feat(streamer): icecast listener-count poller

streamer/src/icecast.ts

@@ -0,0 +1,43 @@
+import { EventEmitter } from "node:events";
+
+export interface IcecastOpts {
+  statusUrl: string;
+  mountName: string;
+  intervalMs?: number;
+}
+
+export interface IcecastListeners { current: number; peak: number; }
+
+export class IcecastPoller extends EventEmitter {
+  private timer: NodeJS.Timeout | null = null;
+  private peak = 0;
+
+  constructor(private opts: IcecastOpts) { super(); }
+
+  start(): void {
+    this.poll();
+    this.timer = setInterval(() => this.poll(), this.opts.intervalMs ?? 30000);
+  }
+
+  stop(): void {
+    if (this.timer) clearInterval(this.timer);
+  }
+
+  private async poll(): Promise<void> {
+    try {
+      const r = await fetch(this.opts.statusUrl, { signal: AbortSignal.timeout(5000) });
+      if (!r.ok) throw new Error(`icecast status ${r.status}`);
+      const j = await r.json() as {
+        icestats: { source?: { listenurl: string; listeners: number }[] | { listenurl: string; listeners: number } };
+      };
+      const sources = j.icestats.source;
+      const list = Array.isArray(sources) ? sources : sources ? [sources] : [];
+      const found = list.find((s) => s.listenurl.endsWith(this.opts.mountName));
+      const current = found?.listeners ?? 0;
+      this.peak = Math.max(this.peak, current);
+      this.emit("listeners", { current, peak: this.peak });
+    } catch (err) {
+      this.emit("warn", err);
+    }
+  }
+}