import http from "node:http";
import { readFile } from "node:fs/promises";
import { dirname, join } from "node:path";
import { fileURLToPath } from "node:url";

const __dirname = dirname(fileURLToPath(import.meta.url));
const htmlPath = join(__dirname, "lucky-gift-test.html");
const port = Number(process.env.PORT || 8788);
const upstreamBase = (process.env.LUCKY_GIFT_API_BASE || "http://127.0.0.1:13000").replace(/\/+$/, "");

function readBody(req) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    req.on("data", (chunk) => chunks.push(chunk));
    req.on("end", () => resolve(Buffer.concat(chunks)));
    req.on("error", reject);
  });
}

function copyProxyHeaders(req) {
  const headers = new Headers();
  for (const [key, value] of Object.entries(req.headers)) {
    if (!value) continue;
    const lower = key.toLowerCase();
    if (["host", "origin", "referer", "connection", "content-length", "accept-encoding"].includes(lower)) continue;
    headers.set(key, Array.isArray(value) ? value.join(", ") : value);
  }
  headers.set("Accept-Encoding", "identity");
  return headers;
}

async function proxyAPI(req, res) {
  const body = req.method === "GET" || req.method === "HEAD" ? undefined : await readBody(req);
  const upstream = await fetch(`${upstreamBase}${req.url}`, {
    method: req.method,
    headers: copyProxyHeaders(req),
    body,
    redirect: "manual",
  });
  const responseBody = Buffer.from(await upstream.arrayBuffer());
  res.writeHead(upstream.status, {
    "Content-Type": upstream.headers.get("content-type") || "application/octet-stream",
    "Cache-Control": "no-store",
  });
  res.end(responseBody);
}

const server = http.createServer(async (req, res) => {
  try {
    if (req.method === "OPTIONS") {
      res.writeHead(204);
      res.end();
      return;
    }
    if (req.url === "/" || req.url === "/lucky-gift-test.html") {
      const html = await readFile(htmlPath);
      res.writeHead(200, {
        "Content-Type": "text/html; charset=utf-8",
        "Cache-Control": "no-store",
      });
      res.end(html);
      return;
    }
    if (req.url?.startsWith("/api/")) {
      await proxyAPI(req, res);
      return;
    }
    res.writeHead(404, { "Content-Type": "text/plain; charset=utf-8" });
    res.end("not found");
  } catch (err) {
    res.writeHead(502, { "Content-Type": "text/plain; charset=utf-8" });
    res.end(err instanceof Error ? err.message : String(err));
  }
});

server.listen(port, "127.0.0.1", () => {
  console.log(`Lucky gift test page: http://127.0.0.1:${port}`);
  console.log(`Proxy upstream: ${upstreamBase}`);
});