/**
 * This file Copyright (c) 2011 Magnolia International
 * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
 *
 *
 * This file is dual-licensed under both the Magnolia
 * Network Agreement and the GNU General Public License.
 * You may elect to use one or the other of these licenses.
 *
 * This file is distributed in the hope that it will be
 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
 * implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
 * Redistribution, except as permitted by whichever of the GPL
 * or MNA you select, is prohibited.
 *
 * 1. For the GPL license (GPL), you can redistribute and/or
 * modify this file under the terms of the GNU General
 * Public License, Version 3, as published by the Free Software
 * Foundation.  You should have received a copy of the GNU
 * General Public License, Version 3 along with this program;
 * if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * 2. For the Magnolia Network Agreement (MNA), this file
 * and the accompanying materials are made available under the
 * terms of the MNA which accompanies this distribution, and
 * is available at http://www.magnolia-cms.com/mna.html
 *
 * Any modifications to this file must keep this entire header
 * intact.
 *
 */
package info.magnolia.event;

import java.util.HashSet;
import java.util.Set;

/**
 * Wraps an EventBus and remembers all handlers registered via this wrapper, so that they can easily all be cleared at once.
 *
 * Inspired by com.google.gwt.event.shared.ResettableEventBus.
 */
public class ResettableEventBus implements EventBus {

    private final EventBus wrapped;
    private final Set<HandlerRegistration> registrations = new HashSet<HandlerRegistration>();

    public ResettableEventBus(EventBus wrappedBus) {
        this.wrapped = wrappedBus;
    }

    @Override
    public synchronized <H extends EventHandler> HandlerRegistration addHandler(Class<? extends Event<H>> eventClass, H handler) {
        final HandlerRegistration registration = wrapped.addHandler(eventClass, handler);
        registrations.add(registration);
        return new HandlerRegistration() {
            @Override
            public void removeHandler() {
                synchronized (ResettableEventBus.this) {
                    registration.removeHandler();
                    registrations.remove(registration);
                }
            }
        };
    }

    @Override
    public <H extends EventHandler> void fireEvent(Event<H> event) {
        wrapped.fireEvent(event);
    }

    /**
     * Remove all handlers that have been added through this wrapper.
     */
    public synchronized void reset() {
        for (HandlerRegistration registration : registrations) {
            registration.removeHandler();
        }
        registrations.clear();
    }
}