app.js

const FacebookMessengerBot = require('calamars').FacebookMessengerBot;

const Forks = require('./src/forks/forks');
const payloads = require('./src/forks/payloads');

const menu = require('./src/menu');
const Helpers = require('./src/helpers');
const messages = require('./src/messages');

let storage = [];



const onMessage = function(updateEvent){
  Helpers.setUserStorage(updateEvent, storage, mybot)
  .then(() => {
    let { step } = storage[updateEvent.update.sender.id]
    step = step === 0? 'initial': step

    if(Forks[step] && Forks[step].resolve)
      Forks[step].resolve(updateEvent, storage, mybot)
  })
};



const onPostback = function(updateEvent){
  Helpers.setUserStorage(updateEvent, storage, mybot)
  .then(()=>{
    let payload = updateEvent.update.postback.payload;
    let p = Helpers.isJSON(payload)? Helpers.getJSON(payload).type : payload

    if(p.indexOf('/') !== -1){
      let p1 = p.split('/')[0]
      let p2 = p.split('/')[1]
      if(payloads[p1]) payloads[p1](updateEvent, storage, p2)
    } else {
      if(payloads[p]) payloads[p](updateEvent, storage)
    }

  })
}

const mybot = new FacebookMessengerBot({
    port:  process.env.PORT || 3000,
    callbackPath: process.env.FB_CALLBACK_PATH,
    verifyToken: process.env.FB_VERIFY_TOKEN,
    pageTokens: [process.env.FB_PAGE_ACCESS_TOKEN],
    listeners: { onMessage, onPostback }
});

mybot.start().then(function(){
    console.log(`server is running on port ${process.env.PORT || 3000}`);

    mybot.setWelcomeMessage({
        text: messages('greeting')
    })

    mybot.setThreadSettings({
        type: 'call_to_actions',
        state: 'existing_thread',
        cta: menu
    })
})