package com.toxi.nio;

import java.net.*;
import java.io.*;
import java.nio.*;
import java.nio.channels.*;
import java.nio.channels.spi.SelectorProvider;
import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author tux
 */
public class UDPClient {

    /**
     *
     */
    public final static int DEFAULT_PORT = 9876;

    int port = DEFAULT_PORT;
    SocketAddress remote;
    DatagramChannel channel;
    Selector selector;
    ByteBuffer buffer1;
    ByteBuffer buffer2;

    int clientID;

    /**
     *
     * @param clientID
     */
    public UDPClient(int clientID) {
        this.clientID = clientID;
        System.out.println("new client ID: " + clientID);
        try {
            remote = new InetSocketAddress("192.168.1.64", port);
            channel = DatagramChannel.open();
            channel.configureBlocking(false);
            channel.connect(remote);
            selector = SelectorProvider.provider().openSelector();
            channel.register(selector, SelectionKey.OP_READ
                    | SelectionKey.OP_WRITE);
            buffer1 = ByteBuffer.allocate(4);
            buffer2 = ByteBuffer.allocate(4);
        } catch (IOException ex) {
            System.err.println(ex);
        }
    }

    /**
     *
     * @param command
     */
    public void send(int command) {
        try {
            selector.select(clientID);
            Set readyKeys = selector.selectedKeys();
            Iterator iterator = readyKeys.iterator();
            if (iterator.hasNext()) {
                SelectionKey key = (SelectionKey) iterator.next();
                iterator.remove();
                if (key.isWritable()) {
                    buffer1.clear();
                    buffer1.putInt(command);
                    buffer1.flip();
                    channel.write(buffer1);
                }
            }
        } catch (IOException ex) {
            System.err.println(ex);
        }
    }

    /**
     *
     * @return
     */
    public int receive() {
        int r = 0;
        try {
            selector.select(clientID);
            Set readyKeys2 = selector.selectedKeys();
            Iterator iterator2 = readyKeys2.iterator();
            if (iterator2.hasNext()) {
                SelectionKey key2 = (SelectionKey) iterator2.next();
                iterator2.remove();
                if (key2.isReadable()) {
                    buffer2.clear();
                    channel.read(buffer2);
                    buffer2.flip();
                    int command = buffer2.getInt();
                    r = command;
                }
            }
        } catch (IOException ex) {
            System.err.println(ex);
        }
        return r;
    }

    /**
     *
     * @param args
     */
    public static void main(String[] args) {
        UDPClient client = new UDPClient(Integer.parseInt(args[0]));
        client.send(1);
        while (true) {
            System.out.println(client.receive());
            try {
                Thread.sleep(33);
            } catch (InterruptedException ex) {
                Logger.getLogger(UDPClient.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }
}