diff --git a/plugins/libkolab/lib/kolab_format_event.php b/plugins/libkolab/lib/kolab_format_event.php
index 0a960b1a..505b6177 100644
--- a/plugins/libkolab/lib/kolab_format_event.php
+++ b/plugins/libkolab/lib/kolab_format_event.php
@@ -1,223 +1,395 @@
 <?php
 
 /**
  * Kolab Event model class
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2012, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 class kolab_format_event extends kolab_format
 {
     public $CTYPE = 'application/x-vnd.kolab.event';
 
     protected $xmltype = 'event';
 
     public static $fulltext_cols = array('title', 'description', 'location', 'attendees:name', 'attendees:email', 'categories');
 
+    // old Kolab 2 format field map
+    private $kolab2_fieldmap = array(
+      // kolab       => roundcube
+      'summary'      => 'title',
+      'location'     => 'location',
+      'body'         => 'description',
+      'categories'   => 'categories',
+      'sensitivity'  => 'sensitivity',
+      'show-time-as' => 'free_busy',
+      'priority'     => 'priority',
+    );
     private $kolab2_rolemap = array(
         'required' => 'REQ-PARTICIPANT',
         'optional' => 'OPT-PARTICIPANT',
         'resource' => 'CHAIR',
     );
     private $kolab2_statusmap = array(
         'none'      => 'NEEDS-ACTION',
         'tentative' => 'TENTATIVE',
         'accepted'  => 'CONFIRMED',
         'accepted'  => 'ACCEPTED',
         'declined'  => 'DECLINED',
     );
+    private $kolab2_weekdaymap = array('MO'=>'monday', 'TU'=>'tuesday', 'WE'=>'wednesday', 'TH'=>'thursday', 'FR'=>'friday', 'SA'=>'saturday', 'SU'=>'sunday');
     private $kolab2_monthmap = array('', 'january', 'february', 'march', 'april', 'may', 'june', 'july', 'august', 'september', 'october', 'november', 'december');
 
 
     /**
      * Clones into an instance of libcalendaring's extended EventCal class
      *
      * @return mixed EventCal object or false on failure
      */
     public function to_libcal()
     {
         return false;
     }
 
     /**
      * Set event properties to the kolabformat object
      *
      * @param array  Event data as hash array
      */
     public function set(&$object)
     {
         $this->init();
 
-        // TODO: implement this
+        if ($object['uid'])
+            $this->kolab_object['uid'] = $object['uid'];
+
+        $this->kolab_object['last-modification-date'] = time();
+
+        // map basic fields rcube => $kolab
+        foreach ($this->kolab2_fieldmap as $kolab => $rcube) {
+            $this->kolab_object[$kolab] = $object[$rcube];
+        }
+
+        // all-day event
+        if (intval($object['allday'])) {
+            // shift times from user's timezone to server's timezone
+            // because Horde_Kolab_Format_Date::encodeDate() uses strftime() which operates in server tz
+            $server_tz = new DateTimeZone(date_default_timezone_get());
+            $start = clone $object['start'];
+            $end = clone $object['end'];
+
+            $start->setTimezone($server_tz);
+            $end->setTimezone($server_tz);
+            $start->setTime(0,0,0);
+            $end->setTime(0,0,0);
+
+            // create timestamps at exactly 00:00. This is also needed for proper re-interpretation in _to_rcube_event() after updating an event
+            $this->kolab_object['start-date'] = mktime(0,0,0, $start->format('n'), $start->format('j'), $start->format('Y'));
+            $this->kolab_object['end-date']   = mktime(0,0,0, $end->format('n'),   $end->format('j'),   $end->format('Y')) + 86400;
+
+            // sanity check: end date is same or smaller than start
+            if (date('Y-m-d', $this->kolab_object['end-date']) <= date('Y-m-d', $this->kolab_object['start-date']))
+              $this->kolab_object['end-date'] = mktime(13,0,0, $start->format('n'), $start->format('j'), $start->format('Y')) + 86400;
+
+            $this->kolab_object['_is_all_day'] = 1;
+        }
+        else {
+            $this->kolab_object['start-date'] = $object['start']->format('U');
+            $this->kolab_object['end-date']   = $object['end']->format('U');
+        }
+
+        // handle alarms
+        if ($object['alarms']) {
+            $alarmbase = explode(":", $object['alarms']);
+            $avalue = preg_replace('/[^0-9]/', '', $alarmbase[0]); 
+
+            if (preg_match("/H/",$alarmbase[0])) {
+                $this->kolab_object['alarm'] = $avalue*60;
+            }
+            else if (preg_match("/D/",$alarmbase[0])) {
+                $this->kolab_object['alarm'] = $avalue*24*60;
+            }
+            else {
+                $this->kolab_object['alarm'] = $avalue;
+            }
+        }
+
+        // recurr object/array
+        if (count($object['recurrence']) > 1) {
+            $ra = $object['recurrence'];
+
+            // frequency and interval
+            $this->kolab_object['recurrence'] = array(
+                'cycle' => strtolower($ra['FREQ']),
+                'interval' => intval($ra['INTERVAL']),
+            );
+
+            // range Type
+            if ($ra['UNTIL']) {
+                $this->kolab_object['recurrence']['range-type'] = 'date';
+                $this->kolab_object['recurrence']['range'] = $ra['UNTIL']->format('U');
+            }
+            if ($ra['COUNT']) {
+                $this->kolab_object['recurrence']['range-type'] = 'number';
+                $this->kolab_object['recurrence']['range'] = $ra['COUNT'];
+            }
+
+            // WEEKLY
+            if ($ra['FREQ'] == 'WEEKLY') {
+                if ($ra['BYDAY']) {
+                    foreach (explode(',', $ra['BYDAY']) as $day)
+                        $this->kolab_object['recurrence']['day'][] = $this->kolab2_weekdaymap[$day];
+                }
+                else {
+                    // use weekday of start date if empty
+                    $this->kolab_object['recurrence']['day'][] = strtolower($object['start']->format('l'));
+                }
+            }
+
+            // MONTHLY (temporary hack to follow Horde logic)
+            if ($ra['FREQ'] == 'MONTHLY') {
+                if ($ra['BYDAY'] && preg_match('/(-?[1-4])([A-Z]+)/', $ra['BYDAY'], $m)) {
+                    $this->kolab_object['recurrence']['daynumber'] = $m[1];
+                    $this->kolab_object['recurrence']['day'] = array($this->kolab2_weekdaymap[$m[2]]);
+                    $this->kolab_object['recurrence']['cycle'] = 'monthly';
+                    $this->kolab_object['recurrence']['type']  = 'weekday';
+                }
+                else {
+                    $this->kolab_object['recurrence']['daynumber'] = preg_match('/^\d+$/', $ra['BYMONTHDAY']) ? $ra['BYMONTHDAY'] : $object['start']->format('j');
+                    $this->kolab_object['recurrence']['cycle'] = 'monthly';
+                    $this->kolab_object['recurrence']['type']  = 'daynumber';
+                }
+            }
+
+            // YEARLY
+            if ($ra['FREQ'] == 'YEARLY') {
+                if (!$ra['BYMONTH'])
+                    $ra['BYMONTH'] = $object['start']->format('n');
+
+                $this->kolab_object['recurrence']['cycle'] = 'yearly';
+                $this->kolab_object['recurrence']['month'] = $this->month_map[intval($ra['BYMONTH'])];
+
+                if ($ra['BYDAY'] && preg_match('/(-?[1-4])([A-Z]+)/', $ra['BYDAY'], $m)) {
+                    $this->kolab_object['recurrence']['type'] = 'weekday';
+                    $this->kolab_object['recurrence']['daynumber'] = $m[1];
+                    $this->kolab_object['recurrence']['day'] = array($this->kolab2_weekdaymap[$m[2]]);
+                }
+                else {
+                    $this->kolab_object['recurrence']['type'] = 'monthday';
+                    $this->kolab_object['recurrence']['daynumber'] = $object['start']->format('j');
+                }
+            }
+
+            // exclusions
+            foreach ((array)$ra['EXDATE'] as $excl) {
+                $this->kolab_object['recurrence']['exclusion'][] = $excl->format('Y-m-d');
+            }
+        }
+        else if (isset($object['recurrence']))
+            unset($this->kolab_object['recurrence']);
+
+        // process event attendees
+        $status_map = array_flip($this->kolab2_statusmap);
+        $role_map = array_flip($this->kolab2_rolemap);
+        $this->kolab_object['attendee'] = array();
+        foreach ((array)$object['attendees'] as $attendee) {
+            $role = $attendee['role'];
+            if ($role == 'ORGANIZER') {
+                $this->kolab_object['organizer'] = array(
+                    'display-name' => $attendee['name'],
+                    'smtp-address' => $attendee['email'],
+                );
+            }
+            else {
+                $this->kolab_object['attendee'][] = array(
+                    'display-name' => $attendee['name'],
+                    'smtp-address' => $attendee['email'],
+                    'status'       => $status_map[$attendee['status']],
+                    'role'         => $role_map[$role],
+                    'request-response' => $attendee['rsvp'],
+                );
+            }
+        }
+
+        // clear old cid: list attachments
+        $links = array();
+        foreach ((array)$this->kolab_object['link-attachment'] as $i => $url) {
+            if (strpos($url, 'cid:') !== 0)
+                $links[] = $url;
+        }
+        foreach ((array)$object['_attachments'] as $key => $attachment) {
+            if ($attachment)
+                $links[] = 'cid:' . $key;
+        }
+        $this->kolab_object['link-attachment'] = $links;
 
         // cache this data
         $this->data = $object;
         unset($this->data['_formatobj']);
     }
 
     /**
      *
      */
     public function is_valid()
     {
-        return $this->data;
+        return !empty($this->data['uid']) && $this->data['start'] && $this->data['end'];
     }
 
     /**
      * Callback for kolab_storage_cache to get object specific tags to cache
      *
      * @return array List of tags to save in cache
      */
     public function get_tags()
     {
         $tags = array();
 
         foreach ((array)$this->data['categories'] as $cat) {
             $tags[] = rcube_utils::normalize_string($cat);
         }
 
         if (!empty($this->data['alarms'])) {
             $tags[] = 'x-has-alarms';
         }
 
         return $tags;
     }
 
     /**
      * Load data from old Kolab2 format
      */
     public function fromkolab2($rec)
     {
         if (PEAR::isError($rec))
             return;
 
         $start_time = date('H:i:s', $rec['start-date']);
         $allday = $rec['_is_all_day'] || ($start_time == '00:00:00' && $start_time == date('H:i:s', $rec['end-date']));
 
         // in Roundcube all-day events go from 12:00 to 13:00
         if ($allday) {
             $now = new DateTime('now', self::$timezone);
             $gmt_offset = $now->getOffset();
 
             $rec['start-date'] += 12 * 3600;
             $rec['end-date']   -= 11 * 3600;
             $rec['end-date']   -= $gmt_offset - date('Z', $rec['end-date']);    // shift times from server's timezone to user's timezone
             $rec['start-date'] -= $gmt_offset - date('Z', $rec['start-date']);  // because generated with mktime() in Horde_Kolab_Format_Date::decodeDate()
             // sanity check
             if ($rec['end-date'] <= $rec['start-date'])
-              $rec['end-date'] += 86400;
+                $rec['end-date'] += 86400;
         }
 
         // convert alarm time into internal format
         if ($rec['alarm']) {
             $alarm_value = $rec['alarm'];
             $alarm_unit = 'M';
             if ($rec['alarm'] % 1440 == 0) {
                 $alarm_value /= 1440;
                 $alarm_unit = 'D';
             }
             else if ($rec['alarm'] % 60 == 0) {
                 $alarm_value /= 60;
                 $alarm_unit = 'H';
             }
             $alarm_value *= -1;
         }
 
         // convert recurrence rules into internal pseudo-vcalendar format
         if ($recurrence = $rec['recurrence']) {
             $rrule = array(
                 'FREQ' => strtoupper($recurrence['cycle']),
                 'INTERVAL' => intval($recurrence['interval']),
             );
 
             if ($recurrence['range-type'] == 'number')
                 $rrule['COUNT'] = intval($recurrence['range']);
             else if ($recurrence['range-type'] == 'date')
                 $rrule['UNTIL'] = date_create('@'.$recurrence['range']);
 
             if ($recurrence['day']) {
                 $byday = array();
                 $prefix = ($rrule['FREQ'] == 'MONTHLY' || $rrule['FREQ'] == 'YEARLY') ? intval($recurrence['daynumber'] ? $recurrence['daynumber'] : 1) : '';
                 foreach ($recurrence['day'] as $day)
                     $byday[] = $prefix . substr(strtoupper($day), 0, 2);
                 $rrule['BYDAY'] = join(',', $byday);
             }
             if ($recurrence['daynumber']) {
                 if ($recurrence['type'] == 'monthday' || $recurrence['type'] == 'daynumber')
                     $rrule['BYMONTHDAY'] = $recurrence['daynumber'];
                 else if ($recurrence['type'] == 'yearday')
                     $rrule['BYYEARDAY'] = $recurrence['daynumber'];
             }
             if ($recurrence['month']) {
                 $monthmap = array_flip($this->kolab2_monthmap);
                 $rrule['BYMONTH'] = strtolower($monthmap[$recurrence['month']]);
             }
 
             if ($recurrence['exclusion']) {
                 foreach ((array)$recurrence['exclusion'] as $excl)
                     $rrule['EXDATE'][] = date_create($excl . date(' H:i:s', $rec['start-date']));  // use time of event start
             }
         }
 
         $attendees = array();
         if ($rec['organizer']) {
             $attendees[] = array(
                 'role' => 'ORGANIZER',
                 'name' => $rec['organizer']['display-name'],
                 'email' => $rec['organizer']['smtp-address'],
                 'status' => 'ACCEPTED',
             );
             $_attendees .= $rec['organizer']['display-name'] . ' ' . $rec['organizer']['smtp-address'] . ' ';
         }
 
         foreach ((array)$rec['attendee'] as $attendee) {
             $attendees[] = array(
                 'role' => $this->kolab2_rolemap[$attendee['role']],
                 'name' => $attendee['display-name'],
                 'email' => $attendee['smtp-address'],
                 'status' => $this->kolab2_statusmap[$attendee['status']],
                 'rsvp' => $attendee['request-response'],
             );
             $_attendees .= $rec['organizer']['display-name'] . ' ' . $rec['organizer']['smtp-address'] . ' ';
         }
 
         $this->data = array(
             'uid' => $rec['uid'],
             'title' => $rec['summary'],
             'location' => $rec['location'],
             'description' => $rec['body'],
             'start' => new DateTime('@'.$rec['start-date']),
             'end'   => new DateTime('@'.$rec['end-date']),
             'allday' => $allday,
             'recurrence' => $rrule,
             'alarms' => $alarm_value . $alarm_unit,
-            'categories' => explode(',', $rec['categories']),
-            'attachments' => $attachments,
+            'categories' => $rec['categories'],
             'attendees' => $attendees,
             'free_busy' => $rec['show-time-as'],
             'priority' => $rec['priority'],
             'sensitivity' => $rec['sensitivity'],
             'changed' => $rec['last-modification-date'],
         );
 
-        // assign current timezone to event start/end
+        // assign current timezone to event start/end which are in UTC
         $this->data['start']->setTimezone(self::$timezone);
         $this->data['end']->setTimezone(self::$timezone);
     }
 }