// 合成音效：鼓点·钟鸣·纸韵（Web Audio，零素材依赖）
let ctx: AudioContext | null = null
let enabled = true

export function setSoundEnabled(on: boolean): void {
  enabled = on
}

export function isSoundEnabled(): boolean {
  return enabled
}

function ac(): AudioContext | null {
  if (!enabled) return null
  try {
    if (!ctx) {
      const AC = window.AudioContext ?? (window as unknown as { webkitAudioContext: typeof AudioContext }).webkitAudioContext
      ctx = new AC()
    }
    if (ctx.state === 'suspended') void ctx.resume()
    return ctx
  } catch {
    return null
  }
}

function tone(freq: number, dur: number, gain: number, type: OscillatorType = 'sine', when = 0, slideTo?: number): void {
  const a = ac()
  if (!a) return
  const t0 = a.currentTime + when
  const o = a.createOscillator()
  const g = a.createGain()
  o.type = type
  o.frequency.setValueAtTime(freq, t0)
  if (slideTo) o.frequency.exponentialRampToValueAtTime(slideTo, t0 + dur)
  g.gain.setValueAtTime(0, t0)
  g.gain.linearRampToValueAtTime(gain, t0 + 0.012)
  g.gain.exponentialRampToValueAtTime(0.0001, t0 + dur)
  o.connect(g)
  g.connect(a.destination)
  o.start(t0)
  o.stop(t0 + dur + 0.05)
}

function noise(dur: number, gain: number, when = 0, freq = 3200): void {
  const a = ac()
  if (!a) return
  const t0 = a.currentTime + when
  const len = Math.floor(a.sampleRate * dur)
  const buf = a.createBuffer(1, len, a.sampleRate)
  const data = buf.getChannelData(0)
  for (let i = 0; i < len; i++) data[i] = (Math.random() * 2 - 1) * (1 - i / len)
  const src = a.createBufferSource()
  src.buffer = buf
  const f = a.createBiquadFilter()
  f.type = 'highpass'
  f.frequency.value = freq
  const g = a.createGain()
  g.gain.setValueAtTime(gain, t0)
  g.gain.exponentialRampToValueAtTime(0.0001, t0 + dur)
  src.connect(f)
  f.connect(g)
  g.connect(a.destination)
  src.start(t0)
}

/** 月度推进：极轻的硖墨声 */
export function sTick(): void {
  noise(0.05, 0.015, 0, 5000)
}

/** 开卷 / 纸笺 */
export function sPaper(): void {
  noise(0.12, 0.03, 0, 2400)
  tone(620, 0.1, 0.015, 'sine', 0.02)
}

/** 好消息：铜钟一声 */
export function sGood(): void {
  tone(660, 0.5, 0.06, 'sine')
  tone(990, 0.42, 0.03, 'sine', 0.05)
  tone(1320, 0.3, 0.018, 'sine', 0.09)
}

/** 坏消息：折磬低响 */
export function sBad(): void {
  tone(196, 0.4, 0.05, 'triangle', 0, 130)
  tone(131, 0.5, 0.04, 'triangle', 0.04, 82)
}

/** 战报：鼓点急雨 */
export function sWar(): void {
  tone(120, 0.16, 0.07, 'sine', 0, 60)
  tone(120, 0.16, 0.06, 'sine', 0.16, 60)
  tone(160, 0.3, 0.06, 'sine', 0.32, 80)
  noise(0.28, 0.02, 0.36, 1500)
}

/** 钟鸣：大事件（碑立/飞升） */
export function sBell(): void {
  tone(392, 1.4, 0.06, 'sine')
  tone(494, 1.2, 0.035, 'sine', 0.08)
  tone(587, 1.0, 0.028, 'sine', 0.16)
}

/** 突破：磬缶清越 */
export function sGong(): void {
  tone(440, 0.9, 0.05, 'sine')
  tone(660, 0.7, 0.03, 'sine', 0.06)
}

/** 按钮：纸面轻叩 */
export function sClick(): void {
  noise(0.045, 0.03, 0, 4200)
}