feat(streamer): page http server with sse + cover proxy

streamer/src/page-server.ts

@@ -0,0 +1,127 @@
+import { createServer, IncomingMessage, ServerResponse } from "node:http";
+import { createReadStream, existsSync } from "node:fs";
+import { extname, join } from "node:path";
+import { EventEmitter } from "node:events";
+
+export interface PageServerOpts {
+  port: number;
+  staticDir: string;
+  libraryDir: string;
+  style: "denpa" | "modern";
+  station: string;
+  tz: string;
+  tuneInUrl: string;
+}
+
+export class PageServer extends EventEmitter {
+  private nowClients = new Set<ServerResponse>();
+  private specClients = new Set<ServerResponse>();
+  private latestNowJson: string | null = null;
+  private latestListeners: { current: number; peak: number } = { current: 0, peak: 0 };
+  private server = createServer((req, res) => this.handle(req, res));
+
+  constructor(private opts: PageServerOpts) { super(); }
+
+  start(): Promise<void> {
+    return new Promise((resolve) => this.server.listen(this.opts.port, "127.0.0.1", () => resolve()));
+  }
+
+  stop(): Promise<void> {
+    for (const c of this.nowClients) c.end();
+    for (const c of this.specClients) c.end();
+    return new Promise((resolve) => this.server.close(() => resolve()));
+  }
+
+  pushNowPlaying(json: unknown): void {
+    this.latestNowJson = JSON.stringify(json);
+    const payload = `data: ${this.latestNowJson}\n\n`;
+    for (const c of this.nowClients) c.write(payload);
+  }
+
+  pushSpectrum(bars: number[]): void {
+    const payload = `data: ${JSON.stringify(bars)}\n\n`;
+    for (const c of this.specClients) c.write(payload);
+  }
+
+  pushListeners(l: { current: number; peak: number }): void {
+    this.latestListeners = l;
+  }
+
+  private handle(req: IncomingMessage, res: ServerResponse): void {
+    const url = new URL(req.url ?? "/", "http://localhost");
+
+    if (url.pathname === "/") return this.serveIndex(res);
+    if (url.pathname.startsWith("/assets/")) return this.serveStatic(url.pathname, res);
+    if (url.pathname === "/now-playing") return this.serveSse(res, this.nowClients, this.latestNowJson);
+    if (url.pathname === "/spectrum") return this.serveSse(res, this.specClients, null);
+    if (url.pathname === "/listeners") {
+      res.setHeader("content-type", "application/json");
+      res.end(JSON.stringify(this.latestListeners));
+      return;
+    }
+    if (url.pathname === "/cover") return this.serveCover(url, res);
+
+    res.statusCode = 404;
+    res.end("not found");
+  }
+
+  private serveIndex(res: ServerResponse): void {
+    const indexPath = join(this.opts.staticDir, "index.html");
+    if (!existsSync(indexPath)) {
+      res.statusCode = 500;
+      res.end("index not built");
+      return;
+    }
+    const inject = `<script>window.__STREAMER_CONFIG__=${JSON.stringify({
+      style: this.opts.style,
+      station: this.opts.station,
+      tz: this.opts.tz,
+      tuneInUrl: this.opts.tuneInUrl,
+    })}</script>`;
+    let html = "";
+    createReadStream(indexPath, "utf8")
+      .on("data", (chunk) => (html += chunk))
+      .on("end", () => {
+        res.setHeader("content-type", "text/html; charset=utf-8");
+        res.end(html.replace("</head>", `${inject}</head>`));
+      });
+  }
+
+  private serveStatic(pathname: string, res: ServerResponse): void {
+    const file = join(this.opts.staticDir, pathname.replace(/^\/assets\//, ""));
+    if (!file.startsWith(this.opts.staticDir) || !existsSync(file)) {
+      res.statusCode = 404; res.end("not found"); return;
+    }
+    const ct = ({
+      ".js": "application/javascript",
+      ".css": "text/css",
+      ".woff2": "font/woff2",
+    } as const)[extname(file) as ".js" | ".css" | ".woff2"] ?? "application/octet-stream";
+    res.setHeader("content-type", ct);
+    res.setHeader("cache-control", "max-age=86400");
+    createReadStream(file).pipe(res);
+  }
+
+  private serveSse(res: ServerResponse, set: Set<ServerResponse>, initial: string | null): void {
+    res.setHeader("content-type", "text/event-stream");
+    res.setHeader("cache-control", "no-cache");
+    res.setHeader("connection", "keep-alive");
+    res.flushHeaders();
+    set.add(res);
+    if (initial) res.write(`data: ${initial}\n\n`);
+    res.on("close", () => set.delete(res));
+  }
+
+  private serveCover(url: URL, res: ServerResponse): void {
+    const requested = url.searchParams.get("path") ?? "";
+    if (!requested.startsWith("/library/")) { res.statusCode = 400; res.end(); return; }
+    const file = join(this.opts.libraryDir, requested.slice("/library/".length));
+    if (!file.startsWith(this.opts.libraryDir) || !existsSync(file)) {
+      res.statusCode = 404; res.end(); return;
+    }
+    const ext = extname(file).toLowerCase();
+    res.setHeader("content-type", ext === ".png" ? "image/png" : ext === ".webp" ? "image/webp" : "image/jpeg");
+    res.setHeader("cache-control", "no-store");
+    createReadStream(file).pipe(res);
+  }
+}