Building an Automated Flight Status Notification System with Aviationstack API

				
					const express = require("express");
const PORT = process.env.PORT || 3000;
const app = express();


require('dotenv').config();
const MAILBOXLAYER_API_KEY = process.env.MAILBOXLAYER_KEY;
const MAILBOXLAYER_API_URL = process.env.MAILBOXLAYER_URL;
const AVIATIONSTACK_API_KEY = process.env.AVIATIONSTACK_KEY;
const AVIATIONSTACK_API_URL = process.env.AVIATIONSTACK_URL;


const fs = require('fs')
const flightDataFile = '/tmp/flight-data.json'


const nodemailer = require('nodemailer');


const transporter = nodemailer.createTransport({
 service: 'gmail',
 auth: {
   user: 'your-email@gmail.com',
   pass: 'your-app-password' // NOT your regular Gmail password
 }
});


const { startPolling } = require("./poll");


const checkCacheAndNotify = async (req, res) => {
   const {flightNumber, airportCode, userEmail} = req.query;
   const response = await fetch(AVIATIONSTACK_API_URL + `?access_key=${AVIATIONSTACK_API_KEY}&flight_iata=${flightNumber}&dep_iata=${airportCode}`);
   const json = await response.json();


   try {
       if (fs.existsSync(flightDataFile)) {
           const cache = JSON.parse(fs.readFileSync(flightDataFile));
           const {delay, gate} = json.data[0].departure;
           if (cache.departure.delay !== delay || cache.departure.gate !== gate) {
               const mailOptions = {
                   from: 'your-email@gmail.com',
                   to: userEmail,
                   subject: 'Your flight details have changed',
                   text: `There is new information for flight ${flightNumber}. Delay: ${delay}. Gate: ${gate}`
               };
               transporter.sendMail(mailOptions, (error, info) => {
                   if (error) {
                       console.error(error)
                   } else {
                       console.log('Email sent:', info.response);
                   }
               });
           }
       }
       const toWrite = JSON.stringify(json.data[0]);
       fs.writeFileSync(flightDataFile, toWrite);
       res.send("Signed user up for email notifications")
       } catch(err) {
           console.error(err)
           res.status(500).send(err.message)
       }
}


app.get('/notify', async (req, res) => {
   const {userEmail} = req.query;
   const response = await fetch(MAILBOXLAYER_API_URL + `?access_key=${MAILBOXLAYER_API_KEY}&email=${userEmail}`);
   const json = await response.json();
   const isValid = json.format_valid;


   if (isValid) {
       try {
           startPolling(() => checkCacheAndNotify(req, res))
       } catch(err) {
           console.error(err)
       }  


   }
})


app.listen(PORT, () => {
console.log(`Server listening on ${PORT}`);
});