/**
 * 获取私有桶文件的预签名访问 URL
 *
 * 用于展示/下载 TOS 私有桶中的文件。
 * 自动缓存签名 URL，过期前 5 分钟刷新。
 */
import { useState, useEffect, useCallback, useRef } from 'react'
import { api } from '@/lib/api'
import { USE_MOCK } from '@/contexts/AuthContext'

const urlCache = new Map<string, { signedUrl: string; expireAt: number }>()

export function useSignedUrl(originalUrl: string | undefined | null) {
  const [signedUrl, setSignedUrl] = useState<string | null>(null)
  const [loading, setLoading] = useState(false)
  const mountedRef = useRef(true)

  useEffect(() => {
    mountedRef.current = true
    return () => { mountedRef.current = false }
  }, [])

  const fetchSignedUrl = useCallback(async () => {
    if (!originalUrl) {
      setSignedUrl(null)
      return
    }

    // Mock 模式直接返回原始 URL
    if (USE_MOCK) {
      setSignedUrl(originalUrl)
      return
    }

    // 非 TOS URL（如外部链接）直接返回
    if (!originalUrl.includes('tos-cn-') && !originalUrl.includes('volces.com') && !originalUrl.startsWith('uploads/')) {
      setSignedUrl(originalUrl)
      return
    }

    // 检查缓存（提前 5 分钟过期）
    const cached = urlCache.get(originalUrl)
    if (cached && cached.expireAt > Date.now() + 5 * 60 * 1000) {
      setSignedUrl(cached.signedUrl)
      return
    }

    setLoading(true)
    try {
      const expireSeconds = 3600
      const url = await api.getSignedUrl(originalUrl, expireSeconds)
      if (mountedRef.current) {
        setSignedUrl(url)
        urlCache.set(originalUrl, {
          signedUrl: url,
          expireAt: Date.now() + expireSeconds * 1000,
        })
      }
    } catch {
      // 签名失败时回退到原始 URL
      if (mountedRef.current) {
        setSignedUrl(originalUrl)
      }
    } finally {
      if (mountedRef.current) {
        setLoading(false)
      }
    }
  }, [originalUrl])

  useEffect(() => {
    fetchSignedUrl()
  }, [fetchSignedUrl])

  return { signedUrl, loading, refresh: fetchSignedUrl }
}

/**
 * 批量获取签名 URL 的工具函数
 */
export async function getSignedUrls(urls: string[]): Promise<Map<string, string>> {
  const result = new Map<string, string>()

  if (USE_MOCK) {
    urls.forEach(u => result.set(u, u))
    return result
  }

  await Promise.all(
    urls.map(async (url) => {
      try {
        const signed = await api.getSignedUrl(url)
        result.set(url, signed)
      } catch {
        result.set(url, url)
      }
    })
  )

  return result
}