feat(web): react wave and ambient visuals to live audio

apps/web/src/player/audio.test.ts

@@ -0,0 +1,48 @@
+import type { AuthSession } from '@pipu/core';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+
+import { Player } from './player';
+
+afterEach(() => vi.restoreAllMocks());
+
+function fixture() {
+  const player = new Player({} as AuthSession, document.createElement('audio'));
+  const sample = vi.fn((data: Uint8Array) => {
+    data.fill(0);
+    // 48 kHz / 1024: bins 1..4 cover the bass band.
+    data.fill(255, 1, 5);
+  });
+  Object.assign(player, {
+    state: { ...player.getState(), playing: true },
+    analyser: { context: { sampleRate: 48000 }, fftSize: 1024, getByteFrequencyData: sample },
+  });
+  return { player, sample };
+}
+
+describe('audio reactivity', () => {
+  it('separates bass from the other frequency bands and shares the frame', () => {
+    vi.spyOn(performance, 'now').mockReturnValue(100);
+    const { player, sample } = fixture();
+    expect(player.readAudio()).toEqual({ bass: 1, mid: 0, treble: 0 });
+    player.readAudio();
+    expect(sample).toHaveBeenCalledTimes(1);
+  });
+
+  it('returns silence after pausing or muting', () => {
+    const clock = vi.spyOn(performance, 'now').mockReturnValue(100);
+    const { player, sample } = fixture();
+    player.readAudio();
+    Object.assign(player, { state: { ...player.getState(), playing: false } });
+    clock.mockReturnValue(120);
+    expect(player.readAudio()).toEqual({ bass: 0, mid: 0, treble: 0 });
+    Object.assign(player, { state: { ...player.getState(), playing: true, muted: true } });
+    clock.mockReturnValue(140);
+    expect(player.readAudio()).toEqual({ bass: 0, mid: 0, treble: 0 });
+    expect(sample).toHaveBeenCalledTimes(1);
+  });
+
+  it('works when Web Audio is unavailable', () => {
+    const player = new Player({} as AuthSession, document.createElement('audio'));
+    expect(player.readAudio()).toEqual({ bass: 0, mid: 0, treble: 0 });
+  });
+});