college/ws2012/P2P/uebungen/4/src/peer/Node.java

package peer;

import java.io.IOException;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;

import common.MessageType;

public class Node {

	private final static Logger LOGGER = Logger.getLogger(Node.class.getName());

	private static final int BUF_SIZE = 256;

	private DatagramChannel channel;
	private ByteBuffer buf;

	private String name = "Not initialized";

	private List<SocketAddress> neighbors = new ArrayList<SocketAddress>();

	private Thread thread;
	private UDPListen udpListen;

	public Node() {
		try {
			channel = DatagramChannel.open();
			channel.socket().bind(null);
			buf = ByteBuffer.allocate(BUF_SIZE);

			this.name = channel.getLocalAddress().toString();

			udpListen = new UDPListen();
			thread = new Thread(udpListen);
			thread.start();

			LOGGER.info("Initialized node " + name);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	/**
	 * Create another peer, mutually link creator and spawn.
	 * 
	 * @return
	 * @throws IOException
	 */
	public Node spawn() throws IOException {
		LOGGER.info("Name: " + getName() + ", Spawning new node.");

		// create a new node
		Node newNode = new Node();

		buf.clear();
		buf.put(MessageType.INVITE);
		buf.flip();

		try {
			channel.send(buf, newNode.getAddress());
		} catch (IOException e) {
			e.printStackTrace();
		}

		neighbors.add(newNode.getAddress());

		return newNode;
	}

	public SocketAddress getAddress() {
		try {
			return channel.getLocalAddress();
		} catch (IOException e) {
			LOGGER.severe("Address not set yet.");
		}
		return null;
	}

	private byte[] addrToByte(SocketAddress addr) {
		// TODO Wäre cool, die IP nicht einfach als String zu schicken.
		// Was machen mit IPV4 vs IPV6?
		InetSocketAddress a = (InetSocketAddress) addr;
		
		if (a.getAddress() instanceof Inet6Address) {
			// seems to be IPv6
		} else if (a.getAddress() instanceof Inet4Address) {
			// seems to be IPv4
		} else {
			// invalid ip address
		}
		
		return a.getAddress().getAddress();
	}

	/**
	 * Circularly link all neighbors, remove itself form all neighbors and exit.
	 */
	public void leave() {
		LOGGER.info("Name: " + getName() + ", Leaving...");

		for (int i = 0; i < neighbors.size(); i++) {

			if (neighbors.size() > 1) {
				buf.clear();
				buf.put(MessageType.NEW_NEIGHBOR_IPV6);
				if (i == 0) {

					buf.put(addrToByte(neighbors.get(1)));
					buf.put(addrToByte(neighbors.get(neighbors.size() - 1)));

				} else if (i == neighbors.size() - 1) {

					buf.put(addrToByte(neighbors.get(0)));
					buf.put(addrToByte(neighbors.get(i - 1)));

				} else {

					buf.put(addrToByte(neighbors.get(i - 1)));
					buf.put(addrToByte(neighbors.get(i + 1)));
				}
				buf.flip();
				try {
					channel.send(buf, neighbors.get(i));
				} catch (IOException e) {
					e.printStackTrace();
				}
			}

			buf.clear();
			buf.put(MessageType.LEAVE);
			buf.flip();

			try {
				channel.send(buf, neighbors.get(i));
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		try {
			if (thread != null) {
				udpListen.terminate();
				thread.join();
			}
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

	public boolean hasNeighbors() {
		return (this.neighbors.size() > 0);
	}

	public String getName() {
		return this.name;
	}

	public void printInfos() {
		StringBuilder result = new StringBuilder(128);
		result.append("Name: " + this.name + ", Neighbours: ");
		for (int i = 0; i < this.neighbors.size(); i++) {
			result.append(this.neighbors.get(i).toString() + ", ");
		}
		LOGGER.info(result.toString());
	}

	public class UDPListen implements Runnable {
		private volatile boolean running = true;

		public void run() {
			while (running) {
				SocketAddress receivedFrom = null;
				buf.clear();

				try {
					receivedFrom = channel.receive(buf);
				} catch (IOException e) {
					e.printStackTrace();
				}

				buf.flip();

				byte messageType = buf.get();

				switch (messageType) {
				case MessageType.INVITE:
					LOGGER.info(name + " received invite from "
							+ receivedFrom.toString());
					break;

				case MessageType.LEAVE:

					neighbors.remove(receivedFrom);

					break;

				case MessageType.NEW_NEIGHBOR_IPV4:
					LOGGER.info(name + " received new IPV4 neighbor"
							+ receivedFrom.toString() + ": "
							+ new String(buf.array()));

					break;
				case MessageType.NEW_NEIGHBOR_IPV6:
					LOGGER.info(name + " received new IPV6 neighbor"
							+ receivedFrom.toString() + ": "
							+ new String(buf.array()));
					break;

				default:
					LOGGER.info(name + " received unknown command from "
							+ receivedFrom.toString() + ": "
							+ new String(buf.array()));
				}
			}
		}

		public void terminate() {
			running = false;
		}
	}
}