diff --git a/plugins/kolab_addressbook/kolab_addressbook.php b/plugins/kolab_addressbook/kolab_addressbook.php
index 7c6719aa..2ddf8db2 100644
--- a/plugins/kolab_addressbook/kolab_addressbook.php
+++ b/plugins/kolab_addressbook/kolab_addressbook.php
@@ -1,1205 +1,1207 @@
 <?php
 
 /**
  * Kolab address book
  *
  * Sample plugin to add a new address book source with data from Kolab storage
  * It provides also a possibilities to manage contact folders
  * (create/rename/delete/acl) directly in Addressbook UI.
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  * @author Aleksander Machniak <machniak@kolabsys.com>
  *
  * Copyright (C) 2011-2015, 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 kolab_addressbook extends rcube_plugin
 {
     public $task = '?(?!logout).*';
 
     private $sources;
     private $folders;
     private $rc;
     private $ui;
 
     public $bonnie_api = false;
 
     const GLOBAL_FIRST = 0;
     const PERSONAL_FIRST = 1;
     const GLOBAL_ONLY = 2;
     const PERSONAL_ONLY = 3;
 
     /**
      * Startup method of a Roundcube plugin
      */
     public function init()
     {
         require_once(dirname(__FILE__) . '/lib/rcube_kolab_contacts.php');
 
         $this->rc = rcube::get_instance();
 
         // load required plugin
         $this->require_plugin('libkolab');
 
         // register hooks
         $this->add_hook('addressbooks_list', array($this, 'address_sources'));
         $this->add_hook('addressbook_get', array($this, 'get_address_book'));
         $this->add_hook('config_get', array($this, 'config_get'));
 
         if ($this->rc->task == 'addressbook') {
             $this->add_texts('localization');
             $this->add_hook('contact_form', array($this, 'contact_form'));
             $this->add_hook('contact_photo', array($this, 'contact_photo'));
             $this->add_hook('template_object_directorylist', array($this, 'directorylist_html'));
 
             // Plugin actions
             $this->register_action('plugin.book', array($this, 'book_actions'));
             $this->register_action('plugin.book-save', array($this, 'book_save'));
             $this->register_action('plugin.book-search', array($this, 'book_search'));
             $this->register_action('plugin.book-subscribe', array($this, 'book_subscribe'));
 
             $this->register_action('plugin.contact-changelog', array($this, 'contact_changelog'));
             $this->register_action('plugin.contact-diff', array($this, 'contact_diff'));
             $this->register_action('plugin.contact-restore', array($this, 'contact_restore'));
 
             // get configuration for the Bonnie API
             $this->bonnie_api = libkolab::get_bonnie_api();
 
             // Load UI elements
             if ($this->api->output->type == 'html') {
                 $this->load_config();
                 require_once($this->home . '/lib/kolab_addressbook_ui.php');
                 $this->ui = new kolab_addressbook_ui($this);
 
                 if ($this->bonnie_api) {
                     $this->add_button(array(
                         'command'    => 'contact-history-dialog',
                         'class'      => 'history contact-history',
                         'classact'   => 'history contact-history active',
                         'innerclass' => 'icon inner',
                         'label'      => 'kolab_addressbook.showhistory',
                         'type'       => 'link-menuitem'
                     ), 'contactmenu');
                 }
             }
         }
         else if ($this->rc->task == 'settings') {
             $this->add_texts('localization');
             $this->add_hook('preferences_list', array($this, 'prefs_list'));
             $this->add_hook('preferences_save', array($this, 'prefs_save'));
         }
 
         $this->add_hook('folder_delete', array($this, 'prefs_folder_delete'));
         $this->add_hook('folder_rename', array($this, 'prefs_folder_rename'));
         $this->add_hook('folder_update', array($this, 'prefs_folder_update'));
     }
 
     /**
      * Handler for the addressbooks_list hook.
      *
      * This will add all instances of available Kolab-based address books
      * to the list of address sources of Roundcube.
      * This will also hide some addressbooks according to kolab_addressbook_prio setting.
      *
      * @param array $p Hash array with hook parameters
      *
      * @return array Hash array with modified hook parameters
      */
     public function address_sources($p)
     {
         $abook_prio = $this->addressbook_prio();
 
         // Disable all global address books
         // Assumes that all non-kolab_addressbook sources are global
         if ($abook_prio == self::PERSONAL_ONLY) {
             $p['sources'] = array();
         }
 
         $sources = array();
         foreach ($this->_list_sources() as $abook_id => $abook) {
             // register this address source
             $sources[$abook_id] = $this->abook_prop($abook_id, $abook);
 
             // flag folders with 'i' right as writeable
             if ($this->rc->action == 'add' && strpos($abook->rights, 'i') !== false) {
                 $sources[$abook_id]['readonly'] = false;
             }
         }
 
         // Add personal address sources to the list
         if ($abook_prio == self::PERSONAL_FIRST) {
             // $p['sources'] = array_merge($sources, $p['sources']);
             // Don't use array_merge(), because if you have folders name
             // that resolve to numeric identifier it will break output array keys
             foreach ($p['sources'] as $idx => $value)
                 $sources[$idx] = $value;
             $p['sources'] = $sources;
         }
         else {
             // $p['sources'] = array_merge($p['sources'], $sources);
             foreach ($sources as $idx => $value)
                 $p['sources'][$idx] = $value;
         }
 
         return $p;
     }
 
     /**
      * Helper method to build a hash array of address book properties
      */
     protected function abook_prop($id, $abook)
     {
         if ($abook->virtual) {
             return array(
                 'id'       => $id,
                 'name'     => $abook->get_name(),
                 'listname' => $abook->get_foldername(),
                 'group'    => $abook instanceof kolab_storage_folder_user ? 'user' : $abook->get_namespace(),
                 'readonly' => true,
                 'rights'   => 'l',
                 'kolab'    => true,
                 'virtual'  => true,
             );
         }
         else {
             return array(
                 'id'       => $id,
                 'name'     => $abook->get_name(),
                 'listname' => $abook->get_foldername(),
                 'readonly' => $abook->readonly,
                 'rights'   => $abook->rights,
                 'groups'   => $abook->groups,
                 'undelete' => $abook->undelete && $this->rc->config->get('undo_timeout'),
                 'realname' => rcube_charset::convert($abook->get_realname(), 'UTF7-IMAP'), // IMAP folder name
                 'group'    => $abook->get_namespace(),
                 'subscribed' => $abook->is_subscribed(),
                 'carddavurl' => $abook->get_carddav_url(),
                 'removable'  => true,
                 'kolab'      => true,
                 'audittrail' => !empty($this->bonnie_api),
             );
         }
     }
 
     /**
      *
      */
     public function directorylist_html($args)
     {
         $out = '';
         $jsdata = array();
         $sources = (array)$this->rc->get_address_sources();
 
         // list all non-kolab sources first
         foreach (array_filter($sources, function($source){ return empty($source['kolab']); }) as $j => $source) {
             $id = strval(strlen($source['id']) ? $source['id'] : $j);
             $out .= $this->addressbook_list_item($id, $source, $jsdata) . '</li>';
         }
 
         // render a hierarchical list of kolab contact folders
         kolab_storage::folder_hierarchy($this->folders, $tree);
-        $out .= $this->folder_tree_html($tree, $sources, $jsdata);
+        if ($tree && !empty($tree->children)) {
+            $out .= $this->folder_tree_html($tree, $sources, $jsdata);
+        }
 
         $this->rc->output->set_env('contactgroups', array_filter($jsdata, function($src){ return $src['type'] == 'group'; }));
         $this->rc->output->set_env('address_sources', array_filter($jsdata, function($src){ return $src['type'] != 'group'; }));
 
         $args['content'] = html::tag('ul', $args, $out, html::$common_attrib);
         return $args;
     }
 
     /**
      * Return html for a structured list <ul> for the folder tree
      */
     public function folder_tree_html($node, $data, &$jsdata)
     {
         $out = '';
         foreach ($node->children as $folder) {
             $id = $folder->id;
             $source = $data[$id];
             $is_collapsed = strpos($this->rc->config->get('collapsed_abooks',''), '&'.rawurlencode($id).'&') !== false;
 
             if ($folder->virtual) {
                 $source = $this->abook_prop($folder->id, $folder);
             }
             else if (empty($source)) {
                 $this->sources[$id] = new rcube_kolab_contacts($folder->name);
                 $source = $this->abook_prop($id, $this->sources[$id]);
             }
 
             $content = $this->addressbook_list_item($id, $source, $jsdata);
 
             if (!empty($folder->children)) {
                 $child_html = $this->folder_tree_html($folder, $data, $jsdata);
 
                 // copy group items...
                 if (preg_match('!<ul[^>]*>(.*)</ul>\n*$!Ums', $content, $m)) {
                     $child_html = $m[1] . $child_html;
                     $content = substr($content, 0, -strlen($m[0]) - 1);
                 }
                 // ... and re-create the subtree
                 if (!empty($child_html)) {
                     $content .= html::tag('ul', array('class' => 'groups', 'style' => ($is_collapsed ? "display:none;" : null)), $child_html);
                 }
             }
 
             $out .= $content . '</li>';
         }
 
         return $out;
     }
 
     /**
      *
      */
     protected function addressbook_list_item($id, $source, &$jsdata, $search_mode = false)
     {
         $current = rcube_utils::get_input_value('_source', rcube_utils::INPUT_GPC);
 
         if (!$source['virtual']) {
             $jsdata[$id] = $source;
             $jsdata[$id]['name'] = html_entity_decode($source['name'], ENT_NOQUOTES, RCUBE_CHARSET);
         }
 
         // set class name(s)
         $classes = array('addressbook');
         if ($source['group'])
             $classes[] = $source['group'];
         if ($current === $id)
             $classes[] = 'selected';
         if ($source['readonly'])
             $classes[] = 'readonly';
         if ($source['virtual'])
             $classes[] = 'virtual';
         if ($source['class_name'])
             $classes[] = $source['class_name'];
 
         $name = !empty($source['listname']) ? $source['listname'] : (!empty($source['name']) ? $source['name'] : $id);
         $label_id = 'kabt:' . $id;
         $inner = ($source['virtual'] ?
             html::a(array('tabindex' => '0'), $name) :
             html::a(array(
                     'href' => $this->rc->url(array('_source' => $id)),
                     'rel' => $source['id'],
                     'id' => $label_id,
                     'onclick' => "return " . rcmail_output::JS_OBJECT_NAME.".command('list','" . rcube::JQ($id) . "',this)",
                 ), $name)
         );
 
         if (isset($source['subscribed'])) {
             $inner .= html::span(array(
                 'class' => 'subscribed',
                 'title' => $this->gettext('foldersubscribe'),
                 'role' => 'checkbox',
                 'aria-checked' => $source['subscribed'] ? 'true' : 'false',
             ), '');
         }
 
         // don't wrap in <li> but add a checkbox for search results listing
         if ($search_mode) {
             $jsdata[$id]['group'] = join(' ', $classes);
 
             if (!$source['virtual']) {
                 $inner .= html::tag('input', array(
                     'type' => 'checkbox',
                     'name' => '_source[]',
                     'value' => $id,
                     'checked' => false,
                     'aria-labelledby' => $label_id,
                 ));
             }
             return html::div(null, $inner);
         }
 
         $out .= html::tag('li', array(
                 'id' => 'rcmli' . rcube_utils::html_identifier($id, true),
                 'class' => join(' ', $classes), 
                 'noclose' => true,
             ),
             html::div($source['subscribed'] ? 'subscribed' : null, $inner)
         );
 
         $groupdata = array('out' => '', 'jsdata' => $jsdata, 'source' => $id);
         if ($source['groups'] && function_exists('rcmail_contact_groups')) {
             $groupdata = rcmail_contact_groups($groupdata);
         }
 
         $jsdata = $groupdata['jsdata'];
         $out .= $groupdata['out'];
 
         return $out;
     }
 
     /**
      * Sets autocomplete_addressbooks option according to
      * kolab_addressbook_prio setting extending list of address sources
      * to be used for autocompletion.
      */
     public function config_get($args)
     {
         if ($args['name'] != 'autocomplete_addressbooks' || $this->recurrent) {
             return $args;
         }
 
         $abook_prio = $this->addressbook_prio();
 
         // Get the original setting, use temp flag to prevent from an infinite recursion
         $this->recurrent = true;
         $sources = $this->rc->config->get('autocomplete_addressbooks');
         $this->recurrent = false;
 
         // Disable all global address books
         // Assumes that all non-kolab_addressbook sources are global
         if ($abook_prio == self::PERSONAL_ONLY) {
             $sources = array();
         }
 
         if (!is_array($sources)) {
             $sources = array();
         }
 
         $kolab_sources = array();
         foreach (array_keys($this->_list_sources()) as $abook_id) {
             if (!in_array($abook_id, $sources))
                 $kolab_sources[] = $abook_id;
         }
 
         // Add personal address sources to the list
         if (!empty($kolab_sources)) {
             if ($abook_prio == self::PERSONAL_FIRST) {
                 $sources = array_merge($kolab_sources, $sources);
             }
             else {
                 $sources = array_merge($sources, $kolab_sources);
             }
         }
 
         $args['result'] = $sources;
 
         return $args;
     }
 
 
     /**
      * Getter for the rcube_addressbook instance
      *
      * @param array $p Hash array with hook parameters
      *
      * @return array Hash array with modified hook parameters
      */
     public function get_address_book($p)
     {
         if ($p['id']) {
             $id = kolab_storage::id_decode($p['id']);
 
             // check for falsely base64 decoded identifier
             if (preg_match('![^A-Za-z0-9=/+&._ -]!', $id)) {
                 $id = $p['id'];
             }
 
             $folder = kolab_storage::get_folder($id);
 
             // try with unencoded (old-style) identifier
             if ((!$folder || $folder->type != 'contact') && $id != $p['id']) {
                 $folder = kolab_storage::get_folder($p['id']);
             }
 
             if ($folder && $folder->type == 'contact') {
                 $p['instance'] = new rcube_kolab_contacts($folder->name);
 
                 // flag source as writeable if 'i' right is given
                 if ($p['writeable'] && $this->rc->action == 'save' && strpos($p['instance']->rights, 'i') !== false) {
                     $p['instance']->readonly = false;
                 }
                 else if ($this->rc->action == 'delete' && strpos($p['instance']->rights, 't') !== false) {
                     $p['instance']->readonly = false;
                 }
             }
         }
 
         return $p;
     }
 
 
     private function _list_sources()
     {
         // already read sources
         if (isset($this->sources))
             return $this->sources;
 
         kolab_storage::$encode_ids = true;
         $this->sources = array();
         $this->folders = array();
 
         $abook_prio = $this->addressbook_prio();
 
         // Personal address source(s) disabled?
         if ($abook_prio == self::GLOBAL_ONLY) {
             return $this->sources;
         }
 
         // get all folders that have "contact" type
         $folders = kolab_storage::sort_folders(kolab_storage::get_folders('contact'));
 
         if (PEAR::isError($folders)) {
             rcube::raise_error(array(
               'code' => 600, 'type' => 'php',
               'file' => __FILE__, 'line' => __LINE__,
               'message' => "Failed to list contact folders from Kolab server:" . $folders->getMessage()),
             true, false);
         }
         else {
             // we need at least one folder to prevent from errors in Roundcube core
             // when there's also no sql nor ldap addressbook (Bug #2086)
             if (empty($folders)) {
                 if ($folder = kolab_storage::create_default_folder('contact')) {
                     $folders = array(new kolab_storage_folder($folder, 'contact'));
                 }
             }
 
             // convert to UTF8 and sort
             foreach ($folders as $folder) {
                 // create instance of rcube_contacts
                 $abook_id = $folder->id;
                 $abook = new rcube_kolab_contacts($folder->name);
                 $this->sources[$abook_id] = $abook;
                 $this->folders[$abook_id] = $folder;
             }
         }
 
         return $this->sources;
     }
 
 
     /**
      * Plugin hook called before rendering the contact form or detail view
      *
      * @param array $p Hash array with hook parameters
      *
      * @return array Hash array with modified hook parameters
      */
     public function contact_form($p)
     {
         // none of our business
         if (!is_object($GLOBALS['CONTACTS']) || !is_a($GLOBALS['CONTACTS'], 'rcube_kolab_contacts'))
             return $p;
 
         // extend the list of contact fields to be displayed in the 'personal' section
         if (is_array($p['form']['personal'])) {
             $p['form']['personal']['content']['profession']    = array('size' => 40);
             $p['form']['personal']['content']['children']      = array('size' => 40);
             $p['form']['personal']['content']['freebusyurl']   = array('size' => 40);
             $p['form']['personal']['content']['pgppublickey']  = array('size' => 70);
             $p['form']['personal']['content']['pkcs7publickey'] = array('size' => 70);
 
             // re-order fields according to the coltypes list
             $p['form']['contact']['content']  = $this->_sort_form_fields($p['form']['contact']['content'], $GLOBALS['CONTACTS']);
             $p['form']['personal']['content'] = $this->_sort_form_fields($p['form']['personal']['content'], $GLOBALS['CONTACTS']);
 
             /* define a separate section 'settings'
             $p['form']['settings'] = array(
                 'name'    => $this->gettext('settings'),
                 'content' => array(
                     'freebusyurl'  => array('size' => 40, 'visible' => true),
                     'pgppublickey' => array('size' => 70, 'visible' => true),
                     'pkcs7publickey' => array('size' => 70, 'visible' => false),
                 )
             );
             */
         }
 
         if ($this->bonnie_api && $this->rc->action == 'show' && empty($p['record']['rev'])) {
             $this->rc->output->set_env('kolab_audit_trail', true);
         }
 
         return $p;
     }
 
     /**
      * Plugin hook for the contact photo image
      */
     public function contact_photo($p)
     {
         // add photo data from old revision inline as data url
         if (!empty($p['record']['rev']) && !empty($p['data'])) {
             $p['url'] = 'data:image/gif;base64,' . base64_encode($p['data']);
         }
 
         return $p;
     }
 
     /**
      * Handler for contact audit trail changelog requests
      */
     public function contact_changelog()
     {
         if (empty($this->bonnie_api)) {
             return false;
         }
 
         $contact = rcube_utils::get_input_value('cid', rcube_utils::INPUT_POST, true);
         $source = rcube_utils::get_input_value('source', rcube_utils::INPUT_POST);
 
         list($uid, $mailbox, $msguid) = $this->_resolve_contact_identity($contact, $source);
 
         $result = $uid && $mailbox ? $this->bonnie_api->changelog('contact', $uid, $mailbox, $msguid) : null;
         if (is_array($result) && $result['uid'] == $uid) {
             if (is_array($result['changes'])) {
                 $rcmail = $this->rc;
                 $dtformat = $this->rc->config->get('date_format') . ' ' . $this->rc->config->get('time_format');
                 array_walk($result['changes'], function(&$change) use ($rcmail, $dtformat) {
                   if ($change['date']) {
                       $dt = rcube_utils::anytodatetime($change['date']);
                       if ($dt instanceof DateTime) {
                           $change['date'] = $rcmail->format_date($dt, $dtformat);
                       }
                   }
                 });
             }
             $this->rc->output->command('contact_render_changelog', $result['changes']);
         }
         else {
             $this->rc->output->command('contact_render_changelog', false);
         }
 
         $this->rc->output->send();
     }
 
     /**
      * Handler for audit trail diff view requests
      */
     public function contact_diff()
     {
         if (empty($this->bonnie_api)) {
             return false;
         }
 
         $contact = rcube_utils::get_input_value('cid', rcube_utils::INPUT_POST, true);
         $source = rcube_utils::get_input_value('source', rcube_utils::INPUT_POST);
         $rev1 = rcube_utils::get_input_value('rev1', rcube_utils::INPUT_POST);
         $rev2 = rcube_utils::get_input_value('rev2', rcube_utils::INPUT_POST);
 
         list($uid, $mailbox, $msguid) = $this->_resolve_contact_identity($contact, $source);
 
         $result = $this->bonnie_api->diff('contact', $uid, $rev1, $rev2, $mailbox, $msguid);
         if (is_array($result) && $result['uid'] == $uid) {
             $result['rev1'] = $rev1;
             $result['rev2'] = $rev2;
             $result['cid'] = $contact;
 
             // convert some properties, similar to rcube_kolab_contacts::_to_rcube_contact()
             $keymap = array(
                 'lastmodified-date' => 'changed',
                 'additional' => 'middlename',
                 'fn' => 'name',
                 'tel' => 'phone',
                 'url' => 'website',
                 'bday' => 'birthday',
                 'note' => 'notes',
                 'role' => 'profession',
                 'title' => 'jobtitle',
             );
 
             $propmap = array('email' => 'address', 'website' => 'url', 'phone' => 'number');
             $date_format = $this->rc->config->get('date_format', 'Y-m-d');
 
             // map kolab object properties to keys and values the client expects
             array_walk($result['changes'], function(&$change, $i) use ($keymap, $propmap, $date_format) {
                 if (array_key_exists($change['property'], $keymap)) {
                     $change['property'] = $keymap[$change['property']];
                 }
 
                 // format date-time values
                 if ($change['property'] == 'created' || $change['property'] == 'changed') {
                     if ($old_ = rcube_utils::anytodatetime($change['old'])) {
                         $change['old_'] = $this->rc->format_date($old_);
                     }
                     if ($new_ = rcube_utils::anytodatetime($change['new'])) {
                         $change['new_'] = $this->rc->format_date($new_);
                     }
                 }
                 // format dates
                 else if ($change['property'] == 'birthday' || $change['property'] == 'anniversary') {
                     if ($old_ = rcube_utils::anytodatetime($change['old'])) {
                         $change['old_'] = $this->rc->format_date($old_, $date_format);
                     }
                     if ($new_ = rcube_utils::anytodatetime($change['new'])) {
                         $change['new_'] = $this->rc->format_date($new_, $date_format);
                     }
                 }
                 // convert email, website, phone values
                 else if (array_key_exists($change['property'], $propmap)) {
                     $propname = $propmap[$change['property']];
                     foreach (array('old','new') as $k) {
                         $k_ = $k . '_';
                         if (!empty($change[$k])) {
                             $change[$k_] = html::quote($change[$k][$propname] ?: '--');
                             if ($change[$k]['type']) {
                                 $change[$k_] .= '&nbsp;' . html::span('subtype', rcmail_get_type_label($change[$k]['type']));
                             }
                             $change['ishtml'] = true;
                         }
                     }
                 }
                 // serialize address structs
                 if ($change['property'] == 'address') {
                     foreach (array('old','new') as $k) {
                         $k_ = $k . '_';
                         $change[$k]['zipcode'] = $change[$k]['code'];
                         $template = $this->rc->config->get('address_template', '{'.join('} {', array_keys($change[$k])).'}');
                         $composite = array();
                         foreach ($change[$k] as $p => $val) {
                             if (strlen($val))
                                 $composite['{'.$p.'}'] = $val;
                         }
                         $change[$k_] = preg_replace('/\{\w+\}/', '', strtr($template, $composite));
                         if ($change[$k]['type']) {
                             $change[$k_] .= html::div('subtype', rcmail_get_type_label($change[$k]['type']));
                         }
                         $change['ishtml'] = true;
                     }
 
                     $change['diff_'] = libkolab::html_diff($change['old_'], $change['new_'], true);
                 }
                 // localize gender values
                 else if ($change['property'] == 'gender') {
                     if ($change['old']) $change['old_'] = $this->rc->gettext($change['old']);
                     if ($change['new']) $change['new_'] = $this->rc->gettext($change['new']);
                 }
                 // translate 'key' entries in individual properties
                 else if ($change['property'] == 'key') {
                     $p = $change['old'] ?: $change['new'];
                     $t = $p['type'];
                     $change['property'] = $t . 'publickey';
                     $change['old'] = $change['old'] ? $change['old']['key'] : '';
                     $change['new'] = $change['new'] ? $change['new']['key'] : '';
                 }
                 // compute a nice diff of notes
                 else if ($change['property'] == 'notes') {
                     $change['diff_'] = libkolab::html_diff($change['old'], $change['new'], false);
                 }
             });
 
             $this->rc->output->command('contact_show_diff', $result);
         }
         else {
             $this->rc->output->command('display_message', $this->gettext('objectdiffnotavailable'), 'error');
         }
 
         $this->rc->output->send();
     }
 
     /**
      * Handler for audit trail revision restore requests
      */
     public function contact_restore()
     {
         if (empty($this->bonnie_api)) {
             return false;
         }
 
         $success = false;
         $contact = rcube_utils::get_input_value('cid', rcube_utils::INPUT_POST, true);
         $source = rcube_utils::get_input_value('source', rcube_utils::INPUT_POST);
         $rev = rcube_utils::get_input_value('rev', rcube_utils::INPUT_POST);
 
         list($uid, $mailbox, $msguid) = $this->_resolve_contact_identity($contact, $source, $folder);
 
         if ($folder && ($raw_msg = $this->bonnie_api->rawdata('contact', $uid, $rev, $mailbox))) {
             $imap = $this->rc->get_storage();
 
             // insert $raw_msg as new message
             if ($imap->save_message($folder->name, $raw_msg, null, false)) {
                 $success = true;
 
                 // delete old revision from imap and cache
                 $imap->delete_message($msguid, $folder->name);
                 $folder->cache->set($msguid, false);
                 $this->cache = array();
             }
         }
 
         if ($success) {
             $this->rc->output->command('display_message', $this->gettext(array('name' => 'objectrestoresuccess', 'vars' => array('rev' => $rev))), 'confirmation');
             $this->rc->output->command('close_contact_history_dialog', $contact);
         }
         else {
             $this->rc->output->command('display_message', $this->gettext('objectrestoreerror'), 'error');
         }
 
         $this->rc->output->send();
     }
 
     /**
      * Get a previous revision of the given contact record from the Bonnie API
      */
     public function get_revision($cid, $source, $rev)
     {
         if (empty($this->bonnie_api)) {
             return false;
         }
 
         list($uid, $mailbox, $msguid) = $this->_resolve_contact_identity($cid, $source);
 
         // call Bonnie API
         $result = $this->bonnie_api->get('contact', $uid, $rev, $mailbox, $msguid);
         if (is_array($result) && $result['uid'] == $uid && !empty($result['xml'])) {
             $format = kolab_format::factory('contact');
             $format->load($result['xml']);
             $rec = $format->to_array();
 
             if ($format->is_valid()) {
                 $rec['rev'] = $result['rev'];
                 return $rec;
             }
         }
 
         return false;
     }
 
 
     /**
      * Helper method to resolved the given contact identifier into uid and mailbox
      *
      * @return array (uid,mailbox,msguid) tuple
      */
     private function _resolve_contact_identity($id, $abook, &$folder = null)
     {
         $mailbox = $msguid = null;
 
         $source = $this->get_address_book(array('id' => $abook));
         if ($source['instance']) {
             $uid = $source['instance']->id2uid($id);
             $list = kolab_storage::id_decode($abook);
         }
         else {
             return array(null, $mailbox, $msguid);
         }
 
         // get resolve message UID and mailbox identifier
         if ($folder = kolab_storage::get_folder($list)) {
             $mailbox = $folder->get_mailbox_id();
             $msguid = $folder->cache->uid2msguid($uid);
         }
 
         return array($uid, $mailbox, $msguid);
     }
 
     /**
      *
      */
     private function _sort_form_fields($contents, $source)
     {
       $block = array();
 
       foreach (array_keys($source->coltypes) as $col) {
           if (isset($contents[$col]))
               $block[$col] = $contents[$col];
       }
 
       return $block;
     }
 
 
     /**
      * Handler for user preferences form (preferences_list hook)
      *
      * @param array $args Hash array with hook parameters
      *
      * @return array Hash array with modified hook parameters
      */
     public function prefs_list($args)
     {
         if ($args['section'] != 'addressbook') {
             return $args;
         }
 
         $ldap_public = $this->rc->config->get('ldap_public');
         $abook_type  = $this->rc->config->get('address_book_type');
 
         // Hide option if there's no global addressbook
         if (empty($ldap_public) || $abook_type != 'ldap') {
             return $args;
         }
 
         // Check that configuration is not disabled
         $dont_override = (array) $this->rc->config->get('dont_override', array());
         $prio          = $this->addressbook_prio();
 
         if (!in_array('kolab_addressbook_prio', $dont_override)) {
             // Load localization
             $this->add_texts('localization');
 
             $field_id = '_kolab_addressbook_prio';
             $select   = new html_select(array('name' => $field_id, 'id' => $field_id));
 
             $select->add($this->gettext('globalfirst'), self::GLOBAL_FIRST);
             $select->add($this->gettext('personalfirst'), self::PERSONAL_FIRST);
             $select->add($this->gettext('globalonly'), self::GLOBAL_ONLY);
             $select->add($this->gettext('personalonly'), self::PERSONAL_ONLY);
 
             $args['blocks']['main']['options']['kolab_addressbook_prio'] = array(
                 'title' => html::label($field_id, rcube::Q($this->gettext('addressbookprio'))),
                 'content' => $select->show($prio),
             );
         }
 
         return $args;
     }
 
     /**
      * Handler for user preferences save (preferences_save hook)
      *
      * @param array $args Hash array with hook parameters
      *
      * @return array Hash array with modified hook parameters
      */
     public function prefs_save($args)
     {
         if ($args['section'] != 'addressbook') {
             return $args;
         }
 
         // Check that configuration is not disabled
         $dont_override = (array) $this->rc->config->get('dont_override', array());
         $key           = 'kolab_addressbook_prio';
 
         if (!in_array('kolab_addressbook_prio', $dont_override) || !isset($_POST['_'.$key])) {
             $args['prefs'][$key] = (int) rcube_utils::get_input_value('_'.$key, rcube_utils::INPUT_POST);
         }
 
         return $args;
     }
 
 
     /**
      * Handler for plugin actions
      */
     public function book_actions()
     {
         $action = trim(rcube_utils::get_input_value('_act', rcube_utils::INPUT_GPC));
 
         if ($action == 'create') {
             $this->ui->book_edit();
         }
         else if ($action == 'edit') {
             $this->ui->book_edit();
         }
         else if ($action == 'delete') {
             $this->book_delete();
         }
     }
 
 
     /**
      * Handler for address book create/edit form submit
      */
     public function book_save()
     {
         $prop = array(
             'name'    => trim(rcube_utils::get_input_value('_name', rcube_utils::INPUT_POST)),
             'oldname' => trim(rcube_utils::get_input_value('_oldname', rcube_utils::INPUT_POST, true)), // UTF7-IMAP
             'parent'  => trim(rcube_utils::get_input_value('_parent', rcube_utils::INPUT_POST, true)), // UTF7-IMAP
             'type'    => 'contact',
             'subscribed' => true,
         );
 
         $result = $error = false;
         $type = strlen($prop['oldname']) ? 'update' : 'create';
         $prop = $this->rc->plugins->exec_hook('addressbook_'.$type, $prop);
 
         if (!$prop['abort']) {
             if ($newfolder = kolab_storage::folder_update($prop)) {
                 $folder = $newfolder;
                 $result = true;
             }
             else {
                 $error = kolab_storage::$last_error;
             }
         }
         else {
             $result = $prop['result'];
             $folder = $prop['name'];
         }
 
         if ($result) {
             $kolab_folder = kolab_storage::get_folder($folder);
 
             // get folder/addressbook properties
             $abook = new rcube_kolab_contacts($folder);
             $props = $this->abook_prop(kolab_storage::folder_id($folder, true), $abook);
             $props['parent'] = kolab_storage::folder_id($kolab_folder->get_parent(), true);
 
             $this->rc->output->show_message('kolab_addressbook.book'.$type.'d', 'confirmation');
             $this->rc->output->command('book_update', $props, kolab_storage::folder_id($prop['oldname'], true));
         }
         else {
             if (!$error) {
                 $error = $plugin['message'] ? $plugin['message'] : 'kolab_addressbook.book'.$type.'error';
             }
 
             $this->rc->output->show_message($error, 'error');
         }
 
         $this->rc->output->send('iframe');
     }
 
     /**
      *
      */
     public function book_search()
     {
         $results = array();
         $query = rcube_utils::get_input_value('q', rcube_utils::INPUT_GPC);
         $source = rcube_utils::get_input_value('source', rcube_utils::INPUT_GPC);
 
         kolab_storage::$encode_ids = true;
         $search_more_results = false;
         $this->sources = array();
         $this->folders = array();
 
         // find unsubscribed IMAP folders that have "event" type
         if ($source == 'folders') {
             foreach ((array)kolab_storage::search_folders('contact', $query, array('other')) as $folder) {
                 $this->folders[$folder->id] = $folder;
                 $this->sources[$folder->id] = new rcube_kolab_contacts($folder->name);
             }
         }
         // search other user's namespace via LDAP
         else if ($source == 'users') {
             $limit = $this->rc->config->get('autocomplete_max', 15) * 2;  // we have slightly more space, so display twice the number
             foreach (kolab_storage::search_users($query, 0, array(), $limit * 10) as $user) {
                 $folders = array();
                 // search for contact folders shared by this user
                 foreach (kolab_storage::list_user_folders($user, 'contact', false) as $foldername) {
                     $folders[] = new kolab_storage_folder($foldername, 'contact');
                 }
 
                 if (count($folders)) {
                     $userfolder = new kolab_storage_folder_user($user['kolabtargetfolder'], '', $user);
                     $this->folders[$userfolder->id] = $userfolder;
                     $this->sources[$userfolder->id] = $userfolder;
 
                     foreach ($folders as $folder) {
                         $this->folders[$folder->id] = $folder;
                         $this->sources[$folder->id] = new rcube_kolab_contacts($folder->name);;
                         $count++;
                     }
                 }
 
                 if ($count >= $limit) {
                     $search_more_results = true;
                     break;
                 }
             }
         }
 
         $delim = $this->rc->get_storage()->get_hierarchy_delimiter();
 
         // build results list
         foreach ($this->sources as $id => $source) {
             $folder = $this->folders[$id];
             $imap_path = explode($delim, $folder->name);
 
             // find parent
             do {
               array_pop($imap_path);
               $parent_id = kolab_storage::folder_id(join($delim, $imap_path));
             }
             while (count($imap_path) > 1 && !$this->folders[$parent_id]);
 
             // restore "real" parent ID
             if ($parent_id && !$this->folders[$parent_id]) {
                 $parent_id = kolab_storage::folder_id($folder->get_parent());
             }
 
             $prop = $this->abook_prop($id, $source);
             $prop['parent'] = $parent_id;
 
             $html = $this->addressbook_list_item($id, $prop, $jsdata, true);
             unset($prop['group']);
             $prop += (array)$jsdata[$id];
             $prop['html'] = $html;
 
             $results[] = $prop;
         }
 
         // report more results available
         if ($search_more_results) {
             $this->rc->output->show_message('autocompletemore', 'notice');
         }
 
         $this->rc->output->command('multi_thread_http_response', $results, rcube_utils::get_input_value('_reqid', rcube_utils::INPUT_GPC));
     }
 
     /**
      *
      */
     public function book_subscribe()
     {
         $success = false;
         $id = rcube_utils::get_input_value('_source', rcube_utils::INPUT_GPC);
 
         if ($id && ($folder = kolab_storage::get_folder(kolab_storage::id_decode($id)))) {
             if (isset($_POST['_permanent']))
                 $success |= $folder->subscribe(intval($_POST['_permanent']));
             if (isset($_POST['_active']))
                 $success |= $folder->activate(intval($_POST['_active']));
 
             // list groups for this address book
             if (!empty($_POST['_groups'])) {
                 $abook = new rcube_kolab_contacts($folder->name);
                 foreach ((array)$abook->list_groups() as $prop) {
                     $prop['source'] = $id;
                     $prop['id'] = $prop['ID'];
                     unset($prop['ID']);
                     $this->rc->output->command('insert_contact_group', $prop);
                 }
             }
         }
 
         if ($success) {
             $this->rc->output->show_message('successfullysaved', 'confirmation');
         }
         else {
             $this->rc->output->show_message($this->gettext('errorsaving'), 'error');
         }
 
         $this->rc->output->send();
     }
 
 
     /**
      * Handler for address book delete action (AJAX)
      */
     private function book_delete()
     {
         $folder = trim(rcube_utils::get_input_value('_source', rcube_utils::INPUT_GPC, true, 'UTF7-IMAP'));
 
         if (kolab_storage::folder_delete($folder)) {
             $storage = $this->rc->get_storage();
             $delimiter = $storage->get_hierarchy_delimiter();
 
             $this->rc->output->show_message('kolab_addressbook.bookdeleted', 'confirmation');
             $this->rc->output->set_env('pagecount', 0);
             $this->rc->output->command('set_rowcount', rcmail_get_rowcount_text(new rcube_result_set()));
             $this->rc->output->command('set_env', 'delimiter', $delimiter);
             $this->rc->output->command('list_contacts_clear');
             $this->rc->output->command('book_delete_done', kolab_storage::folder_id($folder, true));
         }
         else {
             $this->rc->output->show_message('kolab_addressbook.bookdeleteerror', 'error');
         }
 
         $this->rc->output->send();
     }
 
     /**
      * Returns value of kolab_addressbook_prio setting
      */
     private function addressbook_prio()
     {
         // Load configuration
         if (!$this->config_loaded) {
             $this->load_config();
             $this->config_loaded = true;
         }
 
         $abook_prio = (int) $this->rc->config->get('kolab_addressbook_prio');
 
         // Make sure any global addressbooks are defined
         if ($abook_prio == 0 || $abook_prio == 2) {
             $ldap_public = $this->rc->config->get('ldap_public');
             $abook_type  = $this->rc->config->get('address_book_type');
 
             if (empty($ldap_public) || $abook_type != 'ldap') {
                 $abook_prio = 1;
             }
         }
 
         return $abook_prio;
     }
 
     /**
      * Hook for (contact) folder deletion
      */
     function prefs_folder_delete($args)
     {
         // ignore...
         if ($args['abort'] && !$args['result']) {
             return $args;
         }
 
         $this->_contact_folder_rename($args['name'], false);
     }
 
     /**
      * Hook for (contact) folder renaming
      */
     function prefs_folder_rename($args)
     {
         // ignore...
         if ($args['abort'] && !$args['result']) {
             return $args;
         }
 
         $this->_contact_folder_rename($args['oldname'], $args['newname']);
     }
 
     /**
      * Hook for (contact) folder updates. Forward to folder_rename handler if name was changed
      */
     function prefs_folder_update($args)
     {
         // ignore...
         if ($args['abort'] && !$args['result']) {
             return $args;
         }
 
         if ($args['record']['name'] != $args['record']['oldname']) {
             $this->_contact_folder_rename($args['record']['oldname'], $args['record']['name']);
         }
     }
 
     /**
      * Apply folder renaming or deletion to the registered birthday calendar address books
      */
     private function _contact_folder_rename($oldname, $newname = false)
     {
         $update = false;
         $delimiter = $this->rc->get_storage()->get_hierarchy_delimiter();
         $bday_addressbooks = (array)$this->rc->config->get('calendar_birthday_adressbooks', array());
 
         foreach ($bday_addressbooks as $i => $id) {
             $folder_name = kolab_storage::id_decode($id);
             if ($oldname === $folder_name || strpos($folder_name, $oldname.$delimiter) === 0) {
                 if ($newname) {  // rename
                     $new_folder = $newname . substr($folder_name, strlen($oldname));
                     $bday_addressbooks[$i] = kolab_storage::id_encode($new_folder);
                 }
                 else {  // delete
                     unset($bday_addressbooks[$i]);
                 }
                 $update = true;
             }
         }
 
         if ($update) {
             $this->rc->user->save_prefs(array('calendar_birthday_adressbooks' => $bday_addressbooks));
         }
     }
 
 }