Despegar Telegram bot

index.js

'use strict'

const fetch = require('node-fetch')

const TelegramBot = require('node-telegram-bot-api')
const bot = new TelegramBot(process.env.TELEGRAM_TOKEN, { polling: true })

const low = require('lowdb')
const fileAsync = require('lowdb/lib/file-async')
const db = low(`${__dirname}/data/db.json`, { storage: fileAsync })

db.defaults({ users: [] }).value()

const intervals = {}

const checkFlights = (departure = 'scl', arrival = 'nyc', maxFare = 200000) => {
  const url = `http://www.despegar.cl/vuelos/${departure}/${arrival}/`
  return fetch(url)
    .then(res => res.text())
    .then(html => {
      const payload = html.match(/"jsonData" : ([\s\S]*?),\s"fareSelectorType"/)[1]
      const data = JSON.parse(payload)
      return {
        url,
        notify: data.items.some(item =>
          item.itinerariesBox.emissionPrice.total.fare.raw <= parseInt(maxFare))
      }
    })
}
bot.onText(/^\/?start$/, (msg, match) => {
  bot.sendMessage(msg.from.id,
    'Usage: /start {maxFare} {flights}\n' +
    'e.g /start 200000 scl mia, scl nyc')
})

bot.onText(/\/?start (\d{1,}) ([\s\S]{1,})/, (msg, match) => {
  db.get('users').remove({ id: msg.from.id }).value()
  const user = db.get('users')
    .push({
      id: msg.from.id,
      maxFare: match[1],
      flights: match[2].split(',').map(f => f.trim().split(' '))
    })
    .last()
    .value()
  initUser(user)
})

const stopIntervals = user => {
  user.flights && user.flights.forEach(flight => {
    const intervalId = `${user.id}${flight[0]}${flight[1]}`
    clearInterval(intervals[intervalId])
    delete intervals[intervalId]
  })
}

bot.onText(/^\/?stop/, msg => {
  bot.sendMessage(msg.from.id, 'Done!')
  const user = db.get('users').remove({ id: msg.from.id }).value()
  stopIntervals(user)
})

const initUser = user => {
  bot.sendMessage(user.id, 'Buscando vuelos ✈️')
  console.log('init user', user.id)
  const notify = (flight, user) => {
    return checkFlights(flight[0], flight[1], user.maxFare)
      .then(({ notify, url }) => {
        if (notify) bot.sendMessage(user.id, url)
      })
  }

  stopIntervals(user)
  console.log(user.flights)
  user.flights && user.flights.forEach(flight => {
    notify(flight, user)
    const intervalId = `${user.id}${flight[0]}${flight[1]}`
    intervals[intervalId] = setInterval(() =>
      notify(flight, user), 10 * 60 * 1000)
  })
}

console.log('Starting bot...')
db.get('users').value().forEach(initUser)

package.json

{
  "name": "despegar-bot",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "lowdb": "^0.13.1",
    "node-fetch": "^1.6.3",
    "node-telegram-bot-api": "^0.24.0"
  }
}