layers/plugins/org.eclipse.papyrus.infra.gmfdiag.layers.runtime/src/org/eclipse/papyrus/internal/infra/gmfdiag/layers/runtime/LayersStackApplicationEventNotifier.java

/*******************************************************************************
 * Copyright (c) 2013 CEA LIST.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Cedric Dumoulin - cedric.dumoulin@lifl.fr
 ******************************************************************************/
package org.eclipse.papyrus.internal.infra.gmfdiag.layers.runtime;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.emf.common.notify.Adapter;
import org.eclipse.emf.common.notify.Notification;
import org.eclipse.emf.common.notify.impl.AdapterImpl;
import org.eclipse.papyrus.internal.infra.gmfdiag.layers.model.layers.LayersPackage;
import org.eclipse.papyrus.internal.infra.gmfdiag.layers.model.layers.LayersStack;
import org.eclipse.papyrus.internal.infra.gmfdiag.layers.model.layers.LayersStackApplication;
import org.eclipse.papyrus.internal.infra.gmfdiag.layers.runtime.model.LayersModelResource;


/**
 * This class listen to a {@link LayersStackApplication} and send following to listeners:
 * <ul>
 * <li>LayerStack added</li>
 * <li>LayerStack removed</li>
 * </ul>
 *
 * @author cedric dumoulin
 *
 */
public class LayersStackApplicationEventNotifier {

	protected LayersModelResource layersModel;

	/**
	 * List of listener to notify.
	 */
	protected List<ILayersStackApplicationEventListener> listeners = new ArrayList<ILayersStackApplicationEventListener>();

	/**
	 * listener on LayerStack events
	 */
	protected Adapter layerStackListener = new AdapterImpl() {
		@Override
		public void notifyChanged(Notification msg) {

			switch (msg.getFeatureID(LayersStackApplication.class)) {
			case LayersPackage.LAYERS_STACK_APPLICATION__LAYERS_STACKS:
				switch (msg.getEventType()) {
				case Notification.ADD:
					// a layerStack is added to application
					// layerStack = msg.getNewValue()
					layerStackAdded(msg);
					break;

				case Notification.REMOVE:
					// a layerStack is removed from application
					// layerStack = msg.getOldValue()
					layerStackRemoved(msg);
					break;

				default:
					break;
				}
				break;
			}
			;
		};
	};

	/**
	 * Constructor.
	 *
	 * @param layersModel
	 */
	public LayersStackApplicationEventNotifier(LayersModelResource layersModel) {
		this.layersModel = layersModel;
		activate();
	}

	/**
	 * Constructor.
	 *
	 * @param layersModel
	 * @param activate
	 *            True if the notifier should be activated immediately. False otherwise.
	 */
	public LayersStackApplicationEventNotifier(LayersModelResource layersModel, boolean activate) {
		this.layersModel = layersModel;
		if (activate) {
			activate();
		}
	}

	/**
	 * Activate the listeners.
	 *
	 */
	protected void activate() {
		// Listen on LayerStackApplication for LayerStack creation
		// TODO Avoid to create the application here. Listen on its creation
		// and listen on it when created.

		LayersStackApplication application = layersModel.getLayerStackApplication();

		application.eAdapters().add(layerStackListener);
	}

	/**
	 * Deactivate listeners
	 */
	protected void deactivate() {
		// The application can be already deactivated (because we are in dispose()
		// See bug 431121
		LayersStackApplication application = layersModel.lookupLayerStackApplication();
		if (application != null) {
			application.eAdapters().remove(layerStackListener);
		}
	}

	/**
	 * Dispose the synchronizer
	 */
	public void dispose() {
		// Deactivate listeners
		deactivate();
		layersModel = null;
	}

	/**
	 * Return true if the object is disposed.
	 *
	 * @return
	 */
	public boolean isDisposed() {
		return layersModel == null;
	}

	/**
	 * Add the specified listener to the list of listener.
	 * Do not add it if the listener is already in the list.
	 *
	 * @param listener
	 */
	public void addLayersModelEventListener(ILayersStackApplicationEventListener listener) {

		if (listener == null) {
			return;
		}

		// Check if exist
		if (listeners.contains(listener)) {
			return;
		}

		listeners.add(listener);
	}

	/**
	 * Remove the specified listener from the list of listeners.
	 *
	 * @param listener
	 */
	public void removeLayersModelEventListener(ILayersStackApplicationEventListener listener) {

		listeners.remove(listener);
	}

	/**
	 * Called by events when a {@link LayersStack} is added to the {@link LayersStackApplication}
	 *
	 * @param msg
	 */
	protected void layerStackAdded(Notification msg) {
		for (ILayersStackApplicationEventListener listener : listeners) {
			listener.layerStackAdded(msg);
		}
	}

	/**
	 * Called by events when a {@link LayersStack} is removed from the {@link LayersStackApplication}
	 *
	 * @param msg
	 */
	protected void layerStackRemoved(Notification msg) {
		for (ILayersStackApplicationEventListener listener : listeners) {
			listener.layerStackRemoved(msg);
		}
	}

	/**
	 * Utility method returning the layer stack in case of addedLayer event.
	 *
	 * @param msg
	 * @return
	 */
	public static LayersStack getAddedLayerStack(Notification msg) {
		return (LayersStack) msg.getNewValue();
	}

	/**
	 * Utility method returning the layer stack in case of removeLayer event.
	 *
	 * @param msg
	 * @return
	 */
	public static LayersStack getRemovedLayerStack(Notification msg) {
		return (LayersStack) msg.getOldValue();
	}


}