import { NextRequest, NextResponse } from 'next/server'
import { writeFile, mkdir } from 'fs/promises'
import { join } from 'path'
import { existsSync } from 'fs'
import { getServerSession } from 'next-auth'
import { authOptions } from '@/lib/auth'

export async function POST(req: NextRequest) {
  try {
    // 验证用户登录
    const session = await getServerSession(authOptions)
    if (!session?.user?.id) {
      return NextResponse.json({ error: '未授权' }, { status: 401 })
    }

    const formData = await req.formData()
    const file = formData.get('file') as File
    
    if (!file) {
      return NextResponse.json({ error: '没有文件' }, { status: 400 })
    }

    // 验证文件类型
    if (!file.type.startsWith('image/')) {
      return NextResponse.json({ error: '只能上传图片文件' }, { status: 400 })
    }

    // 验证文件大小（限制为 5MB）
    const maxSize = 5 * 1024 * 1024 // 5MB
    if (file.size > maxSize) {
      return NextResponse.json({ error: '文件大小不能超过 5MB' }, { status: 400 })
    }

    // 读取文件内容
    const bytes = await file.arrayBuffer()
    const buffer = Buffer.from(bytes)

    // 确保上传目录存在
    const uploadDir = join(process.cwd(), 'public', 'uploads')
    if (!existsSync(uploadDir)) {
      await mkdir(uploadDir, { recursive: true })
    }

    // 生成唯一文件名
    const timestamp = Date.now()
    const randomStr = Math.random().toString(36).substring(2, 8)
    const ext = file.name.split('.').pop()
    const fileName = `${timestamp}-${randomStr}.${ext}`
    
    // 保存文件
    const filePath = join(uploadDir, fileName)
    await writeFile(filePath, buffer)

    // 返回可访问的 URL
    const url = `/uploads/${fileName}`
    
    return NextResponse.json({ 
      url,
      fileName,
      size: file.size,
      type: file.type,
    })
  } catch (error) {
    console.error('上传文件失败:', error)
    return NextResponse.json(
      { error: '上传文件失败' },
      { status: 500 }
    )
  }
}