/**
  *
  * @param int $movie_id
  * @param string $date
  * @param string|\DbTableFunction $order
  * @return Showtime[]
  */
 public function getShowtimes($movie_id = null, $date = null, $order = null)
 {
     $showtimesWhere = new \DbTableWhere();
     if ($movie_id) {
         $showtimesWhere->where('movie_id', $movie_id);
     }
     if ($date) {
         $showtimesWhere->where('show_date', $date);
     }
     if (!$order) {
         $order = new \DbTableFunction('type,show_date,show_time');
     }
     $showtimesWhere->setOrderBy($order)->where('theatre_id', $this->_data['id']);
     return Showtime::manager()->getEntitiesWhere($showtimesWhere);
 }