let btn = document.querySelector('#play-button');

// 設置 Tone.js 音訊上下文
Tone.setContext(new Tone.Context());

// 創建 Sampler 音源
const sampler = new Tone.Sampler({
  urls: {
    C4: "https://tonejs.github.io/audio/casio/C4.mp3",
    "D#4": "https://tonejs.github.io/audio/casio/Ds4.mp3",
    "F#4": "https://tonejs.github.io/audio/casio/Fs4.mp3",
    A4: "https://tonejs.github.io/audio/casio/A4.mp3",
  },
  release: 1,
}).toDestination();

// 創建音樂循環
const loop = new Tone.Loop((time) => {
  sampler.triggerAttackRelease(["C4", "E4", "G4", "B4"], 0.5, time);
}, "1m");

// 點擊按鈕時啟動/暫停循環
btn.addEventListener('click', () => {
  if (Tone.Transport.state !== 'started') {
    Tone.start();
    loop.start();
    btn.textContent = 'Pause Music';
  } else {
    Tone.Transport.pause();
    btn.textContent = 'Play Music';
  }
});