backerup-website/frontend/app/api/files/[token]/download/route.ts

import { NextResponse } from 'next/server'
import { getFile, getUploadPath } from '@/lib/store'
import fs from 'fs'

export async function GET(
  _request: Request,
  { params }: { params: Promise<{ token: string }> },
) {
  const { token } = await params
  const record = await getFile(token)
  if (!record) {
    return NextResponse.json({ error: 'Not found' }, { status: 404 })
  }

  const filePath = getUploadPath(token, record.originalName)
  if (!fs.existsSync(filePath)) {
    return NextResponse.json({ error: 'File missing on disk' }, { status: 404 })
  }

  const stream = fs.createReadStream(filePath)
  const webStream = new ReadableStream({
    start(controller) {
      stream.on('data', (chunk) => controller.enqueue(chunk))
      stream.on('end', () => controller.close())
      stream.on('error', (err) => controller.error(err))
    },
    cancel() {
      stream.destroy()
    },
  })

  return new Response(webStream, {
    headers: {
      'Content-Type': 'application/octet-stream',
      'Content-Disposition': `attachment; filename="${record.originalName}"`,
      'Content-Length': String(record.size),
    },
  })
}