egroupware/calendar/inc/class.calendar_activesync.inc.php

<?php
/**
 * EGroupware: ActiveSync access: Calendar plugin
 *
 * @link http://www.egroupware.org
 * @package calendar
 * @subpackage activesync
 * @author Ralf Becker <rb@stylite.de>
 * @author Klaus Leithoff <kl@stylite.de>
 * @author Philip Herbert <philip@knauber.de>
 * @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
 * @version $Id$
 */

/**
 * Calendar activesync plugin
 *
 * Plugin to make EGroupware calendar data available via Active Sync
 */
class calendar_activesync implements activesync_plugin_write
{
	/**
	 * var BackendEGW
	 */
	private $backend;

	/**
	 * Instance of calendar_bo
	 *
	 * @var calendar_boupdate
	 */
	private $calendar;

	/**
	 * Constructor
	 *
	 * @param BackendEGW $backend
	 */
	public function __construct(BackendEGW $backend)
	{
		$this->backend = $backend;
	}

	/**
	 *  This function is analogous to GetMessageList.
	 *
	 *  @ToDo implement preference, include own private calendar
	 */
	public function GetFolderList()
	{
		if (!isset($this->calendar)) $this->calendar = new calendar_boupdate();

		foreach ($this->calendar->list_cals() as $label => $entry)
		{
			$folderlist[] = $f = array(
				'id'	=>	$this->backend->createID('calendar',$entry['grantor']),
				'mod'	=>	$GLOBALS['egw']->accounts->id2name($entry['grantor'],'account_fullname'),
				'parent'=>	'0',
			);
		};
		//error_log(__METHOD__."() returning ".array2string($folderlist));
		return $folderlist;
	}

	/**
	 * Get Information about a folder
	 *
	 * @param string $id
	 * @return SyncFolder|boolean false on error
	 */
	public function GetFolder($id)
	{
		$this->backend->splitID($id, $type, $owner);

		$folderObj = new SyncFolder();
		$folderObj->serverid = $id;
		$folderObj->parentid = '0';
		$folderObj->displayname = $GLOBALS['egw']->accounts->id2name($owner,'account_fullname');
		if ($owner == $GLOBALS['egw_info']['user']['account_id'])
		{
			$folderObj->type = SYNC_FOLDER_TYPE_APPOINTMENT;
		}
		else
		{
			$folderObj->type = SYNC_FOLDER_TYPE_USER_APPOINTMENT;
		}
		//error_log(__METHOD__."('$id') folderObj=".array2string($folderObj));
		return $folderObj;
	}

	/**
	 * Return folder stats. This means you must return an associative array with the
	 * following properties:
	 *
	 * "id" => The server ID that will be used to identify the folder. It must be unique, and not too long
	 *		 How long exactly is not known, but try keeping it under 20 chars or so. It must be a string.
	 * "parent" => The server ID of the parent of the folder. Same restrictions as 'id' apply.
	 * "mod" => This is the modification signature. It is any arbitrary string which is constant as long as
	 *		  the folder has not changed. In practice this means that 'mod' can be equal to the folder name
	 *		  as this is the only thing that ever changes in folders. (the type is normally constant)
	 *
	 * @return array with values for keys 'id', 'mod' and 'parent'
	 */
	public function StatFolder($id)
	{
		$folder = $this->GetFolder($id);
		$this->backend->splitID($id, $type, $owner);

		$stat = array(
			'id'	 => $id,
			'mod'	=> $GLOBALS['egw']->accounts->id2name($owner,'account_fullname'),
			'parent' => '0',
		);

		return $stat;
	}

	/**
	 * Should return a list (array) of messages, each entry being an associative array
	 * with the same entries as StatMessage(). This function should return stable information; ie
	 * if nothing has changed, the items in the array must be exactly the same. The order of
	 * the items within the array is not important though.
	 *
	 * The cutoffdate is a date in the past, representing the date since which items should be shown.
	 * This cutoffdate is determined by the user's setting of getting 'Last 3 days' of e-mail, etc. If
	 * you ignore the cutoffdate, the user will not be able to select their own cutoffdate, but all
	 * will work OK apart from that.
	 *
	 * @param string $id folder id
	 * @param int $cutoffdate=null
	 * @return array
  	 */
	function GetMessageList($id, $cutoffdate=NULL)
	{
		if (!isset($this->calendar)) $this->calendar = new calendar_boupdate();

		debugLog (__METHOD__."('$id',$cutoffdate)");
		$this->backend->splitID($id,$type,$user);

		if (!$cutoffdate) $cutoffdate = $this->bo->now - 100*24*3600;	// default three month back -30 breaks all sync recurrences

		// todo return only etag relevant information
		$filter = array(
			'users' => $user,
			'start' => $cutoffdate,	// default one month back -30 breaks all sync recurrences
			'enum_recuring' => false,
			'daywise' => false,
			'date_format' => 'server',
			'filter' => 'default',	// not rejected
		);

		$messagelist = array();
		foreach ($this->calendar->search($filter) as $k => $event)
		{
			$messagelist[] = $this->StatMessage($id, $event);
		}
		return $messagelist;
	}

	static $status2as = array(
		'U' => 0,	// unknown
		'T' => 2,	// tentative
		'A' => 3,	// accepted
		'R' => 4,	// decline
		// 5 = not responded
	);
	static $role2as = array(
		'REQ-PARTICIPANT' => 1,	// required
		'CHAIR' => 1,			// required
		'OPT-PARTICIPANT' => 2,	// optional
		'NON-PARTICIPANT' => 2,
		// 3 = ressource
	);

	/**
	 * Changes or adds a message on the server
	 *
	 * @param string $folderid
	 * @param int $id for change | empty for create new
	 * @param SyncAppointment $message object to SyncObject to create
	 *
	 * @return array $stat whatever would be returned from StatMessage
	 *
	 * This function is called when a message has been changed on the PDA. You should parse the new
	 * message here and save the changes to disk. The return value must be whatever would be returned
	 * from StatMessage() after the message has been saved. This means that both the 'flags' and the 'mod'
	 * properties of the StatMessage() item may change via ChangeMessage().
	 * Note that this function will never be called on E-mail items as you can't change e-mail items, you
	 * can only set them as 'read'.
	 */
	public function ChangeMessage($folderid, $id, $message)
	{
		if (!isset($this->calendar)) $this->calendar = new calendar_boupdate();

		$event = array();
		$this->backend->splitID($folderid, $type, $account);

		debugLog (__METHOD__."('$folderid', $id, ".array2string($message).") type='$type', account=$account");

		if ($type != 'calendar' || $id && !($event = $this->calendar->read($id,null,false,'server')))
		{
			debugLog(__METHOD__."('$folderid',$id,...) Folder wrong or event does not existing");
			return false;
		}
		if (!$this->calendar->check_perms($id ? EGW_ACL_EDIT : EGW_ACL_ADD,$event ? $event : 0,$account))
		{
			debugLog(__METHOD__."('$folderid',$id,...) no rights to add/edit event!");
			return false;
		}
		// timestamps (created & modified are updated automatically)
		foreach(array(
			'start' => 'starttime',
			'end' => 'endtime',
		) as $key => $attr)
		{
			$event[$key] = egw_time::server2user($message->$attr);
		}
		if (!$id) $event['owner'] = $account;	// we do NOT allow to change the owner of existing events

		// copying strings
		foreach(array(
			'title' => 'subject',
			'uid'   => 'uid',
			'location' => 'location',
		) as $key => $attr)
		{
			if (isset($message->$attr)) $event[$key] = $message->$attr;
		}

		$event['public'] = (int)$message->sensitivity < 1;	// 0=normal, 1=personal, 2=private, 3=confidential
		$event['whole_day'] = $message->alldayevent;

		$participants = array();
		foreach((array)$message->attendees as $attendee)
		{
			if (!($uid = $GLOBALS['egw']->accounts->name2id($attendee->email,'account_email')))
			{
				// todo check for other resource types
				$uid = 'e'.$attendee->name.' <'.$attendee->email.'>';
			}
			if (!($status = array_search($attendee->status,self::$status2as))) $status = 'U';
			if ($attendee->email == $message->organizeremail)
			{
				$role = 'CHAIR';
				$chair_set = true;
			}
			elseif (!($role = array_search($attendee->type,self::$role2as)))
			{
				$role = 'REQ-PARTICIPANT';
			}
			$quantitiy = 1;
			// if old role gives same type, use old role, as we have a lot more roles then AS
			if ($id && isset($event['participants'][$uid]))
			{
				calendar_so::split_status($status, $quantity, $old_role);
				if ((int)self::$role2as[$old_role] == $attendee->type)
				{
					$role = $old_role;
				}
			}
			$participants[$uid] = calendar_so::combine_status($status,$quantitiy,$role);
		}
		// if organizer is not already participant, add him as chair
		if (($uid = $GLOBALS['egw']->accounts->name2id($message->organizeremail,'account_email')) && !isset($participants[$uid]))
		{
			$participants[$uid] = calendar_so::combine_status($uid == $GLOBALS['egw_info']['user']['account_id'] ?
				'A' : 'U',1,'CHAIR');
			$chair_set = true;
		}
		// add calendar owner as participant, as otherwise event will NOT be in his calendar, in which it was posted
		if (!$id && !isset($participants[$account]))
		{
			$participants[$account] = calendar_so::combine_status($account == $GLOBALS['egw_info']['user']['account_id'] ?
				'A' : 'U',1,!$chair_set ? 'CHAIR' : 'REQ-PARTICIPANT');
		}
		$event['participants'] = $participants;

		foreach((array)$message->categories as $name)
		{
			// todo: categories
		}

		// check if event is recurring and import recur information (incl. timezone)
		if ($message->recurrence)
		{
			if ($message->timezone && !$id)	// dont care for timezone, if no new and recurring event
			{
				$event['tzid'] = self::as2tz(self::_getTZFromSyncBlob($message->timezone));
			}
			// todo: recurrence information
		}

		if (!($id = $this->calendar->save($event)))
		{
			debugLog(__METHOD__."('$folderid',$id,...) error saving event=".array2string($event)."!");
			return false;
		}
		debugLog(__METHOD__."('$folderid',$id,...) SUCESS saving event=".array2string($event).", id=$id");
		return $this->StatMessage($folderid, $id);
	}

	/**
	 *  Creates or modifies a folder
	 *
	 * @param $id of the parent folder
	 * @param $oldid => if empty -> new folder created, else folder is to be renamed
	 * @param $displayname => new folder name (to be created, or to be renamed to)
	 * @param type => folder type, ignored in IMAP
	 *
	 * @return stat | boolean false on error
	 */
	public function ChangeFolder($id, $oldid, $displayname, $type)
	{
		debugLog(__METHOD__."('$id', '$oldid', '$displayname', $type) NOT implemented!");
		return false;
	}

	/**
	 * Deletes (really delete) a Folder
	 *
	 * @param $parentid of the folder to delete
	 * @param $id of the folder to delete
	 *
	 * @return
	 * @TODO check what is to be returned
	 */
	public function DeleteFolder($parentid, $id)
	{
		debugLog(__METHOD__."('$parentid', '$id') NOT implemented!");
		return false;
	}

	/**
	 * Moves a message from one folder to another
	 *
	 * @param $folderid of the current folder
	 * @param $id of the message
	 * @param $newfolderid
	 *
	 * @return $newid as a string | boolean false on error
	 *
	 * After this call, StatMessage() and GetMessageList() should show the items
	 * to have a new parent. This means that it will disappear from GetMessageList() will not return the item
	 * at all on the source folder, and the destination folder will show the new message
	 */
	public function MoveMessage($folderid, $id, $newfolderid)
	{
		debugLog(__METHOD__."('$folderid', $id, '$newfolderid') NOT implemented!");
		return false;
	}

	/**
	 * Delete (really delete) a message in a folder
	 *
	 * @param $folderid
	 * @param $id
	 *
	 * @return boolean true on success, false on error, diffbackend does NOT use the returnvalue
	 *
	 * @DESC After this call has succeeded, a call to
	 * GetMessageList() should no longer list the message. If it does, the message will be re-sent to the PDA
	 * as it will be seen as a 'new' item. This means that if you don't implement this function, you will
	 * be able to delete messages on the PDA, but as soon as you sync, you'll get the item back
	 */
	public function DeleteMessage($folderid, $id)
	{
		if (!isset($this->caledar)) $this->calendar = new calendar_boupdate();

		$ret = $this->calendar->delete($id);
		debugLog(__METHOD__."('$folderid', $id) delete($id) returned ".array2string($ret));
		return $ret;
	}

	/**
	 * Get specified item from specified folder.
	 *
	 * Timezone wise we supply zpush with timestamps in servertime (!), which it "converts" in streamer::formatDate($ts)
	 * via gmstrftime("%Y%m%dT%H%M%SZ", $ts) to UTC times.
	 * Timezones are only used to get correct recurring events!
	 *
	 * @param string $folderid
	 * @param string $id
	 * @param int $truncsize
	 * @param int $bodypreference
	 * @param bool $mimesupport
	 * @return SyncAppointment|boolean false on error
	 */
	public function GetMessage($folderid, $id, $truncsize, $bodypreference=false, $mimesupport = 0)
	{
		if (!isset($this->calendar)) $this->calendar = new calendar_boupdate();

		debugLog (__METHOD__."('$folderid', $id, truncsize=$truncsize, bodyprefence=$bodypreference, mimesupport=$mimesupport)");
		$this->backend->splitID($folderid, $type, $account);
		if ($type != 'calendar' || !($event = $this->calendar->read($id,null,false,'server',$account)))
		{
			error_log(__METHOD__."('$folderid', $id, ...) read($id,null,false,'server',$account) returned false");
			return false;
		}
		$message = new SyncAppointment();

		// set timezone
		try {
			$as_tz = self::tz2as($event['tzid']);
			$message->timezone = base64_encode(self::_getSyncBlobFromTZ($as_tz));
		}
		catch(Exception $e) {
			// ignore exception, simply set no timezone, as it is optional
		}
		// copying timestamps
		foreach(array(
			'start' => 'starttime',
			'end'   => 'endtime',
			'created' => 'dtstamp',
			'modified' => 'dtstamp',
		) as $key => $attr)
		{
			if (!empty($event[$key])) $message->$attr = $event[$key];
		}
		// copying strings
		foreach(array(
			'title' => 'subject',
			'uid'   => 'uid',
			'location' => 'location',
		) as $key => $attr)
		{
			if (!empty($event[$key])) $message->$attr = $event[$key];
		}
		$message->organizername  = $GLOBALS['egw']->accounts->id2name($event['owner'],'account_fullname');
		$message->organizeremail = $GLOBALS['egw']->accounts->id2name($event['owner'],'account_email');

		$message->sensitivity = $event['public'] ? 0 : 2;	// 0=normal, 1=personal, 2=private, 3=confidential
		$message->alldayevent = (int)$this->calendar->isWholeDay($event);

		$message->attendees = array();
		foreach($event['participants'] as $uid => $status)
		{
			calendar_so::split_status($status, $quantity, $role);
			$attendee = new SyncAttendee();
			$attendee->status = (int)self::$status2as[$status];
			$attendee->type = (int)self::$role2as[$role];
			if (is_numeric($uid))
			{
				$attendee->name = $GLOBALS['egw']->accounts->id2name($uid,'account_fullname');
				$attendee->email = $GLOBALS['egw']->accounts->id2name($uid,'account_email');
			}
			else
			{
				list($info) = $this->calendar->resources[$uid[0]]['info'] ?
					ExecMethod($this->resources[$uid[0]]['info'],substr($uid,1)) : array(false);

				if (!$info) continue;

				if (!$info['email'] && $info['responsible'])
				{
					$info['email'] = $GLOBALS['egw']->accounts->id2name($info['responsible'],'account_email');
				}
				$attendee->name = empty($info['cn']) ? $info['name'] : $info['cn'];
				$attendee->email = $info['email'];
				if ($uid[0] == 'r') $attendee->type = 3;	// 3 = resource
			}
			$message->attendees[] = $attendee;
		}
		$message->categories = array();
		foreach($event['catgory'] ? explode(',',$event['category']) : array() as $cat_id)
		{
			$message->categories[] = categories::id2name($cat_id);
		}

		// recurring information
		if ($event['recur_type'] != RECUR_NONE)
		{
			$message->recurrence = $recurrence = new SyncRecurrence();
			$rrule = calendar_rrule::event2rrule($event);
			static $recur_type2as = array(
				calendar_rrule::DAILY => 0,
				calendar_rrule::WEEKLY => 1,
				calendar_rrule::MONTHLY_MDAY => 2,	// monthly
				calendar_rrule::MONTHLY_WDAY => 3,	// monthly on nth day
				calendar_rrule::YEARLY => 5,
				// 6 = yearly on nth day
			);
			$recurrence->type = (int)$recur_type2as[$rrule->type];
			$recurrence->interval = $rrule->interval;
			switch ($rrule->type)
			{
				case calendar_rrule::MONTHLY_WDAY:
					$recurrence->weekofmonth = $rrule->monthly_byday_num >= 1 ?
						$rrule->monthly_byday_num : 5;	// 1..5=last week of month, not -1
					// fall throught
				case calendar_rrule::WEEKLY:
					$recurrence->dayofweek = $rrule->weekdays;	// 1=Su, 2=Mo, 4=Tu, .., 64=Sa
					break;
				case calendar_rrule::MONTHLY_MDAY:
					$recurrence->dayofmonth = $rrule->monthly_bymonthday >= 1 ?	// 1..31
						$rrule->monthly_bymonthday : 31;	// not -1 for last day of month!
					break;
				case calendar_rrule::YEARLY:
					$recurrence->dayofmonth = (int)$rrule->time->format('d');	// 1..31
					$recurrence->monthofyear = (int)$rrule->time->format('m');	// 1..12
					break;
			}
			if ($rrule->enddate) $recurrence->until = $rrule->enddate->format('ts');	// Timezone?

			if ($rrule->exceptions)
			{
				$message->exceptions = array();
				foreach($rrule->exceptions as $exception_time)
				{
					$exception = new SyncAppointment();	// exceptions seems to be full SyncAppointments, with only starttime required
					$exception->starttime = $exception_time->format('ts');	// Timezone?
					$message->exceptions[] = $exception;
				}
			}
		}
		//$message->busystatus;
		//$message->reminder;
		//$message->meetingstatus;
		//$message->deleted;
/*
		if (isset($protocolversion) && $protocolversion < 12.0) {
			$message->body;
			$message->bodytruncated;
			$message->rtf;
		}

		if(isset($protocolversion) && $protocolversion >= 12.0) {

		 	$message->airsyncbasebody;	// SYNC SyncAirSyncBaseBody
		}
*/
		return $message;
	}

	/**
	 * StatMessage should return message stats, analogous to the folder stats (StatFolder). Entries are:
	 * 'id'	 => Server unique identifier for the message. Again, try to keep this short (under 20 chars)
	 * 'flags'	 => simply '0' for unread, '1' for read
	 * 'mod'	=> modification signature. As soon as this signature changes, the item is assumed to be completely
	 *			 changed, and will be sent to the PDA as a whole. Normally you can use something like the modification
	 *			 time for this field, which will change as soon as the contents have changed.
	 *
	 * @param string $folderid
	 * @param int|array $id event id or array
	 * @return array
	 */
	public function StatMessage($folderid, $id)
	{
		if (!isset($this->calendar)) $this->calendar = new calendar_boupdate();

		if (!($etag = $this->calendar->get_etag($id)))
		{
			$stat = false;
			// error_log why access is denied (should nevery happen for everything returned by calendar_bo::search)
			$backup = $this->calendar->debug;
			$this->calendar->debug = 2;
			$this->calendar->check_perms(EGW_ACL_FREEBUSY, $id, 0, 'server');
			$this->calendar->debug = $backup;
		}
		else
		{
			$stat = array(
				'mod' => $etag,
				'id' => is_array($id) ? $id['id'] : $id,
				'flags' => 1,
			);
		}
		debugLog (__METHOD__."('$folderid',".array2string($id).") returning ".array2string($stat));

		return $stat;
	}

	/**
	 * Return a changes array
	 *
	 * if changes occurr default diff engine computes the actual changes
	 *
	 * @param string $folderid
	 * @param string &$syncstate on call old syncstate, on return new syncstate
	 * @return array|boolean false if $folderid not found, array() if no changes or array(array("type" => "fakeChange"))
	 */
	function AlterPingChanges($folderid, &$syncstate)
	{
		$this->backend->splitID($folderid, $type, $owner);

		if ($type != 'calendar') return false;

		if (!isset($this->calendar)) $this->calendar = new calendar_boupdate();
		$ctag = $this->calendar->get_ctag($owner);

		$changes = array();	// no change
		$syncstate_was = $syncstate;

		if ($ctag !== $syncstate)
		{
			$syncstate = $ctag;
			$changes = array(array('type' => 'fakeChange'));
		}
		//error_log(__METHOD__."('$folderid','$syncstate_was') syncstate='$syncstate' returning ".array2string($changes));
		return $changes;
	}

	/**
	 * Return AS timezone data from given timezone and time
	 *
	 * AS spezifies the timezone by the date it changes to dst and back and the offsets.
	 * Unfortunately this data is not available from PHP's DateTime(Zone) class.
	 * Just given the exact time of the next transition, which is available via DateTimeZone::getTransistions(),
	 * will fail for recurring events longer then a year, as the transition date/time changes!
	 *
	 * We use now the RRule given in the iCal timezone defintion available via calendar_timezones::tz2id($tz,'component').
	 *
	 * Not every timezone uses DST, in which case only bias matters and dstbias=0
	 * (probably all other values should be 0, as MapiMapping::_getGMTTZ() in backend/ics.php does it).
	 *
	 * @param string|DateTimeZone $tz timezone, timezone name (eg. "Europe/Berlin") or ical with VTIMEZONE
	 * @param int|string|DateTime $ts=null time for which active sync timezone data is requested, default current time
	 * @return array with values for keys:
	 * - "bias": timezone offset from UTC in minutes for NO DST
	 * - "dstendmonth", "dstendday", "dstendweek", "dstendhour", "dstendminute", "dstendsecond", "dstendmillis"
	 * - "stdbias": seems not to be used
	 * - "dststartmonth", "dststartday", "dststartweek", "dststarthour", "dststartminute", "dststartsecond", "dststartmillis"
	 * - "dstbias": offset in minutes for no DST --> DST, usually 60 or 0 for no DST
	 *
	 * @link http://download.microsoft.com/download/5/D/D/5DD33FDF-91F5-496D-9884-0A0B0EE698BB/%5BMS-ASDTYPE%5D.pdf
	 * @throws egw_exception_assertion_failed if no vtimezone data found for given timezone
	 */
	static public function tz2as($tz,$ts=null)
	{
/*
BEGIN:VTIMEZONE
TZID:Europe/Berlin
X-LIC-LOCATION:Europe/Berlin
BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
--> bias: 60 min
TZOFFSETTO:+0200
--> dstbias: +0200 - +0100 = +0100 = 60 min
TZNAME:CEST
DTSTART:19700329T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
--> dststart: month: 3, day: SU(0???), week: -1|5, hour: 2, minute, second, millis: 0
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:19701025T030000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
--> dstend: month: 10, day: SU(0???), week: -1|5, hour: 3, minute, second, millis: 0
END:STANDARD
END:VTIMEZONE
*/
		$data = array(
			'bias' => 0,
			'stdbias' => 0,
			'dstbias' => 0,
			'dststartmonth' => 0, 'dststartday' => 0, 'dststartweek' => 0,
			'dststarthour' => 0, 'dststartminute' => 0, 'dststartsecond' => 0, 'dststartmillis' => 0,
			'dstendmonth' => 0, 'dstendday' => 0, 'dstendweek' => 0,
			'dstendhour' => 0, 'dstendminute' => 0, 'dstendsecond' => 0, 'dstendmillis' => 0,
		);

		$name = $component = is_a($tz,'DateTimeZone') ? $tz->getName() : $tz;
		if (strpos($component, 'VTIMEZONE') === false) $component = calendar_timezones::tz2id($name,'component');
		// parse ical timezone defintion
		$ical = self::ical2array($ical=$component);
		$standard = $ical['VTIMEZONE']['STANDARD'];
		$daylight = $ical['VTIMEZONE']['DAYLIGHT'];

		if (!isset($standard))
		{
			throw new egw_exception_assertion_failed("NO standard component for '$name' in '$component'!");
		}
		// get bias and dstbias from standard component, which is present in all tz's
		// (dstbias is relative to bias and almost always 60 or 0)
		$data['bias'] = 60 * substr($standard['TZOFFSETTO'],0,-2) + substr($standard['TZOFFSETTO'],-2);
		$data['dstbias'] = 60 * substr($standard['TZOFFSETFROM'],0,-2) + substr($standard['TZOFFSETFROM'],-2) - $data['bias'];

		// check if we have an additional DAYLIGHT component and both have a RRULE component --> tz uses daylight saving
		if (isset($standard['RRULE']) && isset($daylight) && isset($daylight['RRULE']))
		{
			foreach(array('dststart' => $daylight,'dstend' => $standard) as $prefix => $comp)
			{
				if (preg_match('/FREQ=YEARLY;BYDAY=(.*);BYMONTH=(\d+)/',$comp['RRULE'],$matches))
				{
					$data[$prefix.'month'] = (int)$matches[2];
					$data[$prefix.'week'] = (int)$matches[1];
					if ($data[$prefix.'week'] < 0) $data[$prefix.'week'] = 5; // -1 for last week might be 5 for as as in recuring events definition
					static $day2int = array('SU'=>0,'MO'=>1,'TU'=>2,'WE'=>3,'TH'=>4,'FR'=>5,'SA'=>6);
					$data[$prefix.'day'] = (int)$day2int[substr($matches[1],-2)];
				}
				if (preg_match('/^\d{8}T(\d{6})$/',$comp['DTSTART'],$matches))
				{
					$data[$prefix.'hour'] = (int)substr($matches[1],0,2);
					$data[$prefix.'minute'] = (int)substr($matches[1],2,2);
					$data[$prefix.'second'] = (int)substr($matches[1],4,2);
				}
			}
		}
		//error_log(__METHOD__."('$name') returning ".array2string($data));
		return $data;
	}

	/**
	 * Simple iCal parser:
	 *
	 * BEGIN:VTIMEZONE
	 * TZID:Europe/Berlin
	 * X-LIC-LOCATION:Europe/Berlin
	 * BEGIN:DAYLIGHT
	 * TZOFFSETFROM:+0100
	 * TZOFFSETTO:+0200
	 * TZNAME:CEST
	 * DTSTART:19700329T020000
	 * RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
	 * END:DAYLIGHT
	 * BEGIN:STANDARD
	 * TZOFFSETFROM:+0200
	 * TZOFFSETTO:+0100
	 * TZNAME:CET
	 * DTSTART:19701025T030000
	 * RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
	 * END:STANDARD
	 * END:VTIMEZONE
	 *
	 * Array
	 * (
	 *	 [VTIMEZONE] => Array
	 *		 (
	 *			 [TZID] => Europe/Berlin
	 *			 [X-LIC-LOCATION] => Europe/Berlin
	 *			 [DAYLIGHT] => Array
	 *				 (
	 *					 [TZOFFSETFROM] => +0100
	 *					 [TZOFFSETTO] => +0200
	 *					 [TZNAME] => CEST
	 *					 [DTSTART] => 19700329T020000
	 *					 [RRULE] => FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
	 *				 )
	 *			 [STANDARD] => Array
	 *				 (
	 *					 [TZOFFSETFROM] => +0200
	 *					 [TZOFFSETTO] => +0100
	 *					 [TZNAME] => CET
	 *					 [DTSTART] => 19701025T030000
	 *					 [RRULE] => FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
	 *				 )
	 *		 )
	 * )
	 *
	 * @param string|array $ical lines of ical file
	 * @param string $component=null
	 * @return array with parsed ical components
	 */
	static public function ical2array(&$ical,$component=null)
	{
		$arr = array();
		if (!is_array($ical)) $ical = preg_split("/[\r\n]+/m", $ical);
		while (($line = array_shift($ical)))
		{
			list($name,$value) = explode(':',$line,2);
			if ($name == 'BEGIN')
			{
				$arr[$value] = self::ical2array($ical,$value);
			}
			elseif($name == 'END')
			{
				break;
			}
			else
			{
				$arr[$name] = $value;
			}
		}
		return $arr;
	}

	/**
	 * Get timezone from AS timezone data
	 *
	 * Here we can only loop through all available timezones (starting with the users timezone) and
	 * try to find a timezone matching the change data and offsets specified in $data.
	 * This conversation is not unique, as multiple timezones can match the given data or none!
	 *
	 * Maybe returning the users timezone, if no match found, might makes more sense.
	 *
	 * @param array $data
	 * @return string|boolean timezone name, eg. "Europe/Berlin" or false if no matching timezone found
	 */
	public static function as2tz(array $data)
	{
		static $cache;	// some caching withing the request

		$key = serialize($data);

		for($n = 0; !isset($cache[$key]); ++$n)
		{
			if (!$n)	// check users timezone first
			{
				$tz = egw_time::$user_timezone->getName();
			}
			elseif (!($tz = calendar_timezones::id2tz($n)))	// no further timezones to check
			{
				$cache[$key] = false;
				error_log(__METHOD__.'('.array2string($data).') NO matching timezone found!');
				break;
			}
			if (self::tz2as($tz) == $data)
			{
				$cache[$key] = $tz;
				break;
			}
		}
		return $cache[$key];
	}

	/**
	 * Unpack timezone info from Sync
	 *
	 * copied from backend/ics.php
	 */
	static private function _getTZFromSyncBlob($data)
	{
		$tz = unpack(	"lbias/a64name/vdstendyear/vdstendmonth/vdstendday/vdstendweek/vdstendhour/vdstendminute/vdstendsecond/vdstendmillis/" .
						"lstdbias/a64name/vdststartyear/vdststartmonth/vdststartday/vdststartweek/vdststarthour/vdststartminute/vdststartsecond/vdststartmillis/" .
						"ldstbias", $data);

		return $tz;
	}

	/**
	 * Pack timezone info for Sync
	 *
	 * copied from backend/ics.php
	 */
	static private function _getSyncBlobFromTZ($tz)
	{
		$packed = pack("la64vvvvvvvv" . "la64vvvvvvvv" . "l",
				$tz["bias"], "", 0, $tz["dstendmonth"], $tz["dstendday"], $tz["dstendweek"], $tz["dstendhour"], $tz["dstendminute"], $tz["dstendsecond"], $tz["dstendmillis"],
				$tz["stdbias"], "", 0, $tz["dststartmonth"], $tz["dststartday"], $tz["dststartweek"], $tz["dststarthour"], $tz["dststartminute"], $tz["dststartsecond"], $tz["dststartmillis"],
				$tz["dstbias"]);

		return $packed;
	}
}

/**
 * Testcode for active sync timezone stuff
 *
$GLOBALS['egw_info'] = array(
	'flags' => array(
		'currentapp' => 'login'
	)
);
require_once('../../header.inc.php');

// get as timezone data for agive timezone
$tz = 'Europe/Zurich';//'America/New_York';//'Australia/Darwin';//'Europe/Berlin';
$ical = calendar_timezones::tz2id($tz,'component');
echo "<pre>".print_r($ical,true)."</pre>\n";
$ical_arr = calendar_activesync::ical2array($ical_tz=$ical);
echo "<pre>".print_r($ical_arr,true)."</pre>\n";
$as_tz = calendar_activesync::tz2as($tz);
echo "<pre>".print_r($as_tz,true)."</pre>\n";

// find matching timezone from as data
echo array2string(calendar_activesync::as2tz($as_tz));
*/