package de.tudarmstadt.informatik.hostage.net;

import java.io.FileDescriptor;
import java.io.IOException;
import java.lang.reflect.Field;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.SocketImpl;

import javax.net.ServerSocketFactory;

import de.tudarmstadt.informatik.hostage.system.Device;
import de.tudarmstadt.informatik.hostage.system.PrivilegedPort;
import de.tudarmstadt.informatik.hostage.system.PrivilegedPort.TYPE;

public class MyServerSocketFactory extends ServerSocketFactory {

	@Override
	public ServerSocket createServerSocket(int port) throws IOException {
		ServerSocket socket = null;
		if (port > 1023) {
			socket = new ServerSocket();
			socket.setReuseAddress(true);
			socket.bind(new InetSocketAddress(port));
		} else if (Device.isPPInstalled()) {
			FileDescriptor fd = new PrivilegedPort(TYPE.TCP, port).getFD();
			socket = new ServerSocket();
			try {
				SocketImpl impl = getImpl(socket);
				injectFD(fd, impl);
				injectImpl(impl, socket);
				setBound(socket);
			} catch (NoSuchFieldException e) {
			} catch (IllegalAccessException e) {
			} catch (IllegalArgumentException e) {
			}
		}
		return socket;
	}

	@Override
	public ServerSocket createServerSocket(int port, int backlog) throws IOException {
		return createServerSocket(port);
	}

	@Override
	public ServerSocket createServerSocket(int port, int backlog, InetAddress iAddress) throws IOException {
		return createServerSocket(port);
	}

	private SocketImpl getImpl(ServerSocket socket) throws NoSuchFieldException, IllegalAccessException, IllegalArgumentException {
		Field implField = socket.getClass().getDeclaredField("impl");
		implField.setAccessible(true);
		return (SocketImpl) implField.get(socket);
	}

	private void injectFD(FileDescriptor fd, SocketImpl impl) throws NoSuchFieldException, IllegalAccessException, IllegalArgumentException {
		Class<?> plainServerSocketImplClazz = impl.getClass();
		Class<?> plainSocketImplClazz = plainServerSocketImplClazz.getSuperclass();
		Class<?> socketImplClazz = plainSocketImplClazz.getSuperclass();
		Field fdField = socketImplClazz.getDeclaredField("fd");
		fdField.setAccessible(true);
		fdField.set(impl, fd);
	}

	private void injectImpl(SocketImpl impl, ServerSocket socket) throws NoSuchFieldException, IllegalAccessException, IllegalArgumentException {
		Field implField = socket.getClass().getDeclaredField("impl");
		implField.setAccessible(true);
		implField.set(socket, impl);
	}

	private void setBound(ServerSocket socket) throws NoSuchFieldException, IllegalAccessException, IllegalArgumentException {
		Field boundField = socket.getClass().getDeclaredField("isBound");
		boundField.setAccessible(true);
		boundField.set(socket, true);
	}

}