/* 
 * Copyright (c) 2008 Stiftung Deutsches Elektronen-Synchrotron, 
 * Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY.
 *
 * THIS SOFTWARE IS PROVIDED UNDER THIS LICENSE ON AN "../AS IS" BASIS. 
 * WITHOUT WARRANTY OF ANY KIND, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED 
 * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE AND 
 * NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE 
 * FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR 
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. SHOULD THE SOFTWARE PROVE DEFECTIVE 
 * IN ANY RESPECT, THE USER ASSUMES THE COST OF ANY NECESSARY SERVICING, REPAIR OR 
 * CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS LICENSE. 
 * NO USE OF ANY SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER THIS DISCLAIMER.
 * DESY HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, 
 * OR MODIFICATIONS.
 * THE FULL LICENSE SPECIFYING FOR THE SOFTWARE THE REDISTRIBUTION, MODIFICATION, 
 * USAGE AND OTHER RIGHTS AND OBLIGATIONS IS INCLUDED WITH THE DISTRIBUTION OF THIS 
 * PROJECT IN THE FILE LICENSE.HTML. IF THE LICENSE IS NOT INCLUDED YOU MAY FIND A COPY 
 * AT HTTP://WWW.DESY.DE/LEGAL/LICENSE.HTM
 */
 package org.csstudio.sds.ui.internal.layers;

import org.csstudio.sds.internal.model.Layer;
import org.csstudio.sds.internal.model.LayerSupport;
import org.csstudio.sds.model.ContainerModel;
import org.eclipse.gef.commands.CommandStack;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.ui.IPartListener;
import org.eclipse.ui.IWorkbenchPart;
import org.eclipse.ui.part.ViewPart;

/**
 * A view which provides access to the layers of {@link ContainerModel}. This
 * view tries to query the layer model from active workbench parts using a
 * {@link ILayerManager} adapter.
 * 
 * @author swende
 * 
 */
public final class LayerManagementView extends ViewPart implements
		IPartListener {
	/**
	 * The view�s ID.
	 */
	public static final String VIEW_ID = "org.csstudio.sds.ui.internal.layers.LayerManagementView";

	/**
	 * Current layer manager adapter (is queried from active workbench parts).
	 */
	private ILayerManager _currentLayerManager;

	/**
	 * The workbench part, that provided the current layer manager.
	 */
	private IWorkbenchPart _layerSourcePart;
	
	/**
	 * The treeviewer which displays the layers.
	 */
	private LayerTreeViewer _layerTreeViewer;

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void createPartControl(final Composite parent) {
		// configure viewer
		_layerTreeViewer = new LayerTreeViewer(getSite(), parent, VIEW_ID);
		_layerTreeViewer.setCommandStack(getCommandStack());

		// handle initial workbench part selection
		IWorkbenchPart activePart = getViewSite().getPage().getActivePart();
		if (activePart != null) {
			partActivated(activePart);
		}

		// listen to workbench part changes
		getViewSite().getPage().addPartListener(this);

	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void dispose() {
		super.dispose();
		// stop listening to the page
		getViewSite().getPage().removePartListener(this);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void setFocus() {

	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void partActivated(final IWorkbenchPart part) {
		ILayerManager layerManager = (ILayerManager) part
				.getAdapter(ILayerManager.class);
		if (layerManager != null && layerManager != _currentLayerManager) {
			// memorize part
			_layerSourcePart = part;

			// memorize layer manager adapter
			_currentLayerManager = layerManager;

			// feed the viewer with the current layers
			_layerTreeViewer.setLayerSupport(_currentLayerManager.getLayerSupport());

			// pre-select the active layer
			Layer activeLayer = _currentLayerManager.getLayerSupport()
					.getActiveLayer();

			if (activeLayer != null) {
				_layerTreeViewer.setSelection(new StructuredSelection(activeLayer));
			}
		}
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void partClosed(final IWorkbenchPart part) {
		if (_layerSourcePart != null && _layerSourcePart == part) {
			// forget the part
			_layerSourcePart = null;

			// invalidate layer manager
			_currentLayerManager = null;
		}
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void partBroughtToTop(final IWorkbenchPart part) {
		// do nothing
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void partDeactivated(final IWorkbenchPart part) {
		// do nothing
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void partOpened(final IWorkbenchPart part) {
		// do nothing
	}

	/**
	 * Returns the current access object to the layer model, which backs this
	 * view.
	 * 
	 * @return the current access object to the layer model, which backs this
	 *         view
	 */
	public LayerSupport getCurrentLayerSupport() {
		return _currentLayerManager.getLayerSupport();
	}

	/**
	 * Returns the command stack that should be used to execute commands that
	 * deal with layers.
	 * 
	 * @return the command stack that should be used to execute commands that
	 *         deal with layers
	 */
	public CommandStack getCommandStack() {
		CommandStack result = null;
		if (_currentLayerManager != null) {
			result = _currentLayerManager.getCommandStack();
		}
		return result;
	}

}