// ============================================================
// AUDIO — procedural Chinese-inspired score (WebAudio)
// Guqin-style Karplus-Strong plucks, taiko drums, wind
// ============================================================

const PENT = [0, 2, 4, 7, 9];          // major pentatonic
const BASE = 220;                       // A3

export class GameAudio {
  constructor() {
    this.ctx = null;
    this.enabled = true;
    this.musicVol = 0.5;
    this.sfxVol = 0.7;
    this.mode = null;
    this._melodyTimer = null;
    this._windNodes = null;
  }

  init() {
    if (this.ctx) return;
    try {
      this.ctx = new (window.AudioContext || window.webkitAudioContext)();
      this.master = this.ctx.createGain();
      this.master.gain.value = 0.9;
      this.master.connect(this.ctx.destination);
      this.musicGain = this.ctx.createGain();
      this.musicGain.gain.value = this.musicVol;
      this.musicGain.connect(this.master);
      this.sfxGain = this.ctx.createGain();
      this.sfxGain.gain.value = this.sfxVol;
      this.sfxGain.connect(this.master);
    } catch { this.ctx = null; }
  }

  setMusicVol(v) { this.musicVol = v; if (this.musicGain) this.musicGain.gain.value = v; }
  setSfxVol(v) { this.sfxVol = v; if (this.sfxGain) this.sfxGain.gain.value = v; }

  // ---------- pluck (Karplus-Strong-ish via noise burst + filtered feedback delay) ----------
  pluck(freq, when = 0, dur = 1.8, gain = 0.5, bright = 0.35) {
    if (!this.ctx) return;
    const t0 = this.ctx.currentTime + when;
    const sr = this.ctx.sampleRate;
    const N = Math.floor(sr * dur);
    const buf = this.ctx.createBuffer(1, N, sr);
    const data = buf.getChannelData(0);
    // excitation
    const period = Math.max(2, Math.floor(sr / freq));
    for (let i = 0; i < period && i < N; i++) {
      data[i] = Math.random() * 2 - 1;
    }
    // string loop with damping
    let last = 0;
    const damp = 0.996 - bright * 0.12;
    for (let i = period; i < N; i++) {
      const s = (data[i - period] + data[i - period + 1 >= N ? i - 1 : i - period + 1]) * 0.5 * damp;
      data[i] = s + last * 0.0001; // tiny body resonance
      last = s;
    }
    const src = this.ctx.createBufferSource();
    src.buffer = buf;
    const g = this.ctx.createGain();
    g.gain.value = gain;
    g.gain.setValueAtTime(gain, t0);
    g.gain.exponentialRampToValueAtTime(0.0001, t0 + dur);
    const lp = this.ctx.createBiquadFilter();
    lp.type = "lowpass"; lp.frequency.value = 2600; lp.Q.value = 0.4;
    src.connect(lp).connect(g).connect(this.musicGain);
    src.start(t0);
    src.stop(t0 + dur + 0.05);
  }

  noteFreq(deg, oct = 0) {
    const semis = PENT[((deg % 5) + 5) % 5] + 12 * (oct + Math.floor(deg / 5));
    return BASE * Math.pow(2, semis / 12);
  }

  // ---------- melody scheduler ----------
  playMusic(mode) {
    this.init();
    if (!this.ctx || this.mode === mode) return;
    this.mode = mode;
    clearInterval(this._melodyTimer);
    this.stopWind();
    if (mode === "off") { this.musicGain?.gain.setTargetAtTime(0, this.ctx.currentTime, 0.4); return; }
    this.musicGain?.gain.setTargetAtTime(this.musicVol, this.ctx.currentTime, 0.3);

    if (mode === "map" || mode === "menu") {
      this.startWind(0.05);
      const tempo = mode === "menu" ? 3400 : 2600;
      const phrase = () => {
        if (!this.enabled || !this.ctx) return;
        // gentle wandering pentatonic phrase
        let deg = Math.floor(Math.random() * 5);
        const steps = 3 + Math.floor(Math.random() * 4);
        for (let i = 0; i < steps; i++) {
          deg += [-2, -1, 1, 1, 2, 3][Math.floor(Math.random() * 6)];
          const f = this.noteFreq(deg, deg > 6 ? 0 : 1);
          this.pluck(f, i * (tempo / 1000) * (0.6 + Math.random() * 0.5), 2.4, 0.32 + Math.random() * 0.15, 0.25);
        }
        // low drone pluck occasionally
        if (Math.random() < 0.6) this.pluck(this.noteFreq(0, -1), 0, 4.5, 0.22, 0.05);
      };
      phrase();
      this._melodyTimer = setInterval(phrase, tempo);
    } else if (mode === "battle") {
      this.startWind(0.09);
      // war drums pattern
      const beat = () => {
        if (!this.enabled || !this.ctx || this.mode !== "battle") return;
        this.drum(0, 0.9);
        setTimeout(() => this.drum(0, 0.5), 380);
        setTimeout(() => this.drum(0, 0.75), 760);
      };
      beat();
      this._melodyTimer = setInterval(beat, 1900);
      // tense low strings
      this.pluck(this.noteFreq(0, -2), 0, 6, 0.3, 0.02);
      this.pluck(this.noteFreq(3, -2), 2.1, 6, 0.24, 0.02);
    } else if (mode === "victory") {
      const seq = [0, 2, 4, 7, 9, 7, 9];
      seq.forEach((d, i) => this.pluck(this.noteFreq(d, 1), i * 0.16, 2.6, 0.4, 0.3));
      this.pluck(this.noteFreq(0, -1), 0.1, 5, 0.3, 0.04);
      this.gong(0.9);
    }
  }

  // ---------- percussion ----------
  drum(when = 0, gain = 0.8, pitch = 72) {
    if (!this.ctx) return;
    const t0 = this.ctx.currentTime + when;
    const osc = this.ctx.createOscillator();
    osc.type = "sine";
    osc.frequency.setValueAtTime(pitch * 2.2, t0);
    osc.frequency.exponentialRampToValueAtTime(pitch * 0.55, t0 + 0.28);
    const g = this.ctx.createGain();
    g.gain.setValueAtTime(gain * 0.9, t0);
    g.gain.exponentialRampToValueAtTime(0.001, t0 + 0.42);
    // skin noise transient
    const nb = this.ctx.createBufferSource();
    const nbuf = this.ctx.createBuffer(1, 2000, this.ctx.sampleRate);
    const nd = nbuf.getChannelData(0);
    for (let i = 0; i < nd.length; i++) nd[i] = (Math.random() * 2 - 1) * (1 - i / nd.length);
    nb.buffer = nbuf;
    const ng = this.ctx.createGain(); ng.gain.value = gain * 0.35;
    nb.connect(ng).connect(this.sfxGain);
    osc.connect(g).connect(this.sfxGain);
    osc.start(t0); osc.stop(t0 + 0.45);
    nb.start(t0);
  }

  gong(when = 0, gain = 0.5) {
    if (!this.ctx) return;
    const t0 = this.ctx.currentTime + when;
    for (const f of [146, 213, 297, 402]) {
      const o = this.ctx.createOscillator();
      o.type = "triangle";
      o.frequency.value = f * (1 + Math.random() * 0.01);
      const g = this.ctx.createGain();
      g.gain.setValueAtTime(0, t0);
      g.gain.linearRampToValueAtTime(gain / 4, t0 + 0.02);
      g.gain.exponentialRampToValueAtTime(0.0001, t0 + 3.4);
      o.connect(g).connect(this.sfxGain);
      o.start(t0); o.stop(t0 + 3.5);
    }
  }

  horn(when = 0, gain = 0.4) {
    if (!this.ctx) return;
    const t0 = this.ctx.currentTime + when;
    const o = this.ctx.createOscillator();
    o.type = "sawtooth";
    o.frequency.setValueAtTime(98, t0);
    o.frequency.linearRampToValueAtTime(110, t0 + 0.5);
    const lp = this.ctx.createBiquadFilter();
    lp.type = "lowpass"; lp.frequency.value = 900;
    const g = this.ctx.createGain();
    g.gain.setValueAtTime(0, t0);
    g.gain.linearRampToValueAtTime(gain, t0 + 0.12);
    g.gain.exponentialRampToValueAtTime(0.0001, t0 + 1.4);
    o.connect(lp).connect(g).connect(this.sfxGain);
    o.start(t0); o.stop(t0 + 1.5);
  }

  click() {
    if (!this.ctx) return;
    const t0 = this.ctx.currentTime;
    const o = this.ctx.createOscillator();
    o.type = "square";
    o.frequency.value = 1400;
    const g = this.ctx.createGain();
    g.gain.setValueAtTime(0.06, t0);
    g.gain.exponentialRampToValueAtTime(0.0001, t0 + 0.07);
    o.connect(g).connect(this.sfxGain);
    o.start(t0); o.stop(t0 + 0.08);
  }

  swordClash() {
    if (!this.ctx) return;
    const t0 = this.ctx.currentTime;
    const nb = this.ctx.createBufferSource();
    const buf = this.ctx.createBuffer(1, 4000, this.ctx.sampleRate);
    const d = buf.getChannelData(0);
    for (let i = 0; i < d.length; i++) d[i] = (Math.random() * 2 - 1) * Math.pow(1 - i / d.length, 2);
    nb.buffer = buf;
    const bp = this.ctx.createBiquadFilter();
    bp.type = "bandpass"; bp.frequency.value = 3200; bp.Q.value = 2;
    const g = this.ctx.createGain(); g.gain.value = 0.25;
    nb.connect(bp).connect(g).connect(this.sfxGain);
    nb.start(t0);
  }

  // ---------- wind ambience ----------
  startWind(gainV = 0.06) {
    if (!this.ctx || this._windNodes) return;
    const sr = this.ctx.sampleRate;
    const buf = this.ctx.createBuffer(1, sr * 4, sr);
    const d = buf.getChannelData(0);
    let v = 0;
    for (let i = 0; i < d.length; i++) { v += (Math.random() * 2 - 1 - v) * 0.02; d[i] = v * 3; }
    const src = this.ctx.createBufferSource();
    src.buffer = buf; src.loop = true;
    const lp = this.ctx.createBiquadFilter();
    lp.type = "lowpass"; lp.frequency.value = 480;
    const g = this.ctx.createGain(); g.gain.value = gainV;
    src.connect(lp).connect(g).connect(this.musicGain);
    src.start();
    this._windNodes = { src, g };
  }

  stopWind() {
    if (this._windNodes) {
      try { this._windNodes.src.stop(); } catch { }
      this._windNodes = null;
    }
  }

  toggleEnabled() {
    this.enabled = !this.enabled;
    if (this.ctx) {
      this.master.gain.setTargetAtTime(this.enabled ? 0.9 : 0, this.ctx.currentTime, 0.1);
    }
    return this.enabled;
  }
}

export const audio = new GameAudio();