const http = require('node:http');

const server = http.createServer(async (req, res) => {
  // req.signal is an AbortSignal that aborts when the client disconnects
  const { signal } = req;

  console.log('Request received. Starting long task...');

  try {
    // You can pass the signal directly to other APIs like fetch() or fs.promises
    await performLongTask(signal);
    
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Task completed successfully!');
  } catch (err) {
    if (err.name === 'AbortError') {
      console.log('Request was aborted by the client. Cleaning up...');
    } else {
      console.error('An error occurred:', err);
      res.statusCode = 500;
      res.end('Internal Server Error');
    }
  }
});

// Mock function representing an asynchronous task
function performLongTask(signal) {
  return new Promise((resolve, reject) => {
    const timeout = setTimeout(() => {
      resolve();
    }, 5000);

    // Manually listen for the abort event if the API doesn't support signals
    signal.addEventListener('abort', () => {
      clearTimeout(timeout);
      reject(new DOMException('Aborted', 'AbortError'));
    }, { once: true });
  });
}

server.listen(3000, () => {
  console.log('Server running at http://localhost:3000/');
});