index.js

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

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'] === 'my_voice_is_my_password_verify_me') {
        res.send(req.query['hub.challenge'])
    }
    res.send('Error, wrong token')
})

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


//Updated webhook API to look for special messages to trigger the cards and send back a postback function when user clicks on message button or card
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) {
            text = event.message.text
            sendTextMessage(sender, "Hello, welcome to Ujamaa.")
        }
    }
    res.sendStatus(200)
})

var token = "EAAXLVzypWUIBALniqbgnR6Q7S5QN7UatVVSejcFVIgjRczLROyA9SpUGFJzZCiZClV9iDC8pVJ9VEZAZA6dSbvgrTIHM7dhq75jHVwGMsFLWlW8U2NmleM0sZAkyofBy6L2N7sKtXV6ugUn6vrOJcrcCTJV5ZAcF6q451nDxi4kAZDZD"

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

function sendGenericMessage(recipientId) {
  var messageData = {
    recipient: {
      id: recipientId
    },
    message: {
      attachment: {
        type: "template",
        payload: {
          template_type: "generic",
          elements: [{
            title: "rift",
            subtitle: "Next-generation virtual reality",
            item_url: "https://www.oculus.com/en-us/rift/",               
            image_url: "http://messengerdemo.parseapp.com/img/rift.png",
            buttons: [{
              type: "web_url",
              url: "https://www.oculus.com/en-us/rift/",
              title: "Open Web URL"
            }, {
              type: "postback",
              title: "Call Postback",
              payload: "Payload for first bubble",
            }],
          }, {
            title: "touch",
            subtitle: "Your Hands, Now in VR",
            item_url: "https://www.oculus.com/en-us/touch/",               
            image_url: "http://messengerdemo.parseapp.com/img/touch.png",
            buttons: [{
              type: "web_url",
              url: "https://www.oculus.com/en-us/touch/",
              title: "Open Web URL"
            }, {
              type: "postback",
              title: "Call Postback",
              payload: "Payload for second bubble",
            }]
          }]
        }
      }
    }
  };  

  callSendAPI(messageData);
}