/** @file site/dev-server.js */
const http = require('http');
const fs = require('fs');
const path = require('path');
const WebSocket = require('ws');

const HTTP_PORT = 9876;
const WEBSOCKET_PORT = 9878;
const CLIENT_WEBSOCKET_CODE = fs.readFileSync(
    path.join(__dirname, 'client-websocket.js'),
    'utf8',
);

// Websocket server (for allowing browser and dev server to have 2-way communication)
// We don't even need to do anything except create the instance!
const wss = new WebSocket.Server({
    port: WEBSOCKET_PORT,
});
wss.on('connection', () => {
    console.log('Client connected');
});

/**
 * @typedef {import('http').IncomingMessage} req
 * @typedef {import('http').ServerResponse} res
 */

/** Use classic server-logic to serve a static file (e.g. default to 'index.html' etc)
 * @param {string} route
 * @param {res} res
 * @returns {boolean} Whether or not the page exists and was served
 */
function serveStaticPageIfExists(route, res) {
    // We don't care about performance for a dev server, so sync functions are fine.
    // If the route exists it's either the exact file we want or the path to a directory
    // in which case we'd serve up the 'index.html' file.
    if (fs.existsSync(route)) {
        if (fs.statSync(route).isDirectory()) {
            return serveStaticPageIfExists(path.join(route, 'index.html'), res);
        } else if (fs.statSync(route).isFile()) {
            res.writeHead(200);
            /** @type {string|Buffer} */
            let file = fs.readFileSync(route);
            if (route.endsWith('.html')) {
                // Inject the client-side websocket code.
                // This sounds fancier than it is; simply
                // append the script to the end since
                // browsers allow for tons of deviation
                // from *technically correct* HTML.
                file = `${file.toString()}\n\n<script>${CLIENT_WEBSOCKET_CODE}</script>`;
            }
            res.end(file);
            return true;
        }
    }
    return false;
}

/** General request handler and router
 * @param {req} req
 * @param {res} res
 */
const requestHandler = function (req, res) {
    const method = req.method.toLowerCase();
    if (method === 'get') {
        // No need to ensure the route can't access other local files,
        // since this is for development only.
        const route = path.normalize(path.join(__dirname, req.url));
        if (serveStaticPageIfExists(route, res)) {
            return;
        }
    }
    res.writeHead(404);
    res.end();
};

const server = http.createServer(requestHandler);
server.listen(HTTP_PORT);