($attendee['role'] == 'ORGANIZER')
               $organizer = $attendee;
             else if ($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'))
             $this->rc->output->command('display_message', $this->gettext(array('name' => 'sentresponseto', 'vars' => array('mailto' => $organizer['name'] ? $organizer['name'] : $organizer['email']))), '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
         $event  = $_SESSION['calendar_event_undo']['data'];
 
         if ($event)
           $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' && $event['to']) {
           $itip = $this->load_itip();
           if ($itip->delegate_to($ev, $event['to'], (bool)$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'] || $event['recurrence'] ? 2 : 1;
           $organizer = null;
           $emails = $this->get_user_emails();
 
           foreach ($event['attendees'] as $i => $attendee) {
             if ($attendee['role'] == 'ORGANIZER') {
               $organizer = $attendee;
             }
             else if ($attendee['email'] && in_array(strtolower($attendee['email']), $emails)) {
               $reply_sender = $attendee['email'];
             }
           }
 
           if (!$noreply) {
             $itip = $this->load_itip();
             $itip->set_sender_email($reply_sender);
             $event['thisandfuture'] = $event['_savemode'] == 'future';
             if ($organizer && $itip->send_itip_message($event, 'REPLY', $organizer, 'itipsubject' . $status, 'itipmailbody' . $status))
               $this->rc->output->command('display_message', $this->gettext(array('name' => 'sentresponseto', 'vars' => array('mailto' => $organizer['name'] ? $organizer['name'] : $organizer['email']))), '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', array('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, $dtformat) {
             if ($change['date']) {
               $dt = $lib->adjust_timezone($change['date']);
               if ($dt instanceof DateTime)
                 $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 (array('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;
           $this->rc->output->command('display_message', $this->gettext(array('name' => 'objectrestoresuccess', 'vars' => array('rev' => $event['rev']))), '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');
 
     // update event object on the client or trigger a complete refretch if too complicated
     if ($reload) {
       $args = array('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 ($event['_savemode'] == 'future' && $event['_notify'] && $old['attendees'] && $old['recurrence_id']) {
         $master = $this->driver->get_event(array('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 ($event['_savemode'] == 'future' || $event['_savemode'] == 'new') {
         $old = null;
       }
 
       $event['id'] = $success;
       $event['_savemode'] = 'all';
     }
 
     // send out notifications
     if ($event['_notify'] && ($event['attendees'] || $old['attendees'])) {
       $_savemode = $event['_savemode'];
 
       // send notification for the main event when savemode is 'all'
       if ($action != 'remove' && $_savemode == 'all' && ($event['recurrence_id'] || $old['recurrence_id'] || ($old && $old['id'] != $event['id']))) {
         $event['id'] = $event['recurrence_id'] ?: ($old['recurrence_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)) {
         $sent = $this->notify_attendees($event, $old, $action, $event['_comment']);
         if ($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()
   {
     $events = $this->driver->load_events(
       rcube_utils::get_input_value('start', rcube_utils::INPUT_GET),
       rcube_utils::get_input_value('end', rcube_utils::INPUT_GET),
       ($query = rcube_utils::get_input_value('q', rcube_utils::INPUT_GET)),
       rcube_utils::get_input_value('source', rcube_utils::INPUT_GET)
     );
     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;
 
     $start = rcube_utils::get_input_value('start', rcube_utils::INPUT_GET);
     if (!$start) {
       $start = new DateTime('today 00:00:00', $this->timezone);
       $start = $start->format('U');
     }
 
     $counts = $this->driver->count_events(
       rcube_utils::get_input_value('source', rcube_utils::INPUT_GET),
       $start,
       rcube_utils::get_input_value('end', rcube_utils::INPUT_GET)
     );
 
     $this->rc->output->command('plugin.update_counts', array('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 = array();
 
     if ($event = $this->lib->mail_get_itip_object($mbox, $uid, $mime_id, 'event')) {
       $partstat = 'NEEDS-ACTION';
 /*
       $user_emails = $this->lib->get_user_emails();
       foreach ($event['attendees'] as $attendee) {
         if (in_array($attendee['email'], $user_emails)) {
           $partstat = $attendee['status'];
           break;
         }
       }
 */
       $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($event['recurrence'])) {
         foreach ($this->driver->get_recurring_events($event, $event['start']) 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', array('refetch' => true));
         return;
     }
 
     $counts = array();
 
     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',
           array('source' => $cal['id'], 'update' => $this->_client_event($event)));
       }
 
       // refresh count for this calendar
       if ($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', array('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 = $p['time'] ?: time();
     if ($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 && $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'])) {
       rcube_upload_progress();
     }
 
     @set_time_limit(0);
 
     // process uploaded file if there is no error
     $err = $_FILES['_data']['error'];
 
     if (!$err && $_FILES['_data']['tmp_name']) {
       $calendar   = rcube_utils::get_input_value('calendar', rcube_utils::INPUT_GPC);
       $rangestart = $_REQUEST['_range'] ? date_create("now -" . intval($_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(array('name' => 'importsuccess', 'vars' => array('nr' => $count))), 'confirmation');
         $this->rc->output->command('plugin.import_success', array('source' => $calendar, 'refetch' => true));
       }
       else if (!$errors) {
         $this->rc->output->command('display_message', $this->gettext('importnone'), 'notice');
         $this->rc->output->command('plugin.import_success', array('source' => $calendar));
       }
       else {
         $this->rc->output->command('plugin.import_error', array('message' => $this->gettext('importerror') . ($msg ? ': ' . $msg : '')));
       }
     }
     else {
       if ($err == UPLOAD_ERR_INI_SIZE || $err == UPLOAD_ERR_FORM_SIZE) {
         $msg = $this->gettext(array('name' => 'filesizeerror', 'vars' => array(
             'size' => show_bytes(parse_bytes(ini_get('upload_max_filesize'))))));
       }
       else {
         $msg = $this->gettext('fileuploaderror');
       }
 
       $this->rc->output->command('plugin.import_error', array('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 $rangestart
       if ($event['end'] < $rangestart && (!$event['recurrence'] || ($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);
 
     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');
 
     $event_id    = rcube_utils::get_input_value('id', rcube_utils::INPUT_GET);
     $attachments = rcube_utils::get_input_value('attachments', rcube_utils::INPUT_GET);
     $calid = $filename = rcube_utils::get_input_value('source', rcube_utils::INPUT_GET);
 
     $calendars = $this->driver->list_calendars();
     $events = array();
 
     if ($calendars[$calid]) {
       $filename = $calendars[$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(array('calendar' => $calid, 'id' => $event_id), 0, true)) {
           if ($event['recurrence_id']) {
             $event = $this->driver->get_event(array('calendar' => $calid, 'id' => $event['recurrence_id']), 0, true);
           }
           $events = array($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, $attachments ? array($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', array(
         '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="Roundcube 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 = array();
 
     // configuration
     $settings['default_calendar'] = $this->rc->config->get('calendar_default_calendar');
     $settings['default_view'] = (string)$this->rc->config->get('calendar_default_view', $this->defaults['calendar_default_view']);
     $settings['date_agenda'] = (string)$this->rc->config->get('calendar_date_agenda', $this->defaults['calendar_date_agenda']);
 
     $settings['timeslots'] = (int)$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['agenda_sections'] = $this->rc->config->get('calendar_agenda_sections', $this->defaults['calendar_agenda_sections']);
     $settings['event_coloring'] = (int)$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']);
     $settings['invitation_calendars'] = (bool)$this->rc->config->get('kolab_invitation_calendars', false);
     $settings['itip_notify'] = (int)$this->rc->config->get('calendar_itip_send_option', $this->defaults['calendar_itip_send_option']);
 
     // get user identity to create default attendee
     if ($this->ui->screen == 'calendar') {
       foreach ($this->rc->user->list_emails() as $rec) {
         if (!$identity)
           $identity = $rec;
         $identity['emails'][] = $rec['email'];
         $settings['identities'][$rec['identity_id']] = $rec['email'];
       }
       $identity['emails'][] = $this->rc->user->get_username();
       $settings['identity'] = array('name' => $identity['name'], 'email' => strtolower($identity['email']), 'emails' => ';' . strtolower(join(';', $identity['emails'])));
     }
 
     return $settings;
   }
 
   /**
    * Encode events as JSON
    *
    * @param  array  Events as array
    * @param  boolean Add CSS class names according to calendar and categories
    * @return string JSON encoded events
    */
   function encode($events, $addcss = false)
   {
     $json = array();
     foreach ($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, $addcss = false)
   {
     // compose a human readable strings for alarms_text and recurrence_text
     if ($event['valarms']) {
       $event['alarms_text'] = libcalendaring::alarms_text($event['valarms']);
       $event['valarms'] = libcalendaring::to_client_alarms($event['valarms']);
     }
     if ($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']);
     }
 
     foreach ((array)$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 (!$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 = $attendee;
       }
       if ($attendee['status'] == 'DELEGATED' && $attendee['rsvp'] == false) {
         $event['attendees'][$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']))
         $event['attendees'] = array();
       array_unshift($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 because of the fullcalendar client script
     $event['vurl'] = $event['url'];
     unset($event['url']);
 
     return array(
       '_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' => $event['changed'] ? $this->lib->adjust_timezone($event['changed'])->format('c') : null,
       'created' => $event['created'] ? $this->lib->adjust_timezone($event['created'])->format('c') : null,
       'title'       => strval($event['title']),
       'description' => strval($event['description']),
       'location'    => strval($event['location']),
       'className'   => ($addcss ? 'fc-event-cal-'.asciiwords($event['calendar'], true).' ' : '') .
           'fc-event-cat-' . asciiwords(strtolower(join('-', (array)$event['categories'])), true) .
           rtrim(' ' . $event['className']),
       'allDay'      => ($event['allday'] == 1),
     ) + $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   = $_REQUEST['_num'] ? intval($_REQUEST['_num']) : 100;
     $date  = $_REQUEST['_date'] ?: 'now';
     $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(array(
         '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()
   {
     $this->lib->attachment_upload(self::SESSION_KEY, 'cal-');
   }
 
   /**
    * Handler for attachments download/displaying
    */
   public function attachment_get()
   {
     // show loading page
     if (!empty($_GET['_preload'])) {
         return $this->lib->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 = array('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'])) {
         $this->lib->attachment = $attachment;
         $this->register_handler('plugin.attachmentframe', array($this->lib, 'attachment_frame'));
         $this->register_handler('plugin.attachmentcontrols', array($this->lib, 'attachment_header'));
         $this->rc->output->send('calendar.attachment');
     }
     // deliver attachment content
     else if ($attachment) {
         if ($calendar != '--invitation--itip') {
             $attachment['body'] = $this->driver->get_attachment_body($id, $event);
         }
 
         $this->lib->attachment_get($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 (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)
   {
     // 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);
     $event['allday'] = (bool)$event['allday'];
 
     // start/end is all we need for 'move' action (#1480)
     if ($action == 'move') {
       return;
     }
 
     // convert the submitted recurrence settings
     if (is_array($event['recurrence'])) {
       $event['recurrence'] = $this->lib->from_client_recurrence($event['recurrence'], $event['start']);
     }
 
     // convert the submitted alarm values
     if ($event['valarms']) {
       $event['valarms'] = libcalendaring::from_client_alarms($event['valarms']);
     }
 
     $attachments = array();
     $eventid     = 'cal-'.$event['id'];
 
     if (is_array($_SESSION[self::SESSION_KEY]) && $_SESSION[self::SESSION_KEY]['id'] == $eventid) {
       if (!empty($_SESSION[self::SESSION_KEY]['attachments'])) {
         foreach ($_SESSION[self::SESSION_KEY]['attachments'] as $id => $attachment) {
           if (is_array($event['attachments']) && in_array($id, $event['attachments'])) {
             $attachments[$id] = $this->rc->plugins->exec_hook('attachment_get', $attachment);
           }
         }
       }
     }
 
     $event['attachments'] = $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' || $action == 'edit') {
       if (!$event['attendees'])
         $event['attendees'] = array();
 
       $emails = $this->get_user_emails();
       $organizer = $owner = false;
       foreach ((array)$event['attendees'] as $i => $attendee) {
         if ($attendee['role'] == 'ORGANIZER')
           $organizer = $i;
         if ($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';
       }
 
       // set new organizer identity
       if ($organizer !== false && !empty($event['_identity']) && ($identity = $this->rc->user->get_identity($event['_identity']))) {
         $event['attendees'][$organizer]['name'] = $identity['name'];
         $event['attendees'][$organizer]['email'] = $identity['email'];
       }
 
       // set owner as organizer if yet missing
       if ($organizer === false && $owner !== false) {
         $event['attendees'][$owner]['role'] = 'ORGANIZER';
         unset($event['attendees'][$owner]['rsvp']);
       }
     }
 
     // mapping url => vurl because of the fullcalendar client script
     if (array_key_exists('vurl', $event)) {
       $event['url'] = $event['vurl'];
       unset($event['vurl']);
     }
   }
 
   /**
    * Releases some resources after successful event save
    */
   private function cleanup_event(&$event)
   {
     // remove temp. attachment files
     if (!empty($_SESSION[self::SESSION_KEY]) && ($eventid = $_SESSION[self::SESSION_KEY]['id'])) {
       $this->rc->plugins->exec_hook('attachments_cleanup', array('group' => $eventid));
       $this->rc->session->remove(self::SESSION_KEY);
     }
   }
 
   /**
    * Send out an invitation/notification to all event attendees
    */
   private function notify_attendees($event, $old, $action = 'edit', $comment = null, $rsvp = null)
   {
     if ($action == 'remove' || ($event['status'] == 'CANCELLED' && $old['status'] != $event['status'])) {
       $event['cancelled'] = true;
       $is_cancelled = true;
     }
 
     if ($rsvp === null)
       $rsvp = !$old || $event['sequence'] > $old['sequence'];
 
     $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
     $old_attendees = array();
     foreach ((array)$old['attendees'] as $attendee) {
       $old_attendees[] = $attendee['email'];
     }
 
     // send to every attendee
     $sent = 0; $current = array();
     foreach ((array)$event['attendees'] as $attendee) {
       $current[] = strtolower($attendee['email']);
       
       // skip myself for obvious reasons
       if (!$attendee['email'] || in_array(strtolower($attendee['email']), $emails))
         continue;
 
       // skip if notification is disabled for this attendee
       if ($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
     foreach ((array)$old['attendees'] as $attendee) {
       if ($attendee['role'] == 'ORGANIZER' || !$attendee['email'] || in_array(strtolower($attendee['email']), $current))
         continue;
 
       $vevent = $old;
       $vevent['cancelled'] = $is_cancelled;
       $vevent['attendees'] = array($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 = rcube_utils::get_input_value('start', rcube_utils::INPUT_GPC);
     $end   = rcube_utils::get_input_value('end', rcube_utils::INPUT_GPC);
 
     // convert dates into unix timestamps
     if (!empty($start) && !is_numeric($start)) {
       $dts = new DateTime($start, $this->timezone);
       $start = $dts->format('U');
     }
     if (!empty($end) && !is_numeric($end)) {
       $dte = new DateTime($end, $this->timezone);
       $end = $dte->format('U');
     }
     
     if (!$start) $start = time();
     if (!$end) $end = $start + 3600;
     
     $fbtypemap = array(calendar::FREEBUSY_UNKNOWN => 'UNKNOWN', calendar::FREEBUSY_FREE => 'FREE', calendar::FREEBUSY_BUSY => 'BUSY', calendar::FREEBUSY_TENTATIVE => 'TENTATIVE', calendar::FREEBUSY_OOF => 'OUT-OF-OFFICE');
     $status = 'UNKNOWN';
     
     // 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) && $fbtypemap[$type] ? $fbtypemap[$type] : 'BUSY';
           break;
         }
       }
     }
     
     // let this information be cached for 5min
     send_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 = rcube_utils::get_input_value('start', rcube_utils::INPUT_GPC);
     $end   = rcube_utils::get_input_value('end', rcube_utils::INPUT_GPC);
     $interval  = intval(rcube_utils::get_input_value('interval', rcube_utils::INPUT_GPC));
     $strformat = $interval > 60 ? 'Ymd' : 'YmdHis';
 
     // convert dates into unix timestamps
     if (!empty($start) && !is_numeric($start)) {
       $dts = rcube_utils::anytodatetime($start, $this->timezone);
       $start = $dts ? $dts->format('U') : null;
     }
     if (!empty($end) && !is_numeric($end)) {
       $dte = rcube_utils::anytodatetime($end, $this->timezone);
       $end = $dte ? $dte->format('U') : null;
     }
 
     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 = array();
     
     // build a list from $start till $end with blocks representing the fb-status
     for ($s = 0, $t = $start; $t <= $end; $s++) {
       $status = self::FREEBUSY_UNKNOWN;
       $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;
 
           // check for possible all-day times
           if (gmdate('His', $from) == '000000' && gmdate('His', $to) == '235959') {
               // shift into the user's timezone for sane matching
               $from -= $this->gmt_offset;
               $to   -= $this->gmt_offset;
           }
 
           if ($from < $t_end && $to > $t) {
             $status = isset($type) ? $type : self::FREEBUSY_BUSY;
             if ($status == self::FREEBUSY_BUSY)  // can't get any worse :-)
               break;
           }
         }
       }
       
       $slots[$s] = $status;
       $times[$s] = intval($dt->format($strformat));
       $t = $t_end;
     }
     
     $dte = new DateTime('@'.$t_end);
     $dte->setTimezone($this->timezone);
     
     // let this information be cached for 5min
     send_future_expire_header(300);
     
     echo rcube_output::json_serialize(array(
       'email' => $email,
       'start' => $dts->format('c'),
       'end'   => $dte->format('c'),
       'interval' => $interval,
       'slots' => $slots,
       'times' => $times,
     ));
     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, array('agendaWeek', 'agendaDay', 'month', 'table')))
       $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 (isset($_REQUEST['sections']))
       $this->rc->output->set_env('listSections', rcube_utils::get_input_value('sections', rcube_utils::INPUT_GPC));
 
     if ($search = rcube_utils::get_input_value('search', rcube_utils::INPUT_GPC)) {
       $this->rc->output->set_env('search', $search);
       $title .= ' "' . $search . '"';
     }
 
     // Add CSS stylesheets to the page header
     $skin_path = $this->local_skin_path();
     $this->include_stylesheet($skin_path . '/fullcalendar.css');
     $this->include_stylesheet($skin_path . '/print.css');
     
     // Add JS files to the page header
     $this->include_script('print.js');
     $this->include_script('lib/js/fullcalendar.js');
     
     $this->register_handler('plugin.calendar_css', array($this->ui, 'calendar_css'));
     $this->register_handler('plugin.calendar_list', array($this->ui, 'calendar_list'));
     
     $this->rc->output->set_pagetitle($title);
     $this->rc->output->send("calendar.print");
   }
 
   /**
    *
    */
   public function get_inline_ui()
   {
     foreach (array('save','cancel','savingdata') as $label)
       $texts['calendar.'.$label] = $this->gettext($label);
     
     $texts['calendar.new_event'] = $this->gettext('createfrommail');
     
     $this->ui->init_templates();
     $this->ui->calendar_list();  # set env['calendars']
     echo $this->api->output->parse('calendar.eventedit', false, false);
     echo html::tag('script', array('type' => 'text/javascript'),
       "rcmail.set_env('calendars', " . rcube_output::json_serialize($this->api->output->env['calendars']) . ");\n".
       "rcmail.set_env('deleteicon', '" . $this->api->output->env['deleteicon'] . "');\n".
       "rcmail.set_env('cancelicon', '" . $this->api->output->env['cancelicon'] . "');\n".
       "rcmail.set_env('loadingicon', '" . $this->api->output->env['loadingicon'] . "');\n".
       "rcmail.gui_object('attachmentlist', '"  . $this->ui->attachmentlist_id . "');\n".
       "rcmail.add_label(" . rcube_output::json_serialize($texts) . ");\n"
     );
     exit;
   }
 
   /**
    * 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 = array();
     $ignore = array('changed' => 1, 'attachments' => 1);
     foreach (array_unique(array_merge(array_keys($a), array_keys($b))) as $key) {
       if (!$ignore[$key] && $key[0] != '_' && $a[$key] != $b[$key])
         $diff[] = $key;
     }
     
     // only compare number of attachments
     if (count($a['attachments']) != count($b['attachments']))
       $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])) {
       $attendees = array($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 (is_object($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 = array();
 
     if ($directory = $this->resources_directory()) {
       foreach ($directory->load_resources($search, $maxnum) as $rec) {
         $results[]  = array(
             '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 = array();
 
     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 = array();
 
     if ($directory = $this->resources_directory()) {
       $events = $directory->get_resource_calendar(
         rcube_utils::get_input_value('_id', rcube_utils::INPUT_GPC),
         rcube_utils::get_input_value('start', rcube_utils::INPUT_GET),
         rcube_utils::get_input_value('end', rcube_utils::INPUT_GET));
     }
 
     echo $this->encode($events);
     exit;
   }
 
 
   /****  Event invitation plugin hooks ****/
 
+  /**
+   * Find an event in user calendars
+   */
+  protected function find_event($event)
+  {
+    $this->load_driver();
+
+    // We search for writeable calendars in personal namespace by default
+    $result = $this->driver->get_event($event, calendar_driver::FILTER_WRITEABLE | calendar_driver::FILTER_PERSONAL);
+
+    // Some plugins may search in other users calendars, e.g. where delegation is involved
+    $plugin = $this->rc->plugins->exec_hook('calendar_event_find', array(
+            'search'   => $event,
+            'result'   => $result,
+            'calendar' => $this,
+    ));
+
+    return $plugin['result'];
+  }
+
   /**
    * Handler for calendar/itip-status requests
    */
   function event_itip_status()
   {
     $data = rcube_utils::get_input_value('data', rcube_utils::INPUT_POST, true);
 
-    // find local copy of the referenced event
     $this->load_driver();
-    $existing = $this->driver->get_event($data, calendar_driver::FILTER_WRITEABLE | calendar_driver::FILTER_PERSONAL);
 
-    $itip = $this->load_itip();
+    // find local copy of the referenced event
+    $existing = $this->find_event($data);
+    $itip     = $this->load_itip();
     $response = $itip->get_itip_status($data, $existing);
 
     // get a list of writeable calendars to save new events to
     if (!$existing && !$data['nosave'] && $response['action'] == 'rsvp' || $response['action'] == 'import') {
       $calendars = $this->driver->list_calendars(calendar_driver::FILTER_PERSONAL);
       $calendar_select = new html_select(array('name' => 'calendar', 'id' => 'itip-saveto', 'is_escaped' => true));
       $calendar_select->add('--', '');
       $numcals = 0;
       foreach ($calendars as $calendar) {
         if ($calendar['editable']) {
           $calendar_select->add($calendar['name'], $calendar['id']);
           $numcals++;
         }
       }
       if ($numcals <= 1)
         $calendar_select = null;
     }
 
     if ($calendar_select) {
       $default_calendar = $this->get_default_calendar($data['sensitivity']);
       $response['select'] = html::span('folder-select', $this->gettext('saveincalendar') . '&nbsp;' .
         $calendar_select->show($default_calendar['id']));
     }
     else if ($data['nosave']) {
       $response['select'] = html::tag('input', array('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 = $after = array();
       foreach ($events as $event) {
         // TODO: skip events with free_busy == 'free' ?
         if ($event['uid'] == $data['uid'] || $event['end'] < $day_start || $event['start'] > $day_end)
           continue;
         else if ($event['start'] < $event_start)
           $before[] = $this->mail_agenda_event_row($event);
         else
           $after[] = $this->mail_agenda_event_row($event);
       }
 
       $response['append'] = array(
         'selector' => '.calendar-agenda-preview',
         'replacements' => array(
           '%before%' => !empty($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()
   {
     $success  = false;
     $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);
 
     // search for event if only UID is given
     if ($event = $this->driver->get_event(array('uid' => $uid, '_instance' => $instance), calendar_driver::FILTER_WRITEABLE)) {
       $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 ($invitation['cancelled']) {
           $this->invitestatus = html::div('rsvp-status declined', $itip->gettext('eventcancelled'));
         }
         // save submitted RSVP status
         else if (!empty($_POST['rsvp'])) {
           $status = null;
           foreach (array('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...
           if ($this->rc->user->ID) {
             $this->load_driver();
             $invitation = $itip->get_invitation($token);
 
             // save the event to his/her default calendar if not yet present
             if (!$this->driver->get_event($this->event) && ($calendar = $this->get_default_calendar($invitation['event']['sensitivity']))) {
               $invitation['event']['calendar'] = $calendar['id'];
               if ($this->driver->new_event($invitation['event']))
                 $this->rc->output->command('display_message', $this->gettext(array('name' => 'importedsuccessfully', 'vars' => array('calendar' => $calendar['name']))), 'confirmation');
             }
           }
         }
         
         $this->register_handler('plugin.event_inviteform', array($this, 'itip_event_inviteform'));
         $this->register_handler('plugin.event_invitebox', array($this->ui, 'event_invitebox'));
         
         if (!$this->invitestatus) {
           $this->itip->set_rsvp_actions(array('accepted','tentative','declined'));
           $this->register_handler('plugin.event_rsvp_buttons', array($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(array('name' => "_t", 'value' => $this->token));
     return html::tag('form', array('action' => $this->rc->url(array('task' => 'calendar', 'action' => 'attend')), 'method' => 'post', 'noclose' => true) + $attrib) . $hidden->show();
   }
 
   /**
    * 
    */
   private function mail_agenda_event_row($event, $class = '')
   {
     $time = $event['allday'] ? $this->gettext('all-day') :
       $this->rc->format_date($event['start'], $this->rc->config->get('time_format')) . ' - ' .
         $this->rc->format_date($event['end'], $this->rc->config->get('time_format'));
 
     return html::div(rtrim('event-row ' . $class),
       html::span('event-date', $time) .
       html::span('event-title', rcube::Q($event['title']))
     );
   }
   
   /**
    * 
    */
   public function mail_messages_list($p)
   {
     if (in_array('attachment', (array)$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, array('multipart/alternative', 'multipart/mixed'))) {
           // TODO: fetch bodystructure and search for ical parts. Maybe too expensive?
 
           if (!empty($header->structure) && is_array($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 = '';
 
         // 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', $this->rc->format_date($event['start'], $this->rc->config->get('date_format')))
             ) . '%before%' . $this->mail_agenda_event_row($event, 'current') . '%after%');
         }
 
         $html .= html::div('calendar-invitebox',
           $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(array('task' => 'calendar')) . '&view=agendaDay&date=' . $event['start']->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(array(
         'id'         => 'attachmentsavecal',
         'name'       => 'attachmentsavecal',
         'type'       => 'link',
         'wrapper'    => 'li',
         'command'    => 'attachment-save-calendar',
         'class'      => 'icon calendarlink',
         '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;
 
     if ($status == 'delegated') {
       $delegates = rcube_mime::decode_address_list(rcube_utils::get_input_value('_to', rcube_utils::INPUT_POST, true), 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, $mime_id, 'event')) {
       // forward iTip request to delegatee
       if ($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';
       }
 
       // find writeable calendar to store event
       $cal_id = !empty($_REQUEST['_folder']) ? rcube_utils::get_input_value('_folder', rcube_utils::INPUT_POST) : null;
       $dontsave = ($_REQUEST['_folder'] === '' && $event['_method'] == 'REQUEST');
       $calendars = $this->driver->list_calendars(calendar_driver::FILTER_PERSONAL);
       $calendar = $calendars[$cal_id];
 
       // select default calendar except user explicitly selected 'none'
       if (!$calendar && !$dontsave)
          $calendar = $this->get_default_calendar($event['sensitivity']);
 
       $metadata = array(
         'uid' => $event['uid'],
         '_instance' => $event['_instance'],
         'changed' => is_object($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 = $attendee;
           }
           else if ($attendee['email'] && in_array(strtolower($attendee['email']), $emails)) {
             $event['attendees'][$i]['status'] = strtoupper($status);
             if (!in_array($event['attendees'][$i]['status'], array('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'][] = array(
             'name' => $sender_identity['name'],
             'email' => $sender_identity['email'],
             'role' => 'OPT-PARTICIPANT',
             'status' => strtoupper($status),
           );
           $metadata['attendee'] = $sender_identity['email'];
         }
       }
       
       // save to calendar
       if ($calendar && $calendar['editable']) {
         // check for existing event with the same UID
-        $existing = $this->driver->get_event($event, calendar_driver::FILTER_WRITEABLE | calendar_driver::FILTER_PERSONAL);
+        $existing = $this->find_event($event);
 
         if ($existing) {
           // forward savemode for correct updates of recurring events
           $existing['_savemode'] = $savemode ?: $event['_savemode'];
 
           // only update attendee status
           if ($event['_method'] == 'REPLY') {
             // try to identify the attendee using the email sender address
             $existing_attendee = -1;
             $existing_attendee_emails = array();
             foreach ($existing['attendees'] as $i => $attendee) {
               $existing_attendee_emails[] = $attendee['email'];
               if ($this->itip->compare_email($attendee['email'], $event['_sender'], $event['_sender_utf'])) {
                 $existing_attendee = $i;
               }
             }
             $event_attendee = null;
             $update_attendees = array();
             foreach ($event['attendees'] as $attendee) {
               if ($this->itip->compare_email($attendee['email'], $event['_sender'], $event['_sender_utf'])) {
                 $event_attendee = $attendee;
                 $update_attendees[] = $attendee;
                 $metadata['fallback'] = $attendee['status'];
                 $metadata['attendee'] = $attendee['email'];
                 $metadata['rsvp'] = $attendee['rsvp'] || $attendee['role'] != 'NON-PARTICIPANT';
                 if ($attendee['status'] != 'DELEGATED') {
                   break;
                 }
               }
               // also copy delegate attendee
               else if (!empty($attendee['delegated-from'])
                 && $this->itip->compare_email($attendee['delegated-from'], $event['_sender'], $event['_sender_utf'])
               ) {
                 $update_attendees[] = $attendee;
                 if (!in_array_nocase($attendee['email'], $existing_attendee_emails)) {
                   $existing['attendees'][] = $attendee;
                 }
               }
             }
 
             // if delegatee has declined, set delegator's RSVP=True
             if ($event_attendee && $event_attendee['status'] == 'DECLINED' && $event_attendee['delegated-from']) {
               foreach ($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 >= 0 && $event_attendee) {
               $existing['attendees'][$existing_attendee] = $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 {
               $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'];
 
             // preserve my participant status for regular updates
             if (empty($status)) {
               $this->lib->merge_attendees($event, $existing);
             }
 
             // 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' || $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'] && !$master['_instance']) {
               // compute recurring events until this instance's date
               if ($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) {
       $message = $event['_method'] == 'REPLY' ? 'attendeupdateesuccess' : ($deleted ? 'successremoval' : ($existing ? 'updatedsuccessfully' : 'importedsuccessfully'));
       $this->rc->output->command('display_message', $this->gettext(array('name' => $message, 'vars' => array('calendar' => $calendar['name']))), 'confirmation');
     }
 
     if ($success || $dontsave) {
       $metadata['calendar'] = $event['calendar'];
       $metadata['nosave'] = $dontsave;
       $metadata['rsvp'] = intval($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' && $organizer && !$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))
         $this->rc->output->command('display_message', $this->gettext(array('name' => 'sentresponseto', 'vars' => array('mailto' => $organizer['name'] ? $organizer['name'] : $organizer['email']))), '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'))
         $this->rc->output->command('display_message', $this->gettext(array('name' => 'sentresponseto', 'vars' => array('mailto' => $attendee['name'] ? $attendee['name'] : $attendee['email']))), '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, $mime_id);
       if ($part->ctype_parameters['charset'])
         $charset = $part->ctype_parameters['charset'];
 //      $headers = $imap->get_message_headers($uid);
 
       if ($part) {
         $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 = $calendars[$cal_id] ?: $this->get_default_calendar($event['sensitivity']);
         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) {
       $this->rc->output->command('display_message', $this->gettext(array(
         'name' => 'importsuccess',
         'vars' => array('nr' => $success),
       )), 'confirmation');
     }
     else if ($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()
   {
     $uid   = rcube_utils::get_input_value('_uid', rcube_utils::INPUT_POST);
     $mbox  = rcube_utils::get_input_value('_mbox', rcube_utils::INPUT_POST);
     $event = array();
 
     // establish imap connection
     $imap = $this->rc->get_storage();
     $imap->set_folder($mbox);
     $message = new rcube_message($uid);
 
     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)) {
         $event['links'] = array($msgref);
       }
       // copy mail attachments to event
       else if ($message->attachments) {
         $eventid = 'cal-';
         if (!is_array($_SESSION[self::SESSION_KEY]) || $_SESSION[self::SESSION_KEY]['id'] != $eventid) {
           $_SESSION[self::SESSION_KEY] = array();
           $_SESSION[self::SESSION_KEY]['id'] = $eventid;
           $_SESSION[self::SESSION_KEY]['attachments'] = array();
         }
 
         foreach ((array)$message->attachments as $part) {
           $attachment = array(
             'data' => $imap->get_message_part($uid, $part->mime_id, $part),
             'size' => $part->size,
             'name' => $part->filename,
             'mimetype' => $part->mimetype,
             'group' => $eventid,
           );
 
           $attachment = $this->rc->plugins->exec_hook('attachment_save', $attachment);
 
           if ($attachment['status'] && !$attachment['abort']) {
             $id = $attachment['id'];
             $attachment['classname'] = rcube_utils::file2class($attachment['mimetype'], $attachment['name']);
 
             // store new attachment in session
             unset($attachment['status'], $attachment['abort'], $attachment['data']);
             $_SESSION[self::SESSION_KEY]['attachments'][$id] = $attachment;
 
             $attachment['id'] = 'rcmfile' . $attachment['id'];  // add prefix to consider it 'new'
             $event['attachments'][] = $attachment;
           }
         }
       }
       
       $this->rc->output->command('plugin.mail2event_dialog', $event);
     }
     else {
       $this->rc->output->command('display_message', $this->gettext('messageopenerror'), 'error');
     }
     
     $this->rc->output->send();
   }
 
   /**
    * 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(array('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');
         file_put_contents($tmp_path, $this->get_ical()->export(array($event), '', false, array($this->driver, 'get_attachment_body')));
 
         $args['attachments'][] = array('path' => $tmp_path, 'name' => $filename . '.ics', 'mimetype' => 'text/calendar');
         $args['param']['subject'] = $event['title'];
       }
     }
 
     return $args;
   }
 
 
   /**
    * 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 = array())
   {
     $param += array('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);
   }
 
   /**
    * 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_delegation/kolab_delegation.php b/plugins/kolab_delegation/kolab_delegation.php
index 31e55d34..f7b88e99 100644
--- a/plugins/kolab_delegation/kolab_delegation.php
+++ b/plugins/kolab_delegation/kolab_delegation.php
@@ -1,547 +1,564 @@
 <?php
 
 /**
  * Delegation configuration utility for Kolab accounts
  *
  * @version @package_version@
  * @author Aleksander Machniak <machniak@kolabsys.com>
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2011-2012, 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_delegation extends rcube_plugin
 {
     public $task = 'login|mail|settings|calendar';
 
     private $rc;
     private $engine;
 
 
     /**
      * Plugin initialization.
      */
     public function init()
     {
         $this->rc = rcube::get_instance();
 
         $this->require_plugin('libkolab');
         $this->require_plugin('kolab_auth');
 
         // on-login delegation initialization
         $this->add_hook('login_after', array($this, 'login_hook'));
         // on-check-recent delegation support
         $this->add_hook('check_recent', array($this, 'check_recent_hook'));
 
         // on-message-send delegation support
         $this->add_hook('message_before_send', array($this, 'message_before_send'));
 
         // delegation support in Calendar plugin
         $this->add_hook('message_load', array($this, 'message_load'));
         $this->add_hook('calendar_user_emails', array($this, 'calendar_user_emails'));
         $this->add_hook('calendar_list_filter', array($this, 'calendar_list_filter'));
         $this->add_hook('calendar_load_itip', array($this, 'calendar_load_itip'));
+        $this->add_hook('calendar_event_find', array($this, 'calendar_event_find'));
 
         // delegation support in kolab_auth plugin
         $this->add_hook('kolab_auth_emails', array($this, 'kolab_auth_emails'));
 
         if ($this->rc->task == 'settings') {
             // delegation management interface
             $this->register_action('plugin.delegation',              array($this, 'controller_ui'));
             $this->register_action('plugin.delegation-delete',       array($this, 'controller_action'));
             $this->register_action('plugin.delegation-save',         array($this, 'controller_action'));
             $this->register_action('plugin.delegation-autocomplete', array($this, 'controller_action'));
 
             $this->add_hook('settings_actions', array($this, 'settings_actions'));
 
             if ($this->rc->action == 'plugin.delegation' || empty($_REQUEST['_framed'])) {
                 $this->add_texts('localization/', array('deleteconfirm', 'savingdata', 'yes', 'no'));
 
                 if ($this->rc->action == 'plugin.delegation') {
                     $this->include_script('kolab_delegation.js');
                 }
 
                 $this->skin_path = $this->local_skin_path();
                 $this->include_stylesheet($this->skin_path . '/style.css');
             }
         }
         // Calendar plugin UI bindings
         else if ($this->rc->task == 'calendar' && empty($_REQUEST['_framed'])) {
             if ($this->rc->output->type == 'html') {
                 $this->calendar_ui();
             }
         }
     }
 
     /**
      * Adds Delegation section in Settings
      */
     function settings_actions($args)
     {
         $args['actions'][] = array(
             'action' => 'plugin.delegation',
             'class'  => 'delegation',
             'label'  => 'tabtitle',
             'domain' => 'kolab_delegation',
             'title'  => 'delegationtitle',
         );
 
         return $args;
     }
 
     /**
      * Engine object getter
      */
     private function engine()
     {
         if (!$this->engine) {
             require_once $this->home . '/kolab_delegation_engine.php';
 
             $this->load_config();
             $this->engine = new kolab_delegation_engine();
         }
 
         return $this->engine;
     }
 
     /**
      * On-login action
      */
     public function login_hook($args)
     {
         // Manage (create) identities for delegator's email addresses
         // and subscribe to delegator's folders. Also remove identities
         // after delegation is removed
 
         $engine = $this->engine();
         $engine->delegation_init();
 
         return $args;
     }
 
     /**
      * Check-recent action
      */
     public function check_recent_hook($args)
     {
         // Checking for new messages shall be extended to Inbox folders of all
         // delegators if 'check_all_folders' is set to false.
 
         if ($this->rc->task != 'mail') {
             return $args;
         }
 
         if (!empty($args['all'])) {
             return $args;
         }
 
         if (empty($_SESSION['delegators'])) {
             return $args;
         }
 
         $storage  = $this->rc->get_storage();
         $other_ns = $storage->get_namespace('other');
         $folders  = $storage->list_folders_subscribed('', '*', 'mail');
 
         foreach (array_keys($_SESSION['delegators']) as $uid) {
             foreach ($other_ns as $ns) {
                 $folder = $ns[0] . $uid;
                 if (in_array($folder, $folders) && !in_array($folder, $args['folders'])) {
                     $args['folders'][] = $folder;
                 }
             }
         }
 
         return $args;
     }
 
     /**
      * Mail send action
      */
     public function message_before_send($args)
     {
         // Checking headers of email being send, we'll add
         // Sender: header if mail is send on behalf of someone else
 
         if (!empty($_SESSION['delegators'])) {
             $engine = $this->engine();
             $engine->delegator_delivery_filter($args);
         }
 
         return $args;
     }
 
     /**
      * E-mail message loading action
      */
     public function message_load($args)
     {
         // This is a place where we detect delegate context
         // So we can handle event invitations on behalf of delegator
         // @TODO: should we do this only in delegators' folders?
 
         // skip invalid messages or Kolab objects (for better performance)
         if (empty($args['object']->headers) || $args['object']->headers->get('x-kolab-type', false)) {
             return $args;
         }
 
         $engine = $this->engine();
         $context = $engine->delegator_context_from_message($args['object']);
 
         if ($context) {
             $this->rc->output->set_env('delegator_context', $context);
             $this->include_script('kolab_delegation.js');
         }
 
         return $args;
     }
 
     /**
      * calendar::get_user_emails() handler
      */
     public function calendar_user_emails($args)
     {
         // In delegator context we'll use delegator's addresses
         // instead of current user addresses
 
         if (!empty($_SESSION['delegators'])) {
             $engine = $this->engine();
             $engine->delegator_emails_filter($args);
         }
 
         return $args;
     }
 
     /**
      * calendar_driver::list_calendars() handler
      */
     public function calendar_list_filter($args)
     {
         // In delegator context we'll use delegator's folders
         // instead of current user folders
 
         if (!empty($_SESSION['delegators'])) {
             $engine = $this->engine();
             $engine->delegator_folder_filter($args);
         }
 
         return $args;
     }
 
     /**
      * calendar::load_itip() handler
      */
     public function calendar_load_itip($args)
     {
         // In delegator context we'll use delegator's address/name
         // for invitation responses
 
         if (!empty($_SESSION['delegators'])) {
             $engine = $this->engine();
             $engine->delegator_identity_filter($args);
         }
 
         return $args;
     }
 
+    /**
+     * calendar::find_event() handler
+     */
+    public function calendar_event_find($args)
+    {
+        // If the event can't be found in user personal folders, we'll
+        // look in delegators' folders (T1264)
+
+        if (!empty($_SESSION['delegators']) && empty($args['result'])) {
+            $engine = $this->engine();
+            $engine->delegator_find_event($args);
+        }
+
+        return $args;
+    }
+
     /**
      * Delegation support in Calendar plugin UI
      */
     public function calendar_ui()
     {
         // Initialize handling of delegators' identities in event form
 
         if (!empty($_SESSION['delegators'])) {
             $engine = $this->engine();
             $this->rc->output->set_env('namespace', $engine->namespace_js());
             $this->rc->output->set_env('delegators', $engine->list_delegators_js());
             $this->include_script('kolab_delegation.js');
         }
     }
 
     /**
      * Delegation support in kolab_auth plugin
      */
     public function kolab_auth_emails($args)
     {
         // Add delegators addresses to address selector in user identity form
 
         if (!empty($_SESSION['delegators'])) {
             // @TODO: Consider not adding all delegator addresses to the list.
             // Instead add only address of currently edited identity
             foreach ($_SESSION['delegators'] as $emails) {
                 $args['emails'] = array_merge($args['emails'], $emails);
             }
 
             $args['emails'] = array_unique($args['emails']);
             sort($args['emails']);
         }
 
         return $args;
     }
 
     /**
      * Delegation UI handler
      */
     public function controller_ui()
     {
         // main interface (delegates list)
         if (empty($_REQUEST['_framed'])) {
             $this->register_handler('plugin.delegatelist', array($this, 'delegate_list'));
 
             $this->rc->output->include_script('list.js');
             $this->rc->output->send('kolab_delegation.settings');
         }
         // delegate frame
         else {
             $this->register_handler('plugin.delegateform', array($this, 'delegate_form'));
             $this->register_handler('plugin.delegatefolders', array($this, 'delegate_folders'));
 
             $this->rc->output->set_env('autocomplete_max', (int)$this->rc->config->get('autocomplete_max', 15));
             $this->rc->output->set_env('autocomplete_min_length', $this->rc->config->get('autocomplete_min_length'));
             $this->rc->output->add_label('autocompletechars', 'autocompletemore');
 
             $this->rc->output->send('kolab_delegation.editform');
         }
     }
 
     /**
      * Delegation action handler
      */
     public function controller_action()
     {
         $this->add_texts('localization/');
 
         $engine = $this->engine();
 
         // Delegate delete
         if ($this->rc->action == 'plugin.delegation-delete') {
             $id      = rcube_utils::get_input_value('id', rcube_utils::INPUT_GPC);
             $success = $engine->delegate_delete($id, (bool) rcube_utils::get_input_value('acl', rcube_utils::INPUT_GPC));
 
             if ($success) {
                 $this->rc->output->show_message($this->gettext('deletesuccess'), 'confirmation');
                 $this->rc->output->command('plugin.delegate_save_complete', array('deleted' => $id));
             }
             else {
                 $this->rc->output->show_message($this->gettext('deleteerror'), 'error');
             }
         }
         // Delegate add/update
         else if ($this->rc->action == 'plugin.delegation-save') {
             $id  = rcube_utils::get_input_value('id', rcube_utils::INPUT_GPC);
             $acl = rcube_utils::get_input_value('folders', rcube_utils::INPUT_GPC);
 
             // update
             if ($id) {
                 $delegate = $engine->delegate_get($id);
                 $success  = $engine->delegate_acl_update($delegate['uid'], $acl);
 
                 if ($success) {
                     $this->rc->output->show_message($this->gettext('updatesuccess'), 'confirmation');
                     $this->rc->output->command('plugin.delegate_save_complete', array('updated' => $id));
                 }
                 else {
                     $this->rc->output->show_message($this->gettext('updateerror'), 'error');
                 }
             }
             // new
             else {
                 $login    = rcube_utils::get_input_value('newid', rcube_utils::INPUT_GPC);
                 $delegate = $engine->delegate_get_by_name($login);
                 $success  = $engine->delegate_add($delegate, $acl);
 
                 if ($success) {
                     $this->rc->output->show_message($this->gettext('createsuccess'), 'confirmation');
                     $this->rc->output->command('plugin.delegate_save_complete', array(
                         'created' => $delegate['ID'],
                         'name'    => $delegate['name'],
                     ));
                 }
                 else {
                     $this->rc->output->show_message($this->gettext('createerror'), 'error');
                 }
             }
         }
         // Delegate autocompletion
         else if ($this->rc->action == 'plugin.delegation-autocomplete') {
             $search = rcube_utils::get_input_value('_search', rcube_utils::INPUT_GPC, true);
             $reqid  = rcube_utils::get_input_value('_reqid', rcube_utils::INPUT_GPC);
             $users  = $engine->list_users($search);
 
             $this->rc->output->command('ksearch_query_results', $users, $search, $reqid);
         }
 
         $this->rc->output->send();
     }
 
     /**
      * Template object of delegates list
      */
     public function delegate_list($attrib = array())
     {
         $attrib += array('id' => 'delegate-list');
 
         $engine = $this->engine();
         $list   = $engine->list_delegates();
         $table  = new html_table();
 
         // sort delegates list
         asort($list, SORT_LOCALE_STRING);
 
         foreach ($list as $id => $delegate) {
             $table->add_row(array('id' => 'rcmrow' . $id));
             $table->add(null, rcube::Q($delegate));
         }
 
         $this->rc->output->add_gui_object('delegatelist', $attrib['id']);
         $this->rc->output->set_env('delegatecount', count($list));
 
         return $table->show($attrib);
     }
 
     /**
      * Template object of delegate form
      */
     public function delegate_form($attrib = array())
     {
         $engine   = $this->engine();
         $table    = new html_table(array('cols' => 2));
         $id       = rcube_utils::get_input_value('_id', rcube_utils::INPUT_GPC);
         $field_id = 'delegate';
 
         if ($id) {
             $delegate = $engine->delegate_get($id);
         }
 
         if ($delegate) {
             $input = new html_hiddenfield(array('name' => $field_id, 'id' => $field_id, 'size' => 40));
             $input = rcube::Q($delegate['name']) . $input->show($id);
 
             $this->rc->output->set_env('active_delegate', $id);
             $this->rc->output->command('parent.enable_command','delegate-delete', true);
         }
         else {
             $input = new html_inputfield(array('name' => $field_id, 'id' => $field_id, 'size' => 40));
             $input = $input->show();
         }
 
         $table->add('title', html::label($field_id, $this->gettext('delegate')));
         $table->add(null, $input);
 
         if ($attrib['form']) {
             $this->rc->output->add_gui_object('editform', $attrib['form']);
         }
 
         return $table->show($attrib);
     }
 
     /**
      * Template object of folders list
      */
     public function delegate_folders($attrib = array())
     {
         if (!$attrib['id']) {
             $attrib['id'] = 'delegatefolders';
         }
 
         $engine = $this->engine();
         $id     = rcube_utils::get_input_value('_id', rcube_utils::INPUT_GPC);
 
         if ($id) {
             $delegate = $engine->delegate_get($id);
         }
 
         $folder_data   = $engine->list_folders($delegate['uid']);
         $rights        = array();
         $folder_groups = array();
 
         foreach ($folder_data as $folder_name => $folder) {
             $folder_groups[$folder['type']][] = $folder_name;
             $rights[$folder_name] = $folder['rights'];
         }
 
         // build block for every folder type
         foreach ($folder_groups as $type => $group) {
             if (empty($group)) {
                 continue;
             }
             $attrib['type'] = $type;
             $html .= html::div('foldersblock',
                 html::tag('h3', $type, $this->gettext($type)) .
                     $this->delegate_folders_block($group, $attrib, $rights));
         }
 
         $this->rc->output->add_gui_object('folderslist', $attrib['id']);
 
         return html::div($attrib, $html);
     }
 
     /**
      * List of folders in specified group
      */
     private function delegate_folders_block($a_folders, $attrib, $rights)
     {
         $path      = 'plugins/kolab_delegation/' . $this->skin_path . '/';
         $read_ico  = $attrib['readicon'] ? html::img(array('src' =>  $path . $attrib['readicon'], 'title' => $this->gettext('read'))) : '';
         $write_ico = $attrib['writeicon'] ? html::img(array('src' => $path . $attrib['writeicon'], 'title' => $this->gettext('write'))) : '';
 
         $table = new html_table(array('cellspacing' => 0));
         $table->add_header(array('class' => 'read', 'title' => $this->gettext('read'), 'tabindex' => 0), $read_ico);
         $table->add_header(array('class' => 'write', 'title' => $this->gettext('write'), 'tabindex' => 0), $write_ico);
         $table->add_header('foldername', $this->rc->gettext('folder'));
 
         $checkbox_read  = new html_checkbox(array('name' => 'read[]', 'class' => 'read'));
         $checkbox_write = new html_checkbox(array('name' => 'write[]', 'class' => 'write'));
 
         $names = array();
         foreach ($a_folders as $folder) {
             $foldername = $origname = preg_replace('/^INBOX &raquo;\s+/', '', kolab_storage::object_name($folder));
 
             // find folder prefix to truncate (the same code as in kolab_addressbook plugin)
             for ($i = count($names)-1; $i >= 0; $i--) {
                 if (strpos($foldername, $names[$i].' &raquo; ') === 0) {
                     $length = strlen($names[$i].' &raquo; ');
                     $prefix = substr($foldername, 0, $length);
                     $count  = count(explode(' &raquo; ', $prefix));
                     $foldername = str_repeat('&nbsp;&nbsp;', $count-1) . '&raquo; ' . substr($foldername, $length);
                     break;
                 }
             }
 
             $folder_id = 'rcmf' . rcube_utils::html_identifier($folder);
             $names[] = $origname;
             $classes = array('mailbox');
 
             if ($folder_class = $this->rc->folder_classname($folder)) {
                 $foldername = html::quote($this->rc->gettext($folder_class));
                 $classes[] = $folder_class;
             }
 
             $table->add_row();
             $table->add('read', $checkbox_read->show(
                 $rights[$folder] >= kolab_delegation_engine::ACL_READ ? $folder : null,
                 array('value' => $folder)));
             $table->add('write', $checkbox_write->show(
                 $rights[$folder] >= kolab_delegation_engine::ACL_WRITE ? $folder : null,
                 array('value' => $folder, 'id' => $folder_id)));
 
             $table->add(join(' ', $classes), html::label($folder_id, $foldername));
         }
 
         return $table->show();
     }
 }
diff --git a/plugins/kolab_delegation/kolab_delegation_engine.php b/plugins/kolab_delegation/kolab_delegation_engine.php
index e1a62299..a84bc07d 100644
--- a/plugins/kolab_delegation/kolab_delegation_engine.php
+++ b/plugins/kolab_delegation/kolab_delegation_engine.php
@@ -1,932 +1,965 @@
 <?php
 
 /**
  * Kolab Delegation Engine
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  * @author Aleksander Machniak <machniak@kolabsys.com>
  *
  * Copyright (C) 2011-2012, 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_delegation_engine
 {
     public $context;
 
     private $rc;
     private $ldap_filter;
     private $ldap_delegate_field;
     private $ldap_login_field;
     private $ldap_name_field;
     private $ldap_email_field;
     private $ldap_org_field;
     private $ldap_dn;
     private $cache = array();
     private $folder_types = array('mail', 'event', 'task');
 
     const ACL_READ  = 1;
     const ACL_WRITE = 2;
 
     /**
      * Class constructor
      */
     public function __construct()
     {
         $this->rc = rcube::get_instance();
     }
 
     /**
      * Add delegate
      *
      * @param string|array $delegate Delegate DN (encoded) or delegate data (result of delegate_get())
      * @param array        $acl      List of folder->right map
      */
     public function delegate_add($delegate, $acl)
     {
         if (!is_array($delegate)) {
             $delegate = $this->delegate_get($delegate);
         }
 
         $dn = $delegate['ID'];
         if (empty($delegate) || empty($dn)) {
             return false;
         }
 
         $list = $this->list_delegates();
 
         // add delegate to the list
         $list = array_keys((array)$list);
         $list = array_filter($list);
         if (!in_array($dn, $list)) {
             $list[] = $dn;
         }
         $list = array_map(array('kolab_auth_ldap', 'dn_decode'), $list);
 
         // update user record
         $result = $this->user_update_delegates($list);
 
         // Set ACL on folders
         if ($result && !empty($acl)) {
             $this->delegate_acl_update($delegate['uid'], $acl);
         }
 
         return $result;
     }
 
     /**
      * Set/Update ACL on delegator's folders
      *
      * @param string $uid    Delegate authentication identifier
      * @param array  $acl    List of folder->right map
      * @param bool   $update Update (remove) old rights
      */
     public function delegate_acl_update($uid, $acl, $update = false)
     {
         $storage     = $this->rc->get_storage();
         $right_types = $this->right_types();
         $folders     = $update ? $this->list_folders($uid) : array();
 
         foreach ($acl as $folder_name => $rights) {
             $r = $right_types[$rights];
             if ($r) {
                 $storage->set_acl($folder_name, $uid, $r);
             }
             else {
                 $storage->delete_acl($folder_name, $uid);
             }
 
             if (!empty($folders) && isset($folders[$folder_name])) {
                 unset($folders[$folder_name]);
             }
         }
 
         foreach ($folders as $folder_name => $folder) {
             if ($folder['rights']) {
                 $storage->delete_acl($folder_name, $uid);
             }
         }
 
         return true;
     }
 
     /**
      * Delete delgate
      *
      * @param string $dn      Delegate DN (encoded)
      * @param bool   $acl_del Enable ACL deletion on delegator folders
      */
     public function delegate_delete($dn, $acl_del = false)
     {
         $delegate = $this->delegate_get($dn);
         $list     = $this->list_delegates();
         $user     = $this->user();
 
         if (empty($delegate) || !isset($list[$dn])) {
             return false;
         }
 
         // remove delegate from the list
         unset($list[$dn]);
         $list = array_keys($list);
         $list = array_map(array('kolab_auth_ldap', 'dn_decode'), $list);
         $user[$this->ldap_delegate_field] = $list;
 
         // update user record
         $result = $this->user_update_delegates($list);
 
         // remove ACL
         if ($result && $acl_del) {
             $this->delegate_acl_update($delegate['uid'], array(), true);
         }
 
         return $result;
     }
 
     /**
      * Return delegate data
      *
      * @param string $dn Delegate DN (encoded)
      *
      * @return array Delegate record (ID, name, uid, imap_uid)
      */
     public function delegate_get($dn)
     {
         // use internal cache so we not query LDAP more than once per request
         if (!isset($this->cache[$dn])) {
             $ldap = $this->ldap();
 
             if (!$ldap || empty($dn)) {
                 return array();
             }
 
             // Get delegate
             $user = $ldap->get_record(kolab_auth_ldap::dn_decode($dn));
 
             if (empty($user)) {
                 return array();
             }
 
             $delegate = $this->parse_ldap_record($user);
             $delegate['ID'] = $dn;
 
             $this->cache[$dn] = $delegate;
         }
 
         return $this->cache[$dn];
     }
 
     /**
      * Return delegate data
      *
      * @param string $login Delegate name (the 'uid' returned in get_users())
      *
      * @return array Delegate record (ID, name, uid, imap_uid)
      */
     public function delegate_get_by_name($login)
     {
         $ldap = $this->ldap();
 
         if (!$ldap || empty($login)) {
             return array();
         }
 
         $list = $ldap->dosearch($this->ldap_login_field, $login, 1);
 
         if (count($list) == 1) {
             $dn   = key($list);
             $user = $list[$dn];
 
             return $this->parse_ldap_record($user, $dn);
         }
     }
 
     /**
      * LDAP object getter
      */
     private function ldap()
     {
         $ldap = kolab_auth::ldap();
 
         if (!$ldap || !$ldap->ready) {
             return null;
         }
 
         // Default filter of LDAP queries
         $this->ldap_filter = $this->rc->config->get('kolab_delegation_filter', '(|(objectClass=kolabInetOrgPerson)(&(objectclass=kolabsharedfolder)(kolabFolderType=mail)))');
         // Name of the LDAP field for delegates list
         $this->ldap_delegate_field = $this->rc->config->get('kolab_delegation_delegate_field', 'kolabDelegate');
         // Encoded LDAP DN of current user, set on login by kolab_auth plugin
         $this->ldap_dn = $_SESSION['kolab_dn'];
 
         // Name of the LDAP field with authentication ID
         $this->ldap_login_field = $this->rc->config->get('kolab_auth_login');
         // Name of the LDAP field with user name used for identities
         $this->ldap_name_field = $this->rc->config->get('kolab_auth_name');
         // Name of the LDAP field with email addresses used for identities
         $this->ldap_email_field = $this->rc->config->get('kolab_auth_email');
         // Name of the LDAP field with organization name for identities
         $this->ldap_org_field = $this->rc->config->get('kolab_auth_organization');
 
         $ldap->set_filter($this->ldap_filter);
         $ldap->extend_fieldmap(array($this->ldap_delegate_field => $this->ldap_delegate_field));
 
         return $ldap;
     }
 
     /**
      * List current user delegates
      */
     public function list_delegates()
     {
         $result = array();
         $ldap   = $this->ldap();
         $user   = $this->user();
 
         if (empty($ldap) || empty($user)) {
             return array();
         }
 
         // Get delegates of current user
         $delegates = $user[$this->ldap_delegate_field];
 
         if (!empty($delegates)) {
             foreach ((array)$delegates as $dn) {
                 $delegate = $ldap->get_record($dn);
                 $data     = $this->parse_ldap_record($delegate, $dn);
 
                 if (!empty($data) && !empty($data['name'])) {
                     $result[$data['ID']] = $data['name'];
                 }
             }
         }
 
         return $result;
     }
 
     /**
      * List current user delegators
      *
      * @return array List of delegators
      */
     public function list_delegators()
     {
         $result = array();
         $ldap   = $this->ldap();
 
         if (empty($ldap) || empty($this->ldap_dn)) {
             return array();
         }
 
         $list = $ldap->dosearch($this->ldap_delegate_field, $this->ldap_dn, 1);
 
         foreach ($list as $dn => $delegator) {
             $delegator = $this->parse_ldap_record($delegator, $dn);
             $result[$delegator['ID']] = $delegator;
         }
 
         return $result;
     }
 
     /**
      * List current user delegators in format compatible with Calendar plugin
      *
      * @return array List of delegators
      */
     public function list_delegators_js()
     {
         $list   = $this->list_delegators();
         $result = array();
 
         foreach ($list as $delegator) {
             $name = $delegator['name'];
             if ($pos = strrpos($name, '(')) {
                 $name = trim(substr($name, 0, $pos));
             }
 
             $result[$delegator['imap_uid']] = array(
                 'emails' => ';' . implode(';', $delegator['email']),
                 'email'  => $delegator['email'][0],
                 'name'   => $name,
             );
         }
 
         return $result;
     }
 
     /**
      * Prepare namespace prefixes for JS environment
      *
      * @return array List of prefixes
      */
     public function namespace_js()
     {
         $storage = $this->rc->get_storage();
         $ns      = $storage->get_namespace('other');
 
         if ($ns) {
             foreach ($ns as $idx => $nsval) {
                 $ns[$idx] = kolab_storage::folder_id($nsval[0]);
             }
         }
 
         return $ns;
     }
 
     /**
      * Get all folders to which current user has admin access
      *
      * @param string $delegate IMAP user identifier
      *
      * @return array Folder type/rights
      */
     public function list_folders($delegate = null)
     {
         $storage  = $this->rc->get_storage();
         $folders  = $storage->list_folders();
         $metadata = kolab_storage::folders_typedata();
         $result   = array();
 
         if (!is_array($metadata)) {
             return $result;
         }
 
         // Definition of read and write ACL
         $right_types = $this->right_types();
 
         foreach ($folders as $folder) {
             // get only folders in personal namespace
             if ($storage->folder_namespace($folder) != 'personal') {
                 continue;
             }
 
             $rights = null;
             $type   = $metadata[$folder] ?: 'mail';
             list($class, $subclass) = explode('.', $type);
 
             if (!in_array($class, $this->folder_types)) {
                 continue;
             }
 
             // in edit mode, get folder ACL
             if ($delegate) {
                 // @TODO: cache ACL
                 $acl = $storage->get_acl($folder);
                 if ($acl = $acl[$delegate]) {
                     if ($this->acl_compare($acl, $right_types[self::ACL_WRITE])) {
                         $rights = self::ACL_WRITE;
                     }
                     else if ($this->acl_compare($acl, $right_types[self::ACL_READ])) {
                         $rights = self::ACL_READ;
                     }
                 }
             }
             else if ($folder == 'INBOX' || $subclass == 'default' || $subclass == 'inbox') {
                 $rights = self::ACL_WRITE;
             }
 
             $result[$folder] = array(
                 'type'   => $class,
                 'rights' => $rights,
             );
         }
 
         return $result;
     }
 
     /**
      * Returns list of users for autocompletion
      *
      * @param string $search Search string
      *
      * @return array Users list
      */
     public function list_users($search)
     {
         $ldap = $this->ldap();
 
         if (empty($ldap) || $search === '' || $search === null) {
             return array();
         }
 
         $max    = (int) $this->rc->config->get('autocomplete_max', 15);
         $mode   = (int) $this->rc->config->get('addressbook_search_mode');
         $fields = array_unique(array_filter(array_merge((array)$this->ldap_name_field, (array)$this->ldap_login_field)));
         $users  = array();
         $keys   = array();
 
         $result = $ldap->dosearch($fields, $search, $mode, (array)$this->ldap_login_field, $max);
 
         foreach ($result as $record) {
             // skip self
             if ($record['dn'] == $_SESSION['kolab_dn']) {
                 continue;
             }
 
             $user = $this->parse_ldap_record($record);
 
             if ($user['uid']) {
                 $display = rcube_addressbook::compose_search_name($record);
                 $user    = array('name' => $user['uid'], 'display' => $display);
                 $users[] = $user;
                 $keys[]  = $display ?: $user['uid'];
             }
         }
 
         if (count($users)) {
             // sort users index
             asort($keys, SORT_LOCALE_STRING);
             // re-sort users according to index
             foreach (array_keys($keys) as $idx) {
                 $keys[$idx] = $users[$idx];
             }
             $users = array_values($keys);
         }
 
         return $users;
     }
 
     /**
      * Extract delegate identifiers and pretty name from LDAP record
      */
     private function parse_ldap_record($data, $dn = null)
     {
         $email = array();
         $uid   = $data[$this->ldap_login_field];
 
         if (is_array($uid)) {
             $uid = array_filter($uid);
             $uid = $uid[0];
         }
 
         // User name for identity
         foreach ((array)$this->ldap_name_field as $field) {
             $name = is_array($data[$field]) ? $data[$field][0] : $data[$field];
             if (!empty($name)) {
                 break;
             }
         }
 
         // User email(s) for identity
         foreach ((array)$this->ldap_email_field as $field) {
             $user_email = is_array($data[$field]) ? array_filter($data[$field]) : $data[$field];
             if (!empty($user_email)) {
                 $email = array_merge((array)$email, (array)$user_email);
             }
         }
 
         // Organization for identity
         foreach ((array)$this->ldap_org_field as $field) {
             $organization = is_array($data[$field]) ? $data[$field][0] : $data[$field];
             if (!empty($organization)) {
                 break;
             }
         }
 
         $realname = $name;
         if ($uid && $name) {
             $name .= ' (' . $uid . ')';
         }
         else {
             $name = $uid;
         }
 
         // get IMAP uid - identifier used in shared folder hierarchy
         $imap_uid = $uid;
         if ($pos = strpos($imap_uid, '@')) {
             $imap_uid = substr($imap_uid, 0, $pos);
         }
 
         return array(
             'ID'       => kolab_auth_ldap::dn_encode($dn),
             'uid'      => $uid,
             'name'     => $name,
             'realname' => $realname,
             'imap_uid' => $imap_uid,
             'email'    => $email,
             'organization' => $organization,
         );
     }
 
     /**
      * Returns LDAP record of current user
      *
      * @return array User data
      */
     public function user($parsed = false)
     {
         if (!isset($this->cache['user'])) {
             $ldap = $this->ldap();
 
             if (!$ldap) {
                 return array();
             }
 
             // Get current user record
             $this->cache['user'] = $ldap->get_record($this->ldap_dn);
         }
 
         return $parsed ? $this->parse_ldap_record($this->cache['user']) : $this->cache['user'];
     }
 
     /**
      * Update LDAP record of current user
      *
      * @param array List of delegates
      */
     public function user_update_delegates($list)
     {
         $ldap = $this->ldap();
         $pass = $this->rc->decrypt($_SESSION['password']);
 
         if (!$ldap) {
             return false;
         }
 
         // need to bind as self for sufficient privilages
         if (!$ldap->bind($this->ldap_dn, $pass)) {
             return false;
         }
 
         $user[$this->ldap_delegate_field] = $list;
 
         unset($this->cache['user']);
 
         // replace delegators list in user record
         return $ldap->replace($this->ldap_dn, $user);
     }
 
     /**
      * Manage delegation data on user login
      */
     public function delegation_init()
     {
         // Fetch all delegators from LDAP who assigned the
         // current user as their delegate and create identities
         //  a) if identity with delegator's email exists, continue
         //  b) create identity ($delegate on behalf of $delegator
         //        <$delegator-email>) for new delegators
         //  c) remove all other identities which do not match the user's primary
         //       or alias email if 'kolab_delegation_purge_identities' is set.
 
         $delegators = $this->list_delegators();
         $use_subs   = $this->rc->config->get('kolab_use_subscriptions');
         $identities = $this->rc->user->list_emails();
         $emails     = array();
         $uids       = array();
 
         if (!empty($delegators)) {
             $storage  = $this->rc->get_storage();
             $other_ns = $storage->get_namespace('other');
             $folders  = $storage->list_folders();
         }
 
         // convert identities to simpler format for faster access
         foreach ($identities as $idx => $ident) {
             // get user name from default identity
             if (!$idx) {
                 $default = array(
                     'name' => $ident['name'],
                 );
             }
             $emails[$ident['identity_id']] = $ident['email'];
         }
 
         // for every delegator...
         foreach ($delegators as $delegator) {
             $uids[$delegator['imap_uid']] = $email_arr = $delegator['email'];
             $diff = array_intersect($emails, $email_arr);
 
             // identity with delegator's email already exist, do nothing
             if (count($diff)) {
                 $emails = array_diff($emails, $email_arr);
                 continue;
             }
 
             // create identities for delegator emails
             foreach ($email_arr as $email) {
                 // @TODO: "Delegatorname" or "Username on behalf of Delegatorname"?
                 $default['name']  = $delegator['realname'];
                 $default['email'] = $email;
                 // Database field for organization is NOT NULL
                 $default['organization'] = empty($delegator['organization']) ? '' : $delegator['organization'];
                 $this->rc->user->insert_identity($default);
             }
 
             // IMAP folders shared by new delegators shall be subscribed on login,
             // as well as existing subscriptions of previously shared folders shall
             // be removed. I suppose the latter one is already done in Roundcube.
 
             // for every accessible folder...
             foreach ($folders as $folder) {
                 // for every 'other' namespace root...
                 foreach ($other_ns as $ns) {
                     $prefix = $ns[0] . $delegator['imap_uid'];
                     // subscribe delegator's folder
                     if ($folder === $prefix || strpos($folder, $prefix . substr($ns[0], -1)) === 0) {
                         // Event/Task folders need client-side activation
                         $type = kolab_storage::folder_type($folder);
                         if (preg_match('/^(event|task)/i', $type)) {
                             kolab_storage::folder_activate($folder);
                         }
                         // Subscribe to mail folders and (if system is configured
                         // to display only subscribed folders) to other
                         if ($use_subs || preg_match('/^mail/i', $type)) {
                             $storage->subscribe($folder);
                         }
                     }
                 }
             }
         }
 
         // remove identities that "do not belong" to user nor delegators
         if ($this->rc->config->get('kolab_delegation_purge_identities')) {
             $user   = $this->user(true);
             $emails = array_diff($emails, $user['email']);
 
             foreach (array_keys($emails) as $idx) {
                 $this->rc->user->delete_identity($idx);
             }
         }
 
         $_SESSION['delegators'] = $uids;
     }
 
     /**
      * Sets delegator context according to email message recipient
      *
      * @param rcube_message $message Email message object
      */
     public function delegator_context_from_message($message)
     {
         if (empty($_SESSION['delegators'])) {
             return;
         }
 
         // Match delegators' addresses with message To: address
         // @TODO: Is this reliable enough?
         // Roundcube sends invitations to every attendee separately,
         // but maybe there's a software which sends with CC header or many addresses in To:
 
         $emails = $message->get_header('to');
         $emails = rcube_mime::decode_address_list($emails, null, false);
 
         foreach ($emails as $email) {
             foreach ($_SESSION['delegators'] as $uid => $addresses) {
                 if (in_array($email['mailto'], $addresses)) {
                     return $this->context = $uid;
                 }
             }
         }
     }
 
     /**
      * Return (set) current delegator context
      *
      * @return string Delegator UID
      */
     public function delegator_context()
     {
         if (!$this->context && !empty($_SESSION['delegators'])) {
             $context = rcube_utils::get_input_value('_context', rcube_utils::INPUT_GPC);
             if ($context && isset($_SESSION['delegators'][$context])) {
                 $this->context = $context;
             }
         }
 
         return $this->context;
     }
 
     /**
      * Set user identity according to delegator delegator
      *
      * @param array $args Reference to plugin hook arguments
      */
     public function delegator_identity_filter(&$args)
     {
         $context = $this->delegator_context();
 
         if (!$context) {
             return;
         }
 
         $identities = $this->rc->user->list_emails();
         $emails     = $_SESSION['delegators'][$context];
 
         foreach ($identities as $ident) {
             if (in_array($ident['email'], $emails)) {
                 $args['identity'] = $ident;
                 return;
             }
         }
 
         // fallback to default identity
         $args['identity'] = array_shift($identities);
     }
 
     /**
      * Filter user emails according to delegator context
      *
      * @param array $args Reference to plugin hook arguments
      */
     public function delegator_emails_filter(&$args)
     {
         $context = $this->delegator_context();
 
         // try to derive context from the given user email
         if (!$context && !empty($args['emails'])) {
             if (($user = preg_replace('/@.+$/', '', $args['emails'][0])) && isset($_SESSION['delegators'][$user])) {
                 $context = $user;
             }
         }
 
         // return delegator's addresses
         if ($context) {
             $args['emails'] = $_SESSION['delegators'][$context];
             $args['abort']  = true;
         }
         // return only user addresses (exclude all delegators addresses)
         else if (!empty($_SESSION['delegators'])) {
             $identities = $this->rc->user->list_emails();
             $emails[]   = $this->rc->user->get_username();
 
             foreach ($identities as $identity) {
                 $emails[] = $identity['email'];
             }
 
             foreach ($_SESSION['delegators'] as $delegator_emails) {
                 $emails = array_diff($emails, $delegator_emails);
             }
 
             $args['emails'] = array_unique($emails);
             $args['abort']  = true;
         }
     }
 
     /**
      * Filters list of calendars according to delegator context
      *
      * @param array $args Reference to plugin hook arguments
      */
     public function delegator_folder_filter(&$args)
     {
         $context   = $this->delegator_context();
         $storage   = $this->rc->get_storage();
         $other_ns  = $storage->get_namespace('other');
         $delim     = $storage->get_hierarchy_delimiter();
         $calendars = array();
 
         // code parts derived from kolab_driver::filter_calendars()
         foreach ($args['list'] as $cal) {
             if (!$cal->ready) {
                 continue;
             }
             if ($args['writeable'] && $cal->readonly) {
                 continue;
             }
             if ($args['active'] && !$cal->storage->is_active()) {
                 continue;
             }
             if ($args['personal']) {
                 $ns   = $cal->get_namespace();
 
                 if (empty($context)) {
                     if ($ns != 'personal') {
                         continue;
                     }
                 }
                 else {
                     if ($ns != 'other') {
                         continue;
                     }
 
                     foreach ($other_ns as $ns) {
                         $folder = $ns[0] . $context . $delim;
                         if (strpos($cal->name, $folder) !== 0) {
                             continue;
                         }
                     }
                 }
             }
 
             $calendars[$cal->id] = $cal;
         }
 
         $args['calendars'] = $calendars;
         $args['abort']     = true;
     }
 
     /**
      * Filters/updates message headers according to delegator context
      *
      * @param array $args Reference to plugin hook arguments
      */
     public function delegator_delivery_filter(&$args)
     {
         // no context, but message still can be send on behalf of...
         if (!empty($_SESSION['delegators'])) {
             $message = $args['message'];
             $headers = $message->headers();
 
             // get email address from From: header
             $from = rcube_mime::decode_address_list($headers['From']);
             $from = array_shift($from);
             $from = $from['mailto'];
 
             foreach ($_SESSION['delegators'] as $uid => $addresses) {
                 if (in_array($from, $addresses)) {
                     $context = $uid;
                     break;
                 }
             }
 
             // add Sender: header with current user default identity
             if ($context) {
                 $identity = $this->rc->user->get_identity();
                 $sender   = format_email_recipient($identity['email'], $identity['name']);
 
                 $message->headers(array('Sender' => $sender), false, true);
             }
         }
     }
 
+    /**
+     * Finds an event in delegators' folders. Calendar looks only in
+     * personal namespace, we "extend" this to delegators' folders.
+     *
+     * @param array $args Reference to plugin hook arguments
+     */
+    public function delegator_find_event(&$args)
+    {
+        // The event wasn't found and current user has delegators
+        if (!empty($_SESSION['delegators']) && empty($args['result'])) {
+            $event     = $args['search'];
+            $ns_root   = kolab_storage::namespace_root('other');
+            $storage   = $this->rc->get_storage();
+            $delimiter = $storage->get_hierarchy_delimiter();
+            $folders   = $storage->list_folders_subscribed($ns_root, '*', 'event', 'w');
+
+            // search in all delegators' calendars
+            foreach ($folders as $folder) {
+                list($uid, $path) = explode($delimiter, substr($folder, strlen($ns_root)), 2);
+
+                if (!empty($_SESSION['delegators'][$uid])) {
+                    $event['calendar'] = kolab_storage::folder_id($folder, true);
+                    $result = $args['calendar']->driver->get_event($event, calendar_driver::FILTER_WRITEABLE);
+
+                    if ($result) {
+                        $args['result'] = $result;
+                        return;
+                    }
+                }
+            }
+        }
+    }
+
     /**
      * Compares two ACLs (according to supported rights)
      *
      * @param array $acl1 ACL rights array (or string)
      * @param array $acl2 ACL rights array (or string)
      *
      * @param bool True if $acl1 contains all rights from $acl2
      */
     function acl_compare($acl1, $acl2)
     {
         if (!is_array($acl1)) $acl1 = str_split($acl1);
         if (!is_array($acl2)) $acl2 = str_split($acl2);
 
         $rights = $this->rights_supported();
 
         $acl1 = array_intersect($acl1, $rights);
         $acl2 = array_intersect($acl2, $rights);
         $res  = array_intersect($acl1, $acl2);
 
         $cnt1 = count($res);
         $cnt2 = count($acl2);
 
         if ($cnt1 >= $cnt2) {
             return true;
         }
     }
 
     /**
      * Get list of supported access rights (according to RIGHTS capability)
      *
      * @todo: this is stolen from acl plugin, move to rcube_storage/rcube_imap
      *
      * @return array List of supported access rights abbreviations
      */
     public function rights_supported()
     {
         if ($this->supported !== null) {
             return $this->supported;
         }
 
         $storage = $this->rc->get_storage();
         $capa    = $storage->get_capability('RIGHTS');
 
         if (is_array($capa)) {
             $rights = strtolower($capa[0]);
         }
         else {
             $rights = 'cd';
         }
 
         return $this->supported = str_split('lrswi' . $rights . 'pa');
     }
 
     private function right_types()
     {
         // Get supported rights and build column names
         $supported = $this->rights_supported();
 
         // depending on server capability either use 'te' or 'd' for deleting msgs
         $deleteright = implode(array_intersect(str_split('ted'), $supported));
 
         return array(
             self::ACL_READ  => 'lrs',
             self::ACL_WRITE => 'lrswi'.$deleteright,
         );
     }
 }