reader-star/apps/admin/src/utils/audio.ts

export class AudioController {
  private audioContext: AudioContext | null = null
  private soundFiles: Record<string, string> = {}
  private audioCache: Record<string, HTMLAudioElement> = {}

  constructor(soundFiles: Record<string, string> = {}) {
    this.soundFiles = soundFiles
  }

  private initAudioContext() {
    if (!this.audioContext) {
      this.audioContext = new (window.AudioContext || (window as any).webkitAudioContext)()
    }
  }

  /**
   * 播放指定类型的音效
   * 优先使用预设的音频文件，如果没有配置或加载失败，则使用 Web Audio API 合成音效
   */
  async play(type: 'start' | 'tick' | 'flip') {
    // 尝试播放音频文件
    if (this.soundFiles[type]) {
      try {
        await this.playFile(type)
        return
      }
      catch (error) {
        console.warn(`Failed to play audio file for ${type}, falling back to synth.`, error)
      }
    }

    // 回退到合成音效
    this.playSynth(type)
  }

  private playFile(type: string): Promise<void> {
    return new Promise((resolve, reject) => {
      const url = this.soundFiles[type]
      if (!url) {
        reject(new Error('No file url'))
        return
      }

      // 使用缓存的 Audio 对象
      if (!this.audioCache[type]) {
        this.audioCache[type] = new Audio(url)
      }

      const audio = this.audioCache[type]
      audio.currentTime = 0
      audio.play()
        .then(() => resolve())
        .catch(e => reject(e))
    })
  }

  private playSynth(type: 'start' | 'tick' | 'flip') {
    this.initAudioContext()
    if (!this.audioContext)
      return

    const ctxTime = this.audioContext.currentTime
    const gain = this.audioContext.createGain()
    gain.connect(this.audioContext.destination)

    if (type === 'start') {
      const osc = this.audioContext.createOscillator()
      osc.connect(gain)
      // 开始音效：高音短促提示
      osc.type = 'sine'
      osc.frequency.setValueAtTime(880, ctxTime)
      osc.frequency.exponentialRampToValueAtTime(440, ctxTime + 0.3)
      gain.gain.setValueAtTime(0.5, ctxTime)
      gain.gain.exponentialRampToValueAtTime(0.01, ctxTime + 0.3)
      osc.start(ctxTime)
      osc.stop(ctxTime + 0.3)
    }
    else if (type === 'tick') {
      const osc = this.audioContext.createOscillator()
      osc.connect(gain)
      // 倒计时音效：急促的滴答声
      osc.type = 'triangle'
      osc.frequency.setValueAtTime(600, ctxTime)
      gain.gain.setValueAtTime(0.3, ctxTime)
      gain.gain.exponentialRampToValueAtTime(0.01, ctxTime + 0.1)
      osc.start(ctxTime)
      osc.stop(ctxTime + 0.1)
    }
    else if (type === 'flip') {
      // 翻书音效：使用白噪声模拟纸张摩擦
      const bufferSize = this.audioContext.sampleRate * 0.5 // 0.5秒缓冲
      const buffer = this.audioContext.createBuffer(1, bufferSize, this.audioContext.sampleRate)
      const data = buffer.getChannelData(0)

      // 生成白噪声
      for (let i = 0; i < bufferSize; i++) {
        data[i] = Math.random() * 2 - 1
      }

      const noise = this.audioContext.createBufferSource()
      noise.buffer = buffer

      // 滤波器：低通滤波器，模拟纸张的闷声
      const filter = this.audioContext.createBiquadFilter()
      filter.type = 'lowpass'
      filter.frequency.setValueAtTime(400, ctxTime)
      filter.frequency.exponentialRampToValueAtTime(3000, ctxTime + 0.1) // 频率快速扫过，模拟快速翻动

      noise.connect(filter)
      filter.connect(gain)

      // 音量包络：快速淡入淡出
      gain.gain.setValueAtTime(0, ctxTime)
      gain.gain.linearRampToValueAtTime(0.8, ctxTime + 0.05)
      gain.gain.exponentialRampToValueAtTime(0.01, ctxTime + 0.3)

      noise.start(ctxTime)
      noise.stop(ctxTime + 0.3)
    }
  }
}