Appointment Scheduler in Fulfillment

appointment.js

"use strict";

const { WebhookClient, Payload } = require("dialogflow-fulfillment");
const functions = require("firebase-functions");

const { google } = require('googleapis');
const calendarId = "88888888888888@group.calendar.google.com";
const serviceAccount = {
  "type": "service_account",
  "project_id": "line-bot",
  "private_key_id": "xxxxx",
  "private_key": "xxxxx",
  "client_email": "dialogflow-appointment@line-bot.iam.gserviceaccount.com",
  "client_id": "88888888888",
  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
  "token_uri": "https://oauth2.googleapis.com/token",
  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/dialogflow-appointment%40line-bot.iam.gserviceaccount.com"
};
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:debug";

exports.dialogflowFirebaseFulfillment = functions.https.onRequest((request, response) => {
  const agent = new WebhookClient({ request, response });
  function confirmAppointment(agent) {
    const dateTimeStart = new Date(
      Date.parse(agent.parameters.date.split('T')[0] + 'T' + agent.parameters.time.split('T')[1])
    );
    const appointmentTimeString = dateTimeStart.toLocaleString(
      'en-US',
      { weekday: 'short', day: 'numeric', month: 'short', hour: 'numeric', minute: 'numeric', timeZone: 'Asia/Bangkok' }
    );
    return agent.add(`ยืนยันนัด ` + appointmentTimeString + ` ไหมคะ?`);
  }

  function makeAppointment(agent) {
    const appointment_type = agent.parameters.AppointmentType;
    const dateTimeStart = new Date(
      Date.parse(agent.parameters.date.split('T')[0] + 'T' + agent.parameters.time.split('T')[1])
    );
    // Calculate appointment start and end datetimes (end = +1hr from start)
    const dateTimeEnd = new Date(new Date(dateTimeStart).setHours(dateTimeStart.getHours() + 1));

    const appointmentTimeString = dateTimeStart.toLocaleString(
      'en-US',
      { weekday: 'short', day: 'numeric', month: 'short', hour: 'numeric', minute: 'numeric', timeZone: 'Asia/Bangkok' }
    );

    // 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(`ลงตาราง ${appointmentTimeString} ให้เรียบร้อยแล้วจ้า`);
    }).catch(() => {
      agent.add(`ขออภัยค่ะ ช่วงเวลานี้ ${appointmentTimeString} ไม่ว่างนะคะ`);
    });
  }

  let intentMap = new Map();
  intentMap.set('Appointment', confirmAppointment);
  intentMap.set('Appointment - yes', 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) => {
          if (err !== null) {
            reject(err);
          } else {
            resolve(event);
          }
        });
      }
    });
  });
}