function configureProxy(options, config) {
  // Check for explicitly configured proxy
  let proxy = config.proxy;
  
  if (!proxy) {
    // Check for environment variables
    const proxyEnv = parsed.protocol.slice(0, -1) + '_proxy';
    const proxyUrl = process.env[proxyEnv] || 
                     process.env[proxyEnv.toUpperCase()] ||
                     process.env.all_proxy || 
                     process.env.ALL_PROXY;
    
    if (proxyUrl) {
      const parsedProxyUrl = url.parse(proxyUrl);
      proxy = {
        host: parsedProxyUrl.hostname,  // Use hostname, not host (which includes port)
        port: parsedProxyUrl.port,
        protocol: parsedProxyUrl.protocol
      };
      
      // Handle proxy authentication if present
      if (parsedProxyUrl.auth) {
        // Configure proxy authentication
      }
    }
  }
  
  if (proxy) {
    // Use proxy's protocol for connection to proxy
    // Set up tunneling for HTTPS requests through HTTP proxy
    const usesTunnel = proxy.protocol === "http:" && options.protocol === "https:";
    if (usesTunnel) {
      // Configure HTTP CONNECT tunneling
    }
  }
  
  return options;
}