/// <summary>
/// Receive an SMS message.
/// </summary>
public async Task <APIGatewayProxyResponse> ReceiveSmsAsync(APIGatewayProxyRequest request, ILambdaContext context)
{
var logger = context.Logger;
logger.LogLine("Receiving SMS");
// API Gateway isn't nice like MVC. We need to parse the form ourselves.
var formValues = GetFormValues(request);
if (!TwilioRequestValidator.IsValidPostRequest(request, formValues))
{
throw new PreTalkSurveyException("Unable to validate signature on request");
}
// Get the SMS message from the form and make sure it comes from the expected phone number.
var sms = GetSmsMessage(formValues);
if (sms.To != ServerlessConfig.TwilioPhoneNumber)
{
throw new PreTalkSurveyException("Invalid incoming phone number");
}
// figure out what to do with the incoming message.
try
{
var surveyResponse = await _DataAccess.GetSurveyResponseAsync(Sanitizer.HashPhoneNumber(sms.From)).ConfigureAwait(false);
if (surveyResponse == null)
{
// if we've never seen this phone number before, it's the start of a new survey
logger.LogLine($"New phone number {Sanitizer.MaskPhoneNumber(sms.From)}, starting new survey");
await StartNewSurveyAsync(sms.From, logger).ConfigureAwait(false);
}
else if (!string.IsNullOrEmpty(surveyResponse.TaskToken))
{
if (EqualsIgnoreCase(sms.Body, "hello") || EqualsIgnoreCase(sms.Body, "start"))
{
// if they send "hello" or "start", terminate the workflow and start it again
logger.LogLine($"Restarting workflow for {Sanitizer.MaskPhoneNumber(sms.From)}");
await FailWaitForResponseAsync(surveyResponse.TaskToken).ConfigureAwait(false);
await StartNewSurveyAsync(sms.From, logger).ConfigureAwait(false);
}
// if there's a task token, we need to advance the state machine
var taskToken = surveyResponse.TaskToken;
var state = surveyResponse.SavedState;
// evaluate the answer to the question
var questionResponse = Survey.EvaluateResponseToQuestion(state.Question, sms.Body.Trim());
state.IsValidResponse = questionResponse.IsValidResponse;
logger.LogLine($"Evaluated response to question \"{state.Question}\". Response \"{sms.Body}\" from {Sanitizer.MaskPhoneNumber(sms.From)}. IsValidResponse={questionResponse.IsValidResponse};StandardizedResponse={questionResponse.StandardizedResponse}");
// clear the token and the saved state -- we want to make sure these values aren't reused
// so we save before completing the activity.
logger.LogLine($"Clearing state for {Sanitizer.MaskPhoneNumber(sms.From)}");
surveyResponse.TaskToken = "";
surveyResponse.SavedState = null;
// store the answer
if (state.IsValidResponse)
{
surveyResponse.Responses[questionResponse.Question] = questionResponse.StandardizedResponse;
}
await _DataAccess.SaveSurveyResponeAsync(surveyResponse);
// store the answer to the question
// advance the state machine
logger.LogLine($"Completing response for task token {taskToken}");
await CompleteWaitForResponseAsync(taskToken, state).ConfigureAwait(false);
}
else
{
// they must have previously completed the survey - start again
logger.LogLine($"Restarting workflow for {Sanitizer.MaskPhoneNumber(sms.From)} - previously completed");
await StartNewSurveyAsync(sms.From, logger).ConfigureAwait(false);
}
}
catch
{
logger.LogLine($"Sending snarky error message to {Sanitizer.MaskPhoneNumber(sms.From)}");
await SendErrorMessage(sms.From).ConfigureAwait(false);
throw;
}
logger.LogLine("Returning OK response");
return(GetOkResponse());
}
public async Task <State> ErrorQuestionXAsync(int questionNumber, State state, ILambdaContext context)
{
await SendSms(state.PhoneNumber, Survey.GetErrorMessage(questionNumber));
return(state);
}