const http = require('http');

// Create an HTTP server that sends trailers
const server = http.createServer((req, res) => {
  // Inform the client we'll be sending trailers
  res.writeHead(200, {
    'Content-Type': 'text/plain',
    'Transfer-Encoding': 'chunked', // Required for trailers
    'Trailer': 'Content-MD5, X-Response-Time' // Declare which trailers will be sent
  });
  
  // Write some response data
  res.write('Beginning of the response\n');
  
  // Simulate processing time
  setTimeout(() => {
    res.write('Middle of the response\n');
    
    setTimeout(() => {
      // Final part of the body
      res.write('End of the response\n');
      
      // Add trailers
      res.addTrailers({
        'Content-MD5': 'e4e68fb7bd0e697a0ae8f1bb342846d3', // Would normally be the hash of the body
        'X-Response-Time': `${Date.now() - req.start}ms` // Processing time
      });
      
      // End the response
      res.end();
    }, 500);
  }, 500);
});

// Track request start time
server.on('request', (req) => {
  req.start = Date.now();
});

// Start server
const PORT = 8080;
server.listen(PORT, () => {
  console.log(`Server running at http://localhost:${PORT}/`);
  
  // Make a request to test trailers
  http.get(`http://localhost:${PORT}`, (res) => {
    console.log('Response status:', res.statusCode);
    console.log('Response headers:', res.headers);
    
    // Check if trailers are declared
    if (res.headers.trailer) {
      console.log('Trailer headers declared:', res.headers.trailer);
    }
    
    // Read the response body
    let body = '';
    
    res.on('data', (chunk) => {
      body += chunk;
      console.log('Received chunk:', chunk.toString());
    });
    
    // The 'end' event is emitted when the entire body has been received
    res.on('end', () => {
      console.log('Complete response body:', body);
      console.log('Trailers received:', res.trailers);
      
      // Server should close after test is complete
      server.close();
    });
  }).on('error', (err) => {
    console.error('Request error:', err);
  });
});