feat(templates): add voice-queue template

[jonedavis]

Description

Add template: voice-queue
Template Description: A simple call queuing system. Place the inbound caller into a queue with hold music while waiting for the intended recipient to answer.

Checklist

• I ran npm test locally and it passed without errors.
• I acknowledge that all my contributions will be made under the project's license.

Related issues

None

[philnash]

Hey Jon, thanks for this, top idea for a function.

I am worried about the race condition within the enqueue function. Also, the test for that function doesn't test that the outbound call is placed. Could you take a look at those bits please?

[philnash]

Should name this project voice-queue not example (or change to cd into example).

[philnash]

Returning a string here should be sufficient to trigger a 500 error from the Function. Runtime, as far as I know, won't do anything special with this as an object.

[philnash]

Is there a chance of a race condition here between creating the call and the function ending, as we don't wait for this asynchronous call to complete before calling back?

Also, should the function just fail if there's no From?

So could this all be?

exports.handler = async function (context, event, callback) {
  const { CallSid, From } = event;

  if (!From) {
    callback("Calls must have a `From`.");
  } else {
    const client = context.getTwilioClient();
    const path = `https://${context.DOMAIN_NAME}`;
    // Make an outbound call to your phone number to connect the two legs.
    // Use the inbound CallSid as the unique identifier for the queue.
    try {
      await client.calls.create({
        to: context.YOUR_PHONE_NUMBER,
        from: context.TWILIO_PHONE_NUMBER,
        url: `${path}/dial-queue?fromCallSid=${CallSid}&from=${From}`
      });
      // Enqueue the inbound caller.
      // waitUrl points to an endpoint to <Play> the mp3 set in the env variables.
      const response = new Twilio.twiml.VoiceResponse();
      response.enqueue({
        waitUrl: '/hold-music'
      }, CallSid);
      callback(null, response);
    } catch (error) {
      callback(error);
    }
  }
}; 

[philnash]

We're missing a From here, so the function never tests whether a call is placed. Check out other functions, like the airtable one, to see how to mock getTwilioClient on the context.