import { writeFileSync, existsSync, mkdirSync } from 'fs'
import { join } from 'path'
import { requireAdmin } from '../../utils/auth.js'

/**
 * 下载外部图片到本地
 * POST /api/admin/download-image
 * Body: { url: "https://..." }
 * Returns: { localUrl: "/uploads/covers/xxx.webp" }
 */

const ALLOWED_HOSTS = [
  'sns-webpic-qc.xhscdn.com',
  'ci.xiaohongshu.com',
  'sns-img-bd.xhscdn.com',
]

/**
 * 将签名 CDN URL 转为永久可下载的 URL
 */
function toPermanentUrl(url) {
  try {
    const parsed = new URL(url)
    if (parsed.hostname === 'sns-webpic-qc.xhscdn.com') {
      const parts = parsed.pathname.split('/')
      if (parts.length >= 4) {
        const imagePath = parts.slice(3).join('/')
        return `https://ci.xiaohongshu.com/${imagePath}`
      }
    }
  } catch {}
  return url
}

export default defineEventHandler(async (event) => {
  requireAdmin(event)

  const { url } = await readBody(event)
  if (!url || !url.startsWith('http')) {
    throw createError({ statusCode: 400, message: '请提供有效的图片 URL' })
  }

  // 验证域名白名单
  let parsedUrl
  try {
    parsedUrl = new URL(url)
  } catch {
    throw createError({ statusCode: 400, message: '无效的 URL' })
  }

  if (!ALLOWED_HOSTS.includes(parsedUrl.hostname)) {
    throw createError({ statusCode: 403, message: '该域名不支持自动下载，请手动上传图片' })
  }

  // 生成本地文件名
  const pathParts = parsedUrl.pathname.split('/')
  const imageId = pathParts[pathParts.length - 1].split('!')[0] || `img-${Date.now()}`
  const filename = `${imageId}.webp`
  const coversDir = join(process.cwd(), 'public', 'uploads', 'covers')

  if (!existsSync(coversDir)) {
    mkdirSync(coversDir, { recursive: true })
  }

  const localPath = join(coversDir, filename)
  const localUrl = `/uploads/covers/${filename}`

  // 如果已下载过，直接返回
  if (existsSync(localPath)) {
    return { localUrl }
  }

  // 下载图片
  const downloadUrl = toPermanentUrl(url)
  try {
    const res = await fetch(downloadUrl, {
      headers: {
        'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36',
      },
    })
    if (!res.ok) {
      throw createError({ statusCode: 502, message: `图片下载失败 (${res.status})` })
    }
    const buffer = Buffer.from(await res.arrayBuffer())
    writeFileSync(localPath, buffer)
    return { localUrl }
  } catch (err) {
    if (err.statusCode) throw err
    throw createError({ statusCode: 502, message: `图片下载出错: ${err.message}` })
  }
})