import type { NextApiRequest, NextApiResponse } from 'next'
export const config = { api: { bodyParser: false, responseLimit: '8mb' } }
export default async function handler(req: NextApiRequest, res: NextApiResponse) {
  const path = req.query.path
  if (!Array.isArray(path) || path.some((p) => p === '..' || p.includes('/') || p.includes('\\')))
    return res.status(400).json({ error: 'Invalid path' })
  const base = process.env.API_URL || process.env.NEXT_PUBLIC_API_URL || 'http://localhost:8000'
  const target = new URL('/' + path.map(encodeURIComponent).join('/'), base)
  const incoming = new URL(req.url ?? '/', 'http://localhost')
  target.search = incoming.search
  const headers = new Headers()
  const hop = new Set([
    'host',
    'connection',
    'transfer-encoding',
    'content-length',
    'keep-alive',
    'upgrade',
    'x-forwarded-host',
    'x-forwarded-proto',
  ])
  for (const [k, v] of Object.entries(req.headers))
    if (v && !hop.has(k)) headers.set(k, Array.isArray(v) ? v.join(',') : v)
  headers.set('accept-encoding', 'identity')
  try {
    const chunks: Buffer[] = []
    let bytes = 0
    for await (const chunk of req) {
      const b = Buffer.from(chunk)
      bytes += b.length
      if (bytes > 1024 * 1024) return res.status(413).end()
      chunks.push(b)
    }
    const body = req.method === 'GET' || req.method === 'HEAD' ? undefined : Buffer.concat(chunks)
    const upstream = await fetch(target, {
      method: req.method,
      headers,
      body,
      signal: AbortSignal.timeout(30_000),
      redirect: 'manual',
    })
    upstream.headers.forEach((v, k) => {
      if (!hop.has(k) && k !== 'content-encoding') res.setHeader(k, v)
    })
    res.status(upstream.status).send(Buffer.from(await upstream.arrayBuffer()))
  } catch {
    res.status(502).json({ error: 'Upstream request failed' })
  }
}