const http = require('http');

// Create an HTTP server
const server = http.createServer((req, res) => {
  // req is an http.IncomingMessage, which is a ReadStream
  console.log(`Received ${req.method} request to ${req.url}`);
  
  // Set response headers
  res.setHeader('Content-Type', 'text/plain');
  
  // Handle different types of requests
  if (req.method === 'GET') {
    res.end('Send a POST request with a body to see the ReadStream in action');
  } 
  else if (req.method === 'POST') {
    // Set encoding for the request stream
    req.setEncoding('utf8');
    
    let body = '';
    
    // Handle data events from the request stream
    req.on('data', (chunk) => {
      console.log(`Received chunk of ${chunk.length} bytes`);
      body += chunk;
      
      // Implement a simple flood protection
      if (body.length > 1e6) {
        // If body is too large, destroy the stream
        body = '';
        res.writeHead(413, {'Content-Type': 'text/plain'});
        res.end('Request entity too large');
        req.destroy();
      }
    });
    
    // Handle the end of the request stream
    req.on('end', () => {
      console.log('End of request data');
      
      try {
        // Try to parse as JSON
        const data = JSON.parse(body);
        console.log('Parsed JSON data:', data);
        
        // Send a response
        res.writeHead(200, {'Content-Type': 'application/json'});
        res.end(JSON.stringify({
          message: 'Data received',
          size: body.length,
          data: data
        }));
      } catch (e) {
        // If not valid JSON, just echo back the raw data
        console.log('Could not parse as JSON, treating as plain text');
        
        res.writeHead(200, {'Content-Type': 'text/plain'});
        res.end(`Received ${body.length} bytes of data:\n${body}`);
      }
    });
  } 
  else {
    // For other HTTP methods
    res.writeHead(405, {'Content-Type': 'text/plain'});
    res.end('Method not allowed');
  }
});

// Start the server
const PORT = 8080;
server.listen(PORT, () => {
  console.log(`HTTP ReadStream example server running at http://localhost:${PORT}`);
  console.log('To test:');
  console.log(`1. Open http://localhost:${PORT} in a browser for GET request`);
  console.log(`2. Use curl or Postman to send POST requests with a body to http://localhost:${PORT}`);
});

// Note: To test with curl:
// curl -X POST -H "Content-Type: application/json" -d '{"name":"John","age":30}' http://localhost:8080