// Web Audio API Audio System with Voice Polyphony Limiting & SFX Throttling
(function() {
  'use strict';

  // Musical note frequency lookup
  const N = {
    D2: 73.42, E2: 82.41, F2: 87.31, G2: 98.00, A2: 110.00, Bb2: 116.54, B2: 123.47,
    C3: 130.81, D3: 146.83, Eb3: 155.56, E3: 164.81, F3: 174.61, G3: 196.00, A3: 220.00, Bb3: 233.08, B3: 246.94,
    C4: 261.63, Csharp4: 277.18, D4: 293.66, Eb4: 311.13, E4: 329.63, F4: 349.23, Fsharp4: 369.99, G4: 392.00, Gsharp4: 415.30, A4: 440.00, Bb4: 466.16, B4: 493.88,
    C5: 523.25, Csharp5: 554.37, D5: 587.33, Eb5: 622.25, E5: 659.25, F5: 698.46, Fsharp5: 739.99, G5: 783.99, A5: 880.00, Bb5: 932.33, B5: 987.77,
    C6: 1046.50
  };

  const THEMES = {
    day: {
      tempo: 230,
      bassType: 'triangle',
      leadType: 'sine',
      bassVol: 0.10,
      leadVol: 0.08,
      bass: [
        N.A2, null, N.E3, null, N.A2, null, N.E3, null,
        N.D3, null, N.A3, null, N.E3, null, N.G3, null
      ],
      lead: [
        N.A4, null, N.C5, N.E5, null, N.D5, N.C5, N.B4,
        N.A4, null, N.C5, N.A4, null, N.B4, N.C5, N.B4
      ]
    },
    night: {
      tempo: 280,
      bassType: 'sine',
      leadType: 'triangle',
      bassVol: 0.12,
      leadVol: 0.07,
      bass: [
        N.C3, null, N.G3, null, N.A2, null, N.E3, null,
        N.F3, null, N.C4, null, N.G3, null, N.B3, null
      ],
      lead: [
        N.C5, null, N.Eb5, N.G5, null, N.F5, null, N.D5,
        N.Eb5, null, N.C5, null, N.G4, null, N.Bb4, null
      ]
    },
    pool: {
      tempo: 210,
      bassType: 'triangle',
      leadType: 'sine',
      bassVol: 0.11,
      leadVol: 0.09,
      bass: [
        N.G2, null, N.D3, N.G3, N.C3, null, N.G3, N.C4,
        N.D3, null, N.A3, N.D4, N.G3, null, N.B3, null
      ],
      lead: [
        N.B4, N.D5, null, N.G5, N.Fsharp5, N.D5, null, N.B4,
        N.C5, N.E5, null, N.A5, N.G5, N.E5, N.D5, null
      ]
    },
    fog: {
      tempo: 310,
      bassType: 'sawtooth',
      leadType: 'triangle',
      bassVol: 0.07,
      leadVol: 0.07,
      bass: [
        N.D2, null, N.A2, null, N.D2, null, N.Bb2, null,
        N.A2, null, N.F2, null, N.G2, null, N.A2, null
      ],
      lead: [
        N.D5, null, null, N.F5, null, N.E5, null, N.Csharp5,
        N.D5, null, N.A4, null, null, N.F5, N.E5, null
      ]
    },
    roof: {
      tempo: 190,
      bassType: 'triangle',
      leadType: 'sawtooth',
      bassVol: 0.11,
      leadVol: 0.06,
      bass: [
        N.F3, N.F3, N.C4, N.F3, N.Bb3, N.Bb3, N.F4, N.Bb3,
        N.C3, N.C3, N.G3, N.C4, N.F3, null, N.C4, null
      ],
      lead: [
        N.F4, N.A4, N.C5, null, N.D5, N.F5, null, N.C5,
        N.Bb4, N.D5, N.F5, null, N.A5, N.G5, N.F5, null
      ]
    },
    boss: {
      tempo: 165,
      bassType: 'sawtooth',
      leadType: 'square',
      bassVol: 0.09,
      leadVol: 0.06,
      bass: [
        N.E2, N.E2, N.G2, N.E2, N.Bb2, N.A2, N.G2, N.E2,
        N.E2, N.E2, N.B2, N.Bb2, N.A2, N.G2, N.E2, N.D3
      ],
      lead: [
        N.E5, N.E5, N.G5, null, N.Bb5, N.A5, N.G5, N.E5,
        null, N.B5, N.Bb5, N.A5, null, N.G5, N.F5, N.E5
      ]
    }
  };

  class AudioSystem {
    constructor() {
      this.ctx = null;
      this.muted = false;

      // Music State
      this.musicInterval = null;
      this.musicPlaying = false;
      this.musicStep = 0;
      this.currentThemeName = 'day';

      // Polyphony & Voice Limiting State
      this.maxGlobalVoices = 24;
      this.activeVoiceCount = 0;
      this.activeVoicesPerKey = new Map();
      this.lastPlayTime = new Map();

      // Per-sound configuration (polyphony cap & throttle cooldown ms)
      this.sfxLimits = {
        shoot: { maxVoices: 4, minIntervalMs: 40 },
        hit: { maxVoices: 4, minIntervalMs: 35 },
        splat: { maxVoices: 4, minIntervalMs: 35 },
        chomp: { maxVoices: 3, minIntervalMs: 65 },
        coin: { maxVoices: 4, minIntervalMs: 35 },
        sun: { maxVoices: 3, minIntervalMs: 50 },
        plant: { maxVoices: 3, minIntervalMs: 40 },
        explosion: { maxVoices: 3, minIntervalMs: 80 },
        sizzle: { maxVoices: 2, minIntervalMs: 100 },
        mower: { maxVoices: 2, minIntervalMs: 150 },
        strike: { maxVoices: 3, minIntervalMs: 50 },
        btn: { maxVoices: 2, minIntervalMs: 30 }
      };
    }

    init() {
      if (!this.ctx) {
        const AudioCtx = window.AudioContext || window.webkitAudioContext;
        if (AudioCtx) {
          this.ctx = new AudioCtx();
        }
      }
      if (this.ctx && this.ctx.state === 'suspended') {
        this.ctx.resume().catch(() => {});
      }
    }

    toggleMute() {
      this.muted = !this.muted;
      return this.muted;
    }

    isMuted() {
      return this.muted;
    }

    // Check voice limits and throttling
    canPlayVoice(key) {
      if (this.muted) return false;
      this.init();
      if (!this.ctx) return false;

      const now = performance.now();
      const cfg = this.sfxLimits[key] || { maxVoices: 4, minIntervalMs: 40 };

      // 1. Throttle check
      const last = this.lastPlayTime.get(key) || 0;
      if (now - last < cfg.minIntervalMs) {
        return false;
      }

      // 2. Global polyphony limit
      if (this.activeVoiceCount >= this.maxGlobalVoices) {
        return false;
      }

      // 3. Per-sound polyphony limit
      const currentActive = this.activeVoicesPerKey.get(key) || 0;
      if (currentActive >= cfg.maxVoices) {
        return false;
      }

      // Register timestamp
      this.lastPlayTime.set(key, now);
      return true;
    }

    registerVoice(key, durationSec) {
      this.activeVoiceCount++;
      const current = this.activeVoicesPerKey.get(key) || 0;
      this.activeVoicesPerKey.set(key, current + 1);

      const release = () => {
        this.activeVoiceCount = Math.max(0, this.activeVoiceCount - 1);
        const cur = this.activeVoicesPerKey.get(key) || 1;
        this.activeVoicesPerKey.set(key, Math.max(0, cur - 1));
      };

      setTimeout(release, Math.ceil(durationSec * 1000) + 20);
    }

    playTone(freq, type, duration, startVol = 0.2, endVol = 0.001) {
      if (this.muted) return;
      this.init();
      if (!this.ctx) return;
      try {
        const osc = this.ctx.createOscillator();
        const gain = this.ctx.createGain();
        osc.type = type;
        osc.frequency.setValueAtTime(freq, this.ctx.currentTime);
        gain.gain.setValueAtTime(startVol, this.ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(endVol, this.ctx.currentTime + duration);
        osc.connect(gain);
        gain.connect(this.ctx.destination);
        osc.start();
        osc.stop(this.ctx.currentTime + duration);
      } catch (e) {}
    }

    playShoot() {
      if (!this.canPlayVoice('shoot')) return;
      try {
        const ctx = this.ctx;
        const dur = 0.11;
        this.registerVoice('shoot', dur);

        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'triangle';
        osc.frequency.setValueAtTime(620, ctx.currentTime);
        osc.frequency.exponentialRampToValueAtTime(120, ctx.currentTime + dur);
        gain.gain.setValueAtTime(0.24, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.01, ctx.currentTime + dur);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + dur);
      } catch (e) {}
    }

    playHit() {
      if (!this.canPlayVoice('hit')) return;
      try {
        const ctx = this.ctx;
        const dur = 0.08;
        this.registerVoice('hit', dur);

        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'square';
        osc.frequency.setValueAtTime(180, ctx.currentTime);
        osc.frequency.exponentialRampToValueAtTime(60, ctx.currentTime + dur);
        gain.gain.setValueAtTime(0.2, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.01, ctx.currentTime + dur);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + dur);
      } catch (e) {}
    }

    playSplat() {
      if (!this.canPlayVoice('splat')) return;
      try {
        const ctx = this.ctx;
        const dur = 0.09;
        this.registerVoice('splat', dur);

        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'triangle';
        osc.frequency.setValueAtTime(280, ctx.currentTime);
        osc.frequency.exponentialRampToValueAtTime(70, ctx.currentTime + dur);
        gain.gain.setValueAtTime(0.22, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.01, ctx.currentTime + dur);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + dur);
      } catch (e) {}
    }

    playSun() {
      if (!this.canPlayVoice('sun')) return;
      try {
        const ctx = this.ctx;
        this.registerVoice('sun', 0.35);
        const notes = [523.25, 659.25, 783.99, 1046.50]; // C5, E5, G5, C6
        notes.forEach((freq, idx) => {
          const osc = ctx.createOscillator();
          const gain = ctx.createGain();
          osc.type = 'sine';
          osc.frequency.setValueAtTime(freq, ctx.currentTime + idx * 0.05);
          gain.gain.setValueAtTime(0.18, ctx.currentTime + idx * 0.05);
          gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + idx * 0.05 + 0.2);
          osc.connect(gain);
          gain.connect(ctx.destination);
          osc.start(ctx.currentTime + idx * 0.05);
          osc.stop(ctx.currentTime + idx * 0.05 + 0.2);
        });
      } catch (e) {}
    }

    playPlant() {
      if (!this.canPlayVoice('plant')) return;
      try {
        const ctx = this.ctx;
        const dur = 0.15;
        this.registerVoice('plant', dur);

        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'sine';
        osc.frequency.setValueAtTime(220, ctx.currentTime);
        osc.frequency.exponentialRampToValueAtTime(440, ctx.currentTime + 0.1);
        gain.gain.setValueAtTime(0.3, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.01, ctx.currentTime + dur);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + dur);
      } catch (e) {}
    }

    playChomp() {
      if (!this.canPlayVoice('chomp')) return;
      try {
        const ctx = this.ctx;
        const dur = 0.1;
        this.registerVoice('chomp', dur);

        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'sawtooth';
        osc.frequency.setValueAtTime(140, ctx.currentTime);
        osc.frequency.exponentialRampToValueAtTime(80, ctx.currentTime + dur);
        gain.gain.setValueAtTime(0.15, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.01, ctx.currentTime + dur);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + dur);
      } catch (e) {}
    }

    playExplosion() {
      if (!this.canPlayVoice('explosion')) return;
      try {
        const ctx = this.ctx;
        const dur = 0.5;
        this.registerVoice('explosion', dur);

        const bufferSize = Math.floor(ctx.sampleRate * dur);
        const buffer = ctx.createBuffer(1, bufferSize, ctx.sampleRate);
        const data = buffer.getChannelData(0);
        for (let i = 0; i < bufferSize; i++) {
          data[i] = Math.random() * 2 - 1;
        }
        const noise = ctx.createBufferSource();
        noise.buffer = buffer;
        const filter = ctx.createBiquadFilter();
        filter.type = 'lowpass';
        filter.frequency.setValueAtTime(800, ctx.currentTime);
        filter.frequency.exponentialRampToValueAtTime(50, ctx.currentTime + dur);
        const gain = ctx.createGain();
        gain.gain.setValueAtTime(0.5, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.01, ctx.currentTime + dur);
        noise.connect(filter);
        filter.connect(gain);
        gain.connect(ctx.destination);
        noise.start();
      } catch (e) {}
    }

    playMower() {
      if (!this.canPlayVoice('mower')) return;
      try {
        const ctx = this.ctx;
        const dur = 1.2;
        this.registerVoice('mower', dur);

        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'sawtooth';
        osc.frequency.setValueAtTime(90, ctx.currentTime);
        osc.frequency.linearRampToValueAtTime(240, ctx.currentTime + dur);
        gain.gain.setValueAtTime(0.3, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.01, ctx.currentTime + dur);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + dur);
      } catch (e) {}
    }

    playCoin() {
      if (!this.canPlayVoice('coin')) return;
      try {
        const ctx = this.ctx;
        const dur = 0.3;
        this.registerVoice('coin', dur);

        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'sine';
        osc.frequency.setValueAtTime(987.77, ctx.currentTime); // B5
        osc.frequency.setValueAtTime(1318.51, ctx.currentTime + 0.06); // E6
        gain.gain.setValueAtTime(0.2, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + dur);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + dur);
      } catch (e) {}
    }

    playSizzle() {
      if (!this.canPlayVoice('sizzle')) return;
      try {
        const ctx = this.ctx;
        const dur = 0.8;
        this.registerVoice('sizzle', dur);

        const bufferSize = Math.floor(ctx.sampleRate * dur);
        const buffer = ctx.createBuffer(1, bufferSize, ctx.sampleRate);
        const data = buffer.getChannelData(0);
        for (let i = 0; i < bufferSize; i++) {
          data[i] = Math.random() * 2 - 1;
        }
        const noise = ctx.createBufferSource();
        noise.buffer = buffer;
        const filter = ctx.createBiquadFilter();
        filter.type = 'bandpass';
        filter.frequency.setValueAtTime(1400, ctx.currentTime);
        filter.frequency.exponentialRampToValueAtTime(300, ctx.currentTime + dur);
        const gain = ctx.createGain();
        gain.gain.setValueAtTime(0.4, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.01, ctx.currentTime + dur);
        noise.connect(filter);
        filter.connect(gain);
        gain.connect(ctx.destination);
        noise.start();
      } catch (e) {}
    }

    playMine() {
      this.playExplosion();
      this.playTone(550, 'sine', 0.15, 0.3, 0.01);
    }

    playVault() {
      if (this.muted) return;
      this.init();
      if (!this.ctx) return;
      try {
        const osc = this.ctx.createOscillator();
        const gain = this.ctx.createGain();
        osc.type = 'triangle';
        osc.frequency.setValueAtTime(180, this.ctx.currentTime);
        osc.frequency.exponentialRampToValueAtTime(620, this.ctx.currentTime + 0.3);
        gain.gain.setValueAtTime(0.25, this.ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.01, this.ctx.currentTime + 0.3);
        osc.connect(gain);
        gain.connect(this.ctx.destination);
        osc.start();
        osc.stop(this.ctx.currentTime + 0.3);
      } catch (e) {}
    }

    playGulp() {
      this.playTone(180, 'sine', 0.18, 0.35, 0.01);
      setTimeout(() => this.playTone(120, 'sine', 0.22, 0.3, 0.01), 90);
    }

    playStrike() {
      if (!this.canPlayVoice('strike')) return;
      this.registerVoice('strike', 0.2);
      this.playTone(240, 'square', 0.1, 0.3, 0.01);
      this.playTone(120, 'sawtooth', 0.2, 0.35, 0.01);
    }

    playHugeWave() {
      this.playTone(180, 'sawtooth', 0.6, 0.35, 0.01);
    }

    playButtonClick() {
      if (!this.canPlayVoice('btn')) return;
      this.registerVoice('btn', 0.06);
      this.playTone(480, 'sine', 0.05, 0.18, 0.01);
    }

    playWin() {
      if (this.muted) return;
      this.init();
      if (!this.ctx) return;
      const fanfare = [392, 523, 659, 784, 1046];
      fanfare.forEach((f, i) => {
        setTimeout(() => this.playTone(f, 'triangle', 0.35, 0.3, 0.01), i * 160);
      });
    }

    playLose() {
      if (this.muted) return;
      this.init();
      if (!this.ctx) return;
      const doom = [400, 360, 320, 280, 220];
      doom.forEach((f, i) => {
        setTimeout(() => this.playTone(f, 'sawtooth', 0.4, 0.3, 0.01), i * 200);
      });
    }

    // Background Music (Multi-Biome Procedural Chiptune Synthesizer)
    startMusic(themeName = 'day') {
      const targetTheme = THEMES[themeName] ? themeName : 'day';

      if (this.musicPlaying && this.currentThemeName === targetTheme && this.musicInterval) {
        return;
      }

      this.currentThemeName = targetTheme;
      this.musicPlaying = true;
      this.init();

      if (this.musicInterval) {
        clearInterval(this.musicInterval);
        this.musicInterval = null;
      }

      this.musicStep = 0;
      const theme = THEMES[this.currentThemeName];

      this.musicInterval = setInterval(() => {
        if (!this.musicPlaying || this.muted) return;
        const b = theme.bass[this.musicStep % theme.bass.length];
        const l = theme.lead[this.musicStep % theme.lead.length];
        if (b) {
          this.playTone(b, theme.bassType, (theme.tempo / 1000) * 1.05, theme.bassVol, 0.001);
        }
        if (l) {
          this.playTone(l, theme.leadType, (theme.tempo / 1000) * 0.95, theme.leadVol, 0.001);
        }
        this.musicStep++;
      }, theme.tempo);
    }

    setTheme(themeName) {
      if (this.musicPlaying) {
        this.startMusic(themeName);
      } else {
        this.currentThemeName = THEMES[themeName] ? themeName : 'day';
      }
    }

    getTheme() {
      return this.currentThemeName;
    }

    stopMusic() {
      this.musicPlaying = false;
      if (this.musicInterval) {
        clearInterval(this.musicInterval);
        this.musicInterval = null;
      }
    }

    toggleMusic() {
      if (this.musicPlaying) {
        this.stopMusic();
        return false;
      } else {
        this.startMusic(this.currentThemeName);
        return true;
      }
    }

    isMusicPlaying() {
      return this.musicPlaying;
    }
  }

  // Instantiate singleton instance
  const audioInstance = new AudioSystem();
  window.AudioSystem = AudioSystem;
  window.PvZAudio = audioInstance;
})();