VoxEngine Dialogflow Voicebot example

voxengine_dialogflow_voicebot.js

// Voximplant's original Dialogflow integration template here: https://voximplant.com/blog/how-to-use-dialogflow-connector


require(Modules.AI)
require(Modules.Recorder)

const MAX_NO_INPUT_TIME = 10000             // Number of seconds of not hearing anything to wait before prompting the user again
const VOICEBOT_PHONE_NUMBER = 18576002939   // CallerID used to place a transfer call
let dialogflow, call, hangup = false       

// Fire the "NO_INPUT" event if there is no speech for MAX_NO_INPUT_TIME
class Timer {
  constructor() {
    this.expired = false
    this.noInputTimer = null
    }
    start(){
        this.noInputTimer = setTimeout(()=>{
            this.expired = true
            Logger.write("No_Input timer exceeded")
            dialogflow.sendQuery({event : {name: "NO_INPUT", language_code: "en"}})
        }, MAX_NO_INPUT_TIME || 15 * 1000)
        Logger.write("No_Input timer started")
    }
    stop(){
        this.expired = false
        clearTimeout(this.noInputTimer)
        Logger.write("No_Input cleared")
    }
  }

let timer = new Timer()
let waitForTone = false

// Inbound call processing
VoxEngine.addEventListener(AppEvents.CallAlerting, (e) => {
  call = e.call
  call.addEventListener(CallEvents.Connected, onCallConnected)
  call.addEventListener(CallEvents.Disconnected, VoxEngine.terminate)
  call.addEventListener(CallEvents.RecordStarted, e => { Logger.write("Recording URL: " + e.url)})
  call.handleTones(true)
  call.addEventListener(CallEvents.ToneReceived, onTone)
  call.answer()
})

function onCallConnected(e) {
  // Start recording
  call.record({stereo: true})

  // Create Dialogflow object
  dialogflow = AI.createDialogflow({
    lang: DialogflowLanguage.ENGLISH_US
  })
  dialogflow.addEventListener(AI.Events.DialogflowResponse, onDialogflowResponse)
    // Set a phone context with phone parameters
    // ToDo: error handling if returned parameters are null?
    phoneContext = {
        name: "phone",
        lifespanCount: 99,
        parameters: {
            caller_id: call.callerid(),
            called_number: call.number()
        }
    }  

    dialogflow.setQueryParameters({contexts: [phoneContext]})

    // Sending WELCOME event to let the agent says a welcome message
    dialogflow.sendQuery({event : {name: "WELCOME", language_code: "en"}})
    // Playback marker used for better user experience
    dialogflow.addMarker(-300)
    // Start sending media from Dialogflow to the call
    dialogflow.sendMediaTo(call)
    dialogflow.addEventListener(AI.Events.DialogflowPlaybackFinished, (e) => {
      // Dialogflow TTS playback finished. Hangup the call if hangup flag was set to true
      if (hangup) call.hangup()
      
      timer.start()
      waitForTone = false
    })
    dialogflow.addEventListener(AI.Events.DialogflowPlaybackStarted, (e) => {
      // Dialogflow TTS playback started
      timer.stop()
    })
    dialogflow.addEventListener(AI.Events.DialogflowPlaybackMarkerReached, (e) => {
      // Playback marker reached - start sending audio from the call to Dialogflow
      call.sendMediaTo(dialogflow)
    })

}

// Handle Dialogflow responses
function onDialogflowResponse(e) {
  // If DialogflowResponse with queryResult received - the call stops sending media to Dialogflow
  // in case of response with queryResult but without responseId we can continue sending media to dialogflow
  if (e.response.queryResult !== undefined && e.response.responseId === undefined) {
        if (!timer.expired && !waitForTone)
          call.sendMediaTo(dialogflow)
  } else if (e.response.queryResult !== undefined && e.response.responseId !== undefined) {
    // Do whatever required with e.response.queryResult or e.response.webhookStatus
    // If we need to hangup because end of conversation has been reached
    if (e.response.queryResult.diagnosticInfo !== undefined &&
            e.response.queryResult.diagnosticInfo.end_conversation == true) {
              hangup = true
            }

    // Telephony messages arrive in fulfillmentMessages array
    if (e.response.queryResult.fulfillmentMessages != undefined) {
      e.response.queryResult.fulfillmentMessages.forEach((msg) => {
          if (msg.platform !== undefined && msg.platform === "TELEPHONY") processTelephonyMessage(msg)
      })
    }
  }
}

// Process telephony messages from Dialogflow
function processTelephonyMessage(msg) {
  // Transfer call to msg.telephonyTransferCall.phoneNumber
  if (msg.telephonyTransferCall !== undefined) {
    dialogflow.stop()
    let newcall = VoxEngine.callPSTN(msg.telephonyTransferCall.phoneNumber, VOICEBOT_PHONE_NUMBER)
    VoxEngine.easyProcess(call, newcall)
  }
  // Synthesize speech from msg.telephonySynthesizeSpeech
  if (msg.telephonySynthesizeSpeech !== undefined) {
    // See the list of available TTS languages at https://voximplant.com/docs/references/voxengine/language
    if(msg.telephonySynthesizeSpeech.ssml !== undefined)
      call.say(msg.telephonySynthesizeSpeech.ssml, Language.Premium.AU_ENGLISH_MALE)
    else
      call.say(msg.telephonySynthesizeSpeech.text, Language.Premium.AU_ENGLISH_MALE)
  }
  // Play audio file located at msg.telephonyPlayAudio.audioUri
  if (msg.telephonyPlayAudio !== undefined) {
    // audioUri contains Google Storage URI (gs://), we need to transform it to URL (https://)
    let url = msg.telephonyPlayAudio.audioUri.replace("gs://", "https://storage.cloud.google.com/")
    call.startPlayback(url)
  }

  // ToDo: control needs to be handed back to Dialogflow for telephonySynthesizeSpeech 
  // . and telephonyPlayAudio. Some event handler will be needed to watch for playback completion
  // ToDo: make sure any playback or synthesized speech has finished playback first
  if (hangup) call.hangup()
}

function onTone(e){
  // ToDo: error handling - i.e. check to make sure Dialogflow is connected and running first, tone valuess
  // ToDo: aggregate multiple DTMF keys that are pressed in succession and send as a single string
  waitForTone = true
  dialogflow.sendQuery({event : {name: "DTMF", language_code: "en", parameters: { dtmf_digits: e.tone} }})
}