ActStepAsync.cs

private async Task<DialogTurnResult> ActStepAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
{
    if (!_luisRecognizer.IsConfigured)
    {
        // LUIS is not configured, we just run the BookingDialog path with an empty BookingDetailsInstance.
        return await stepContext.BeginDialogAsync(nameof(AppointmentBookingDialog), new AppointmentDetails(), cancellationToken);
    }

    // Call LUIS and gather any potential booking details. (Note the TurnContext has the response to the prompt.)
    var luisResult = await _luisRecognizer.RecognizeAsync<DoctorBooking>(stepContext.Context, cancellationToken);
    switch (luisResult.TopIntent().intent)
    {
        case DoctorBooking.Intent.BookAppointment:
            var validDoctor = await ValidateDoctors(stepContext.Context, luisResult, cancellationToken);
            if (!validDoctor)
            {
                return await stepContext.ReplaceDialogAsync(InitialDialogId, "Doctor Peter, Susan and Kathy are available?", cancellationToken);
            }

            // Initialize BookingDetails with any entities we may have found in the response.
            var bookingDetails = new AppointmentDetails()
            {
                // Get destination and origin from the composite entities arrays.
                Doctor = luisResult.Doctor,
                AppointmenDate = luisResult.AppointmentDate,
            };

            // Run the AppointmentBookingDialog giving it whatever details we have from the LUIS call, it will fill out the remainder.
            return await stepContext.BeginDialogAsync(nameof(AppointmentBookingDialog), bookingDetails, cancellationToken);

        case DoctorBooking.Intent.GetAvailableDoctors:
            // We haven't implemented the GetAvailableDoctorsDialog so we just display a mock message.
            var getAvailableDoctorsMessageText = "Doctor Kathy, Doctor Peter are available today";
            var getAvailableDoctorsMessage = MessageFactory.Text(getAvailableDoctorsMessageText, getAvailableDoctorsMessageText, InputHints.IgnoringInput);
            await stepContext.Context.SendActivityAsync(getAvailableDoctorsMessage, cancellationToken);
            break;

        default:
            // Catch all for unhandled intents
            var didntUnderstandMessageText = $"Sorry, I didn't get that. Please try asking in a different way (intent was {luisResult.TopIntent().intent})";
            var didntUnderstandMessage = MessageFactory.Text(didntUnderstandMessageText, didntUnderstandMessageText, InputHints.IgnoringInput);
            await stepContext.Context.SendActivityAsync(didntUnderstandMessage, cancellationToken);
            break;
    }

    return await stepContext.NextAsync(null, cancellationToken);
}