index.js

'use strict';

const
  express     = require('express'),
  bodyParser  = require('body-parser'),
  request     = require('request'),
  config      = require('./configuration/config.json'),
  events      = require('./event-handler.js'),
  app         = express().use(bodyParser.json());


app.listen(process.env.PORT || 1337, () => console.log('webhook is listening'));

// SAME AS
// app.listen(1337, function() {
//   console.log('webhook is listening'));
// })


app.post('/webhook', (req, res) => {

  let body = req.body;

  // Checks this is an event from a page subscription
  if (body.object === 'page') {

    // Iterates over each entry - there may be multiple if batched
    body.entry.forEach(function(entry) {

      // Gets the message. entry.messaging is an array, but
      // will only ever contain one message, so we get index 0
      let webhookEvent = entry.messaging[0];
      let sender_psid = webhookEvent.sender.id;


      console.log("======================");
      console.log("");
      console.log("REQUEST : ", JSON.stringify(webhookEvent, null, 4));
      console.log("");
      console.log("======================");



      if (webhookEvent.message) {
        events.handleMessage(sender_psid, webhookEvent.message);
      } else if (webhookEvent.postback) {
        events.handlePostback(sender_psid, webhookEvent.postback);
      }

    });

    // Returns a '200 OK' response to all requests
    res.status(200).send('EVENT_RECEIVED');
  } else {
    // Returns a '404 Not Found' if event is not from a page subscription
    res.sendStatus(404);
  }
});


// Adds support for GET requests to our webhook
app.get('/webhook', (req, res) => {

  // Your verify token. Should be a random string.
  let VERIFY_TOKEN = "maverickjoy"

  // Parse the query params
  let mode = req.query['hub.mode'];
  let token = req.query['hub.verify_token'];
  let challenge = req.query['hub.challenge'];

  // Checks if a token and mode is in the query string of the request
  if (mode && token) {

    // Checks the mode and token sent is correct
    if (mode === 'subscribe' && token === VERIFY_TOKEN) {

      // Responds with the 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);
    }
  }
});