import io.undertow.Handlers;
import io.undertow.Undertow;
import io.undertow.server.handlers.proxy.LoadBalancingProxyClient;
import io.undertow.servlet.Servlets;
import io.undertow.servlet.api.DeploymentInfo;
import io.undertow.servlet.api.DeploymentManager;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URI;
import java.net.URL;

public class App {

    public static void main(String[] args) throws ServletException {
        // Application
        DeploymentInfo servletBuilder = Servlets.deployment()
                .setClassLoader(App.class.getClassLoader())
                .setContextPath("/")
                .setDeploymentName("test.war")
                .addServlets(Servlets.servlet("test", RequestPrinter.class).addMapping("/*"));
        DeploymentManager manager = Servlets.defaultContainer().addDeployment(servletBuilder);
        manager.deploy();

        Undertow applicationServer = Undertow.builder()
                .addHttpListener(8080, "localhost")
                .setHandler(manager.start())
                .build();
        applicationServer.start();

        // Proxy
        LoadBalancingProxyClient proxyClient = new LoadBalancingProxyClient();
        proxyClient.addHost(URI.create("http://localhost:8080"));
        Undertow loadBalancer = Undertow.builder()
                .addHttpListener(8180, "localhost")
                .setHandler(Handlers.proxyHandler(proxyClient))
                .build();

        loadBalancer.start();

        try {
            URL url = new URL("http://localhost:8180/");
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            InputStream inputStream = urlConnection.getInputStream();
            // read a small part of the response and exit
            byte[] buffer = new byte[10];
            inputStream.read(buffer, 0, 10);
            System.out.println("Done reading");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static class RequestPrinter extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
            // Write lots of data
            ServletOutputStream outputStream = resp.getOutputStream();
            for (int i = 0; i < 100000; i++) {
                outputStream.println("ResponseLine#" + i);
            }
        }
    }
}