import { NextRequest } from "next/server";

export const runtime = "nodejs";
export const dynamic = "force-dynamic";

const HOP_BY_HOP_HEADERS = new Set([
  "connection",
  "keep-alive",
  "proxy-authenticate",
  "proxy-authorization",
  "te",
  "trailer",
  "transfer-encoding",
  "upgrade",
  "host",
]);

type RouteContext = {
  params: Promise<{ path: string[] }>;
};

function getApiInternalUrl() {
  return (process.env.API_INTERNAL_URL || "http://127.0.0.1:8000").replace(/\/$/, "");
}

function buildHeaders(request: NextRequest) {
  const headers = new Headers();
  request.headers.forEach((value, key) => {
    if (!HOP_BY_HOP_HEADERS.has(key.toLowerCase())) {
      headers.set(key, value);
    }
  });
  return headers;
}

async function proxy(request: NextRequest, context: RouteContext) {
  const { path } = await context.params;
  const apiPath = path.join("/");
  const targetUrl = new URL(`/api/${apiPath}${request.nextUrl.search}`, getApiInternalUrl());
  const method = request.method.toUpperCase();
  const hasBody = !["GET", "HEAD"].includes(method);

  try {
    const upstream = await fetch(targetUrl, {
      method,
      headers: buildHeaders(request),
      body: hasBody ? await request.arrayBuffer() : undefined,
      cache: "no-store",
    });

    const responseHeaders = new Headers(upstream.headers);
    responseHeaders.delete("content-encoding");
    responseHeaders.delete("content-length");

    return new Response(upstream.body, {
      status: upstream.status,
      statusText: upstream.statusText,
      headers: responseHeaders,
    });
  } catch (error) {
    console.error("API proxy failed", {
      target: targetUrl.toString(),
      error: error instanceof Error ? error.message : String(error),
    });

    return Response.json(
      {
        detail: "后端服务暂时不可用，请检查 API_INTERNAL_URL 或后端容器状态。",
        target: targetUrl.origin,
      },
      { status: 502 },
    );
  }
}

export const GET = proxy;
export const POST = proxy;
export const PUT = proxy;
export const PATCH = proxy;
export const DELETE = proxy;