const http = require('http');
const fs = require('fs');
const path = require('path');
const root = __dirname;
const types = { '.html': 'text/html; charset=utf-8', '.png': 'image/png', '.css': 'text/css; charset=utf-8', '.js': 'text/javascript; charset=utf-8', '.md': 'text/plain; charset=utf-8' };
const server = http.createServer((req, res) => {
  try {
    const url = new URL(req.url, 'http://127.0.0.1:18765');
    const rel = decodeURIComponent(url.pathname).replace(/^\/+/, '');
    const filePath = path.resolve(root, rel);
    if (!filePath.startsWith(path.resolve(root))) {
      res.writeHead(403); res.end('Forbidden'); return;
    }
    fs.readFile(filePath, (err, data) => {
      if (err) { res.writeHead(404); res.end('Not found: ' + filePath); return; }
      res.writeHead(200, { 'Content-Type': types[path.extname(filePath).toLowerCase()] || 'application/octet-stream' });
      res.end(data);
    });
  } catch (e) { res.writeHead(500); res.end(String(e)); }
});
server.listen(18765, '127.0.0.1', () => console.log('preview server on 18765'));
setInterval(() => {}, 1000);