server.js

//dependencies
const sharp = require('sharp');
const express = require('express');
const cors = require('cors');
const bodyParser = require('body-parser');
const fs = require('fs');
const path = require('path');
//const https = require('https');
require('dotenv').config()

//setup
const app = express();
app.use(cors());
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
let serverStats = {
    imagesRendered: 0
};

//handling requests

//if a user tries to go to the backend, redirect their browser to the front end
app.get('/', (req, res) => {
    res.redirect("https://aaroncohen21.github.io/ESSLogos/");
});

//req should contain the svg to be processed
app.post('/', async (req, res) => {
    //create date string and log request to server
    const startDate = new Date();
    const dateString = (date) => `${('0' + (date.getMonth() + 1)).slice(-2)}/${('0' + date.getDate()).slice(-2)}/${date.getFullYear()} - ${('0' + date.getHours()).slice(-2)}:${('0' + date.getMinutes()).slice(-2)}:${('0' + date.getSeconds()).slice(-2)}`
    console.log(`[${dateString(startDate)}] - recieved new request: ${req.body.logo}${req.body.color}`);

    //parse xml into png file and send it
    const xml = req.body.xml;
    const buf = (await sharp(Buffer.from(xml)).png().toBuffer({resolveWithObject: true})).data;
    res.send(buf);
    res.status(200).end()

    //log successful completion
    console.log(`[${dateString(new Date())}] - successfully fulfilled request: ${req.body.logo}${req.body.color} (${dateString(startDate)})`);
    serverStats.imagesRendered++;
});

//endpoint for status shield
app.get('/status', (req, res) => {
    const data = {
        "schemaVersion": 1,
        "label": "Server Status",
        "message": "online",
        "color": "green"
    }
    res.json(data);
    res.status(200).end();
});

//endpoint for images rendered shield
app.get('/rendered', (req, res) => {
    const data = {
        "schemaVersion": 1,
        "label": "Images Rendered",
        "message": serverStats.imagesRendered.toString(),
        "color": "9cf"
    }
    res.json(data);
    res.status(200).end();
});

//start https server
// const httpsServer = https.createServer({
//     key: process.env.SSL_KEY,
//     cert: process.env.SSL_CERT
// }, app);

/*
 * NOTE:
 * 
 * Cyclic automatically hosts with HTTPS, so the
 * deployment does not need to manually host with HTTPS
 * 
 * However if being hosted manually, it may be
 * neccesarry to set up an HTTPS server. If this is
 * required, uncomment line 8 and the above code on lines 91-94,
 * and replace 'app' with 'httpsServer' on line 108
 * 
*/

app.listen(process.env.PORT, () => {
    try {
        //load serverStats from JSON file if it exists
        if (fs.existsSync(path.resolve('serverstats.json')))
            serverStats = JSON.parse(fs.readFileSync(path.resolve('serverstats.json')));        
    } catch (err) {
        console.error("Error: cannot access FileSystem:\n" + err);
    }

    //log that the server has started
    console.log('Server Listening on port ' + process.env.PORT);
});

//on server shutdown save all important stats
process.on('exit', () => {
    try {
        fs.writeFileSync(path.resolve('serverstats.json'), JSON.stringify(serverStats));
    } catch (err) {
        console.error('Error: cannot save server stats:\n' + err);
    }
});