// $codepro.audit.disable com.instantiations.assist.eclipse.analysis.audit.rule.effectivejava.alwaysOverridetoString.alwaysOverrideToString, com.instantiations.assist.eclipse.analysis.deserializeabilitySecurity, com.instantiations.assist.eclipse.analysis.disallowReturnMutable, com.instantiations.assist.eclipse.analysis.enforceCloneableUsageSecurity
/*******************************************************************************
 * Copyright (c) 2010, 2012 Ericsson AB and others.
 * 
 * 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
 * 
 * Description:
 * 
 * This class implements the review navigator view toolbar command used 
 * to browse the view's treeviewer elements and open the ones that can be open
 * 
 * Contributors:
 *   Sebastien Dubois - Created for Mylyn Review R4E project
 *   
 ******************************************************************************/
package org.eclipse.mylyn.reviews.r4e.ui.internal.commands.handlers;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.mylyn.reviews.r4e.ui.R4EUIPlugin;
import org.eclipse.mylyn.reviews.r4e.ui.internal.editors.EditorProxy;
import org.eclipse.mylyn.reviews.r4e.ui.internal.model.IR4EUIModelElement;
import org.eclipse.mylyn.reviews.r4e.ui.internal.model.R4EUIAnomalyBasic;
import org.eclipse.mylyn.reviews.r4e.ui.internal.model.R4EUIContent;
import org.eclipse.mylyn.reviews.r4e.ui.internal.model.R4EUIFileContext;
import org.eclipse.mylyn.reviews.r4e.ui.internal.model.R4EUIModelController;
import org.eclipse.mylyn.reviews.r4e.ui.internal.navigator.ReviewNavigatorTreeViewer;
import org.eclipse.mylyn.reviews.r4e.ui.internal.navigator.ReviewNavigatorView;
import org.eclipse.swt.widgets.TreeItem;
import org.eclipse.ui.handlers.HandlerUtil;
import org.eclipse.ui.progress.UIJob;

/**
 * @author Sebastien Dubois
 * @version $Revision: 1.0 $
 */
public class SelectPreviousHandler extends AbstractHandler {

	// ------------------------------------------------------------------------
	// Constants
	// ------------------------------------------------------------------------

	/**
	 * Field COMMAND_MESSAGE. (value is ""Selecting Previous Element..."")
	 */
	private static final String COMMAND_MESSAGE = "Selecting Previous Element...";

	// ------------------------------------------------------------------------
	// Methods
	// ------------------------------------------------------------------------

	/**
	 * Method execute.
	 * 
	 * @param aEvent
	 *            ExecutionEvent
	 * @return Object
	 * @see org.eclipse.core.commands.IHandler#execute(ExecutionEvent)
	 */
	public Object execute(final ExecutionEvent aEvent) {

		final UIJob job = new UIJob(COMMAND_MESSAGE) {
			@Override
			public IStatus runInUIThread(IProgressMonitor monitor) {
				monitor.beginTask(COMMAND_MESSAGE, 1);

				final ISelection selection = HandlerUtil.getCurrentSelection(aEvent);
				if (selection instanceof IStructuredSelection) {
					if (null != selection && !selection.isEmpty()) {
						final ReviewNavigatorView view = R4EUIModelController.getNavigatorView();

						//Get the previous element
						final IR4EUIModelElement previousElement = getPreviousElement((ReviewNavigatorTreeViewer) view.getTreeViewer());

						//If there is one, select it
						if (null != previousElement) {
							R4EUIPlugin.Ftracer.traceInfo("Select previous element " + previousElement.getName());
							final ISelection previousSelection = new StructuredSelection(previousElement);
							view.getTreeViewer().setSelection(previousSelection);

							//Open the editor on FileContexts, selections amd anomalies
							if (previousElement instanceof R4EUIFileContext || previousElement instanceof R4EUIContent
									|| previousElement instanceof R4EUIAnomalyBasic) {
								EditorProxy.openEditor(view.getSite().getPage(), previousSelection, false);
							}
						}
					}
				}
				monitor.worked(1);
				monitor.done();
				return Status.OK_STATUS;
			}
		};
		job.setUser(true);
		job.schedule();
		return null;
	}

	/**
	 * Method getPreviousElement.
	 * 
	 * @param aTreeViewer
	 *            ReviewNavigatorTreeViewer
	 * @return IR4EUIModelElement
	 */
	private IR4EUIModelElement getPreviousElement(ReviewNavigatorTreeViewer aTreeViewer) {
		final TreeItem item = aTreeViewer.getTree().getSelection()[0];
		final TreeItem previousItem = aTreeViewer.getPrevious(item);
		return (IR4EUIModelElement) previousItem.getData();
	}
}