gmail api integration

gmail_send_api_notworking.js

var google = require('googleapis');
var googleAuth = require('google-auth-library');
var mimelib = require("mimelib");
let btoa = require('btoa');
// If modifying these scopes, delete your previously saved credentials
// at ~/.credentials/sheets.googleapis.com-nodejs-quickstart.json
var SCOPES = ['https://www.googleapis.com/auth/spreadsheets', 'https://www.googleapis.com/auth/gmail.send'];

var key = require('./client_secret.json');
var jwtClient = new google.auth.JWT(key.client_email, null, key.private_key, SCOPES, null);

jwtClient.authorize(function(err, tokens) {
  if (err) {
    console.log("error ");
    console.log(err);
    return;
  }

  console.log("success");
  console.log(tokens);
  listMajors(tokens);
});

function listMajors(auth) {
  function makeBody(to, from, subject, message) {
      var str = ["Content-Type: text/plain; charset=\"UTF-8\"\n",
          "MIME-Version: 1.0\n",
          "Content-Transfer-Encoding: 7bit\n",
          "to: ", to, "\n",
          "from: ", from, "\n",
          "subject: ", subject, "\n\n",
          message
      ].join('');
      var encodedMail = mimelib.foldLine(str);
      return encodedMail;
  }

  function sendMessage(auth) {
      var gmail = google.gmail('v1');
      var raw = makeBody('toemail@gmail.com', 'fromEmail@gmail.com', 'test subject', 'test message');
      gmail.users.messages.send({
          access_token : auth.access_token,
          userId: 'me',
          message: {
            raw : btoa(raw)
          }
      }, function(err, response) {
          if(err){
            console.log("error");
            console.dir(err);
            return;
          }
          console.dir(response);
      });
  }

  sendMessage(auth);
}

//output 
/* 
{ Error: Bad Request
    at Request._callback (/Users/arvinds/code/node_modules/google-auth-library/lib/transporters.js:85:15)
    at Request.self.callback (/Users/arvinds/code/node_modules/google-auth-library/node_modules/request/request.js:198:22)
    at emitTwo (events.js:106:13)
    at Request.emit (events.js:191:7)
    at Request.<anonymous> (/Users/arvinds/code/node_modules/google-auth-library/node_modules/request/request.js:1057:14)
    at emitOne (events.js:101:20)
    at Request.emit (events.js:188:7)
    at IncomingMessage.<anonymous> (/Users/arvinds/code/node_modules/google-auth-library/node_modules/request/request.js:1003:12)
    at emitNone (events.js:91:20)
    at IncomingMessage.emit (events.js:185:7)
  code: 400,
  errors: 
   [ { domain: 'global',
       reason: 'failedPrecondition',
       message: 'Bad Request' } ] }
*/