CEventCalendar::ReturnICal

function ReturnICal($arParams)
{
	$calendarId = $arParams['calendarId'];
	$userId = $arParams['userId'];
	$sign = $arParams['sign'];
	$arParams['ownerType'] = mb_strtoupper($arParams['ownerType']);

	$ownerType = (isset($arParams['ownerType']) && in_array($arParams['ownerType'], array('GROUP', 'USER'))) ? $arParams['ownerType'] : false;
	$ownerId = isset($arParams['ownerId']) ? intval($arParams['ownerId']) : $this->ownerId;
	$iblockId = (isset($arParams['iblockId']) && intval($arParams['iblockId']) > 0) ? intval($arParams['iblockId']) : $this->iblockId;

	$GLOBALS['APPLICATION']->RestartBuffer();
	if (!$this->CheckSign($sign, $userId, $calendarId))
		return CEventCalendar::ThrowError(GetMessage('EC_ACCESS_DENIED'));

	$this->bCurUserOwner = $ownerType != 'USER' || $ownerId == $userId;
	$privateStatus = CECCalendar::GetPrivateStatus($iblockId, $calendarId, $ownerType);

	if (!$this->arCalenderIndex[$calendarId]) // For get events check
		$this->arCalenderIndex[$calendarId] = array('PRIVATE_STATUS' => $privateStatus);

	if ($this->bCache)
	{
		$cache = new CPHPCache;
		$cacheId = serialize(array($iblockId, $calendarId));
		$cachePath = $this->cachePath.'ical/';

		if ($cache->InitCache($this->cacheTime, $cacheId, $cachePath))
		{
			$res = $cache->GetVars();
			$iCalEvents = $res['iCalEvents'];
		}
	}

	if (!$this->bCache || empty($iCalEvents))
	{
		// Get iblock permissions
		$arGroups = CUser::GetUserGroup($userId);
		$arGroupPerm = CIBlock::GetGroupPermissions($iblockId);
		$maxPerm = 'D';
		foreach($arGroupPerm as $k => $perm)
			if (in_array($k, $arGroups) && $perm > $maxPerm)
				$maxPerm = $perm;

		// Check permissions
		if (($maxPerm < 'R') // iblock
			||
			(
				$ownerType == 'USER' &&  // socnet: USER
				(
					!CSocNetFeatures::IsActiveFeature(SONET_ENTITY_USER, $ownerId, "calendar")
					||
					!CSocNetFeaturesPerms::CanPerformOperation($userId, SONET_ENTITY_USER, $ownerId, "calendar", 'view')
				)
			)
			||
			(
				$ownerType == 'GROUP' && // socnet: GROUP
				(
					!CSocNetFeatures::IsActiveFeature(SONET_ENTITY_GROUP, $ownerId, "calendar")
					||
					!CSocNetFeaturesPerms::CanPerformOperation($userId, SONET_ENTITY_GROUP, $ownerId, "calendar", 'view')
				)
			)
		)
			return CEventCalendar::ThrowError(GetMessage('EC_ACCESS_DENIED'));

		// === Fetch events from calendar ===
		$r = CIBlockSection::GetList(Array(), Array("ID"=>$calendarId, "CHECK_PERMISSIONS"=>"N"));
		if(!($arCal = $r->Fetch()))
			return CEventCalendar::ThrowError('INCORRECT CALENDAR ID');
		$arExport = CECCalendar::GetExportParams($iblockId, $calendarId, $ownerType, $ownerId); // LINK is incorrect, but we dont need for LINK...

		if (!$arExport['ALLOW']) // Calendar is not accessible for export
			return CEventCalendar::ThrowError(GetMessage('EC_ACCESS_DENIED'));
		if ($arExport['SET'] == 'all') // Get all events
		{
			$bLoadAll =true;
			$from_limit = $to_limit = false;
		}
		else // Get events from some period
		{
			$bLoadAll = false;
			if ($arExport['SET'] == '3_9') // 3 month ago and 9 future
			{
				$ago = 3;
				$future = 9;
			}
			else// if ($arExport['SET'] == '6_12')
			{
				$ago = 6;
				$future = 12;
			}
			$from_limit = date(getDateFormat(false), mktime(0, 0, 0, date("m") - $ago, 1, date("Y")));
			$to_limit = date(getDateFormat(false), mktime(0, 0, 0, date("m") + $future + 1, 1, date("Y")));
		}

		$arItems = $this->GetEvents(array(
			'ownerType' => $ownerType,
			'ownerId' => $ownerId,
			'iblockId' => $iblockId,
			'sectionId' => $calendarId,
			'fromLimit' => $from_limit,
			'toLimit' => $to_limit,
			'bLoadAll' => $bLoadAll,
			'arCalendarIds' => false,
			'forExport' => true
		));

		$iCalEvents = $this->FormatICal($arCal, $arItems);

		if ($this->bCache) // cache data
		{
			$cache->StartDataCache($this->cacheTime, $cacheId, $cachePath);
			$cache->EndDataCache(array("iCalEvents" => $iCalEvents));
		}
	}
	$this->ShowICalHeaders();
	echo $iCalEvents;
	exit();
}