import { createServer } from "node:http";
import { readFile } from "node:fs/promises";
import { extname, join, normalize } from "node:path";

const root = new URL("./", import.meta.url);
const port = Number(process.env.GUI_PREVIEW_PORT || 4173);

const contentTypes = {
  ".html": "text/html; charset=utf-8",
  ".css": "text/css; charset=utf-8",
  ".js": "text/javascript; charset=utf-8",
};

const server = createServer(async (req, res) => {
  const requestPath = req.url === "/" ? "/index.html" : req.url || "/index.html";
  const safePath = normalize(requestPath).replace(/^(\.\.[/\\])+/, "");
  const filePath = new URL(`.${safePath}`, root);

  try {
    const body = await readFile(filePath);
    const type = contentTypes[extname(filePath.pathname)] || "text/plain; charset=utf-8";
    res.writeHead(200, { "Content-Type": type });
    res.end(body);
  } catch {
    const fallback = await readFile(join(root.pathname, "index.html"));
    res.writeHead(200, { "Content-Type": "text/html; charset=utf-8" });
    res.end(fallback);
  }
});

server.listen(port, "127.0.0.1", () => {
  console.log(`GUI prototype server running at http://127.0.0.1:${port}`);
});