import { useCallback, useState } from 'react'
import * as FileSystem from 'expo-file-system'
import * as MediaLibrary from 'expo-media-library'

export type MediaType = 'image' | 'video'

export interface DownloadResult {
  success: boolean
  error?: string
}

export const useDownloadMedia = () => {
  const [loading, setLoading] = useState(false)
  const [error, setError] = useState<string | null>(null)
  const [progress, setProgress] = useState(0)

  const download = useCallback(async (url: string, type: MediaType): Promise<DownloadResult> => {
    setLoading(true)
    setError(null)
    setProgress(0)

    let fileUri: string | null = null

    try {
      // 1. 请求媒体库权限
      const { status } = await MediaLibrary.requestPermissionsAsync()
      if (status !== 'granted') {
        setError('Permission denied')
        setLoading(false)
        return { success: false, error: 'Permission denied' }
      }

      // 2. 生成临时文件名
      const extension = type === 'video' ? 'mp4' : 'jpg'
      const fileName = `download_${Date.now()}.${extension}`
      fileUri = FileSystem.documentDirectory + fileName

      // 3. 下载文件（带进度）
      const downloadResumable = FileSystem.createDownloadResumable(
        url,
        fileUri,
        {},
        (downloadProgress) => {
          const progressValue = downloadProgress.totalBytesWritten / downloadProgress.totalBytesExpectedToWrite
          setProgress(progressValue)
        }
      )

      const downloadResult = await downloadResumable.downloadAsync()
      if (!downloadResult?.uri) {
        throw new Error('Download failed')
      }

      // 4. 保存到相册
      await MediaLibrary.saveToLibraryAsync(downloadResult.uri)

      // 5. 清理临时文件
      await FileSystem.deleteAsync(fileUri, { idempotent: true })

      setLoading(false)
      setProgress(0)
      return { success: true }
    } catch (e) {
      const errorMessage = e instanceof Error ? e.message : 'Download failed'
      setError(errorMessage)
      setLoading(false)
      setProgress(0)

      // 尝试清理临时文件
      if (fileUri) {
        try {
          await FileSystem.deleteAsync(fileUri, { idempotent: true })
        } catch {
          // 忽略清理错误
        }
      }

      return { success: false, error: errorMessage }
    }
  }, [])

  return { download, loading, error, progress }
}