Gmail Api OAuth Using Node.js Express - part 1

README.md

How to Run?

• Make sure there is a mongodb instance running locally.

• First export the environment variables.

export CLIENT_ID=your-client-id
export CLIENT_SECRET=your-client-secret
export DOMAIN_URL=your-domain-url

• Then install the dependencies.

npm install

• Run the app.

npm start

app.js

const express = require('express')
  , http = require('http')
  , path = require('path')
  , cookieParser = require('cookie-parser')
  , bodyParser = require('body-parser')
  , mongoose = require('mongoose')
  , port = 3000
  , Token = require('./token')
  , google = require('googleapis')
  , clientId = process.env.CLIENT_ID
  , clientSecret = process.env.CLIENT_SECRET
  , redirectUrl = process.env.DOMAIN_URL + '/create'
  , oauth2Client = new google.auth.OAuth2(clientId, clientSecret, redirectUrl)
  , authConfig = {
    access_type: 'offline',
    scope: [
      'https://www.googleapis.com/auth/plus.me',
      'https://www.googleapis.com/auth/calendar',
      'https://www.googleapis.com/auth/gmail.modify'
    ],
    approval_prompt: 'force'
  }
  , app = express();

app.set('port', port);
app.set('views', path.join(__dirname));
app.set('view engine', 'pug');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());

app.get('/', (req, res) => {
  const url = oauth2Client.generateAuthUrl(authConfig);

  res.send(`<a href="${url}">Click here to login with your Google Account</a>`);
});

app.get('/create', (req, res, next) => {
  oauth2Client.getToken(req.query.code, (err, tokens) => {
    if (err) return next(err);

    oauth2Client.setCredentials(tokens);
    const query = { accessToken: tokens['access_token'] };
    const entity = {
      accessToken: tokens['access_token'],
      refreshToken: tokens['refresh_token'],
      expiresAt: new Date(tokens['expiry_date'])
    };
    const opts = { upsert: true };
    const cb = (err, info) => { 
      if (err) next(err);

      Token.findOne((err, token) => (err) ? next(err) : res.send(token));
    };
    
    Token.update(query, entity, opts, cb);
  });
});

mongoose.connect('mongodb://localhost/gmail-alerts-node');

http.createServer(app).listen(port);
console.log(`App up and running on port ${port}`);

module.exports = app;

package.json

{
  "name": "gmail-alerts-node",
  "version": "0.0.0",
  "private": true,
  "scripts": {
    "start": "node ./app",
  },
  "dependencies": {
    "body-parser": "~1.13.2",
    "cookie-parser": "~1.3.5",
    "express": "~4.13.1",
    "googleapis": "^12.4.0",
    "moment": "^2.14.1",
    "mongoose": "^4.5.10",
    "pug": "^2.0.0-beta6",
    "request": "^2.74.0",
    "twilio": "^2.9.2",
    "underscore": "^1.8.3"
  }
}

token.js

'use strict';

const mongoose = require('mongoose')
  , request = require('request')
  , moment = require('moment')
  , schema = new mongoose.Schema({
  accessToken: String,
  refreshToken: String,
  expiresAt: Date
});

schema.methods.refresh = function(callback) {
  const url = 'https://accounts.google.com/o/oauth2/token';
  const params = {
    'refresh_token': this.refreshToken,
    'client_id': process.env.CLIENT_ID,
    'client_secret': process.env.CLIENT_SECRET,
    'grant_type': 'refresh_token'
  };
  const that = this;

  request.post(url, params, (error, response, body) => {
    if (error) {
      return callback(error, undefined);
    }

    const data = JSON.parse(body);
    this.accessToken = data.access_token;
    this.expiresAt = moment().add(data.expires_at, 'seconds').toDate();
    this.update((err) => {
        if (err) {
          callback(err, undefined);
        } else {
          callback(undefined, that.accessToken);  
        }
    });
  });
};

schema.methods.freshToken = function(callback) {
  if (moment().isAfter(this.expiresAt)) {
    this.refresh(callback);
  } else {
    callback(undefined, this.accessToken);
  }
};

module.exports = mongoose.model('token', schema);