package avian;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;

public class Traces {
  private static final String Newline = System.getProperty("line.separator");

  private static String traceAllThreads() {
    StringBuilder buffer = new StringBuilder();

    Thread[] threads = new Thread[Thread.activeCount()];

    int count = Thread.enumerate(threads);
    for (int i = 0; i < count; ++i) {
      traceThread(threads[i], buffer);
    }

    return buffer.toString();
  }

  private static String traceThread(Thread thread) {
    StringBuilder buffer = new StringBuilder();

    traceThread(thread, buffer);

    return buffer.toString();
  }

  private static void traceThread(Thread thread, StringBuilder buffer) {
    buffer.append(thread).append(Newline);
    for (StackTraceElement e: thread.getStackTrace()) {
      buffer.append("\tat ").append(e).append(Newline);
    }
  }

  public static void startTraceListener(final String host, final int port) {
    Thread t = new Thread(new Runnable() {
        public void run() {
          try {
            ServerSocketChannel server = ServerSocketChannel.open();
            server.socket().bind(new InetSocketAddress(host, port));
            while (true) {
              SocketChannel c = server.accept();
              try {
                c.write(ByteBuffer.wrap(traceAllThreads().getBytes()));
              } finally {
                c.close();
              }
            }
          } catch (Exception e) {
            e.printStackTrace();
          }
        }
      });
    t.setDaemon(true);
    t.start();
  }
}