feat: add audio engine — Opus encoder, play queue with 4 modes, FFmpeg player

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/audio/queue.test.ts

@@ -0,0 +1,126 @@
+import { describe, it, expect, beforeEach } from "vitest";
+import { PlayQueue, type QueuedSong, PlayMode } from "./queue.js";
+
+function makeSong(id: string, name: string = id): QueuedSong {
+  return {
+    id,
+    name,
+    artist: "Artist",
+    album: "Album",
+    platform: "netease",
+    url: `https://example.com/${id}.mp3`,
+    coverUrl: `https://example.com/${id}.jpg`,
+    duration: 240,
+  };
+}
+
+describe("PlayQueue", () => {
+  let queue: PlayQueue;
+
+  beforeEach(() => {
+    queue = new PlayQueue();
+  });
+
+  it("starts empty", () => {
+    expect(queue.isEmpty()).toBe(true);
+    expect(queue.current()).toBeNull();
+    expect(queue.size()).toBe(0);
+  });
+
+  it("adds and retrieves songs", () => {
+    queue.add(makeSong("1", "Song A"));
+    queue.add(makeSong("2", "Song B"));
+    expect(queue.size()).toBe(2);
+    expect(queue.list()[0].name).toBe("Song A");
+    expect(queue.list()[1].name).toBe("Song B");
+  });
+
+  it("plays first song when starting", () => {
+    queue.add(makeSong("1"));
+    queue.add(makeSong("2"));
+    queue.play();
+    expect(queue.current()?.id).toBe("1");
+  });
+
+  it("advances to next song in sequential mode", () => {
+    queue.setMode(PlayMode.Sequential);
+    queue.add(makeSong("1"));
+    queue.add(makeSong("2"));
+    queue.add(makeSong("3"));
+    queue.play();
+    expect(queue.current()?.id).toBe("1");
+    const next = queue.next();
+    expect(next?.id).toBe("2");
+    expect(queue.current()?.id).toBe("2");
+  });
+
+  it("returns null at end in sequential mode", () => {
+    queue.setMode(PlayMode.Sequential);
+    queue.add(makeSong("1"));
+    queue.play();
+    const next = queue.next();
+    expect(next).toBeNull();
+  });
+
+  it("loops in loop mode", () => {
+    queue.setMode(PlayMode.Loop);
+    queue.add(makeSong("1"));
+    queue.play();
+    const next = queue.next();
+    expect(next?.id).toBe("1");
+  });
+
+  it("goes to previous song", () => {
+    queue.add(makeSong("1"));
+    queue.add(makeSong("2"));
+    queue.play();
+    queue.next();
+    expect(queue.current()?.id).toBe("2");
+    queue.prev();
+    expect(queue.current()?.id).toBe("1");
+  });
+
+  it("removes song by index", () => {
+    queue.add(makeSong("1"));
+    queue.add(makeSong("2"));
+    queue.add(makeSong("3"));
+    queue.remove(1);
+    expect(queue.size()).toBe(2);
+    expect(queue.list()[1].id).toBe("3");
+  });
+
+  it("clears all songs", () => {
+    queue.add(makeSong("1"));
+    queue.add(makeSong("2"));
+    queue.clear();
+    expect(queue.isEmpty()).toBe(true);
+    expect(queue.current()).toBeNull();
+  });
+
+  it("random mode returns a song", () => {
+    queue.setMode(PlayMode.Random);
+    queue.add(makeSong("1"));
+    queue.add(makeSong("2"));
+    queue.add(makeSong("3"));
+    queue.play();
+    const next = queue.next();
+    expect(next).not.toBeNull();
+  });
+
+  it("random-loop mode never returns null", () => {
+    queue.setMode(PlayMode.RandomLoop);
+    queue.add(makeSong("1"));
+    queue.play();
+    for (let i = 0; i < 10; i++) {
+      expect(queue.next()).not.toBeNull();
+    }
+  });
+
+  it("playAt jumps to specific index", () => {
+    queue.add(makeSong("1"));
+    queue.add(makeSong("2"));
+    queue.add(makeSong("3"));
+    queue.playAt(2);
+    expect(queue.current()?.id).toBe("3");
+  });
+});