// Zero external audio assets — synthesized tones via Web Audio, matching
// this app's existing "generate what we need with code" approach (the PWA
// icons are a hand-rolled PNG encoder for the same reason). One lazily
// created AudioContext, unlocked by the first real tap (the kiosk's start
// button) so later milestone sounds triggered by a setInterval — with no
// gesture of their own — are still allowed to play for the rest of the
// page's lifetime on iOS.

let audioCtx = null;

function getAudioContext() {
  if (!audioCtx) {
    const Ctor = window.AudioContext || window.webkitAudioContext;
    audioCtx = new Ctor();
  }
  if (audioCtx.state === 'suspended') {
    audioCtx.resume();
  }
  return audioCtx;
}

function playNote(ctx, { frequency, startTime, duration, peakGain, type }) {
  const osc = ctx.createOscillator();
  const gain = ctx.createGain();
  osc.type = type;
  osc.frequency.setValueAtTime(frequency, startTime);

  gain.gain.setValueAtTime(0, startTime);
  gain.gain.linearRampToValueAtTime(peakGain, startTime + 0.015);
  gain.gain.exponentialRampToValueAtTime(0.001, startTime + duration);

  osc.connect(gain);
  gain.connect(ctx.destination);
  osc.start(startTime);
  osc.stop(startTime + duration + 0.02);
}

const CHIMES = {
  started: [{ frequency: 660, type: 'sine', duration: 0.12, peakGain: 0.15 }],
  halfway: [
    { frequency: 523, type: 'sine', duration: 0.11, peakGain: 0.2 },
    { frequency: 659, type: 'sine', duration: 0.11, peakGain: 0.2 },
  ],
  almostDone: [
    { frequency: 784, type: 'triangle', duration: 0.11, peakGain: 0.22 },
    { frequency: 659, type: 'triangle', duration: 0.11, peakGain: 0.22 },
  ],
  done: [
    { frequency: 523, type: 'sine', duration: 0.14, peakGain: 0.25 },
    { frequency: 659, type: 'sine', duration: 0.14, peakGain: 0.25 },
    { frequency: 784, type: 'sine', duration: 0.14, peakGain: 0.25 },
  ],
};

function playChime(name) {
  const notes = CHIMES[name];
  if (!notes) return;
  try {
    const ctx = getAudioContext();
    let t = ctx.currentTime;
    const gap = 0.03;
    notes.forEach((note) => {
      playNote(ctx, { ...note, startTime: t });
      t += note.duration + gap;
    });
  } catch {
    // Audio unavailable/blocked — timers still work visually without it.
  }
}