text: / this file get email threads from google's api and then gets the corresponding raw encoded messages per thread id
  //
  //
  //
  //
  
  
   const mongoose = require('mongoose');
  
  
  //mongoose.Promise = global.Promise;
    //Set up default mongoose connection
    var mongoDB = 'mongodb://heroku_4jtg3rvf:r9nq5ealpnfrlda5la4fj8r192@ds161503.mlab.com:61503/heroku_4jtg3rvf'
    //var mongoDB = 'mongodb://localhost:27017/test';
  
    mongoose.connect(mongoDB, {
      useMongoClient: true
    });
  
  mongoose.connection.on('error', (err) => {
    console.error(err);
    console.log('%s MongoDB connection error. Please make sure MongoDB is running.', chalk.red('✗'));
    process.exit();
  });
  
  const async = require('async');
  const Message = require('../models/Message.js');
  var fs = require('fs');
  var readline = require('readline');
  var google = require('googleapis');
  var googleAuth = require('google-auth-library');
  var gmail = google.gmail('v1');
  
  // If modifying these scopes, delete your previously saved credentials
  // at ~/.credentials/gmail-nodejs-quickstart.json
  var SCOPES = ['https://www.googleapis.com/auth/gmail.readonly'];
  var TOKEN_DIR = (process.env.HOME || process.env.HOMEPATH ||
      process.env.USERPROFILE) + '/.credentials/';
  var TOKEN_PATH = TOKEN_DIR + 'gmail-nodejs-quickstart.json';
  
  // Load client secrets from a local file.
  fs.readFile('../client_secret.json', function processClientSecrets(err, content) {
    if (err) {
      console.log('Error loading client secret file: ' + err);
      return;
    }
    // Authorize a client with the loaded credentials, then call the
    // Gmail API.
  
    //authorize(JSON.parse(content), listLabels);
    authorize(JSON.parse(content), listThreads);
  });
  
  /**
   * Create an OAuth2 client with the given credentials, and then execute the
   * given callback function.
   *
   * @param {Object} credentials The authorization client credentials.
   * @param {function} callback The callback to call with the authorized client.
   */
  function authorize(credentials, callback) {
    var clientSecret = credentials.web.client_secret;
    var clientId = credentials.web.client_id;
    var redirectUrl = credentials.web.redirect_uris[0];
    var auth = new googleAuth();
    var oauth2Client = new auth.OAuth2(clientId, clientSecret, redirectUrl);
  
    // Check if we have previously stored a token.
    fs.readFile(TOKEN_PATH, function(err, token) {
      if (err) {
        getNewToken(oauth2Client, callback);
      } else {
        oauth2Client.credentials = JSON.parse(token);
        callback(oauth2Client);
      }
    });
  }
  
  /**
   * Get and store new token after prompting for user authorization, and then
   * execute the given callback with the authorized OAuth2 client.
   *
   * @param {google.auth.OAuth2} oauth2Client The OAuth2 client to get token for.
   * @param {getEventsCallback} callback The callback to call with the authorized
   *     client.
   */
  function getNewToken(oauth2Client, callback) {
    var authUrl = oauth2Client.generateAuthUrl({
      access_type: 'offline',
      scope: SCOPES
    });
    console.log('Authorize this app by visiting this url: ', authUrl);
    var rl = readline.createInterface({
      input: process.stdin,
      output: process.stdout
    });
    rl.question('Enter the code from that page here: ', function(code) {
      rl.close();
      oauth2Client.getToken(code, function(err, token) {
        if (err) {
          console.log('Error while trying to retrieve access token', err);
          return;
        }
        oauth2Client.credentials = token;
        storeToken(token);
        callback(oauth2Client);
      });
    });
  }
  
  /**
   * Store token to disk be used in later program executions.
   *
   * @param {Object} token The token to store to disk.
   */
  function storeToken(token) {
    try {
      fs.mkdirSync(TOKEN_DIR);
    } catch (err) {
      if (err.code != 'EEXIST') {
        throw err;
      }
    }
    fs.writeFile(TOKEN_PATH, JSON.stringify(token));
    console.log('Token stored to ' + TOKEN_PATH);
  }
  
  
  
  //sub function to get message from gmail api
   function getMessage(i, auth, thread_id, callback) {
     gmail.users.messages.get({
       auth:auth,
       userId: 'crystal.wesnoski@gmail.com',
       id: thread_id.id,
       format: 'raw'
     },
       function(err, response2) {
         if (err) {
  
           console.log('The API returned an error: ' + err);
           return;
         }
  
         //for some reason i needed to create an _id to save to mongoose...:(
         var mongoose = require('mongoose');
         var ObjectId =  mongoose.Types.ObjectId;
         var x = new ObjectId();
  
         var date = new Date().getTime()
         const email_thread = new Message(
           {
             _id: x,
             userid: 'user_id',
             email: 'crystal.wesnoski@gmail.com',
             date_extracted: date,
             thread_id: thread_id.id,
             encoded_message: response2['raw']
          }
         );
         console.log(thread_id.id)
         email_thread.save();
  
      }
    )
  
   }
  
  
  
     function listThreads(auth) {
  
       var mongoose = require('mongoose');
       mongoose.Promise = require('bluebird');
  
       var message
       //only focusing on nordstrom , 'VictoriasSecret@e1.victoriassecret.com','help@walmart.com', 'BestBuyInfo@emailinfo.bestbuy.com'
       var retailers = ['contact@em.nordstrom.com']
       var key_words = '{subject:order subject:reciept subject:confirmation subject:purchase}'
       query = 'in: anywhere,' + retailers +','+ key_words
       //console.log(query)
       var gmail = google.gmail('v1');
       gmail.users.threads.list({
         auth: auth,
         userId: 'crystal.wesnoski@gmail.com',
         q: query
       }, function(err, response) {
         if (err) {
  
           console.log('The API returned an error: ' + err);
           return;
         }
  
         var threads = response['threads']
         if (threads.length == 0) {
  
           console.log('No labels found.');
  
         } else {
  
           for (var i = 0; i < threads.length; i++) {
             var thread = threads[i];
  
             getMessage(i ,auth, thread)
  
           }
         }
       });
     }