--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/plugins/calendar/drivers/database/database_driver.php	Sat Jan 13 08:56:12 2018 -0500
@@ -0,0 +1,1496 @@
+<?php
+
+/**
+ * Database driver for the Calendar plugin
+ *
+ * @author Lazlo Westerhof <hello@lazlo.me>
+ * @author Thomas Bruederli <bruederli@kolabsys.com>
+ *
+ * Copyright (C) 2010, Lazlo Westerhof <hello@lazlo.me>
+ * Copyright (C) 2012-2015, Kolab Systems AG <contact@kolabsys.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+class database_driver extends calendar_driver
+{
+  const DB_DATE_FORMAT = 'Y-m-d H:i:s';
+
+  public static $scheduling_properties = array('start', 'end', 'allday', 'recurrence', 'location', 'cancelled');
+
+  // features this backend supports
+  public $alarms = true;
+  public $attendees = true;
+  public $freebusy = false;
+  public $attachments = true;
+  public $alarm_types = array('DISPLAY');
+
+  private $rc;
+  private $cal;
+  private $cache = array();
+  private $calendars = array();
+  private $calendar_ids = '';
+  private $free_busy_map = array('free' => 0, 'busy' => 1, 'out-of-office' => 2, 'outofoffice' => 2, 'tentative' => 3);
+  private $sensitivity_map = array('public' => 0, 'private' => 1, 'confidential' => 2);
+  private $server_timezone;
+  
+  private $db_events = 'events';
+  private $db_calendars = 'calendars';
+  private $db_attachments = 'attachments';
+
+
+  /**
+   * Default constructor
+   */
+  public function __construct($cal)
+  {
+    $this->cal = $cal;
+    $this->rc = $cal->rc;
+    $this->server_timezone = new DateTimeZone(date_default_timezone_get());
+    
+    // read database config
+    $db = $this->rc->get_dbh();
+    $this->db_events = $this->rc->config->get('db_table_events', $db->table_name($this->db_events));
+    $this->db_calendars = $this->rc->config->get('db_table_calendars', $db->table_name($this->db_calendars));
+    $this->db_attachments = $this->rc->config->get('db_table_attachments', $db->table_name($this->db_attachments));
+    
+    $this->_read_calendars();
+  }
+
+  /**
+   * Read available calendars for the current user and store them internally
+   */
+  private function _read_calendars()
+  {
+    $hidden = array_filter(explode(',', $this->rc->config->get('hidden_calendars', '')));
+    
+    if (!empty($this->rc->user->ID)) {
+      $calendar_ids = array();
+      $result = $this->rc->db->query(
+        "SELECT *, calendar_id AS id FROM " . $this->db_calendars . "
+         WHERE user_id=?
+         ORDER BY name",
+         $this->rc->user->ID
+      );
+      while ($result && ($arr = $this->rc->db->fetch_assoc($result))) {
+        $arr['showalarms'] = intval($arr['showalarms']);
+        $arr['active']     = !in_array($arr['id'], $hidden);
+        $arr['name']       = html::quote($arr['name']);
+        $arr['listname']   = html::quote($arr['name']);
+        $arr['rights']     = 'lrswikxteav';
+        $arr['editable']  = true;
+        $this->calendars[$arr['calendar_id']] = $arr;
+        $calendar_ids[] = $this->rc->db->quote($arr['calendar_id']);
+      }
+      $this->calendar_ids = join(',', $calendar_ids);
+    }
+  }
+
+  /**
+   * Get a list of available calendars from this source
+   *
+   * @param integer Bitmask defining filter criterias
+   *
+   * @return array List of calendars
+   */
+  public function list_calendars($filter = 0)
+  {
+    // attempt to create a default calendar for this user
+    if (empty($this->calendars)) {
+      if ($this->create_calendar(array('name' => 'Default', 'color' => 'cc0000', 'showalarms' => true)))
+        $this->_read_calendars();
+    }
+
+    $calendars = $this->calendars;
+
+    // filter active calendars
+    if ($filter & self::FILTER_ACTIVE) {
+      foreach ($calendars as $idx => $cal) {
+        if (!$cal['active']) {
+          unset($calendars[$idx]);
+        }
+      }
+    }
+
+    // 'personal' is unsupported in this driver
+
+    // append the virtual birthdays calendar
+    if ($this->rc->config->get('calendar_contact_birthdays', false)) {
+      $prefs = $this->rc->config->get('birthday_calendar', array('color' => '87CEFA'));
+      $hidden = array_filter(explode(',', $this->rc->config->get('hidden_calendars', '')));
+
+      $id = self::BIRTHDAY_CALENDAR_ID;
+      if (!$active || !in_array($id, $hidden)) {
+        $calendars[$id] = array(
+          'id'         => $id,
+          'name'       => $this->cal->gettext('birthdays'),
+          'listname'   => $this->cal->gettext('birthdays'),
+          'color'      => $prefs['color'],
+          'showalarms' => (bool)$this->rc->config->get('calendar_birthdays_alarm_type'),
+          'active'     => !in_array($id, $hidden),
+          'group'      => 'x-birthdays',
+          'editable'  => false,
+          'default'    => false,
+          'children'   => false,
+        );
+      }
+    }
+
+    return $calendars;
+  }
+
+  /**
+   * Create a new calendar assigned to the current user
+   *
+   * @param array Hash array with calendar properties
+   *    name: Calendar name
+   *   color: The color of the calendar
+   * @return mixed ID of the calendar on success, False on error
+   */
+  public function create_calendar($prop)
+  {
+    $result = $this->rc->db->query(
+      "INSERT INTO " . $this->db_calendars . "
+       (user_id, name, color, showalarms)
+       VALUES (?, ?, ?, ?)",
+       $this->rc->user->ID,
+       $prop['name'],
+       $prop['color'],
+       $prop['showalarms']?1:0
+    );
+    
+    if ($result)
+      return $this->rc->db->insert_id($this->db_calendars);
+    
+    return false;
+  }
+
+  /**
+   * Update properties of an existing calendar
+   *
+   * @see calendar_driver::edit_calendar()
+   */
+  public function edit_calendar($prop)
+  {
+    // birthday calendar properties are saved in user prefs
+    if ($prop['id'] == self::BIRTHDAY_CALENDAR_ID) {
+      $prefs['birthday_calendar'] = $this->rc->config->get('birthday_calendar', array('color' => '87CEFA'));
+      if (isset($prop['color']))
+        $prefs['birthday_calendar']['color'] = $prop['color'];
+      if (isset($prop['showalarms']))
+        $prefs['calendar_birthdays_alarm_type'] = $prop['showalarms'] ? $this->alarm_types[0] : '';
+      $this->rc->user->save_prefs($prefs);
+      return true;
+    }
+
+    $query = $this->rc->db->query(
+      "UPDATE " . $this->db_calendars . "
+       SET   name=?, color=?, showalarms=?
+       WHERE calendar_id=?
+       AND   user_id=?",
+      $prop['name'],
+      $prop['color'],
+      $prop['showalarms']?1:0,
+      $prop['id'],
+      $this->rc->user->ID
+    );
+    
+    return $this->rc->db->affected_rows($query);
+  }
+
+  /**
+   * Set active/subscribed state of a calendar
+   * Save a list of hidden calendars in user prefs
+   *
+   * @see calendar_driver::subscribe_calendar()
+   */
+  public function subscribe_calendar($prop)
+  {
+    $hidden = array_flip(explode(',', $this->rc->config->get('hidden_calendars', '')));
+    
+    if ($prop['active'])
+      unset($hidden[$prop['id']]);
+    else
+      $hidden[$prop['id']] = 1;
+    
+    return $this->rc->user->save_prefs(array('hidden_calendars' => join(',', array_keys($hidden))));
+  }
+
+  /**
+   * Delete the given calendar with all its contents
+   *
+   * @see calendar_driver::delete_calendar()
+   */
+  public function delete_calendar($prop)
+  {
+    if (!$this->calendars[$prop['id']])
+      return false;
+
+    // events and attachments will be deleted by foreign key cascade
+
+    $query = $this->rc->db->query(
+      "DELETE FROM " . $this->db_calendars . "
+       WHERE calendar_id=?",
+       $prop['id']
+    );
+
+    return $this->rc->db->affected_rows($query);
+  }
+
+  /**
+   * Search for shared or otherwise not listed calendars the user has access
+   *
+   * @param string Search string
+   * @param string Section/source to search
+   * @return array List of calendars
+   */
+  public function search_calendars($query, $source)
+  {
+    // not implemented
+    return array();
+  }
+
+  /**
+   * Add a single event to the database
+   *
+   * @param array Hash array with event properties
+   * @see calendar_driver::new_event()
+   */
+  public function new_event($event)
+  {
+    if (!$this->validate($event))
+      return false;
+
+    if (!empty($this->calendars)) {
+      if ($event['calendar'] && !$this->calendars[$event['calendar']])
+        return false;
+      if (!$event['calendar'])
+        $event['calendar'] = reset(array_keys($this->calendars));
+
+      if ($event_id = $this->_insert_event($event)) {
+        $this->_update_recurring($event);
+      }
+
+      return $event_id;
+    }
+    
+    return false;
+  }
+
+  /**
+   *
+   */
+  private function _insert_event(&$event)
+  {
+    $event = $this->_save_preprocess($event);
+
+    $this->rc->db->query(sprintf(
+      "INSERT INTO " . $this->db_events . "
+       (calendar_id, created, changed, uid, recurrence_id, instance, isexception, %s, %s, all_day, recurrence,
+          title, description, location, categories, url, free_busy, priority, sensitivity, status, attendees, alarms, notifyat)
+       VALUES (?, %s, %s, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        $this->rc->db->quote_identifier('start'),
+        $this->rc->db->quote_identifier('end'),
+        $this->rc->db->now(),
+        $this->rc->db->now()
+      ),
+      $event['calendar'],
+      strval($event['uid']),
+      intval($event['recurrence_id']),
+      strval($event['_instance']),
+      intval($event['isexception']),
+      $event['start']->format(self::DB_DATE_FORMAT),
+      $event['end']->format(self::DB_DATE_FORMAT),
+      intval($event['all_day']),
+      $event['_recurrence'],
+      strval($event['title']),
+      strval($event['description']),
+      strval($event['location']),
+      join(',', (array)$event['categories']),
+      strval($event['url']),
+      intval($event['free_busy']),
+      intval($event['priority']),
+      intval($event['sensitivity']),
+      strval($event['status']),
+      $event['attendees'],
+      $event['alarms'],
+      $event['notifyat']
+    );
+
+    $event_id = $this->rc->db->insert_id($this->db_events);
+
+    if ($event_id) {
+      $event['id'] = $event_id;
+
+      // add attachments
+      if (!empty($event['attachments'])) {
+        foreach ($event['attachments'] as $attachment) {
+          $this->add_attachment($attachment, $event_id);
+          unset($attachment);
+        }
+      }
+
+      return $event_id;
+    }
+
+    return false;
+  }
+
+  /**
+   * Update an event entry with the given data
+   *
+   * @param array Hash array with event properties
+   * @see calendar_driver::edit_event()
+   */
+  public function edit_event($event)
+  {
+    if (!empty($this->calendars)) {
+      $update_master = false;
+      $update_recurring = true;
+      $old = $this->get_event($event);
+      $ret = true;
+
+      // check if update affects scheduling and update attendee status accordingly
+      $reschedule = $this->_check_scheduling($event, $old, true);
+
+      // increment sequence number
+      if (empty($event['sequence']) && $reschedule)
+        $event['sequence'] = max($event['sequence'], $old['sequence']) + 1;
+      
+      // modify a recurring event, check submitted savemode to do the right things
+      if ($old['recurrence'] || $old['recurrence_id']) {
+        $master = $old['recurrence_id'] ? $this->get_event(array('id' => $old['recurrence_id'])) : $old;
+        
+        // keep saved exceptions (not submitted by the client)
+        if ($old['recurrence']['EXDATE'])
+          $event['recurrence']['EXDATE'] = $old['recurrence']['EXDATE'];
+        
+        switch ($event['_savemode']) {
+          case 'new':
+            $event['uid'] = $this->cal->generate_uid();
+            return $this->new_event($event);
+          
+          case 'current':
+            // save as exception
+            $event['isexception'] = 1;
+            $update_recurring = false;
+
+            // set exception to first instance (= master)
+            if ($event['id'] == $master['id']) {
+              $event += $old;
+              $event['recurrence_id'] = $master['id'];
+              $event['_instance'] = libcalendaring::recurrence_instance_identifier($old, $master['allday']);
+              $event['isexception'] = 1;
+              $event_id = $this->_insert_event($event);
+              return $event_id;
+            }
+            break;
+          
+          case 'future':
+            if ($master['id'] != $event['id']) {
+              // set until-date on master event, then save this instance as new recurring event
+              $master['recurrence']['UNTIL'] = clone $event['start'];
+              $master['recurrence']['UNTIL']->sub(new DateInterval('P1D'));
+              unset($master['recurrence']['COUNT']);
+              $update_master = true;
+              
+              // if recurrence COUNT, update value to the correct number of future occurences
+              if ($event['recurrence']['COUNT']) {
+                $fromdate = clone $event['start'];
+                $fromdate->setTimezone($this->server_timezone);
+                $sqlresult = $this->rc->db->query(sprintf(
+                  "SELECT event_id FROM " . $this->db_events . "
+                   WHERE calendar_id IN (%s)
+                   AND %s >= ?
+                   AND recurrence_id=?",
+                  $this->calendar_ids,
+                  $this->rc->db->quote_identifier('start')
+                  ),
+                  $fromdate->format(self::DB_DATE_FORMAT),
+                  $master['id']);
+                if ($count = $this->rc->db->num_rows($sqlresult))
+                  $event['recurrence']['COUNT'] = $count;
+              }
+            
+              $update_recurring = true;
+              $event['recurrence_id'] = 0;
+              $event['isexception'] = 0;
+              $event['_instance'] = '';
+              break;
+            }
+            // else: 'future' == 'all' if modifying the master event
+          
+          default:  // 'all' is default
+            $event['id'] = $master['id'];
+            $event['recurrence_id'] = 0;
+            
+            // use start date from master but try to be smart on time or duration changes
+            $old_start_date = $old['start']->format('Y-m-d');
+            $old_start_time = $old['allday'] ? '' : $old['start']->format('H:i');
+            $old_duration = $old['end']->format('U') - $old['start']->format('U');
+            
+            $new_start_date = $event['start']->format('Y-m-d');
+            $new_start_time = $event['allday'] ? '' : $event['start']->format('H:i');
+            $new_duration = $event['end']->format('U') - $event['start']->format('U');
+            
+            $diff = $old_start_date != $new_start_date || $old_start_time != $new_start_time || $old_duration != $new_duration;
+            $date_shift = $old['start']->diff($event['start']);
+            
+            // shifted or resized
+            if ($diff && ($old_start_date == $new_start_date || $old_duration == $new_duration)) {
+              $event['start'] = $master['start']->add($old['start']->diff($event['start']));
+              $event['end'] = clone $event['start'];
+              $event['end']->add(new DateInterval('PT'.$new_duration.'S'));
+            }
+            // dates did not change, use the ones from master
+            else if ($new_start_date . $new_start_time == $old_start_date . $old_start_time) {
+              $event['start'] = $master['start'];
+              $event['end'] = $master['end'];
+            }
+            
+            // adjust recurrence-id when start changed and therefore the entire recurrence chain changes
+            if (is_array($event['recurrence']) && ($old_start_date != $new_start_date || $old_start_time != $new_start_time)
+                && ($exceptions = $this->_load_exceptions($old))) {
+              $recurrence_id_format = libcalendaring::recurrence_id_format($event);
+              foreach ($exceptions as $exception) {
+                $recurrence_id = rcube_utils::anytodatetime($exception['_instance'], $old['start']->getTimezone());
+                if (is_a($recurrence_id, 'DateTime')) {
+                  $recurrence_id->add($date_shift);
+                  $exception['_instance'] = $recurrence_id->format($recurrence_id_format);
+                  $this->_update_event($exception, false);
+                }
+              }
+            }
+            
+            $ret = $event['id'];  // return master ID
+            break;
+        }
+      }
+      
+      $success = $this->_update_event($event, $update_recurring);
+      
+      if ($success && $update_master)
+        $this->_update_event($master, true);
+      
+      return $success ? $ret : false;
+    }
+    
+    return false;
+  }
+
+  /**
+   * Extended event editing with possible changes to the argument
+   *
+   * @param array  Hash array with event properties
+   * @param string New participant status
+   * @param array  List of hash arrays with updated attendees
+   * @return boolean True on success, False on error
+   */
+  public function edit_rsvp(&$event, $status, $attendees)
+  {
+    $update_event = $event;
+
+    // apply changes to master (and all exceptions)
+    if ($event['_savemode'] == 'all' && $event['recurrence_id']) {
+      $update_event = $this->get_event(array('id' => $event['recurrence_id']));
+      $update_event['_savemode'] = $event['_savemode'];
+      calendar::merge_attendee_data($update_event, $attendees);
+    }
+
+    if ($ret = $this->update_attendees($update_event, $attendees)) {
+      // replace $event with effectively updated event (for iTip reply)
+      if ($ret !== true && $ret != $update_event['id'] && ($new_event = $this->get_event(array('id' => $ret)))) {
+        $event = $new_event;
+      }
+      else {
+        $event = $update_event;
+      }
+    }
+
+    return $ret;
+  }
+
+  /**
+   * Update the participant status for the given attendees
+   *
+   * @see calendar_driver::update_attendees()
+   */
+  public function update_attendees(&$event, $attendees)
+  {
+    $success = $this->edit_event($event, true);
+
+    // apply attendee updates to recurrence exceptions too
+    if ($success && $event['_savemode'] == 'all' && !empty($event['recurrence']) && empty($event['recurrence_id']) && ($exceptions = $this->_load_exceptions($event))) {
+      foreach ($exceptions as $exception) {
+        calendar::merge_attendee_data($exception, $attendees);
+        $this->_update_event($exception, false);
+      }
+    }
+
+    return $success;
+  }
+
+  /**
+   * Determine whether the current change affects scheduling and reset attendee status accordingly
+   */
+  private function _check_scheduling(&$event, $old, $update = true)
+  {
+    // skip this check when importing iCal/iTip events
+    if (isset($event['sequence']) || !empty($event['_method'])) {
+      return false;
+    }
+
+    $reschedule = false;
+
+    // iterate through the list of properties considered 'significant' for scheduling
+    foreach (self::$scheduling_properties as $prop) {
+        $a = $old[$prop];
+        $b = $event[$prop];
+        if ($event['allday'] && ($prop == 'start' || $prop == 'end') && $a instanceof DateTime && $b instanceof DateTime) {
+            $a = $a->format('Y-m-d');
+            $b = $b->format('Y-m-d');
+        }
+        if ($prop == 'recurrence' && is_array($a) && is_array($b)) {
+            unset($a['EXCEPTIONS'], $b['EXCEPTIONS']);
+            $a = array_filter($a);
+            $b = array_filter($b);
+
+            // advanced rrule comparison: no rescheduling if series was shortened
+            if ($a['COUNT'] && $b['COUNT'] && $b['COUNT'] < $a['COUNT']) {
+              unset($a['COUNT'], $b['COUNT']);
+            }
+            else if ($a['UNTIL'] && $b['UNTIL'] && $b['UNTIL'] < $a['UNTIL']) {
+              unset($a['UNTIL'], $b['UNTIL']);
+            }
+        }
+        if ($a != $b) {
+            $reschedule = true;
+            break;
+        }
+    }
+
+    // reset all attendee status to needs-action (#4360)
+    if ($update && $reschedule && is_array($event['attendees'])) {
+      $is_organizer = false;
+      $emails = $this->cal->get_user_emails();
+      $attendees = $event['attendees'];
+      foreach ($attendees as $i => $attendee) {
+        if ($attendee['role'] == 'ORGANIZER' && $attendee['email'] && in_array(strtolower($attendee['email']), $emails)) {
+          $is_organizer = true;
+        }
+        else if ($attendee['role'] != 'ORGANIZER' && $attendee['role'] != 'NON-PARTICIPANT' && $attendee['status'] != 'DELEGATED') {
+          $attendees[$i]['status'] = 'NEEDS-ACTION';
+          $attendees[$i]['rsvp'] = true;
+        }
+      }
+
+      // update attendees only if I'm the organizer
+      if ($is_organizer || ($event['organizer'] && in_array(strtolower($event['organizer']['email']), $emails))) {
+        $event['attendees'] = $attendees;
+      }
+    }
+
+    return $reschedule;
+  }
+
+  /**
+   * Convert save data to be used in SQL statements
+   */
+  private function _save_preprocess($event)
+  {
+    // shift dates to server's timezone (except for all-day events)
+    if (!$event['allday']) {
+      $event['start'] = clone $event['start'];
+      $event['start']->setTimezone($this->server_timezone);
+      $event['end'] = clone $event['end'];
+      $event['end']->setTimezone($this->server_timezone);
+    }
+    
+    // compose vcalendar-style recurrencue rule from structured data
+    $rrule = $event['recurrence'] ? libcalendaring::to_rrule($event['recurrence']) : '';
+    $event['_recurrence'] = rtrim($rrule, ';');
+    $event['free_busy'] = intval($this->free_busy_map[strtolower($event['free_busy'])]);
+    $event['sensitivity'] = intval($this->sensitivity_map[strtolower($event['sensitivity'])]);
+
+    if ($event['free_busy'] == 'tentative') {
+        $event['status'] = 'TENTATIVE';
+    }
+
+    if (isset($event['allday'])) {
+      $event['all_day'] = $event['allday'] ? 1 : 0;
+    }
+
+    // compute absolute time to notify the user
+    $event['notifyat'] = $this->_get_notification($event);
+
+    if (is_array($event['valarms'])) {
+        $event['alarms'] = $this->serialize_alarms($event['valarms']);
+    }
+
+    // process event attendees
+    if (!empty($event['attendees']))
+      $event['attendees'] = json_encode((array)$event['attendees']);
+    else
+      $event['attendees'] = '';
+
+    return $event;
+  }
+  
+  /**
+   * Compute absolute time to notify the user
+   */
+  private function _get_notification($event)
+  {
+    if ($event['valarms'] && $event['start'] > new DateTime()) {
+      $alarm = libcalendaring::get_next_alarm($event);
+
+      if ($alarm['time'] && in_array($alarm['action'], $this->alarm_types))
+        return date('Y-m-d H:i:s', $alarm['time']);
+    }
+
+    return null;
+  }
+
+  /**
+   * Save the given event record to database
+   *
+   * @param array Event data
+   * @param boolean True if recurring events instances should be updated, too
+   */
+  private function _update_event($event, $update_recurring = true)
+  {
+    $event = $this->_save_preprocess($event);
+    $sql_set = array();
+    $set_cols = array('start', 'end', 'all_day', 'recurrence_id', 'isexception', 'sequence', 'title', 'description', 'location', 'categories', 'url', 'free_busy', 'priority', 'sensitivity', 'status', 'attendees', 'alarms', 'notifyat');
+    foreach ($set_cols as $col) {
+      if (is_object($event[$col]) && is_a($event[$col], 'DateTime'))
+        $sql_set[] = $this->rc->db->quote_identifier($col) . '=' . $this->rc->db->quote($event[$col]->format(self::DB_DATE_FORMAT));
+      else if (is_array($event[$col]))
+        $sql_set[] = $this->rc->db->quote_identifier($col) . '=' . $this->rc->db->quote(join(',', $event[$col]));
+      else if (array_key_exists($col, $event))
+        $sql_set[] = $this->rc->db->quote_identifier($col) . '=' . $this->rc->db->quote($event[$col]);
+    }
+    
+    if ($event['_recurrence'])
+      $sql_set[] = $this->rc->db->quote_identifier('recurrence') . '=' . $this->rc->db->quote($event['_recurrence']);
+    
+    if ($event['_instance'])
+      $sql_set[] = $this->rc->db->quote_identifier('instance') . '=' . $this->rc->db->quote($event['_instance']);
+    
+    if ($event['_fromcalendar'] && $event['_fromcalendar'] != $event['calendar'])
+        $sql_set[] = 'calendar_id=' . $this->rc->db->quote($event['calendar']);
+    
+    $query = $this->rc->db->query(sprintf(
+      "UPDATE " . $this->db_events . "
+       SET   changed=%s %s
+       WHERE event_id=?
+       AND   calendar_id IN (" . $this->calendar_ids . ")",
+        $this->rc->db->now(),
+        ($sql_set ? ', ' . join(', ', $sql_set) : '')
+      ),
+      $event['id']
+    );
+
+    $success = $this->rc->db->affected_rows($query);
+
+    // add attachments
+    if ($success && !empty($event['attachments'])) {
+      foreach ($event['attachments'] as $attachment) {
+        $this->add_attachment($attachment, $event['id']);
+        unset($attachment);
+      }
+    }
+
+    // remove attachments
+    if ($success && !empty($event['deleted_attachments'])) {
+      foreach ($event['deleted_attachments'] as $attachment) {
+        $this->remove_attachment($attachment, $event['id']);
+      }
+    }
+
+    if ($success) {
+      unset($this->cache[$event['id']]);
+      if ($update_recurring)
+        $this->_update_recurring($event);
+    }
+
+    return $success;
+  }
+
+  /**
+   * Insert "fake" entries for recurring occurences of this event
+   */
+  private function _update_recurring($event)
+  {
+    if (empty($this->calendars))
+      return;
+
+    if (!empty($event['recurrence'])) {
+      $exdata = array();
+      $exceptions = $this->_load_exceptions($event);
+
+      foreach ($exceptions as $exception) {
+        $exdate = substr($exception['_instance'], 0, 8);
+        $exdata[$exdate] = $exception;
+      }
+    }
+
+    // clear existing recurrence copies
+    $this->rc->db->query(
+      "DELETE FROM " . $this->db_events . "
+       WHERE recurrence_id=?
+       AND isexception=0
+       AND calendar_id IN (" . $this->calendar_ids . ")",
+       $event['id']
+    );
+
+    // create new fake entries
+    if (!empty($event['recurrence'])) {
+      // include library class
+      require_once($this->cal->home . '/lib/calendar_recurrence.php');
+      
+      $recurrence = new calendar_recurrence($this->cal, $event);
+
+      $count = 0;
+      $event['allday'] = $event['all_day'];
+      $duration = $event['start']->diff($event['end']);
+      $recurrence_id_format = libcalendaring::recurrence_id_format($event);
+      while ($next_start = $recurrence->next_start()) {
+        $instance = $next_start->format($recurrence_id_format);
+        $datestr = substr($instance, 0, 8);
+
+        // skip exceptions
+        // TODO: merge updated data from master event
+        if ($exdata[$datestr]) {
+          continue;
+        }
+
+        $next_start->setTimezone($this->server_timezone);
+        $next_end = clone $next_start;
+        $next_end->add($duration);
+
+        $notify_at = $this->_get_notification(array('alarms' => $event['alarms'], 'start' => $next_start, 'end' => $next_end, 'status' => $event['status']));
+        $query = $this->rc->db->query(sprintf(
+          "INSERT INTO " . $this->db_events . "
+           (calendar_id, recurrence_id, created, changed, uid, instance, %s, %s, all_day, sequence, recurrence, title, description, location, categories, url, free_busy, priority, sensitivity, status, alarms, attendees, notifyat)
+            SELECT calendar_id, ?, %s, %s, uid, ?, ?, ?, all_day, sequence, recurrence, title, description, location, categories, url, free_busy, priority, sensitivity, status, alarms, attendees, ?
+            FROM  " . $this->db_events . " WHERE event_id=? AND calendar_id IN (" . $this->calendar_ids . ")",
+            $this->rc->db->quote_identifier('start'),
+            $this->rc->db->quote_identifier('end'),
+            $this->rc->db->now(),
+            $this->rc->db->now()
+          ),
+          $event['id'],
+          $instance,
+          $next_start->format(self::DB_DATE_FORMAT),
+          $next_end->format(self::DB_DATE_FORMAT),
+          $notify_at,
+          $event['id']
+        );
+        
+        if (!$this->rc->db->affected_rows($query))
+          break;
+        
+        // stop adding events for inifinite recurrence after 20 years
+        if (++$count > 999 || (!$recurrence->recurEnd && !$recurrence->recurCount && $next_start->format('Y') > date('Y') + 20))
+          break;
+      }
+      
+      // remove all exceptions after recurrence end
+      if ($next_end && !empty($exceptions)) {
+          $this->rc->db->query(
+          "DELETE FROM " . $this->db_events . "
+           WHERE `recurrence_id`=?
+           AND `isexception`=1
+           AND `start` > ?
+           AND `calendar_id` IN (" . $this->calendar_ids . ")",
+           $event['id'],
+           $next_end->format(self::DB_DATE_FORMAT)
+        );
+      }
+    }
+  }
+  
+  /**
+   *
+   */
+  private function _load_exceptions($event, $instance_id = null)
+  {
+    $sql_add_where = '';
+    if (!empty($instance_id)) {
+      $sql_add_where = 'AND `instance`=?';
+    }
+
+    $result = $this->rc->db->query(
+      "SELECT * FROM " . $this->db_events . "
+       WHERE `recurrence_id`=?
+       AND `isexception`=1
+       AND `calendar_id` IN (" . $this->calendar_ids . ")
+       $sql_add_where
+       ORDER BY `instance`, `start`",
+       $event['id'],
+       $instance_id
+    );
+
+    $exceptions = array();
+    while ($result && ($sql_arr = $this->rc->db->fetch_assoc($result)) && $sql_arr['event_id']) {
+      $exception = $this->_read_postprocess($sql_arr);
+      $instance = $exception['_instance'] ?: $exception['start']->format($exception['allday'] ? 'Ymd' : 'Ymd\THis');
+      $exceptions[$instance] = $exception;
+    }
+
+    return $exceptions;
+  }
+
+  /**
+   * Move a single event
+   *
+   * @param array Hash array with event properties
+   * @see calendar_driver::move_event()
+   */
+  public function move_event($event)
+  {
+    // let edit_event() do all the magic
+    return $this->edit_event($event + (array)$this->get_event($event));
+  }
+
+  /**
+   * Resize a single event
+   *
+   * @param array Hash array with event properties
+   * @see calendar_driver::resize_event()
+   */
+  public function resize_event($event)
+  {
+    // let edit_event() do all the magic
+    return $this->edit_event($event + (array)$this->get_event($event));
+  }
+
+  /**
+   * Remove a single event from the database
+   *
+   * @param array   Hash array with event properties
+   * @param boolean Remove record irreversible (@TODO)
+   *
+   * @see calendar_driver::remove_event()
+   */
+  public function remove_event($event, $force = true)
+  {
+    if (!empty($this->calendars)) {
+      $event += (array)$this->get_event($event);
+      $master = $event;
+      $update_master = false;
+      $savemode = 'all';
+      $ret = true;
+
+      // read master if deleting a recurring event
+      if ($event['recurrence'] || $event['recurrence_id']) {
+        $master = $event['recurrence_id'] ? $this->get_event(array('id' => $event['recurrence_id'])) : $event;
+        $savemode = $event['_savemode'];
+      }
+
+      switch ($savemode) {
+        case 'current':
+          // add exception to master event
+          $master['recurrence']['EXDATE'][] = $event['start'];
+          $update_master = true;
+          
+          // just delete this single occurence
+          $query = $this->rc->db->query(
+            "DELETE FROM " . $this->db_events . "
+             WHERE calendar_id IN (" . $this->calendar_ids . ")
+             AND event_id=?",
+            $event['id']
+          );
+          break;
+
+        case 'future':
+          if ($master['id'] != $event['id']) {
+            // set until-date on master event
+            $master['recurrence']['UNTIL'] = clone $event['start'];
+            $master['recurrence']['UNTIL']->sub(new DateInterval('P1D'));
+            unset($master['recurrence']['COUNT']);
+            $update_master = true;
+            
+            // delete this and all future instances
+            $fromdate = clone $event['start'];
+            $fromdate->setTimezone($this->server_timezone);
+            $query = $this->rc->db->query(
+              "DELETE FROM " . $this->db_events . "
+               WHERE calendar_id IN (" . $this->calendar_ids . ")
+               AND " . $this->rc->db->quote_identifier('start') . " >= ?
+               AND recurrence_id=?",
+              $fromdate->format(self::DB_DATE_FORMAT),
+              $master['id']
+            );
+            $ret = $master['id'];
+            break;
+          }
+          // else: future == all if modifying the master event
+
+        default:  // 'all' is default
+          $query = $this->rc->db->query(
+            "DELETE FROM " . $this->db_events . "
+             WHERE (event_id=? OR recurrence_id=?)
+             AND calendar_id IN (" . $this->calendar_ids . ")",
+             $master['id'],
+             $master['id']
+          );
+          break;
+      }
+
+      $success = $this->rc->db->affected_rows($query);
+      if ($success && $update_master)
+        $this->_update_event($master, true);
+
+      return $success ? $ret : false;
+    }
+    
+    return false;
+  }
+
+  /**
+   * Return data of a specific event
+   * @param mixed  Hash array with event properties or event UID
+   * @param integer Bitmask defining the scope to search events in
+   * @param boolean If true, recurrence exceptions shall be added
+   * @return array Hash array with event properties
+   */
+  public function get_event($event, $scope = 0, $full = false)
+  {
+    $id  = is_array($event) ? ($event['id'] ?: $event['uid']) : $event;
+    $cal = is_array($event) ? $event['calendar'] : null;
+    $col = is_array($event) && is_numeric($id) ? 'event_id' : 'uid';
+
+    $where_add = '';
+    if (is_array($event) && !$event['id'] && !empty($event['_instance'])) {
+      $where_add = 'AND instance=' . $this->rc->db->quote($event['_instance']);
+    }
+
+    if ($this->cache[$id])
+      return $this->cache[$id];
+
+    // get event from the address books birthday calendar
+    if ($cal == self::BIRTHDAY_CALENDAR_ID) {
+      return $this->get_birthday_event($id);
+    }
+
+    if ($scope & self::FILTER_ACTIVE) {
+      $calendars = $this->calendars;
+      foreach ($calendars as $idx => $cal) {
+        if (!$cal['active']) {
+          unset($calendars[$idx]);
+        }
+      }
+      $cals = join(',', $calendars);
+    }
+    else {
+      $cals = $this->calendar_ids;
+    }
+
+    $result = $this->rc->db->query(sprintf(
+      "SELECT e.*, (SELECT COUNT(attachment_id) FROM " . $this->db_attachments . " 
+         WHERE event_id = e.event_id OR event_id = e.recurrence_id) AS _attachments
+       FROM " . $this->db_events . " AS e
+       WHERE e.calendar_id IN (%s)
+       AND e.$col=?
+       %s",
+       $cals,
+       $where_add
+      ),
+      $id);
+
+    if ($result && ($sql_arr = $this->rc->db->fetch_assoc($result)) && $sql_arr['event_id']) {
+      $event = $this->_read_postprocess($sql_arr);
+
+      // also load recurrence exceptions
+      if (!empty($event['recurrence']) && $full) {
+        $event['recurrence']['EXCEPTIONS'] = array_values($this->_load_exceptions($event));
+      }
+
+      $this->cache[$id] = $event;
+      return $this->cache[$id];
+    }
+
+    return false;
+  }
+
+  /**
+   * Get event data
+   *
+   * @see calendar_driver::load_events()
+   */
+  public function load_events($start, $end, $query = null, $calendars = null, $virtual = 1, $modifiedsince = null)
+  {
+    if (empty($calendars))
+      $calendars = array_keys($this->calendars);
+    else if (!is_array($calendars))
+      $calendars = explode(',', strval($calendars));
+      
+    // only allow to select from calendars of this use
+    $calendar_ids = array_map(array($this->rc->db, 'quote'), array_intersect($calendars, array_keys($this->calendars)));
+    
+    // compose (slow) SQL query for searching
+    // FIXME: improve searching using a dedicated col and normalized values
+    if ($query) {
+      foreach (array('title','location','description','categories','attendees') as $col)
+        $sql_query[] = $this->rc->db->ilike($col, '%'.$query.'%');
+      $sql_add = 'AND (' . join(' OR ', $sql_query) . ')';
+    }
+    
+    if (!$virtual)
+      $sql_add .= ' AND e.recurrence_id = 0';
+    
+    if ($modifiedsince)
+      $sql_add .= ' AND e.changed >= ' . $this->rc->db->quote(date('Y-m-d H:i:s', $modifiedsince));
+    
+    $events = array();
+    if (!empty($calendar_ids)) {
+      $result = $this->rc->db->query(sprintf(
+        "SELECT e.*, (SELECT COUNT(attachment_id) FROM " . $this->db_attachments . "
+            WHERE event_id = e.event_id OR event_id = e.recurrence_id) AS _attachments
+         FROM " . $this->db_events . " e
+         WHERE e.calendar_id IN (%s)
+            AND e.start <= %s AND e.end >= %s
+            %s",
+         join(',', $calendar_ids),
+         $this->rc->db->fromunixtime($end),
+         $this->rc->db->fromunixtime($start),
+         $sql_add
+       ));
+
+      while ($result && ($sql_arr = $this->rc->db->fetch_assoc($result))) {
+        $event = $this->_read_postprocess($sql_arr);
+        $add = true;
+
+        if (!empty($event['recurrence']) && !$event['recurrence_id']) {
+          // load recurrence exceptions (i.e. for export)
+          if (!$virtual) {
+            $event['recurrence']['EXCEPTIONS'] = $this->_load_exceptions($event);
+          }
+          // check for exception on first instance
+          else {
+            $instance = libcalendaring::recurrence_instance_identifier($event);
+            $exceptions = $this->_load_exceptions($event, $instance);
+            if ($exceptions && is_array($exceptions[$instance])) {
+              $event = $exceptions[$instance];
+              $add = false;
+            }
+          }
+        }
+
+        if ($add)
+          $events[] = $event;
+      }
+    }
+
+    // add events from the address books birthday calendar
+    if (in_array(self::BIRTHDAY_CALENDAR_ID, $calendars) && empty($query)) {
+      $events = array_merge($events, $this->load_birthday_events($start, $end, $search, $modifiedsince));
+    }
+
+    return $events;
+  }
+
+  /**
+   * Get number of events in the given calendar
+   *
+   * @param  mixed   List of calendar IDs to count events (either as array or comma-separated string)
+   * @param  integer Date range start (unix timestamp)
+   * @param  integer Date range end (unix timestamp)
+   * @return array   Hash array with counts grouped by calendar ID
+   */
+  public function count_events($calendars, $start, $end = null)
+  {
+      // not implemented
+      return array();
+  }
+
+  /**
+   * Convert sql record into a rcube style event object
+   */
+  private function _read_postprocess($event)
+  {
+    $free_busy_map = array_flip($this->free_busy_map);
+    $sensitivity_map = array_flip($this->sensitivity_map);
+    
+    $event['id'] = $event['event_id'];
+    $event['start'] = new DateTime($event['start']);
+    $event['end'] = new DateTime($event['end']);
+    $event['allday'] = intval($event['all_day']);
+    $event['created'] = new DateTime($event['created']);
+    $event['changed'] = new DateTime($event['changed']);
+    $event['free_busy'] = $free_busy_map[$event['free_busy']];
+    $event['sensitivity'] = $sensitivity_map[$event['sensitivity']];
+    $event['calendar'] = $event['calendar_id'];
+    $event['recurrence_id'] = intval($event['recurrence_id']);
+    $event['isexception'] = intval($event['isexception']);
+    
+    // parse recurrence rule
+    if ($event['recurrence'] && preg_match_all('/([A-Z]+)=([^;]+);?/', $event['recurrence'], $m, PREG_SET_ORDER)) {
+      $event['recurrence'] = array();
+      foreach ($m as $rr) {
+        if (is_numeric($rr[2]))
+          $rr[2] = intval($rr[2]);
+        else if ($rr[1] == 'UNTIL')
+          $rr[2] = date_create($rr[2]);
+        else if ($rr[1] == 'RDATE')
+          $rr[2] = array_map('date_create', explode(',', $rr[2]));
+        else if ($rr[1] == 'EXDATE')
+          $rr[2] = array_map('date_create', explode(',', $rr[2]));
+        $event['recurrence'][$rr[1]] = $rr[2];
+      }
+    }
+    
+    if ($event['recurrence_id']) {
+      libcalendaring::identify_recurrence_instance($event);
+    }
+    
+    if (strlen($event['instance'])) {
+      $event['_instance'] = $event['instance'];
+
+      if (empty($event['recurrence_id'])) {
+        $event['recurrence_date'] = rcube_utils::anytodatetime($event['_instance'], $event['start']->getTimezone());
+      }
+    }
+    
+    if ($event['_attachments'] > 0) {
+      $event['attachments'] = (array)$this->list_attachments($event);
+    }
+    
+    // decode serialized event attendees
+    if (strlen($event['attendees'])) {
+      $event['attendees'] = $this->unserialize_attendees($event['attendees']);
+    }
+    else {
+      $event['attendees'] = array();
+    }
+    
+    // decode serialized alarms
+    if ($event['alarms']) {
+      $event['valarms'] = $this->unserialize_alarms($event['alarms']);
+    }
+    
+    unset($event['event_id'], $event['calendar_id'], $event['notifyat'], $event['all_day'], $event['instance'], $event['_attachments']);
+    return $event;
+  }
+
+  /**
+   * Get a list of pending alarms to be displayed to the user
+   *
+   * @see calendar_driver::pending_alarms()
+   */
+  public function pending_alarms($time, $calendars = null)
+  {
+    if (empty($calendars))
+      $calendars = array_keys($this->calendars);
+    else if (is_string($calendars))
+      $calendars = explode(',', $calendars);
+    
+    // only allow to select from calendars with activated alarms
+    $calendar_ids = array();
+    foreach ($calendars as $cid) {
+      if ($this->calendars[$cid] && $this->calendars[$cid]['showalarms'])
+        $calendar_ids[] = $cid;
+    }
+    $calendar_ids = array_map(array($this->rc->db, 'quote'), $calendar_ids);
+    
+    $alarms = array();
+    if (!empty($calendar_ids)) {
+      $result = $this->rc->db->query(sprintf(
+        "SELECT * FROM " . $this->db_events . "
+         WHERE calendar_id IN (%s)
+         AND notifyat <= %s AND %s > %s",
+         join(',', $calendar_ids),
+         $this->rc->db->fromunixtime($time),
+         $this->rc->db->quote_identifier('end'),
+         $this->rc->db->fromunixtime($time)
+       ));
+
+      while ($result && ($event = $this->rc->db->fetch_assoc($result)))
+        $alarms[] = $this->_read_postprocess($event);
+    }
+
+    return $alarms;
+  }
+
+  /**
+   * Feedback after showing/sending an alarm notification
+   *
+   * @see calendar_driver::dismiss_alarm()
+   */
+  public function dismiss_alarm($event_id, $snooze = 0)
+  {
+    // set new notifyat time or unset if not snoozed
+    $notify_at = $snooze > 0 ? date(self::DB_DATE_FORMAT, time() + $snooze) : null;
+    
+    $query = $this->rc->db->query(sprintf(
+      "UPDATE " . $this->db_events . "
+       SET   changed=%s, notifyat=?
+       WHERE event_id=?
+       AND calendar_id IN (" . $this->calendar_ids . ")",
+        $this->rc->db->now()),
+      $notify_at,
+      $event_id
+    );
+    
+    return $this->rc->db->affected_rows($query);
+  }
+
+  /**
+   * Save an attachment related to the given event
+   */
+  private function add_attachment($attachment, $event_id)
+  {
+    $data = $attachment['data'] ? $attachment['data'] : file_get_contents($attachment['path']);
+    
+    $query = $this->rc->db->query(
+      "INSERT INTO " . $this->db_attachments .
+      " (event_id, filename, mimetype, size, data)" .
+      " VALUES (?, ?, ?, ?, ?)",
+      $event_id,
+      $attachment['name'],
+      $attachment['mimetype'],
+      strlen($data),
+      base64_encode($data)
+    );
+
+    return $this->rc->db->affected_rows($query);
+  }
+
+  /**
+   * Remove a specific attachment from the given event
+   */
+  private function remove_attachment($attachment_id, $event_id)
+  {
+    $query = $this->rc->db->query(
+      "DELETE FROM " . $this->db_attachments .
+      " WHERE attachment_id = ?" .
+        " AND event_id IN (SELECT event_id FROM " . $this->db_events .
+          " WHERE event_id = ?"  .
+            " AND calendar_id IN (" . $this->calendar_ids . "))",
+      $attachment_id,
+      $event_id
+    );
+
+    return $this->rc->db->affected_rows($query);
+  }
+
+  /**
+   * List attachments of specified event
+   */
+  public function list_attachments($event)
+  {
+    $attachments = array();
+
+    if (!empty($this->calendar_ids)) {
+      $result = $this->rc->db->query(
+        "SELECT attachment_id AS id, filename AS name, mimetype, size " .
+        " FROM " . $this->db_attachments .
+        " WHERE event_id IN (SELECT event_id FROM " . $this->db_events .
+          " WHERE event_id=?"  .
+            " AND calendar_id IN (" . $this->calendar_ids . "))".
+        " ORDER BY filename",
+        $event['recurrence_id'] ? $event['recurrence_id'] : $event['event_id']
+      );
+
+      while ($result && ($arr = $this->rc->db->fetch_assoc($result))) {
+        $attachments[] = $arr;
+      }
+    }
+
+    return $attachments;
+  }
+
+  /**
+   * Get attachment properties
+   */
+  public function get_attachment($id, $event)
+  {
+    if (!empty($this->calendar_ids)) {
+      $result = $this->rc->db->query(
+        "SELECT attachment_id AS id, filename AS name, mimetype, size " .
+        " FROM " . $this->db_attachments .
+        " WHERE attachment_id=?".
+          " AND event_id=?",
+        $id,
+        $event['recurrence_id'] ? $event['recurrence_id'] : $event['id']
+      );
+
+      if ($result && ($arr = $this->rc->db->fetch_assoc($result))) {
+        return $arr;
+      }
+    }
+
+    return null;
+  }
+
+  /**
+   * Get attachment body
+   */
+  public function get_attachment_body($id, $event)
+  {
+    if (!empty($this->calendar_ids)) {
+      $result = $this->rc->db->query(
+        "SELECT data " .
+        " FROM " . $this->db_attachments .
+        " WHERE attachment_id=?".
+          " AND event_id=?",
+        $id,
+        $event['id']
+      );
+
+      if ($result && ($arr = $this->rc->db->fetch_assoc($result))) {
+        return base64_decode($arr['data']);
+      }
+    }
+
+    return null;
+  }
+
+  /**
+   * Remove the given category
+   */
+  public function remove_category($name)
+  {
+    $query = $this->rc->db->query(
+      "UPDATE " . $this->db_events . "
+       SET   categories=''
+       WHERE categories=?
+       AND   calendar_id IN (" . $this->calendar_ids . ")",
+      $name
+    );
+    
+    return $this->rc->db->affected_rows($query);
+  }
+
+  /**
+   * Update/replace a category
+   */
+  public function replace_category($oldname, $name, $color)
+  {
+    $query = $this->rc->db->query(
+      "UPDATE " . $this->db_events . "
+       SET   categories=?
+       WHERE categories=?
+       AND   calendar_id IN (" . $this->calendar_ids . ")",
+      $name,
+      $oldname
+    );
+    
+    return $this->rc->db->affected_rows($query);
+  }
+
+  /**
+   * Helper method to serialize the list of alarms into a string
+   */
+  private function serialize_alarms($valarms)
+  {
+      foreach ((array)$valarms as $i => $alarm) {
+          if ($alarm['trigger'] instanceof DateTime) {
+              $valarms[$i]['trigger'] = '@' . $alarm['trigger']->format('c');
+          }
+      }
+
+      return $valarms ? json_encode($valarms) : null;
+  }
+
+  /**
+   * Helper method to decode a serialized list of alarms
+   */
+  private function unserialize_alarms($alarms)
+  {
+      // decode json serialized alarms
+      if ($alarms && $alarms[0] == '[') {
+          $valarms = json_decode($alarms, true);
+          foreach ($valarms as $i => $alarm) {
+              if ($alarm['trigger'][0] == '@') {
+                  try {
+                      $valarms[$i]['trigger'] = new DateTime(substr($alarm['trigger'], 1));
+                  }
+                  catch (Exception $e) {
+                      unset($valarms[$i]);
+                  }
+              }
+          }
+      }
+      // convert legacy alarms data
+      else if (strlen($alarms)) {
+          list($trigger, $action) = explode(':', $alarms, 2);
+          if ($trigger = libcalendaring::parse_alarm_value($trigger)) {
+              $valarms = array(array('action' => $action, 'trigger' => $trigger[3] ?: $trigger[0]));
+          }
+      }
+
+      return $valarms;
+  }
+
+  /**
+   * Helper method to decode the attendees list from string
+   */
+  private function unserialize_attendees($s_attendees)
+  {
+    $attendees = array();
+
+    // decode json serialized string
+    if ($s_attendees[0] == '[') {
+      $attendees = json_decode($s_attendees, true);
+    }
+    // decode the old serialization format
+    else {
+      foreach (explode("\n", $s_attendees) as $line) {
+        $att = array();
+        foreach (rcube_utils::explode_quoted_string(';', $line) as $prop) {
+          list($key, $value) = explode("=", $prop);
+          $att[strtolower($key)] = stripslashes(trim($value, '""'));
+        }
+        $attendees[] = $att;
+      }
+    }
+
+    return $attendees;
+  }
+
+  /**
+   * Handler for user_delete plugin hook
+   */
+  public function user_delete($args)
+  {
+      $db = $this->rc->db;
+      $user = $args['user'];
+      $event_ids = array();
+
+      $events = $db->query(
+          "SELECT event_id FROM " . $this->db_events . " AS ev" .
+          " LEFT JOIN " . $this->db_calendars . " cal ON (ev.calendar_id = cal.calendar_id)".
+          " WHERE user_id=?",
+          $user->ID);
+
+      while ($row = $db->fetch_assoc($events)) {
+          $event_ids[] = $row['event_id'];
+      }
+
+      if (!empty($event_ids)) {
+          foreach (array($this->db_attachments, $this->db_events) as $table) {
+              $db->query(sprintf("DELETE FROM $table WHERE event_id IN (%s)", join(',', $event_ids)));
+          }
+      }
+
+      foreach (array($this->db_calendars, 'itipinvitations') as $table) {
+          $db->query("DELETE FROM $table WHERE user_id=?", $user->ID);
+      }
+  }
+
+}