index_without_wit.js

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

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

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

// parse application/json
app.use(bodyParser.json());

// index
app.get('/', function (req, res) {
    res.send('hello world i am a secret bot')
});

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

// to post data
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 === 'Yo') {
                sendGenericMessage(sender);
                continue;
            }
            sendTextMessage(sender, "Text received, echo: " + 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)
});

var token = process.env.FB_PAGE_TOKEN;
var var_appsecret_proof = process.env.APP_SECRET_PROOF;

function sendTextMessage(sender, text) {
    messageData = {
        text:text
    };
    request({
        url: 'https://graph.facebook.com/v2.6/me/messages',
        qs: {access_token:token, appsecret_proof: var_appsecret_proof},
        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(sender) {
    messageData = {
        "text":"hello, world!"
    };
    request({
        url: 'https://graph.facebook.com/v2.6/me/messages',
        qs: {access_token:token, appsecret_proof: var_appsecret_proof},
        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 spin sugar
app.listen(app.get('port'), function() {
    console.log('running on port', app.get('port'));
});