landing

dev-server.js

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+/** @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);