import crypto from 'crypto';

Table of Contents

  1. calamar.js
  2. contextSet.js
  3. dbLocalStorage.js
  4. facebook.js
  5. facebookGraphHelpers.js
  6. facebookWebhookSetup.js
  7. index.js
  8. luis.js
  9. router.js
  10. s3ContextSet.js
  11. s3Storage.js
  12. wit.js

facebookWebhookSetup

Helpers for generating Express-style GET and POST functions to be used with Facebook Messenger Webhooks

setupGetWebhook(fbVerifyToken)

High order function that given a verify token returns a function that either sends the challenge as response or a validation error message depending on the requested hub.verify_token parameter value.

const setupGetWebhook = fbVerifyToken => (req, res) => {
    if (req.query['hub.verify_token'] === fbVerifyToken) {
        res.send(req.query['hub.challenge']);
    } else {
        res.send('Error, wrong validation token');
    }
};

const verifySignature = appSecret => (req, res, buf) => {
    const signature = req.headers['x-hub-signature'];
    const sha1Bot = crypto.createHmac('sha1', appSecret).update(buf).digest('hex');
    const sha1Fb = signature ? signature.slice('sha1='.length) : null;

console.log('sha1Bot', sha1Bot); console.log('sha1Fb_', sha1Fb);

    if (sha1Bot !== sha1Fb) {
        return res.status(401).send(false);
    }
    return true;
};

setupPostWebhook(bot, listeners)

High order function that given an object with event handlers, returns a function that will take POST requests and call the proper handlers depending on the contents of the request. Or respond false when no entry value is present in the body of the POST.

The returned function assumes you are using a body parser, such as body-parser, that makes req.body acessible as an object.

Parameters

Listener Description
onUpdate Generic callback, called for every messaging item received.
onMessage Specific callback for messages (text or media)
onAuthentication Specific callback for authentication updates
onDelivery Specific callback for delivery updates
onPostback Specific callback for postback updates 
const setupPostWebhook = (listeners, bot) => (req, res) => {
    if (res.headersSent) {
        return false;
    }
    const fNull = () => null;
    const {
        onUpdate = fNull,
        onMessage = fNull,
        onAuthentication = fNull,
        onDelivery = fNull,
        onPostback = fNull
    } = listeners;
    if (!req.body.entry || !Array.isArray(req.body.entry)) {
        return res.send(false);
    }
    req.body.entry.forEach(({ messaging }) => {
        messaging.forEach(update => {
            const { message, optin, delivery, postback } = update;
            const payload = {
                update,
                bot
            };
            onUpdate(payload);
            if (message) {
                onMessage(payload);
            }
            if (optin) {
                onAuthentication(payload);
            }
            if (delivery) {
                onDelivery(payload);
            }
            if (postback) {
                try {
                    const postbackPayload = JSON.parse(postback.payload);
                    if (postbackPayload.type && postbackPayload.type === 'legacy-welcome') {
                        bot.sendMessage({
                            userId: update.sender.id,
                            text: postbackPayload.message.text
                        });
                    }
                } catch (e) {
                    console.warn('postback is not json');
                }
                onPostback(payload);
            }
        });
    });
    return res.send(true);
};

export { setupGetWebhook, setupPostWebhook, verifySignature };
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