/*****************************************************************
JADE - Java Agent DEvelopment Framework is a framework to develop multi-agent
systems in compliance with the FIPA specifications.
Copyright (C) 2000 CSELT S.p.A. 

GNU Lesser General Public License

This library 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, 
version 2.1 of the License. 

This library 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 library; if not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA  02111-1307, USA.
*****************************************************************/

package jade.core.behaviours;

import jade.util.leap.*;
import jade.util.leap.Serializable;

/**
 * @author Giovanni Caire - Telecom Italia Lab
 * @version $Date: 2005-06-13 19:10:41 +0200 (lun, 13 giu 2005) $ $Revision: 5716 $
 */
class BehaviourList extends LinkedList implements Serializable {
  	private int current = 0;
  	
  	/** 
  	 * Add a Behaviour to the tail of the list. This does not require
  	 * adjusting the current index
  	 */
  	public synchronized void addElement(Behaviour b) {
  		add(b);
  	}
  	
    /** 
     * Remove b from the list. If b was in the list, return true
     * otherwise return false.
     * This requires adjusting the current index in the following cases:
     * - the index of the removed Behaviour is < than the current index
     * - the removed Behaviour is the current one and it is also 
     * the last element of the list. In this case the current index
     * must be set to 0
     */
  	public synchronized boolean removeElement(Behaviour b) {
  		int index = indexOf(b);
    	if(index != -1) {
      		remove(b);
      		if (index < current) {
				--current;
      		}
      		else if (index == current && current == size()) {
      			current = 0;
      		}
    	}
    	return index != -1;
  	}
  	
  	/**
  	   Get the current behaviour
  	*/
  	public Behaviour getCurrent() {
  		Behaviour b = null;
  		try {
  			b = (Behaviour) get(current);
  		}
  		catch (IndexOutOfBoundsException ioobe) {
  			// Just do nothing. Null will be returned
  		}
  		return b;
  	}

  	/**
  	   Set the current index to the beginning of the list
  	*/
  	public synchronized void begin() {
  		current = 0;
  	}

  	/**
  	   Check whether the current behaviour is the last in the list
  	*/
  	private boolean currentIsLast() {
  		return (current == (size() - 1));
  	}
  	
  	/** 
  	 * Advance the current index (taking into account wrap around)
  	 * and return the new current Behaviour
  	 */ 
  	public synchronized Behaviour next() {
  		if (currentIsLast() || isEmpty()) {
  			current = 0;
  		}
  		else {
  			current++;
  		}
  		return getCurrent();
  	}
  	
}