index.js

var express = require('express');
var oauth = require('oauth');
var mongo = require('mongodb');
var gcal = require('google-calendar');
var q = require('q');
var app = express();

var clientId = 'GOOGLE_CLIENT_ID';
var clientSecret = 'GOOGLE_CLIENT_SECRET';
var scopes = 'https://www.googleapis.com/auth/calendar';
var googleUserId;
var refreshToken;
var baseUrl;

// app.env('development',function(){
//   console.log('!! DEVELOPMENT MODE !!');

//   googleUserId = 'GOOGLE_EMAIL_ADDRESS';
//   refreshToken = 'GOOGLE_REFRESH_TOKEN';
//   baseUrl = 'DEV_API_URL';
// });

// app.env('production', function(){
//   console.log('!! PRODUCTION MODE !!');

//   googleUserId = 'GOOGLE_EMAIL_ADDRESS';
//   refreshToken = 'GOOGLE_REFRESH_TOKEN';
//   baseUrl = 'PRODUCTION_API_URL';
// });

var mongoCollectionName = 'MONGO_COLLECTION_NAME';
var mongoUri = process.env.MONGOLAB_URI || process.env.MONGOHQ_URL || 'mongodb://localhost/default';
var database;
function connect(callback)
{
  var deferred = q.defer();

  if(database === undefined)
  {
    mongo.Db.connect(mongoUri, function(err, db){
      if(err) deferred.reject({error: err});

      database = db;
      deferred.resolve();
    });
  }
  else
  {
    deferred.resolve();
  }

  return deferred.promise;
}

function authorize()
{
  var deferred = q.defer();

  oa = new oauth.OAuth2(clientId,
            clientSecret,
            "https://accounts.google.com/o",
            "/oauth2/auth",
            "/oauth2/token");

  if(refreshToken)
  {
    oa.getOAuthAccessToken(refreshToken, {grant_type:'refresh_token', client_id: clientId, client_secret: clientSecret}, function(err, access_token, refresh_token, res){

      //lookup settings from database
      connect().then(function(){
        database.collection(mongoCollectionName).findOne({google_user_id: googleUserId}, function(findError, settings){

          var expiresIn = parseInt(res.expires_in);
          var accessTokenExpiration = new Date().getTime() + (expiresIn * 1000);

          //add refresh token if it is returned
          if(refresh_token != undefined) settings.google_refresh_token = refresh_token;

          //update access token in database
          settings.google_access_token = access_token;
          settings.google_access_token_expiration = accessTokenExpiration;

          database.collection(mongoCollectionName).save(settings);

          deferred.resolve(access_token);
        });
      });

    })
  }
  else
  {
    deferred.reject({error: 'Application needs authorization.'});
  }

  return deferred.promise;
}

function getAccessToken()
{
  var deferred = q.defer();
  var accessToken;

  connect().then(function(){

    database.collection(mongoCollectionName).findOne({google_user_id: googleUserId}, function(findError, settings){
      //check if access token is still valid
      var today = new Date();
      var currentTime = today.getTime();
      if(currentTime < settings.google_access_token_expiration)
      {
        //use the current access token
        accessToken = settings.google_access_token;
        deferred.resolve(accessToken)
      }
      else
      {
        //refresh the access token
        authorize().then(function(token){

          accessToken = token;
          deferred.resolve(accessToken);

        }, function(error){

          deferred.reject(error);

        });
      }
    });

  }, function(error){
    deferred.reject(error);
  });

  return deferred.promise;
}

app.set('port', (process.env.PORT || 5000));

app.use(express.static(__dirname + '/public'));

// views is directory for all template files
app.set('views', __dirname + '/views');
app.set('view engine', 'ejs');

app.get('/', function(request, response) {
  response.render('pages/index',{users: [
 { name: 'Booking' }
 ]})});

app.listen(app.get('port'), function() {
  console.log('Node app is running on port', app.get('port'));
});