import { Drive_blob_path } from "@/lib/drive_server"
import { NextRequest, NextResponse } from "next/server"
import { createReadStream, statSync } from "fs"
import path from "path"

export async function GET(
  request: NextRequest,
  { params }: { params: Promise<{ blobId: string }> }
) {
  try {
    const { blobId } = await params
    const { searchParams } = new URL(request.url)
    const filename = searchParams.get('filename') || 'download'
    
    // Get the filesystem path for this blob
    const blobPath = await Drive_blob_path(blobId)
    
    // Get file stats
    const stats = statSync(blobPath)
    const fileSize = stats.size
    
    // Determine content type based on file extension
    const ext = path.extname(filename).toLowerCase()
    const contentType = getContentType(ext)
    
    // Create readable stream
    const stream = createReadStream(blobPath)
    
    // Convert stream to web stream
    const readableStream = new ReadableStream({
      start(controller) {
        stream.on('data', (chunk: Buffer | string) => {
          const buffer = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk)
          controller.enqueue(new Uint8Array(buffer))
        })
        stream.on('end', () => {
          controller.close()
        })
        stream.on('error', (error) => {
          controller.error(error)
        })
      }
    })
    
    return new NextResponse(readableStream, {
      headers: {
        'Content-Type': contentType,
        'Content-Length': fileSize.toString(),
        'Content-Disposition': `attachment; filename="${filename}"`,
        'Cache-Control': 'public, max-age=31536000', // Cache for 1 year
      },
    })
    
  } catch (error) {
    console.error('Error serving blob:', error)
    return new NextResponse('File not found', { status: 404 })
  }
}

function getContentType(extension: string): string {
  const mimeTypes: Record<string, string> = {
    '.pdf': 'application/pdf',
    '.txt': 'text/plain',
    '.md': 'text/markdown',
    '.docx': 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
    '.doc': 'application/msword',
    '.zip': 'application/zip',
    '.png': 'image/png',
    '.jpg': 'image/jpeg',
    '.jpeg': 'image/jpeg',
    '.gif': 'image/gif',
    '.svg': 'image/svg+xml',
    '.css': 'text/css',
    '.js': 'application/javascript',
    '.json': 'application/json',
    '.html': 'text/html',
    '.htm': 'text/html',
  }
  
  return mimeTypes[extension] || 'application/octet-stream'
}