/*******************************************************************************
 * Copyright (c) 2004, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.resource;

import java.util.Set;

import org.eclipse.core.commands.common.EventManager;

import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;

/**
 * Abstract base class for various JFace registries.
 *
 * @since 3.0
 */
public abstract class ResourceRegistry extends EventManager {

	/**
	 * Adds a property change listener to this registry.
	 *
	 * @param listener a property change listener
	 */
	public void addListener(IPropertyChangeListener listener) {
		addListenerObject(listener);
	}

	/**
	 * Disposes all currently allocated resources.
	 */
	protected abstract void clearCaches();

	/**
	 * @return the set of keys this manager knows about.  This collection
	 * should be immutable.
	 */
	public abstract Set<String> getKeySet();

	/**
	 * Return whether or not the receiver has a value for the supplied key.
	 *
	 * @param key the key
	 * @return <code>true</code> if there is a value for this key
	 */
	public abstract boolean hasValueFor(String key);

	/**
	 * Fires a <code>PropertyChangeEvent</code>.
	 *
	 * @param name the name of the symbolic value that is changing.
	 * @param oldValue the old value.
	 * @param newValue the new value.
	 */
	protected void fireMappingChanged(String name, Object oldValue,
			Object newValue) {
		final Object[] myListeners = getListeners();
		if (myListeners.length > 0) {
			PropertyChangeEvent event = new PropertyChangeEvent(this, name,
					oldValue, newValue);
			for (Object myListener : myListeners) {
				try {
					((IPropertyChangeListener) myListener)
							.propertyChange(event);
				} catch (Exception e) {
					// TODO: how to log?
				}
			}
		}
	}

	/**
	 * Removes the given listener from this registry. Has no effect if the
	 * listener is not registered.
	 *
	 * @param listener a property change listener
	 */
	public void removeListener(IPropertyChangeListener listener) {
		removeListenerObject(listener);
	}
}
