/*
 * Copyright (C) 2003-2004 Red Hat Inc. All Rights Reserved.
 *
 * 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; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * 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 com.redhat.persistence;

import com.redhat.persistence.metadata.Property;

/**
 * SetEvent
 *
 * @author <a href="mailto:rhs@mit.edu">rhs@mit.edu</a>
 * @version $Revision: #6 $ $Date: 2004/08/16 $
 **/

public class SetEvent extends PropertyEvent {

    public final static String versionId = "$Id: SetEvent.java 287 2005-02-22 00:29:02Z sskracic $ by $Author: sskracic $, $DateTime: 2004/08/16 18:10:38 $";

    private Object m_oldValue;

    SetEvent(Session ssn, Object obj, Property prop, Object arg) {
        super(ssn, obj, prop, arg);
    }

    SetEvent(Session ssn, Object obj, Property prop, Object arg,
             PropertyEvent origin) {
        super(ssn, obj, prop, arg, origin);
    }

    public void dispatch(Switch sw) {
        sw.onSet(this);
    }

    void activate() {
        PropertyEvent pe = getSession().getEventStream().getLastEvent(this);
        if (pe != null) {
            m_oldValue = pe.getArgument();
        } else {
            m_oldValue = getSession().get(getObject(), getProperty());
        }

        super.activate();

        // PD dependencies
        if (getArgument() != null) {
            getPropertyData().transferNotNullDependentEvents(this);
        } else if (!getProperty().isNullable()) {
            getPropertyData().addNotNullDependent(this);
        }
    }

    void sync() {
        super.sync();
        PropertyData pd = getPropertyData();
        pd.setValue(getArgument());
    }

    public Object getPreviousValue() { return m_oldValue; }

    public String getName() { return "set"; }

}
