<?php
/**
 * Copyright (c) 2012 Georg Ehrke <ownclouddev@georgswebsite.de>
 * This file is licensed under the Affero General Public License version 3 or
 * later.
 * See the COPYING-README file.
 */
/**
 * This class manages shared calendars
 */
class OC_Calendar_Share{
	const CALENDAR = 'calendar';
	const EVENT = 'event';
	/**
	 * @brief: returns informations about all calendar or events which users are sharing with the user - userid
	 * @param: string $userid - id of the user
	 * @param: string $type - use const self::CALENDAR or self::EVENT
	 * @return: array $return - information about calendars
	 */
	public static function allSharedwithuser($userid, $type, $active=null, $permission=null){
		$format = OC_Share_Backend_Calendar::FORMAT_CALENDAR;
		if ($type == self::EVENT) {
			$format = OC_Share_Backend_Event::FORMAT_EVENT;
		}
		$return = OCP\Share::getItemsSharedWith($type,
			$format,
			array(
				'active' => $active,
				'permissions' => $permission,
			));
		return $return;
	}
	/**
	 * @brief: returns all users a calendar / event is shared with
	 * @param: integer id - id of the calendar / event
	 * @param: string $type - use const self::CALENDAR or self::EVENT
	 * @return: array $users - information about users a calendar / event is shared with
	 */
	public static function allUsersSharedwith($id, $type){
		$stmt = OCP\DB::prepare('SELECT * FROM `*PREFIX*calendar_share_' . $type . '` WHERE `' . $type . 'id` = ? ORDER BY `share`');
		$result = $stmt->execute(array($id));
		$users = array();
		while( $row = $result->fetchRow()){
			$users[] = $row;
		}
		return $users;
	}
	/**
	 * @brief: shares a calendar / event
	 * @param: string $owner - userid of the owner
	 * @param: string $share - userid (if $sharetype == user) / groupid (if $sharetype == group) / token (if $sharetype == public)
	 * @param: string $sharetype - type of sharing (can be: user/group/public)
	 * @param: string $id - id of the calendar / event
	 * @param: string $type - use const self::CALENDAR or self::EVENT
	 * @return (mixed) - token (if $sharetype == public) / bool (if $sharetype != public)
	 */
	public static function share($owner, $share, $sharetype, $id, $type){
		if(self::is_already_shared($owner, $share, $sharetype, $id, $type)){
			return false;
		}
		switch($sharetype){
			case 'user':
			case 'group':
			case 'public':
				break;
			default:
				return false;
		}
		if($sharetype == 'public'){
			$share = self::generate_token($id, $type);
		}
		$stmt = OCP\DB::prepare('INSERT INTO `*PREFIX*calendar_share_' . $type . '` (`owner`,`share`,`sharetype`,`' . $type . 'id`,`permissions`' . (($type == self::CALENDAR)?',`active`':'') . ') VALUES(?,?,?,?,0' . (($type == self::CALENDAR)?', 1':'') . ')' );
		$result = $stmt->execute(array($owner,$share,$sharetype,$id));
		if($sharetype == 'public'){
			return $share;
		}else{
			return true;
		}
	}
	/**
	 * @brief: stops sharing a calendar / event
	 * @param: string $owner - userid of the owner
	 * @param: string $share - userid (if $sharetype == user) / groupid (if $sharetype == group) / token (if $sharetype == public)
	 * @param: string $sharetype - type of sharing (can be: user/group/public)
	 * @param: string $id - id of the calendar / event
	 * @param: string $type - use const self::CALENDAR or self::EVENT
	 * @return boolean
	 */
	public static function unshare($owner, $share, $sharetype, $id, $type){
		$stmt = OCP\DB::prepare('DELETE FROM `*PREFIX*calendar_share_' . $type . '` WHERE `owner` = ? ' . (($sharetype != 'public')?'AND `share` = ?':'') . ' AND `sharetype` = ? AND `' . $type . 'id` = ?');
		if($sharetype != 'public'){
			$stmt->execute(array($owner,$share,$sharetype,$id));
		}else{
			$stmt->execute(array($owner,$sharetype,$id));
		}
		return true;
	}
	/**
	 * @brief: changes the permission for a calendar / event
	 * @param: string $share - userid (if $sharetype == user) / groupid (if $sharetype == group) / token (if $sharetype == public)
	 * @param: string $sharetype - type of sharing (can be: user/group/public)
	 * @param: string $id - id of the calendar / event
	 * @param: integer $permission - permission of user the calendar / event is shared with (if $sharetype == public then $permission = 0)
	 * @param: string $type - use const self::CALENDAR or self::EVENT
	 * @return boolean
	 */
	public static function changepermission($share, $sharetype, $id, $permission, $type){
		if($sharetype == 'public' && $permission == 1){
			$permission = 0;
		}
		$stmt = OCP\DB::prepare('UPDATE `*PREFIX*calendar_share_' . $type . '` SET `permissions` = ? WHERE `share` = ? AND `sharetype` = ? AND `' . $type . 'id` = ?');
		$stmt->execute(array($permission, $share, $sharetype, $id));
		return true;
	}
	/**
	 * @brief: generates a token for public calendars / events
	 * @return: string $token
	 */
	private static function generate_token($id, $type){
		$uniqid = uniqid();
		if($type == self::CALENDAR){
			$events = OC_Calendar_Object::all($id);
			$string = '';
			foreach($events as $event){
				$string .= $event['calendardata'];
			}
		}else{
			$string = OC_Calendar_Object::find($id);
		}
		$string = sha1($string['calendardata']);
		$id = sha1($id);
		$array = array($uniqid,$string,$id);
		shuffle($array);
		$string = implode('', $array);
		$token = md5($string);
		return substr($token, rand(0,16), 15);
	}
	/**
	 * @brief: checks if it is already shared
	 * @param: string $owner - userid of the owner
	 * @param: string $share - userid (if $sharetype == user) / groupid (if $sharetype == group) / token (if $sharetype == public)
	 * @param: string $sharetype - type of sharing (can be: user/group/public)
	 * @param: string $id - id of the calendar / event
	 * @param: string $type - use const self::CALENDAR or self::EVENT
	 * @return boolean
	 */
	public static function is_already_shared($owner, $share, $sharetype, $id, $type){
		$stmt = OCP\DB::prepare('SELECT * FROM `*PREFIX*calendar_share_' . $type . '` WHERE `owner` = ? AND `share` = ? AND `sharetype` = ? AND `' . $type . 'id` = ?');
		$result = $stmt->execute(array($owner, $share, $sharetype, $id));
		if($result->numRows() > 0){
			return true;
		}
		return false;
	}
	private static function group_sql($groups){
		$group_where = '';
		$i = 0;
		foreach($groups as $group){
			$group_where .= ' OR ';
			$group_where .= ' (`share` = \'' . $group . '\' AND `sharetype` = \'group\') ';
			$i++;
		}
		return $group_where;
	}
	private static function permission_sql($permission = null){
		$permission_where = '';
		if(!is_null($permission)){
			$permission_where = ' AND `permissions` = ';
			$permission_where .= ($permission=='rw')?"'1'":"'0'";
		}
		return $permission_where;
	}
	private static function active_sql($active = null){
		$active_where = '';
		if(!is_null($active)){
			$active_where = 'AND `active` = ';
			$active_where .= (!is_null($active) && $active)?'1':'0';
		}
		return $active_where;
	}
	/**
	 * @brief: checks the permission for editing an event
	 * @param: string $share - userid (if $sharetype == user) / groupid (if $sharetype == group) / token (if $sharetype == public)
	 * @param: string $id - id of the calendar / event
	 * @param: string $type - use const self::CALENDAR or self::EVENT
	 * @return boolean
	 */
	public static function is_editing_allowed($share, $id, $type){
		$group_where = self::group_sql(OC_Group::getUserGroups($share));
		$permission_where = self::permission_sql('rw');
		$stmt = OCP\DB::prepare('SELECT * FROM `*PREFIX*calendar_share_' . $type . '` WHERE ((`share` = ? AND `sharetype` = \'user\') ' . $group_where . ') ' . $permission_where);
		$result = $stmt->execute(array($share));
		if($result->numRows() == 1){
			return true;
		}
		if($type == self::EVENT){
			$event = OC_Calendar_App::getEventObject($id, false, false);
			return self::is_editing_allowed($share, $event['calendarid'], self::CALENDAR);
		}
		return false;
	}
	/**
	 * @brief: checks the access of 
	 * @param: string $share - userid (if $sharetype == user) / groupid (if $sharetype == group) / token (if $sharetype == public)
	 * @param: string $id - id of the calendar / event
	 * @param: string $type - use const self::CALENDAR or self::EVENT
	 * @return boolean
	 */
	public static function check_access($share, $id, $type){
		$group_where = self::group_sql(OC_Group::getUserGroups($share));
		$stmt = OCP\DB::prepare('SELECT * FROM `*PREFIX*calendar_share_' . $type . '` WHERE (`' . $type . 'id` = ? AND (`share` = ? AND `sharetype` = \'user\') ' . $group_where . ')');
		$result = $stmt->execute(array($id,$share));
		$rows =  $result->numRows();
		if($rows > 0){
			return true;
		}elseif($type == self::EVENT){
			$event = OC_Calendar_App::getEventObject($id, false, false);
			return self::check_access($share, $event['calendarid'], self::CALENDAR);
		}else{
			return false;
		}
	}
        /**
         * @brief: returns the calendardata of an event or a calendar
         * @param: string $token - token which should be searched
         * @return: mixed - bool if false, array with type and id if true
         */
        public static function getElementByToken($token){
            $stmt_calendar = OCP\DB::prepare('SELECT * FROM `*PREFIX*calendar_share_' . OC_Calendar_Share::CALENDAR . '` WHERE `sharetype` = \'public\' AND `share` = ?');
            $result_calendar = $stmt_calendar->execute(array($token));
            $stmt_event = OCP\DB::prepare('SELECT * FROM `*PREFIX*calendar_share_' . OC_Calendar_Share::EVENT . '` WHERE `sharetype` = \'public\' AND `share` = ?');
            $result_event = $stmt_event->execute(array($token));
            $return = array();
            if($result_calendar->numRows() == 0 && $result_event->numRows() == 0){
                return false;
            }elseif($result_calendar->numRows() != 0){
                $return ['type'] = 'calendar';
                $calendar = $result_calendar->fetchRow();
                $return ['id'] = $calendar['calendarid'];
            }else{
                $return ['type'] = 'event';
                $event = $result_event->fetchRow();
                $return ['id'] = $event['eventid'];
            }
			return $return;
        }
		
		/**
		 * @brief sets the active status of the calendar
		 * @param string 
		 */
		public static function set_active($share, $id, $active){
			$stmt = OCP\DB::prepare("UPDATE `*PREFIX*calendar_share_calendar` SET `active` = ? WHERE `share` = ? AND `sharetype` = 'user' AND `calendarid` = ?");
			$stmt->execute(array($active, $share, $id));
		}

		/**
		 * @brief deletes all shared calendars / events after a user was deleted
		 * @param string $userid
		 * @return boolean
		 */
		public static function post_userdelete($userid){			
			$stmt = OCP\DB::prepare('DELETE FROM `*PREFIX*calendar_share_calendar` WHERE `owner` = ?');
			$stmt->execute(array($userid));
			$stmt = OCP\DB::prepare('DELETE FROM `*PREFIX*calendar_share_event` WHERE `owner` = ?');
			$stmt->execute(array($userid));
			$stmt = OCP\DB::prepare("DELETE FROM `*PREFIX*calendar_share_calendar` WHERE `share` = ? AND `sharetype` = 'user'");
			$stmt->execute(array($userid));
			$stmt = OCP\DB::prepare("DELETE FROM `*PREFIX*calendar_share_event` WHERE `share` = ? AND `sharetype` = 'user'");
			$stmt->execute(array($userid));
			return true;
		}
		
		/**
		 * @brief deletes all shared events of a calendar
		 * @param integer $calid
		 * @return boolean
		 */
		public static function post_caldelete($calid){
			$stmt = OCP\DB::prepare('DELETE FROM `*PREFIX*calendar_share_calendar` WHERE `calendarid` = ?');
			$stmt->execute(array($calid));
			return true;
		}
		
		/**
		 * @brief deletes all shares of an event
		 * @param integer $eventid
		 * @return boolean
		 */
		public static function post_eventdelete($eventid){
			$stmt = OCP\DB::prepare('DELETE FROM `*PREFIX*calendar_share_event` WHERE `eventid` = ?');
			$stmt->execute(array($eventid));
			return true;
		}
}