public function saveReservationDetails($check_in, $check_out, $no_of_nights, $customer_id)
 {
     //predefined check in and check out times
     $arr_dep_time = DB::table('HOTEL_INFO')->select('check_in', 'check_out')->first();
     $check_in_time = $arr_dep_time->check_in;
     $check_out_time = $arr_dep_time->check_out;
     //create a carbon timestamp instance merging the dates and time
     $check_in_datetime = Carbon::createFromTimestamp(strtotime($check_in . $check_in_time));
     $check_out_datetime = Carbon::createFromTimestamp(strtotime($check_out . $check_out_time));
     //creates a instance of the ROOM_RESERVATION model
     $reservation = new ROOM_RESERVATION();
     //store the details
     $reservation->check_in = $check_in_datetime;
     $reservation->check_out = $check_out_datetime;
     $reservation->adults = session('adults');
     $reservation->children = session('kids');
     $reservation->num_of_rooms = session('rooms');
     $reservation->num_of_nights = $no_of_nights;
     $reservation->total_amount = session('total_payable');
     $reservation->cus_id = $customer_id;
     $reservation->status = config('constants.RES_PENDING');
     if (Session::has('promo_code')) {
         $reservation->promo_code = session('promo_code');
     }
     $reservation->save();
     //get the last added reservation id
     $res_id = $reservation->room_reservation_id;
     return $res_id;
 }