/*******************************************************************************
 * Copyright (C) 2009, Stefan Lay <stefan.lay@sap.com>
 * Copyright (C) 2012, Robin Stocker <robin@nibor.org>
 * Copyright (C) 2013, Laurent Goubet <laurent.goubet@obeo.fr>
 *
 * 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
 *******************************************************************************/
package org.eclipse.egit.ui.internal.actions;

import java.io.IOException;

import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.resources.IResource;
import org.eclipse.egit.ui.Activator;
import org.eclipse.egit.ui.internal.CompareUtils;
import org.eclipse.egit.ui.internal.UIText;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.handlers.HandlerUtil;

/**
 * Compares the working tree content of a file with the version of the file in
 * the HEAD commit.
 */
public class CompareWithHeadActionHandler extends RepositoryActionHandler {
	@Override
	public Object execute(ExecutionEvent event) throws ExecutionException {
		final Repository repository = getRepository(true, event);
		// assert all resources map to the same repository
		if (repository == null)
			return null;
		final IResource[] resources = getSelectedResources(event);

		IWorkbenchPage workBenchPage = HandlerUtil
				.getActiveWorkbenchWindowChecked(event).getActivePage();
		try {
			CompareUtils.compare(resources, repository, Constants.HEAD,
					Constants.HEAD, true, workBenchPage);
		} catch (IOException e) {
			Activator.handleError(
					UIText.CompareWithRefAction_errorOnSynchronize, e, true);
		}

		return null;
	}

	@Override
	public boolean isEnabled() {
		return selectionMapsToSingleRepository();
	}
}