/* ============================================================
 * pb_audio.js · 物理弹球 Web 复刻版 · WebAudio 合成音效
 * 无外部资源：发射/击中/碎裂/道具/结束 均为振荡器合成。
 * 设置页可开关（PBStorage.soundOn）。
 * ============================================================ */
var PBAudio = (function () {
  'use strict';
  var ctx = null;
  var lastHit = 0, lastWall = 0;   // 分开节流，防砖块命中音被墙壁音吃掉

  function ac() {
    if (!ctx) {
      try { ctx = new (window.AudioContext || window.webkitAudioContext)(); } catch (e) { ctx = null; }
    }
    if (ctx && ctx.state === 'suspended') { try { ctx.resume(); } catch (e) {} }
    return ctx;
  }

  function enabled() {
    try { return PBStorage.soundOn(); } catch (e) { return true; }
  }

  function tone(freq, dur, type, gain, slideTo) {
    var c = ac();
    if (!c || !enabled()) return;
    try {
      var o = c.createOscillator();
      var g = c.createGain();
      o.type = type || 'sine';
      o.frequency.setValueAtTime(freq, c.currentTime);
      if (slideTo) o.frequency.exponentialRampToValueAtTime(slideTo, c.currentTime + dur);
      g.gain.setValueAtTime(gain || 0.08, c.currentTime);
      g.gain.exponentialRampToValueAtTime(0.0001, c.currentTime + dur);
      o.connect(g); g.connect(c.destination);
      o.start(); o.stop(c.currentTime + dur + 0.02);
    } catch (e) {}
  }

  return {
    unlock: function () { ac(); },
    fire: function () { tone(520, 0.12, 'triangle', 0.06, 260); },
    hit: function (speed) {
      var now = Date.now();
      if (now - lastHit < 45) return;   // 限流防炸音
      lastHit = now;
      tone(300 + Math.min(500, speed * 0.15), 0.06, 'square', 0.035);
    },
    wall: function () {
      var now = Date.now();
      if (now - lastWall < 45) return;
      lastWall = now;
      tone(180, 0.05, 'sine', 0.03);
    },
    breakBlock: function () { tone(760, 0.16, 'sawtooth', 0.06, 180); },
    item: function () { tone(660, 0.1, 'sine', 0.07, 990); tone(990, 0.16, 'sine', 0.06, 1320); },
    over: function () { tone(392, 0.25, 'triangle', 0.08, 196); },
    claim: function () { tone(523, 0.09, 'sine', 0.07); tone(659, 0.09, 'sine', 0.07); tone(784, 0.16, 'sine', 0.07); }
  };
})();