index.js

/**
 * Copyright 2017-present, Facebook, Inc. All rights reserved.
 *
 * This source code is licensed under the license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * Messenger Platform Quick Start Tutorial
 *
 * This is the completed code for the Messenger Platform quick start tutorial
 *
 * https://developers.facebook.com/docs/messenger-platform/getting-started/quick-start/
 *
 * To run this code, you must do the following:
 *
 * 1. Deploy this code to a server running Node.js
 * 2. Run `npm install`
 * 3. Update the VERIFY_TOKEN
 * 4. Add your PAGE_ACCESS_TOKEN to your environment vars
 *
 */

require('dotenv').config()

'use strict';
// Imports dependencies and set up http server
const 
  express = require('express'),
  body_parser = require('body-parser'),
  app = express().use(body_parser.json()); // creates express http server

const {handleMessage, handlePostback} = require('./handler/messages')


// Accepts POST requests at /webhook endpoint
app.post('/webhook', (req, res) => {  

  // Parse the request body from the POST
  let body = req.body;

  // Check the webhook event is from a Page subscription
  if (body.object === 'page') {

    body.entry.forEach(function(entry) {

      // Gets the body of the webhook event
      let webhook_event = entry.messaging[0];
      console.log(webhook_event);


      // Get the sender PSID
      let sender_psid = webhook_event.sender.id;
      console.log('Sender ID: ' + sender_psid);

      // Check if the event is a message or postback and
      // pass the event to the appropriate handler function
      if (webhook_event.message) {
        handleMessage(sender_psid, webhook_event.message);        
      } else if (webhook_event.postback) {
        
        handlePostback(sender_psid, webhook_event.postback);
      }
      
    });
    // Return a '200 OK' response to all events
    res.status(200).send('EVENT_RECEIVED');

  } else {
    // Return a '404 Not Found' if event is not from a page subscription
    res.sendStatus(404);
  }

});

// Accepts GET requests at the /webhook endpoint
app.get('/webhook', (req, res) => {
  
  /** UPDATE YOUR VERIFY TOKEN **/
  const VERIFY_TOKEN = process.env.VERIFY_TOKEN;

  
  // Parse params from the webhook verification request
  let mode = req.query['hub.mode'];
  let token = req.query['hub.verify_token'];
  let challenge = req.query['hub.challenge'];
    
  // Check if a token and mode were sent
  if (mode && token) {
  
    // Check the mode and token sent are correct
    if (mode === 'subscribe' && token === VERIFY_TOKEN) {
      
      // Respond with 200 OK and challenge token from the request
      console.log('WEBHOOK_VERIFIED');
      res.status(200).send(challenge);
    
    } else {
      // Responds with '403 Forbidden' if verify tokens do not match
      res.sendStatus(403);      
    }
  }
});

// Sets server port and logs message on success
var PORT = process.env.PORT || 1337
app.listen(PORT, () => console.log(`webhook is listening on port ${PORT}`));