sky_phone/frontend/src/utils/mediaRecorder.ts

export function bindMediaRecorderError(
  recorder: MediaRecorder,
  isCurrent: () => boolean,
  onError: (event: Event) => void,
): () => void {
  let bound = true
  const handleError = (event: Event): void => {
    if (!bound || !isCurrent()) return
    bound = false
    recorder.removeEventListener('error', handleError)
    onError(event)
  }
  recorder.addEventListener('error', handleError)
  return () => {
    if (!bound) return
    bound = false
    recorder.removeEventListener('error', handleError)
  }
}

export async function stopMediaRecorder(
  recorder: MediaRecorder,
): Promise<void> {
  if (recorder.state === 'inactive') return

  await new Promise<void>((resolve, reject) => {
    const cleanup = (): void => {
      recorder.removeEventListener('stop', onStop)
      recorder.removeEventListener('error', onError)
    }
    const onStop = (): void => {
      cleanup()
      resolve()
    }
    const onError = (): void => {
      cleanup()
      reject(new Error('media_recorder_stop_failed'))
    }

    recorder.addEventListener('stop', onStop, { once: true })
    recorder.addEventListener('error', onError, { once: true })
    try {
      recorder.stop()
    } catch (error) {
      cleanup()
      reject(error)
    }
  })
}

export function setBoundedMapEntry<Key, Value>(
  entries: Map<Key, Value>,
  key: Key,
  value: Value,
  maximumSize: number,
): void {
  entries.delete(key)
  entries.set(key, value)
  while (entries.size > Math.max(0, maximumSize)) {
    const oldest = entries.keys().next()
    if (oldest.done) break
    entries.delete(oldest.value)
  }
}

export function compressWaveformSamples(
  samples: number[],
  sampleCount: number,
  minimum = 0.08,
): number[] {
  const count = Math.max(1, Math.floor(sampleCount))
  const floor = Math.max(0, Math.min(1, minimum))
  if (!samples.length) return Array(count).fill(floor)

  const bucketSize = samples.length / count
  const fallback = samples.at(-1) ?? floor
  return Array.from({ length: count }, (_, index) => {
    const start = Math.floor(index * bucketSize)
    const end = Math.max(start + 1, Math.floor((index + 1) * bucketSize))
    const bucket = samples.slice(start, end)
    const average = bucket.length
      ? bucket.reduce((total, sample) => total + sample, 0) / bucket.length
      : fallback
    return Math.max(floor, Math.min(1, average))
  })
}