import { createReadStream } from 'node:fs'
import { Readable } from 'node:stream'
import type { PackageStore } from './package-store.js'
import { parseRange } from './range.js'

export async function packageMediaResponse(
  store: PackageStore,
  request: Request,
): Promise<Response> {
  const url = new URL(request.url)
  const match = /^\/packages\/([a-f0-9]{64})\/([a-f0-9]{64})$/.exec(url.pathname)
  if (url.host !== 'app' || request.method !== 'GET' || !match)
    return new Response(null, { status: 404 })
  try {
    const file = await store.localFile(match[1]!, match[2]!)
    const rangeHeader = request.headers.get('range')
    const range = parseRange(rangeHeader, file.size)
    const headers: Record<string, string> = {
      'Content-Type': file.mime,
      'Accept-Ranges': 'bytes',
      'Cache-Control': 'no-store',
      'X-Content-Type-Options': 'nosniff',
      'Content-Security-Policy': "default-src 'none'; frame-ancestors 'none'; sandbox",
    }
    if (!range)
      return new Response(null, {
        status: 416,
        headers: { ...headers, 'Content-Range': `bytes */${file.size}` },
      })
    headers['Content-Length'] = String(range.end - range.start + 1)
    if (rangeHeader) headers['Content-Range'] = `bytes ${range.start}-${range.end}/${file.size}`
    const stream = createReadStream(file.path, range)
    const abort = () => stream.destroy()
    request.signal.addEventListener('abort', abort, { once: true })
    stream.on('close', () => request.signal.removeEventListener('abort', abort))
    if (request.signal.aborted) stream.destroy()
    return new Response(Readable.toWeb(stream) as ReadableStream<Uint8Array>, {
      status: rangeHeader ? 206 : 200,
      headers,
    })
  } catch {
    return new Response(null, { status: 404 })
  }
}