class IsSeatBookedUseCase(
  private val ticketService: TicketService
) {

  fun execute(request: Request): Observable<Result<Boolean>> {
    return ticketService.isSeatAlloted(request.seatNumber)
      .concatMap { it.toDataObservable() }
      .concatMap {
        when (it) {
          false -> it.toResult().toObservable()
          true -> SEAT_ALREADY_BOOKED_ERROR.toResult<Boolean>().toObservable()
        }
      }
      .onErrorReturn { it.toErrorResult() }
  }

  class Request(
    val seatNumber: String
  )

  companion object {
    val SEAT_ALREADY_BOOKED_ERROR = Error(103, "This seat is already booked")
  }
}