/**
 * AudioEngine — 纯 Web Audio API 程序化合成，零音频文件依赖
 *
 * 使用单例模式，所有音效通过 AudioEngine.getInstance().play('soundName') 调用
 * 背景音乐通过 startBGM() / stopBGM() 控制
 */
export class AudioEngine {
  private static _instance: AudioEngine | null = null
  private ctx: AudioContext | null = null
  private bgmNodes: AudioNode[] = []
  private bgmRunning = false
  private muted = false
  private masterGain!: GainNode

  private constructor() {}

  static getInstance(): AudioEngine {
    if (!AudioEngine._instance) AudioEngine._instance = new AudioEngine()
    return AudioEngine._instance
  }

  /** 首次用户交互后调用，初始化 AudioContext */
  init(): void {
    if (this.ctx) return
    try {
      this.ctx = new AudioContext()
      this.masterGain = this.ctx.createGain()
      this.masterGain.gain.value = 0.55
      this.masterGain.connect(this.ctx.destination)
    } catch {
      // 浏览器不支持 Web Audio，静默失败
    }
  }

  setMuted(v: boolean): void {
    this.muted = v
    if (this.masterGain) this.masterGain.gain.value = v ? 0 : 0.55
  }
  isMuted(): boolean { return this.muted }

  private get ac(): AudioContext | null { return this.ctx }

  // ─── 工具方法 ────────────────────────────────────────────────────────────────

  private osc(
    type: OscillatorType,
    freq: number,
    startTime: number,
    endTime: number,
    gainStart = 0.3,
    gainEnd = 0,
    destination: AudioNode | null = null
  ): void {
    if (!this.ac) return
    const g = this.ac.createGain()
    g.gain.setValueAtTime(gainStart, startTime)
    g.gain.exponentialRampToValueAtTime(Math.max(gainEnd, 0.001), endTime)
    g.connect(destination ?? this.masterGain)
    const o = this.ac.createOscillator()
    o.type = type
    o.frequency.setValueAtTime(freq, startTime)
    o.connect(g)
    o.start(startTime)
    o.stop(endTime)
  }

  private noise(
    startTime: number,
    duration: number,
    gainVal = 0.15,
    hipass = 0,
    destination: AudioNode | null = null
  ): void {
    if (!this.ac) return
    const bufLen = this.ac.sampleRate * duration
    const buf = this.ac.createBuffer(1, bufLen, this.ac.sampleRate)
    const data = buf.getChannelData(0)
    for (let i = 0; i < bufLen; i++) data[i] = Math.random() * 2 - 1
    const src = this.ac.createBufferSource()
    src.buffer = buf
    const g = this.ac.createGain()
    g.gain.setValueAtTime(gainVal, startTime)
    g.gain.exponentialRampToValueAtTime(0.001, startTime + duration)
    if (hipass > 0) {
      const f = this.ac.createBiquadFilter()
      f.type = 'highpass'
      f.frequency.value = hipass
      src.connect(f)
      f.connect(g)
    } else {
      src.connect(g)
    }
    g.connect(destination ?? this.masterGain)
    src.start(startTime)
    src.stop(startTime + duration)
  }

  // ─── 音效库 ─────────────────────────────────────────────────────────────────

  /** 钉钉消息通知音：建塔 / 波次开始 */
  playDingTalk(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    // 叮 — 高频正弦
    this.osc('sine', 1047, t,       t + 0.18, 0.4, 0.001)
    // 咚 — 低频跟随
    this.osc('sine',  523, t + 0.1, t + 0.35, 0.25, 0.001)
  }

  /** 钉钉消息发送音（更轻）：波次开始 */
  playNotify(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.osc('sine', 880, t,        t + 0.12, 0.3, 0.001)
    this.osc('sine', 1320, t + 0.07, t + 0.2, 0.2, 0.001)
  }

  /** 拳击音：实习生近战 */
  playPunch(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.noise(t, 0.06, 0.3, 200)
    this.osc('sine', 120, t, t + 0.06, 0.35, 0.001)
  }

  /** 键盘敲击音：资深开发射击 */
  playKeyboard(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.noise(t, 0.04, 0.18, 1200)
    this.osc('square', 440, t, t + 0.03, 0.12, 0.001)
  }

  /** PPT 大师 AOE — 空洞回声 */
  playPPTBlast(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.osc('sawtooth', 180, t, t + 0.4, 0.2, 0.001)
    this.osc('sine',      90, t, t + 0.5, 0.15, 0.001)
    this.noise(t, 0.3, 0.08, 100)
  }

  /** 产品经理 — 需求变更铃 */
  playPMAttack(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.osc('triangle', 660, t,        t + 0.15, 0.25, 0.001)
    this.osc('triangle', 440, t + 0.08, t + 0.25, 0.2, 0.001)
  }

  /** 运营专员 — 数据上涨 */
  playOpsAttack(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.osc('sine', 523, t,        t + 0.08, 0.2, 0.001)
    this.osc('sine', 659, t + 0.05, t + 0.15, 0.2, 0.001)
    this.osc('sine', 784, t + 0.1,  t + 0.22, 0.2, 0.001)
  }

  /** 外包程序员 — 闷声丢出 */
  playOutsourceAttack(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.noise(t, 0.08, 0.2, 300)
    this.osc('sawtooth', 200, t, t + 0.08, 0.15, 0.001)
  }

  /** 怪物死亡 — 碎纸机 */
  playEnemyDeath(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.noise(t, 0.12, 0.22, 800)
    this.noise(t + 0.05, 0.08, 0.15, 2000)
  }

  /** Boss 登场 — 警报 + 低沉冲击 */
  playBossAppear(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    // 低沉轰鸣
    this.osc('sawtooth', 55, t,      t + 1.2, 0.5, 0.001)
    this.osc('sawtooth', 60, t + 0.1, t + 1.0, 0.3, 0.001)
    // 警报扫频
    for (let i = 0; i < 4; i++) {
      const st = t + i * 0.25
      this.osc('square', 440, st,        st + 0.1, 0.25, 0.001)
      this.osc('square', 660, st + 0.12, st + 0.22, 0.2, 0.001)
    }
  }

  /** Boss 技能触发 — 电话挂断 */
  playBossSkill(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.osc('square', 1480, t,        t + 0.06, 0.3, 0.001)
    this.osc('square', 1109, t + 0.07, t + 0.13, 0.3, 0.001)
    this.osc('square',  740, t + 0.14, t + 0.22, 0.3, 0.001)
    this.noise(t, 0.25, 0.1, 1000)
  }

  /** 塔被摧毁 — 电话挂断 */
  playTowerDestroyed(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.osc('square', 440, t,       t + 0.1,  0.35, 0.001)
    this.osc('square', 350, t + 0.1, t + 0.25, 0.35, 0.001)
    this.osc('square', 220, t + 0.2, t + 0.4,  0.35, 0.001)
    this.noise(t, 0.4, 0.12, 500)
  }

  /** 新波次开始 — 钉钉来电铃声 */
  playWaveStart(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    const pattern = [0, 0.18, 0.36, 0.64, 0.82, 1.0]
    const freqs   = [784, 784, 784, 659, 784, 880]
    pattern.forEach((delay, i) => {
      this.osc('sine', freqs[i], t + delay, t + delay + 0.14, 0.3, 0.001)
    })
  }

  /** KPI 告警（KPI < 30%）— 紧张低音 */
  playKPIWarning(): void {
    if (!this.ac) return
    const t = this.ac.currentTime
    this.osc('sawtooth', 110, t,       t + 0.3, 0.4, 0.001)
    this.osc('sawtooth', 146, t + 0.1, t + 0.3, 0.3, 0.001)
  }

  // ─── 背景音乐 ────────────────────────────────────────────────────────────────

  /**
   * 启动背景音乐（办公室 ambient：低频嗡鸣 + 轻微节奏脉冲）
   * 完全程序化合成，循环播放
   */
  startBGM(): void {
    if (!this.ac || this.bgmRunning) return
    this.bgmRunning = true
    this._scheduleBGM()
  }

  stopBGM(): void {
    this.bgmRunning = false
    this.bgmNodes.forEach(n => {
      try { (n as OscillatorNode).stop?.() } catch { /* ignore */ }
    })
    this.bgmNodes = []
  }

  private _scheduleBGM(): void {
    if (!this.ac || !this.bgmRunning) return
    const t = this.ac.currentTime

    // 底层办公室嗡鸣（电脑风扇感）
    const droneGain = this.ac.createGain()
    droneGain.gain.value = 0.04
    droneGain.connect(this.masterGain)
    const drone = this.ac.createOscillator()
    drone.type = 'sawtooth'
    drone.frequency.setValueAtTime(55, t)
    drone.frequency.linearRampToValueAtTime(58, t + 8)
    drone.frequency.linearRampToValueAtTime(55, t + 16)
    drone.connect(droneGain)
    drone.start(t)
    drone.stop(t + 16)
    this.bgmNodes.push(drone)

    // 低频键盘噪声节拍（每 0.8s 一拍）
    for (let i = 0; i < 20; i++) {
      const beat = t + i * 0.8
      const ng = this.ac.createGain()
      ng.gain.setValueAtTime(0.03, beat)
      ng.gain.exponentialRampToValueAtTime(0.001, beat + 0.15)
      ng.connect(this.masterGain)
      const ns = this.ac.createOscillator()
      ns.type = 'square'
      ns.frequency.value = i % 4 === 0 ? 130 : i % 2 === 0 ? 110 : 87
      ns.connect(ng)
      ns.start(beat)
      ns.stop(beat + 0.12)
      this.bgmNodes.push(ns)
    }

    // 16s 后循环
    setTimeout(() => {
      if (this.bgmRunning) this._scheduleBGM()
    }, 15500)
  }
}