/*

 * JBoss, Home of Professional Open Source

 * Copyright 2011, Red Hat, Inc. and individual contributors

 * by the @authors tag. See the copyright.txt in the distribution for a

 * full listing of individual contributors.

 *

 * This is free software; you can redistribute it and/or modify it

 * under the terms of the GNU Lesser General Public License as

 * published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This software is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this software; if not, write to the Free

 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA

 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.

 */



package org.mobicents.ss7.hardware.dialogic;





import java.io.IOException;



/**

 *

 * @author amit bhayani

 * @author Oleg Kulikov

 * @author sergey vetyutnev

 * 

 */

public class InterProcessCommunicator {



	private final static String LIB_NAME = "mobicents-dialogic-linux";



	/** The identifier of the originated module */

	private int source;

	/** The identifier of the destination module */

	private int destination;



	private byte[] readBuffer = new byte[1000];

	

	/**

	 * Creates a new instance of InterProcessCommunicator

	 * 

	 * @param source

	 *            the integer identifier of the originated module

	 * @param destination

	 *            the integer idenifier of the destination module.

	 */

	public InterProcessCommunicator(int source, int destination) {

		this.source = source;

		this.destination = destination;

	}



	/**

	 * Receives a datagram from GCT Interprocess.

	 * 

	 * @return received datagram.

	 */

	public byte[] read() {

		//TODO Make JNI use native ByteBuffer

		

		int len = receive(source, readBuffer);



		if (len == -1) {

			// no messages in queue

			return null;

		}

	

		byte[] tempBuf = new byte[len];

		System.arraycopy(readBuffer, 0, tempBuf, 0, len);

		return tempBuf;

	}



	/**

	 * Sends datagram to the destination module.

	 * 

	 * @param packet

	 *            the datagram to be sent.

	 */

	public int write(byte[] msg) throws IOException {

		//TODO Make JNI use native ByteBuffer



		//TODO I do not sure if "synchronized" needs here, may be dialogic GCT_send() method is thread-safe ? 

		synchronized (this) {

			int status = send(source, destination, msg);



			if (status != 0) {

				throw new IOException("Dialogic card: Can not send packet by GCT_send() method");

			}

			

			return status;

		}

	}



	/**

	 * Actualy receives datagram using Interprocces communication.

	 * 

	 * @param source

	 *            indicates the module id wich will receive datagrams.

	 * @param buffer

	 *            the buffer wich should be used to store recevied message.

	 * @return the actual length of the received message.

	 */

	private native int receive(int source, byte[] buffer);



	/**

	 * Actualy sends the message using interprocces communication.

	 * 

	 * @param source

	 *            the module id wich sends message.

	 * @param destionation

	 *            the module id wich must receive message.

	 * @param buffer

	 *            the buffer contained message.

	 * @return the number of actualy bytes sent.

	 */

	private native int send(int source, int destination, byte[] buffer);



	static {

		try {

			System.loadLibrary(LIB_NAME);

			System.out.println("Loaded library mobicents-dialogic-linux"); 

		} catch (Exception e) {

			e.printStackTrace();

		}

	}

}