import { ref, readonly } from 'vue'

export interface SilenceDetectorOptions {
  thresholdDb?: number       // default -40
  silenceDurationMs?: number // default 1500
  minRecordingMs?: number    // default 500
}

export function useSilenceDetector(options: SilenceDetectorOptions = {}) {
  const {
    thresholdDb = -40,
    silenceDurationMs = 1500,
    minRecordingMs = 500,
  } = options

  const amplitude = ref(0)
  let audioCtx: AudioContext | null = null
  let intervalId: ReturnType<typeof setInterval> | null = null
  let silenceMs = 0
  let startedAt = 0

  function start(stream: MediaStream, onSilence: () => void): void {
    stop()
    audioCtx = new AudioContext()
    // Some browsers start AudioContext in "suspended" state — resume so
    // getByteFrequencyData returns real values instead of all zeros.
    audioCtx.resume().catch(() => {})
    const source = audioCtx.createMediaStreamSource(stream)
    const analyser = audioCtx.createAnalyser()
    analyser.fftSize = 256
    source.connect(analyser)

    const data = new Uint8Array(analyser.frequencyBinCount)
    silenceMs = 0
    startedAt = Date.now()

    intervalId = setInterval(() => {
      analyser.getByteFrequencyData(data)
      const rms = Math.sqrt(data.reduce((s, v) => s + v * v, 0) / data.length) / 255
      amplitude.value = rms

      const db = rms > 0 ? 20 * Math.log10(rms) : -100
      if (db < thresholdDb) {
        silenceMs += 100
        if (silenceMs >= silenceDurationMs && Date.now() - startedAt >= minRecordingMs) {
          stop()
          onSilence()
        }
      } else {
        silenceMs = 0
      }
    }, 100)
  }

  function stop(): void {
    if (intervalId !== null) {
      clearInterval(intervalId)
      intervalId = null
    }
    if (audioCtx) {
      audioCtx.close().catch(() => {})
      audioCtx = null
    }
    amplitude.value = 0
    silenceMs = 0
  }

  return { amplitude: readonly(amplitude), start, stop }
}