import { FFmpeg } from '@ffmpeg/ffmpeg'
import { toBlobURL } from '@ffmpeg/util'

let ffmpegInstance: FFmpeg | null = null
let loadPromise: Promise<FFmpeg> | null = null

/**
 * 获取或初始化 FFmpeg 实例（单例模式）
 */
export const useFFmpeg = async () => {
  // 如果已经加载过，直接返回
  if (ffmpegInstance && ffmpegInstance.loaded) {
    return ffmpegInstance
  }

  // 如果正在加载中，等待加载完成
  if (loadPromise) {
    return loadPromise
  }

  loadPromise = initializeFFmpeg()
  return loadPromise
}

async function initializeFFmpeg(enableMT: boolean = false): Promise<FFmpeg> {
  try {
    const ffmpeg = new FFmpeg()

    ffmpeg.on('log', ({ message, type }) => {
      console.log(`[ffmpeg - ${type}]`, message)
    })

    ffmpeg.on('progress', ({ progress, time }) => {
      console.log(`[ffmpeg] P: ${(progress * 100).toFixed(2)}%, T: ${time}ms`)
    })

    const baseURL = enableMT
      ? 'https://cdn.jsdelivr.net/npm/@ffmpeg/core-mt@0.12.10/dist/esm'
      : 'https://cdn.jsdelivr.net/npm/@ffmpeg/core@0.12.10/dist/esm'

    const coreURL = await toBlobURL(
      `${baseURL}/ffmpeg-core.js`,
      'text/javascript'
    )
    const wasmURL = await toBlobURL(
      `${baseURL}/ffmpeg-core.wasm`,
      'application/wasm'
    )

    let loadPayload = {
      coreURL,
      wasmURL,
    }

    if (enableMT) {
      const workerURL = await toBlobURL(
        `${baseURL}/ffmpeg-core.worker.js`,
        'text/javascript'
      )
      Object.assign(loadPayload, { workerURL })
    }

    const isLoaded = await ffmpeg.load(loadPayload)
    console.log('[FFmpeg] FFmpeg 加载完成，isLoaded:', isLoaded)

    ffmpegInstance = ffmpeg
    loadPromise = null
    return ffmpeg
  } catch (error) {
    console.error('[FFmpeg] 初始化失败:', error)
    loadPromise = null
    throw error
  }
}

/**
 * 清理 FFmpeg 资源
 */
export const cleanupFFmpeg = () => {
  if (ffmpegInstance && ffmpegInstance.loaded) {
    console.log('[FFmpeg] 清理 FFmpeg 资源...')
    ffmpegInstance.terminate()
    ffmpegInstance = null
    loadPromise = null
  }
}

/**
 * 将 Blob/File 转换为 Uint8Array
 */
export const fileToUint8Array = async (
  file: File | Blob
): Promise<Uint8Array> => {
  return new Promise((resolve, reject) => {
    const reader = new FileReader()
    reader.onload = (e) => {
      const arrayBuffer = e.target?.result as ArrayBuffer
      resolve(new Uint8Array(arrayBuffer))
    }
    reader.onerror = reject
    reader.readAsArrayBuffer(file)
  })
}