import { NextRequest, NextResponse } from 'next/server'
import { getServerSession } from 'next-auth'
import { authOptions } from '@/lib/auth'
import { prisma } from '@/lib/prisma'
import { readFile, access } from 'fs/promises'
import path from 'path'

export async function GET(req: NextRequest) {
  try {
    // Check if user is logged in
    const session = await getServerSession(authOptions)
    if (!session) {
      return NextResponse.json(
        { error: '请先登录' },
        { status: 401 }
      )
    }

    // Check if user has download permission (skip check for admins)
    const userId = (session.user as any).id
    const userRole = (session.user as any).role
    
    if (userRole !== 'ADMIN') {
      const user = await prisma.user.findUnique({
        where: { id: userId },
        select: { canDownload: true }
      })

      if (!user || !user.canDownload) {
        return NextResponse.json(
          { error: '您的下载权限已被限制，请联系管理员' },
          { status: 403 }
        )
      }
    }

    const { searchParams } = new URL(req.url)
    const id = searchParams.get('id')

    if (!id) {
      return NextResponse.json(
        { error: '缺少素材ID' },
        { status: 400 }
      )
    }

    const material = await prisma.material.findUnique({
      where: { id },
    })

    if (!material) {
      return NextResponse.json(
        { error: '素材不存在' },
        { status: 404 }
      )
    }

    // 增加下载次数
    await prisma.material.update({
      where: { id },
      data: {
        downloadCount: {
          increment: 1
        }
      }
    })

    // Read file from local storage
    // 确保使用绝对路径
    let filePath = material.zipFilePath
    if (!path.isAbsolute(filePath)) {
      filePath = path.join(process.cwd(), filePath)
    }
    
    console.log('Attempting to download file:', filePath)
    
    // 检查文件是否存在
    try {
      await access(filePath)
    } catch (error) {
      console.error('File not found:', filePath)
      return NextResponse.json(
        { error: '文件不存在，可能已被删除' },
        { status: 404 }
      )
    }
    
    const fileBuffer = await readFile(filePath)

    // 生成新的文件名：SPU_一级分类_二级分类_用户名.扩展名
    // 获取原文件扩展名
    const originalExt = path.extname(material.zipFileName) // 例如 .zip 或 .7z 或视频扩展名
    const newFileName = `${material.productModel}_${material.categoryName}_${material.sceneName}_${material.authorName}${originalExt}`
    
    console.log('Download filename:', newFileName)

    // 根据文件类型和素材类型确定Content-Type
    let contentType = 'application/zip'
    let contentDisposition = `attachment; filename="${encodeURIComponent(newFileName)}"`
    
    // 如果是视频类型，使用视频的Content-Type并支持流式传输
    if (material.materialType === '视频') {
      const ext = originalExt.toLowerCase()
      const videoTypes: { [key: string]: string } = {
        '.mp4': 'video/mp4',
        '.avi': 'video/x-msvideo',
        '.mov': 'video/quicktime',
        '.wmv': 'video/x-ms-wmv',
        '.flv': 'video/x-flv',
        '.mkv': 'video/x-matroska',
        '.webm': 'video/webm',
      }
      contentType = videoTypes[ext] || 'video/mp4'
      
      // 视频文件支持流式传输（Range请求）
      const range = req.headers.get('range')
      if (range) {
        // 支持视频流式传输
        const fileSize = fileBuffer.length
        const parts = range.replace(/bytes=/, '').split('-')
        const start = parseInt(parts[0], 10)
        const end = parts[1] ? parseInt(parts[1], 10) : fileSize - 1
        const chunkSize = end - start + 1
        const chunk = fileBuffer.slice(start, end + 1)
        
        return new NextResponse(chunk as any, {
          status: 206,
          headers: {
            'Content-Type': contentType,
            'Content-Range': `bytes ${start}-${end}/${fileSize}`,
            'Accept-Ranges': 'bytes',
            'Content-Length': chunkSize.toString(),
          },
        })
      }
      
      // 非Range请求，返回完整文件（但允许内联播放）
      contentDisposition = `inline; filename="${encodeURIComponent(newFileName)}"`
    }

    return new NextResponse(fileBuffer as any, {
      headers: {
        'Content-Type': contentType,
        'Content-Disposition': contentDisposition,
        'Content-Length': fileBuffer.length.toString(),
        'Accept-Ranges': 'bytes', // 支持Range请求（用于视频流式传输）
      },
    })
  } catch (error) {
    console.error('Download error:', error)
    return NextResponse.json(
      { error: '下载失败: ' + (error instanceof Error ? error.message : '未知错误') },
      { status: 500 }
    )
  }
}