// 纯合成音效（对应 web 版 audio.js 的 WebAudio 合成），无外部资源。
// 在 Dart 侧生成 16-bit PCM WAV 字节，通过 audioplayers 播放（自带播放池以支持重叠）。
import 'dart:math';
import 'dart:typed_data';
import 'package:audioplayers/audioplayers.dart';

class _Voice {
  final Float32List samples; // 已含包络、相对自身 0 起点
  final int delaySamples;
  _Voice(this.samples, this.delaySamples);
}

class Sfx {
  static final Sfx instance = Sfx._();
  factory Sfx() => instance;
  Sfx._();

  static bool enabled = true;
  static double volume = 0.5;

  /// 音频不可用时永久静默。
  ///
  /// 音效纯属装饰，但 audioplayers 的异常会在**别的 Zone 上下文**里冒出来，
  /// 现有的 try/catch 抓不到；一旦冒泡到全局错误钩子，整个界面会被切换成错误详情。
  /// 因此只要音频子系统出过一次错，就彻底关掉，保证「音频坏掉 ≠ 游戏坏掉」。
  static bool broken = false;

  final int rate = 44100;
  final List<AudioPlayer> _pool = [];
  final Map<String, Uint8List> _cache = {};
  bool _init = false;

  void init() {
    if (_init || broken) return;
    _init = true;
    try {
      for (int i = 0; i < 12; i++) {
        final p = AudioPlayer();
        p.setVolume(volume);
        _pool.add(p);
      }
    } catch (_) {
      broken = true;
    }
  }

  void setVolume(double v) {
    volume = v;
    for (final p in _pool) p.setVolume(v);
  }

  /// 首次用户手势时解锁音频（移动端要求用户手势后才能播放）。
  /// 音效被关闭时不创建播放器，省资源也避免插件噪声。
  void unlock() {
    if (!enabled || broken) return;
    init();
  }

  Uint8List _render(List<_Voice> voices) {
    int maxLen = 0;
    for (final v in voices) {
      maxLen = max(maxLen, v.delaySamples + v.samples.length);
    }
    final mix = Float32List(maxLen);
    for (final v in voices) {
      for (int i = 0; i < v.samples.length; i++) {
        mix[v.delaySamples + i] += v.samples[i];
      }
    }
    // 限幅
    for (int i = 0; i < mix.length; i++) {
      if (mix[i] > 1) mix[i] = 1;
      if (mix[i] < -1) mix[i] = -1;
    }
    return _encodeWav(mix);
  }

  Float32List _genTone({required double f, double f2 = 0, required double d, String type = 'square', double vol = 0.25, double delay = 0, double decay = 0}) {
    final total = d + decay + 0.02;
    final n = (total * rate).ceil();
    final out = Float32List(n);
    final t0 = (delay * rate).round();
    final len = (d * rate).round();
    final end = ((d + decay) * rate).round();
    final k = decay > 0 ? -log(0.0001) / max(1e-4, (d + decay - 0.008)) : 0.0;
    double phase = 0;
    for (int i = 0; i < n; i++) {
      final t = i / rate;
      final fr = f2 > 0 ? f * pow(f2 / f, t / max(1e-6, d)) : f;
      phase += 2 * pi * fr / rate;
      if (phase > 1e9) phase = phase % (2 * pi);
      double e;
      if (t < 0.008) {
        e = t / 0.008;
      } else {
        e = exp(-k * (t - 0.008));
      }
      final w = _wave(type, phase);
      out[i] = w * vol * e;
    }
    return out;
  }

  Float32List _genNoise({required double d, double vol = 0.25, double delay = 0, double hp = 400}) {
    final total = d + 0.02;
    final n = (total * rate).ceil();
    final out = Float32List(n);
    final t0 = (delay * rate).round();
    final end = (d * rate).round();
    final a = hp / (hp + rate);
    double hpState = 0, prevX = 0, prevOut = 0;
    for (int i = 0; i < n; i++) {
      final t = i / rate;
      final x = (Random().nextDouble() * 2 - 1) * (1 - i / max(1, n));
      final e = (i < end) ? 1.0 : 0.0;
      hpState = 0.99 * hpState + x - prevX;
      prevX = x;
      prevOut = a * (prevOut + hpState);
      out[i] = prevOut * vol * e;
    }
    return out;
  }

  static double _wave(String type, double phase) {
    switch (type) {
      case 'sine':
        return sin(phase);
      case 'triangle':
        final f = (phase / (2 * pi)) % 1;
        return 4 * (f - 0.5).abs() - 1;
      case 'sawtooth':
        final f = (phase / (2 * pi)) % 1;
        return 2 * f - 1;
      case 'square':
      default:
        return sin(phase) >= 0 ? 1 : -1;
    }
  }

  Uint8List _encodeWav(Float32List samples) {
    final n = samples.length;
    final bytes = ByteData(44 + n * 2);
    final bc = bytes.buffer.asUint8List();
    // RIFF
    bc.setRange(0, 4, [0x52, 0x49, 0x46, 0x46]); // RIFF
    bytes.setUint32(4, 36 + n * 2, Endian.little);
    bc.setRange(8, 12, [0x57, 0x41, 0x56, 0x45]); // WAVE
    bc.setRange(12, 16, [0x66, 0x6d, 0x74, 0x20]); // fmt
    bytes.setUint32(16, 16, Endian.little);
    bytes.setUint16(20, 1, Endian.little); // PCM
    bytes.setUint16(22, 1, Endian.little); // mono
    bytes.setUint32(24, rate, Endian.little);
    bytes.setUint32(28, rate * 2, Endian.little);
    bytes.setUint16(32, 2, Endian.little);
    bytes.setUint16(34, 16, Endian.little);
    bc.setRange(36, 40, [0x64, 0x61, 0x74, 0x61]); // data
    bytes.setUint32(40, n * 2, Endian.little);
    for (int i = 0; i < n; i++) {
      int s = (samples[i] * 32767).round().clamp(-32768, 32767);
      bytes.setInt16(44 + i * 2, s, Endian.little);
    }
    return bc;
  }

  Uint8List _build(String name) {
    late List<_Voice> voices;
    switch (name) {
      case 'jump':
        voices = [_v(_genTone(f: 380, f2: 700, d: 0.09, type: 'square', vol: 0.16))];
        break;
      case 'djump':
        voices = [_v(_genTone(f: 520, f2: 900, d: 0.09, type: 'square', vol: 0.14))];
        break;
      case 'shoot':
        voices = [
          _v(_genTone(f: 900, f2: 260, d: 0.07, type: 'square', vol: 0.14)),
          _v(_genNoise(d: 0.05, vol: 0.06, hp: 2000), 0),
        ];
        break;
      case 'death':
        voices = [
          _v(_genTone(f: 620, f2: 60, d: 0.55, type: 'sawtooth', vol: 0.26)),
          _v(_genNoise(d: 0.35, vol: 0.16, hp: 300), (0.02 * rate).round()),
        ];
        break;
      case 'save':
        voices = [
          _v(_genTone(f: 700, d: 0.08, type: 'triangle', vol: 0.2)),
          _v(_genTone(f: 1050, d: 0.13, type: 'triangle', vol: 0.18), (0.07 * rate).round()),
        ];
        break;
      case 'goal':
        voices = [
          for (int i = 0; i < 4; i++)
            _v(_genTone(f: [523.0, 659.0, 784.0, 1047.0][i], d: 0.16, type: 'triangle', vol: 0.2), (i * 0.1 * rate).round()),
        ];
        break;
      case 'warp':
        voices = [_v(_genTone(f: 300, f2: 1400, d: 0.2, type: 'sine', vol: 0.18))];
        break;
      case 'hit':
        voices = [_v(_genTone(f: 200, f2: 90, d: 0.08, type: 'square', vol: 0.16))];
        break;
      case 'bossHit':
        voices = [_v(_genTone(f: 260, f2: 140, d: 0.1, type: 'sawtooth', vol: 0.14))];
        break;
      case 'bossDie':
        voices = [
          for (int i = 0; i < 5; i++)
            _v(_genTone(f: [400.0, 330.0, 260.0, 180.0, 110.0][i], d: 0.22, type: 'sawtooth', vol: 0.22), (i * 0.11 * rate).round()),
          _v(_genNoise(d: 0.8, vol: 0.2, hp: 150), (0.1 * rate).round()),
        ];
        break;
      case 'menu':
        voices = [_v(_genTone(f: 620, d: 0.05, type: 'square', vol: 0.12))];
        break;
      case 'vanish':
        voices = [_v(_genTone(f: 700, f2: 300, d: 0.12, type: 'sine', vol: 0.1))];
        break;
      case 'troll':
        voices = [_v(_genTone(f: 180, f2: 900, d: 0.3, type: 'sine', vol: 0.18))];
        break;
      case 'splash':
        voices = [_v(_genNoise(d: 0.18, vol: 0.12, hp: 800))];
        break;
      default:
        voices = [_v(_genTone(f: 440, d: 0.05, type: 'square', vol: 0.1))];
    }
    return _render(voices);
  }

  _Voice _v(Float32List s, [int delaySamples = 0]) => _Voice(s, delaySamples);

  void _play(String name) {
    if (!enabled || broken) return;
    try {
      init();
      final bytes = _cache.putIfAbsent(name, () => _build(name));
      // 找一个空闲播放器
      AudioPlayer? free;
      for (final p in _pool) {
        if (p.state == PlayerState.stopped || p.state == PlayerState.completed) {
          free = p;
          break;
        }
      }
      free ??= _pool[_lastIdx = (_lastIdx + 1) % _pool.length];
      free.stop().catchError((Object _) {
        broken = true;
      });
      free
          .play(BytesSource(bytes, mimeType: 'audio/wav'))
          .catchError((Object _) {
        broken = true;
      });
    } catch (_) {
      // 任何失败都只静音，不影响玩法。
      broken = true;
    }
  }

  int _lastIdx = 0;

  void jump() => _play('jump');
  void djump() => _play('djump');
  void shoot() => _play('shoot');
  void death() => _play('death');
  void save() => _play('save');
  void goal() => _play('goal');
  void warp() => _play('warp');
  void hit() => _play('hit');
  void bossHit() => _play('bossHit');
  void bossDie() => _play('bossDie');
  void menu() => _play('menu');
  void vanish() => _play('vanish');
  void troll() => _play('troll');
  void splash() => _play('splash');
}