/*
 * Copyright (c) Thomas Parker, 2009.
 * 
 * This program 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 program 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */
package pcgen.cdom.facet.event;

import java.util.EventObject;

import pcgen.cdom.base.PCGenIdentifier;

/**
 * An DataFacetChangeEvent is an event that indicates when a Facet has changed.
 * 
 * The object that implements the FacetChangeListener interface gets this
 * DataFacetChangeEvent when the event occurs.
 * 
 * NOTE: This Object is reference-semantic. It carries a reference to the
 * affected CDOMObject. Use of this Event does not provide protection from
 * mutability for that CDOMObject by listeners. DataFacetChangeEvent, however,
 * makes the guarantee that no modifications are made by DataFacetChangeEvent to
 * the CDOMObject.
 * 
 * @param <IDT>
 *            The type of Identifier (e.g. CharID) used by this
 *            DataFacetChangeEvent
 * @param <T>
 *            The Type object of changed in the DataFacetChangeEvent
 */
public class DataFacetChangeEvent<IDT extends PCGenIdentifier, T> extends EventObject
{
	/**
	 * The constant ID used by an DataFacetChangeEvent to indicate that a
	 * DataFacetChangeEvent was the result of a CDOMObject being added to a
	 * resource.
	 */
	public static final int DATA_ADDED = 0;

	/**
	 * The constant ID used by an DataFacetChangeEvent to indicate that a
	 * DataFacetChangeEvent was the result of a CDOMObject being removed from a
	 * resource.
	 */
	public static final int DATA_REMOVED = 1;

	/**
	 * The ID indicating the type of this DataFacetChangeEvent (addition to or
	 * removal from a resource)
	 */
	private final int eventID;

	/**
	 * The ID indicating the owning character for this DataFacetChangeEvent
	 */
	private final IDT charID;

	/**
	 * The CDOMObject that was added to or removed from the resource.
	 */
	private final T node;

	/**
	 * Constructs a new DataFacetChangeEvent for the given PCGenIdentifier. The
	 * CDOMObject which was added or removed and an indication of the action
	 * (Addition or Removal) is also provided.
	 * 
	 * @param id
	 *            The PCGenIdentifier identifying the resource in which the event
	 *            took place
	 * @param cdo
	 *            The CDOMObject which was added to or removed from the Graph
	 * @param source           
	 *            The base event object
	 * @param type
	 *            An integer identifying whether the given CDOMObject was added
	 *            or removed from the resource
	 */
	public DataFacetChangeEvent(IDT id, T cdo, Object source, int type)
	{
		super(source);
		if (source == null)
		{
			throw new IllegalArgumentException("Source Object cannot be null");
		}
		if (id == null)
		{
			throw new IllegalArgumentException("PCGenIdentifier cannot be null");
		}
		if (cdo == null)
		{
			throw new IllegalArgumentException("CDOMObject cannot be null");
		}
		charID = id;
		node = cdo;
		eventID = type;
	}

	/**
	 * Returns the CDOMObject which was added to or removed from the
	 * resource.
	 * 
	 * @return The CDOMObject which was added to or removed from the
	 *         resource
	 */
	public T getCDOMObject()
	{
		return node;
	}

	/**
	 * Returns an identifier indicating if the CDOMObject returned by
	 * getCDOMObject() was added to or removed from the resource. This
	 * identifier is either DataFacetChangeEvent.NODE_ADDED or
	 * DataFacetChangeEvent.NODE_REMOVED
	 * 
	 * @return A identifier indicating if the CDOMObject was added to or removed
	 *         from the resource
	 */
	public int getEventType()
	{
		return eventID;
	}

	/**
	 * Returns an identifier indicating the resource on which this event
	 * occurred.
	 * 
	 * @return A identifier indicating the resource on which this event
	 *         occurred.
	 */
	public IDT getCharID()
	{
		return charID;
	}
}