Cloud Function for Scheduling Appointments with Dialogflow using Google Calendar

index.js

/*Copyright 2019 Google LLC.
SPDX-License-Identifier: Apache-2.0
*/

 'use strict';

 const functions = require('firebase-functions');
 const {google} = require('googleapis');
 const {WebhookClient} = require('dialogflow-fulfillment');
 
 // Enter your calendar ID below and service account JSON below
 const calendarId = "<Add your calendar ID here>"
 const serviceAccount = {<Add your service account details here>}; // Starts with {"type": "service_account",...
 
 // Set up Google Calendar Service account credentials
 const serviceAccountAuth = new google.auth.JWT({
   email: serviceAccount.client_email,
   key: serviceAccount.private_key,
   scopes: 'https://www.googleapis.com/auth/calendar'
 });
 
 const calendar = google.calendar('v3');
 process.env.DEBUG = 'dialogflow:*'; // enables lib debugging statements
 
 const timeZone = 'America/Los_Angeles';
 const timeZoneOffset = '-07:00';
 
 exports.dialogflowFirebaseFulfillment = functions.https.onRequest((request, response) => {
   const agent = new WebhookClient({ request, response });
   console.log("Parameters", agent.parameters);
   const appointment_type = agent.parameters.AppointmentType
   function makeAppointment (agent) {
     // Calculate appointment start and end datetimes (end = +1hr from start)
     //console.log("Parameters", agent.parameters.date);
     const dateTimeStart = new Date(Date.parse(agent.parameters.date.split('T')[0] + 'T' + agent.parameters.time.split('T')[1].split('-')[0] + timeZoneOffset));
     const dateTimeEnd = new Date(new Date(dateTimeStart).setHours(dateTimeStart.getHours() + 1));
     const appointmentTimeString = dateTimeStart.toLocaleString(
       'en-US',
       { month: 'long', day: 'numeric', hour: 'numeric', timeZone: timeZone }
     );
 
     // Check the availibility of the time, and make an appointment if there is time on the calendar
     return createCalendarEvent(dateTimeStart, dateTimeEnd, appointment_type).then(() => {
       agent.add(`Ok, let me see if we can fit you in. ${appointmentTimeString} is fine!.`);
     }).catch(() => {
       agent.add(`I'm sorry, there are no slots available for ${appointmentTimeString}.`);
     });
   }
 
   let intentMap = new Map();
   intentMap.set('Schedule Appointment', makeAppointment);
   agent.handleRequest(intentMap);
 });
 
 
 
 function createCalendarEvent (dateTimeStart, dateTimeEnd, appointment_type) {
   return new Promise((resolve, reject) => {
     calendar.events.list({
       auth: serviceAccountAuth, // List events for time period
       calendarId: calendarId,
       timeMin: dateTimeStart.toISOString(),
       timeMax: dateTimeEnd.toISOString()
     }, (err, calendarResponse) => {
       // Check if there is a event already on the Calendar
       if (err || calendarResponse.data.items.length > 0) {
         reject(err || new Error('Requested time conflicts with another appointment'));
       } else {
         // Create event for the requested time period
         calendar.events.insert({ auth: serviceAccountAuth,
           calendarId: calendarId,
           resource: {summary: appointment_type +' Appointment', description: appointment_type,
             start: {dateTime: dateTimeStart},
             end: {dateTime: dateTimeEnd}}
         }, (err, event) => {
           err ? reject(err) : resolve(event);
         }
         );
       }
     });
   });
 }

package.json

{
  "name": "dialogflowFirebaseFulfillment",
  "description": "Dialogflow fulfillment for the bike shop sample",
  "version": "0.0.1",
  "private": true,
  "license": "Apache Version 2.0",
  "author": "Google Inc.",
  "engines": {
    "node": "6"
  },
  "scripts": {
    "lint": "semistandard --fix \"**/*.js\"",
    "start": "firebase deploy --only functions",
    "deploy": "firebase deploy --only functions"
  },
  "dependencies": {
    "firebase-functions": "2.0.2",
    "firebase-admin": "^5.13.1",
    "actions-on-google": "2.2.0", 
    "googleapis": "^27.0.0",
    "dialogflow-fulfillment": "0.5.0"
  }
}