public ActionResult <BusDriver> Add(BusDriverDTO busDriverDTO)
        {
            var existingBusDriver = _busDriverRepository.GetBusDriverByDayIdBusColorAndTimeOfDay(
                busDriverDTO.DayId, busDriverDTO.BusColor, busDriverDTO.TimeOfDay);

            if (existingBusDriver != null)
            {
                return(BadRequest("Er is al een chauffeur die op die dag rijdt!"));
            }

            Day day = _customDayRepository.GetById(busDriverDTO.DayId);

            if (day == null)
            {
                day = _dayRepository.GetById(busDriverDTO.DayId);

                if (day == null)
                {
                    return(NotFound());
                }
            }

            var driver = _driverRepository.GetById(busDriverDTO.DriverId);

            if (driver == null)
            {
                return(NotFound());
            }

            try
            {
                BusDriver newBusDriver = new BusDriver(day, driver, busDriverDTO.TimeOfDay, busDriverDTO.BusColor);

                _busDriverRepository.Add(newBusDriver);
                _busDriverRepository.SaveChanges();

                return(Ok(newBusDriver));
            }
            catch (Exception ex)
            {
                return(BadRequest(ex.Message));
            }
        }