// make assumption here that user can request a specific room number
public async Task <IRoom> BookRoomByNumberAsync(IReservation reservation, int roomNum)
{
var room = await _hotelRepository.GetRoomByNumber(roomNum);
if (!room.IsRoomAvailableForBooking(reservation))
{
throw new Exception($"Room {roomNum} is not available for booking");
}
await _hotelRepository.AddBookedRoom(reservation, roomNum);
return(room);
}