How to authenticate Google Calendar API from Dialogflow Fulfillment using OAuth2 Client? - node.js

Question

I am trying to build Google Calendar assistant chatbot with Dialogflow fulfillment hosted in GCP using node.js, dialogflow-fulfillment, and googleapis client libraries. I have a problem to create an authentication method using OAuth Client ID. The idea is when the user adds the bot in Google Chat the bot should greet him/her and ask the user for permission for the defined scopes (to create events in one's Google Calendar in this case). What I currently managed to do is to send the user a link where the one will see the scopes, approve those and a code will be generated, but then this code should be passed back to the function to get the token and set the credentials.
link sent to the user
generated code
code passed to the user
Is there a way to get this code automatically and authenticate the user?
My code looks like this (it's a bit messy because of all the tests that I made):
const {google} = require('googleapis');
const {WebhookClient} = require('dialogflow-fulfillment');
const credentials = {"installed":{"client_id":"618408396856-vrd3it4s4nk19tlo7qrnbb51a9f8bq6t.apps.googleusercontent.com","project_id":"pg-xc-n-app-577847","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_secret":"d_qDDlFVBtllcotgn2xvc00N","redirect_uris":["urn:ietf:wg:oauth:2.0:oob","http://localhost"]}};
//setting authentication details
const SCOPES = [
'https://www.googleapis.com/auth/calendar.events',
'https://www.googleapis.com/auth/spreadsheets'
];
const {client_secret, client_id, redirect_uris} = credentials.installed;
const authentication = new google.auth.OAuth2(
client_id,
client_secret,
redirect_uris[0]
);
const url = authentication.generateAuthUrl({
access_type: 'offline',
scope: SCOPES
});
const calendarId = 'primary';
const calendar = google.calendar('v3');
process.env.DEBUG = 'dialogflow:*'; // enables lib debugging statements
exports.meetingRoomFulfillment = function meetingRoomFulfillment(req, res) {
const agent = new WebhookClient({ request: req, response: res });
console.log(`Intent ${((req.body.queryResult || {}).intent || {}).displayName}`);
console.log(`Dialogflow Request body`, JSON.stringify(req.body));
if (req.body.queryResult === undefined || req.body.queryResult.intent === undefined || req.body.queryResult.intent.displayName === undefined) {
console.log(`Missing intent so cancelling fulfillment`);
res.send({});
return;
}
function authenticate(agent){
agent.add(`To authenticate this app please visit the following url: ${url}`);
}
function authenticationCode(agent){
const code = agent.parameters.authenticationCode;
console.log('The code: ' + code);
authentication.getToken(code, (err, token) => {
if (err) return console.error('Error retrieving access token', err);
authentication.setCredentials(token);
retrievedToken = token;
console.log(retrievedToken);
});
agent.add('Successfully authenticated!');
}
function makeAppointment (agent) {
const dateTimeStart = new Date(agent.parameters.date.split('T')[0] + 'T' + agent.parameters.time.split('T')[1]);
const dateTimeEnd = new Date(new Date(dateTimeStart).setHours(dateTimeStart.getHours() + 1));
const appointmentTimeString = dateTimeStart.toLocaleString();
const eventDescription = agent.parameters.text;
// Check the availibility of the time, and make an appointment if there is time on the calendar
return createCalendarEvent(dateTimeStart, dateTimeEnd, eventDescription).then(() => {
agent.add(`Ok, let me see if we can fit you in. ${appointmentTimeString} is fine!. I am creating an event called: ${eventDescription}`);
}).catch(() => {
agent.add(`I'm sorry, there are no slots available for this period.`);
});
}
let intentMap = new Map();
intentMap.set('authenticate', authenticate);
intentMap.set('authentication code', authenticationCode);
intentMap.set('Make Appointment', makeAppointment);
agent.handleRequest(intentMap);
}
function createCalendarEvent (dateTimeStart, dateTimeEnd, eventDescription) {
return new Promise((resolve, reject) => {
calendar.events.list({
auth: authentication,
calendarId: calendarId,
timeMin: dateTimeStart.toISOString(),
timeMax: dateTimeEnd.toISOString()
}, (err, calendarResponse) => {
// Check if there is a event already in the calendar
if (err || calendarResponse.data.items.length > 0) {
reject(err || new Error('Requested time conflicts with another appointment'));
console.log(err);
} else {
// Create event for the requested time period
calendar.events.insert({
auth: authentication,
calendarId: calendarId,
resource: {
summary: eventDescription,
start: {dateTime: dateTimeStart},
end: {dateTime: dateTimeEnd}
}
}, (err, event) => {
err ? reject(err) : resolve(event);
console.log(err);
}
);
}
});
});
}

Answer 1

You're on the right track, but having the user go directly to the OAuth link means that they'll get the code, and thus must send it to you.
Instead, you can send them to a page on your site, which redirects them to the OAuth link. The redirection URI you include should redirect back to your site again. This way you get the code and can process it on your server. Once you complete the OAuth dance, your website would tell them they have authorized you and can continue with the chat.