server.js

"use strict";
require('dotenv').config();
const express = require('express');
const app = express();
const request = require('superagent');
const bodyParser = require('body-parser');
const fbAccessToken = process.env.FB_ACCESS_TOKEN;
const engine = require('./src/engine/engine.js');
const fs = require('fs');
const handleMessageEvent = require('./messagingHandler.js');
const handlePostback = require('./postbackHandler.js');


app.use(bodyParser.urlencoded({extended: false}))
app.use(bodyParser.json());

app.get("/", (req, res) => {
  res.send('howdie dreamin');
});

//verification
app.get("/webhook/", (req, res) => {
  if (req.query["hub.mode"]==="subscribe" && req.query["hub.verify_token"]===process.env.VERIFY_TOKEN) {
    res.send(req.query["hub.challenge"]);
  }
});


app.post('/webhook', function (req, res) {
  var data = req.body;

  // Make sure this is a page subscription
  if (data.object == 'page') {
    // Iterate over each entry
    // There may be multiple if batched
    data.entry.forEach(function(pageEntry) {
      var pageID = pageEntry.id;
      var timeOfEvent = pageEntry.time;

      // Iterate over each messaging event
      pageEntry.messaging.forEach(function(messagingEvent) {
        if (messagingEvent.optin) {
          // receivedAuthentication(messagingEvent);
        } else if (messagingEvent.message) {
          handleMessageEvent(messagingEvent)
          // receivedMessage(messagingEvent);
        } else if (messagingEvent.delivery) {
          // receivedDeliveryConfirmation(messagingEvent);
        } else if (messagingEvent.postback) {
          handlePostback(messagingEvent);
        } else {
          console.log("Webhook received unknown messagingEvent: ", messagingEvent);
        }
      });
    });

    // Assume all went well.
    //
    // You must send back a 200, within 20 seconds, to let us know you've
    // successfully received the callback. Otherwise, the request will time out.
    res.sendStatus(200);
  }
});




// listen for requests :)
var listener = app.listen(process.env.PORT, function () {
  console.log('Your app is listening on port ' + listener.address().port);
});