import { NextRequest, NextResponse } from 'next/server'
import { writeFile, mkdir } from 'fs/promises'
import { join } from 'path'
import { existsSync } from 'fs'

export async function POST(request: NextRequest) {
  try {
    const data = await request.formData()
    const file: File | null = data.get('file') as unknown as File
    const awardId = data.get('awardId') as string

    if (!file) {
      return NextResponse.json({ error: '沒有選擇文件' }, { status: 400 })
    }

    // 驗證文件類型
    const allowedTypes = [
      'application/pdf',
      'application/msword',
      'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
      'application/vnd.ms-powerpoint',
      'application/vnd.openxmlformats-officedocument.presentationml.presentation'
    ]

    if (!allowedTypes.includes(file.type)) {
      return NextResponse.json({ 
        error: '不支持的文件格式，請上傳 PDF、DOC、DOCX、PPT、PPTX 格式的文件' 
      }, { status: 400 })
    }

    // 驗證文件大小 (10MB)
    const maxSize = 10 * 1024 * 1024
    if (file.size > maxSize) {
      return NextResponse.json({ 
        error: '文件大小超過 10MB 限制' 
      }, { status: 400 })
    }

    // 創建上傳目錄
    const uploadDir = join(process.cwd(), 'public', 'uploads', 'documents')
    if (!existsSync(uploadDir)) {
      await mkdir(uploadDir, { recursive: true })
    }

    // 生成唯一文件名
    const timestamp = Date.now()
    const fileExtension = file.name.split('.').pop()
    const fileName = `${awardId}_${timestamp}.${fileExtension}`
    const filePath = join(uploadDir, fileName)

    // 保存文件
    const bytes = await file.arrayBuffer()
    const buffer = Buffer.from(bytes)
    await writeFile(filePath, buffer)

    // 返回文件信息
    const fileUrl = `/uploads/documents/${fileName}`
    
    return NextResponse.json({
      success: true,
      url: fileUrl,
      fileName: file.name,
      size: file.size,
      type: file.type
    })

  } catch (error) {
    console.error('文件上傳錯誤:', error)
    return NextResponse.json(
      { error: '文件上傳失敗' },
      { status: 500 }
    )
  }
}