index.js

var express = require('express')
var bodyParser = require('body-parser')
var request = require('request')
var app = express()

var token = "enter token here"

app.set('port', (process.env.PORT || 5000))

// Process application/x-www-form-urlencoded
app.use(bodyParser.urlencoded({ extended: false }))

// Process application/json
app.use(bodyParser.json())

// Index route
app.get('/', function(req, res) {
  res.send('Hello world, I am a chat bot')
})

// for Facebook verification
app.get('/webhook/', function(req, res) {
  if (req.query['hub.verify_token'] === token) {
    res.send(req.query['hub.challenge'])
  }
  res.send('Error, wrong token')
})

app.post('/webhook/', function(req, res) {
  messaging_events = req.body.entry[0].messaging
  for (i = 0; i < messaging_events.length; i++) {
    event = req.body.entry[0].messaging[i]
    sender = event.sender.id
    if (event.message && event.message.text) {
      text = event.message.text
      if (text === 'hi') {
        sendGenericMessage(sender)
        continue
      }
      sendTextMessage(sender, "parrot: " + text.substring(0, 200))
    }
    if (event.postback) {
      text = JSON.stringify(event.postback)
      sendTextMessage(sender, "Postback received: " + text.substring(0, 200), token)
      continue
    }
  }
  res.sendStatus(200)
})


function sendTextMessage(sender, text) {
  messageData = {
    text: text
  }
  sendRequest(sender, messageData)
}

function sendGenericMessage(sender) {
  messageData = {
    "attachment": {
      "type": "template",
      "payload": {
        "template_type": "generic",
        "elements": [{
          "title": "Ai Chat Bot Communities",
          "subtitle": "Communities to Follow",
          "image_url": "http://1u88jj3r4db2x4txp44yqfj1.wpengine.netdna-cdn.com/...",
          "buttons": [{
            "type": "web_url",
            "url": "https://www.facebook.com/groups/aic...",
            "title": "FB Chatbot Group"
          }, {
            "type": "web_url",
            "url": "https://www.reddit.com/r/Chat_Bots/",
            "title": "Chatbots on Reddit"
          }, {
            "type": "web_url",
            "url": "https://twitter.com/aichatbots",
            "title": "Chatbots on Twitter"
          }],
        }, {
          "title": "Chatbots FAQ",
          "subtitle": "Aking the Deep Questions",
          "image_url": "https://tctechcrunch2011.files.wordpress.com/...",
          "buttons": [{
            "type": "postback",
            "title": "What's the benefit?",
            "payload": "Chatbots make content interactive instead of static",
          }, {
            "type": "postback",
            "title": "What can Chatbots do",
            "payload": "One day Chatbots will control the Internet of Things! You will be able to control your homes temperature with a text",
          }, {
            "type": "postback",
            "title": "The Future",
            "payload": "Chatbots are fun! One day your BFF might be a Chatbot",
          }],
        }, {
          "title": "Learning More",
          "subtitle": "Aking the Deep Questions",
          "image_url": "http://www.brandknewmag.com/wp-cont...",
          "buttons": [{
            "type": "postback",
            "title": "AIML",
            "payload": "Checkout Artificial Intelligence Mark Up Language. Its easier than you think!",
          }, {
            "type": "postback",
            "title": "Machine Learning",
            "payload": "Use python to teach your maching in 16D space in 15min",
          }, {
            "type": "postback",
            "title": "Communities",
            "payload": "Online communities & Meetups are the best way to stay ahead of the curve!",
          }],
        }]
      }
    }
  }
  sendRequest(sender, messageData)
}

function sendRequest(sender, messageData) {
  request({
    url: 'https://graph.facebook.com/v2.6/me/messages',
    qs: { access_token: token },
    method: 'POST',
    json: {
      recipient: { id: sender },
      message: messageData,
    }
  }, function(error, response, body) {
    if (error) {
      console.log('Error sending messages: ', error)
    } else if (response.body.error) {
      console.log('Error: ', response.body.error)
    }
  })
}

// Spin up the server
app.listen(app.get('port'), function() {
  console.log('running on port', app.get('port'))
})