EKeyPacketReceiver.java

/**
 * Copyright (c) 2010-2016 by the respective copyright holders.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.openhab.binding.ekey.internal;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import at.fhooe.mc.schlgtwt.parser.HomePacket;
import at.fhooe.mc.schlgtwt.parser.MultiPacket;
import at.fhooe.mc.schlgtwt.parser.RarePacket;
import at.fhooe.mc.schlgtwt.parser.UniformPacket;

/**
 * This Class provides the DatagramSocket that listens for eKey packets on the network
 * This will run in a thread and can be interrupted by calling <code>stopListener()<code>
 * Before starting the thread initialization is required (mode, ip, port and deliminator)
 * 
 * @author Paul Schlagitweit
 * @since 1.5.0
 */
public class EKeyPacketReceiver implements Runnable {

    private static Logger log = LoggerFactory.getLogger(EKeyPacketReceiver.class);

    private final int buffersize = 128;
    private IEKeyListener listener;
    private boolean running;
    private DatagramSocket socket = null;
    private int mode;
    private InetAddress destIp = null;
    private UniformPacket ekeypacket;
    private String deliminator = "_"; // default value

    public EKeyPacketReceiver(IEKeyListener listener) {

        this.listener = listener;
    }

    /**
     * Pass information about the connection to the receiver
     * 
     * @param mode use constants defined in the <code>UniformPacket</code> class
     * @param senderAddress
     * @param port
     * @param deliminator used by HOME and MULTI and defined in the UDP-converter config
     */
    public void initializeReceiver(int mode, String senderAddress, int port, String deliminator) {

        this.mode = mode;

        if (senderAddress != "") {
            try {
                destIp = InetAddress.getByName(senderAddress);
            } catch (UnknownHostException e1) {
                e1.printStackTrace();
            }
        } else {
            destIp = null; // no address specified
        }

        if (deliminator != null) {
            this.deliminator = deliminator;
        }

        if (socket != null) {
            socket.disconnect();
        }

        try { // create socket
            socket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }

    }

    /**
     * Stop the thread
     */
    public void stopListener() {
        running = false;
        if (socket != null) {
            socket.disconnect();
        }
        socket = null;
    }

    @Override
    public void run() {
        running = true; // start loop
        if (socket == null) {
            throw new IllegalStateException(
                    "Cannot access socket. You must call" + " call initializeListener(..) first!");
        }

        byte[] lastpacket = null;
        DatagramPacket packet = new DatagramPacket(new byte[buffersize], buffersize);

        while (running) {

            ekeypacket = null;
            packet.setData(new byte[buffersize]);

            try { // wait for the packet
                socket.receive(packet);
            } catch (IOException e1) {
                e1.printStackTrace();
            }

            // ignore packets from destinations other than the specified address
            // if destIp is not set ignore address check - this is not recommended but valid
            if (destIp == null || packet.getAddress().equals(destIp)) {

                lastpacket = packet.getData();

                try { // catch a possible parsing error

                    switch (mode) {
                        case UniformPacket.tHOME:
                            ekeypacket = new HomePacket(deliminator, lastpacket);
                            break;
                        case UniformPacket.tMULTI:
                            ekeypacket = new MultiPacket(deliminator, lastpacket);
                            break;
                        default: // default configuration is the rare packet
                            ekeypacket = new RarePacket(lastpacket);
                            break;

                    }
                } catch (IllegalArgumentException e) {
                    log.error("Error parsing packet", e);
                }
            }

            if (ekeypacket != null) {
                listener.publishUpdate(ekeypacket);
            } else {
                log.debug("Received a packet that does not match the mode\n" + "you specified in the 'openhab.cfg'!");
            }

        }

        log.debug("eKey Listener stopped!");

    }

}