Google auth token generator for FCM

index.js

/**
 * Firebase Cloud Messaging (FCM) can be used to send messages to clients on iOS, Android and Web.
 *
 * This sample uses FCM to send two types of messages to clients that are subscribed to the `news`
 * topic. One type of message is a simple notification message (display message). The other is
 * a notification message (display notification) with platform specific customizations. For example,
 * a badge is added to messages that are sent to iOS devices.
 */
const https = require('https');
const { google } = require('googleapis');

const PROJECT_ID = 'portal-next-messaging';
const HOST = 'fcm.googleapis.com';
const PATH = '/v1/projects/' + PROJECT_ID + '/messages:send';
const MESSAGING_SCOPE = 'https://www.googleapis.com/auth/firebase.messaging';
const SCOPES = [MESSAGING_SCOPE];

/**
 * Get a valid access token.
 */
// [START retrieve_access_token]
function getAccessToken() {
  return new Promise(function (resolve, reject) {
    const key = require('./service-account.json');
    const jwtClient = new google.auth.JWT(
      key.client_email,
      null,
      key.private_key,
      SCOPES,
      null
    );
    jwtClient.authorize(function (err, tokens) {
      if (err) {
        reject(err);
        return;
      }
      resolve(tokens.access_token);
    });
  });
}
// [END retrieve_access_token]

/**
 * Send HTTP request to FCM with given message.
 *
 * @param {object} fcmMessage will make up the body of the request.
 */
function sendFcmMessage(fcmMessage) {
  getAccessToken().then(function (accessToken) {
    const options = {
      hostname: HOST,
      path: PATH,
      method: 'POST',
      // [START use_access_token]
      headers: {
        Authorization: 'Bearer ' + accessToken,
      },
      // [END use_access_token]
    };

    const request = https.request(options, function (resp) {
      resp.setEncoding('utf8');
      resp.on('data', function (data) {
        console.log('Message sent to Firebase for delivery, response:');
        console.log(data);
      });
    });

    request.on('error', function (err) {
      console.log('Unable to send message to Firebase');
      console.log(err);
    });

    request.write(JSON.stringify(fcmMessage));
    request.end();
  });
}

/**
 * Construct a JSON object that will be used to customize
 * the messages sent to iOS and Android devices.
 */
function buildOverrideMessage() {
  const fcmMessage = buildCommonMessage();
  const apnsOverride = {
    payload: {
      aps: {
        badge: 1,
      },
    },
    headers: {
      'apns-priority': '10',
    },
  };

  const androidOverride = {
    notification: {
      click_action: 'android.intent.action.MAIN',
    },
  };

  fcmMessage['message']['android'] = androidOverride;
  fcmMessage['message']['apns'] = apnsOverride;

  return fcmMessage;
}

/**
 * Construct a JSON object that will be used to define the
 * common parts of a notification message that will be sent
 * to any app instance subscribed to the news topic.
 */
function buildCommonMessage() {
  return {
    message: {
      topic: 'news',
      notification: {
        title: 'FCM Notification',
        body: 'Notification from FCM',
      },
    },
  };
}

function buildTargetedMessage() {
  return {
    message: {
      token:
        'eQbnLcIcR3hQXVxTnE16xz:APA91bEczp19k55KNPo0XnrRfyLOg03_1irM-Z6-4CDXRgLyd35W6BuSH-qjTTWF2MVnXJpH5gwp7Cbms_VTmMYTf29KZT2qiSUAeTP51Nnp_w-MQhNkqw-VJf7IbjhBhfE_f6t__bnU',
      notification: {
        body: 'This is an FCM notification message!',
        title: 'FCM Message',
      },
    },
  };
}

const message = process.argv[2];
if (message && message == 'common-message') {
  const commonMessage = buildCommonMessage();
  console.log('FCM request body for message using common notification object:');
  console.log(JSON.stringify(commonMessage, null, 2));
  sendFcmMessage(buildCommonMessage());
} else if (message && message == 'override-message') {
  const overrideMessage = buildOverrideMessage();
  console.log('FCM request body for override message:');
  console.log(JSON.stringify(overrideMessage, null, 2));
  sendFcmMessage(buildOverrideMessage());
} else if (message && message == 'targeted-message') {
  const targetedMessage = buildTargetedMessage();
  console.log('FCM request body for override message:');
  console.log(JSON.stringify(targetedMessage, null, 2));
  sendFcmMessage(targetedMessage);
} else {
  console.log(
    'Invalid command. Please use one of the following:\n' +
      'node index.js common-message\n' +
      'node index.js override-message'
  );
}