import { createServer } from 'http';
import { readFile } from 'fs/promises';
import path from 'path';
const { join, extname, resolve } = path;
import { fileURLToPath } from 'url';

const __dirname = fileURLToPath(new URL('.', import.meta.url));
const root = resolve(join(__dirname, '..', 'src', 'frontend'));
const PORT = 8474;

const MIME = {
  '.html': 'text/html', '.js': 'application/javascript', '.mjs': 'application/javascript',
  '.css': 'text/css', '.json': 'application/json', '.svg': 'image/svg+xml',
  '.png': 'image/png', '.ico': 'image/x-icon', '.woff2': 'font/woff2',
};

createServer(async (req, res) => {
  const pathname = new URL(req.url, 'http://localhost').pathname;
  const filePath = resolve(root, pathname === '/' ? 'index.html' : pathname.slice(1));
  const rel = path.relative(root, filePath);
  if (rel.startsWith('..') || path.isAbsolute(rel)) {
    res.writeHead(403);
    res.end('Forbidden');
    return;
  }
  try {
    const data = await readFile(filePath);
    res.writeHead(200, { 'Content-Type': MIME[extname(filePath)] || 'application/octet-stream' });
    res.end(data);
  } catch {
    res.writeHead(404);
    res.end('Not Found');
  }
}).listen(PORT, '127.0.0.1', () => {
  console.log(`Frontend dev server ready on http://127.0.0.1:${PORT}`);
});