/*******************************************************************************
 * Copyright (c) 2012 IBM Corporation 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
 *
 * Contributors:
 *    Tomasz Zarna (IBM) - initial implementation
 *******************************************************************************/
package org.eclipse.egit.ui.internal.commit.command;

import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.resources.WorkspaceJob;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.egit.core.op.RevertCommitOperation;
import org.eclipse.egit.ui.Activator;
import org.eclipse.egit.ui.JobFamilies;
import org.eclipse.egit.ui.internal.UIText;
import org.eclipse.egit.ui.internal.commit.RepositoryCommit;
import org.eclipse.egit.ui.internal.dialogs.RevertFailureDialog;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jgit.api.MergeResult;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.ui.PlatformUI;

/**
 * Executes the {@link RevertCommitOperation}
 */
public class RevertHandler extends CommitCommandHandler {

	/**
	 * Command id
	 */
	public static final String ID = "org.eclipse.egit.ui.commit.Revert"; //$NON-NLS-1$

	@Override
	public Object execute(final ExecutionEvent event) throws ExecutionException {
		List<RepositoryCommit> repoCommits = getCommits(event);
		Repository repo = repoCommits.get(0).getRepository();
		final Shell shell = getPart(event).getSite().getShell();

		final List<RevCommit> commits = new ArrayList<>();
		for (RepositoryCommit repoCommit : repoCommits)
			commits.add(repoCommit.getRevCommit());
		final RevertCommitOperation op = new RevertCommitOperation(repo,
				commits);

		Job job = new WorkspaceJob(MessageFormat.format(
				UIText.RevertHandler_JobName, Integer.valueOf(commits.size()))) {

			@Override
			public IStatus runInWorkspace(IProgressMonitor monitor) {
				try {
					op.execute(monitor);
					RevCommit newHead = op.getNewHead();
					List<Ref> revertedRefs = op.getRevertedRefs();
					if (newHead != null && revertedRefs.isEmpty())
						showRevertedDialog(shell);
					if (newHead == null) {
						RevCommit newestUnmergedCommit = null;
						for (RevCommit commit : commits) {
							if (!contains(revertedRefs, commit)) {
								newestUnmergedCommit = commit;
								break;
							}
						}
						showFailureDialog(shell, newestUnmergedCommit,
								op.getFailingResult());
					}
				} catch (CoreException e) {
					Activator.handleError(UIText.RevertOperation_InternalError,
							e, true);
				}
				return Status.OK_STATUS;
			}

			@Override
			public boolean belongsTo(Object family) {
				if (JobFamilies.REVERT_COMMIT.equals(family))
					return true;
				return super.belongsTo(family);
			}
		};
		job.setUser(true);
		job.setRule(op.getSchedulingRule());
		job.schedule();
		return null;
	}

	private boolean contains(List<Ref> refs, RevCommit commit) {
		for (Ref ref : refs) {
			ObjectId objectId = ref.getObjectId();
			if (objectId != null && objectId.equals(commit.getId())) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Shows a dialog with failing result of revert.
	 *
	 * @param shell
	 *            the shell to parent the dialog from
	 * @param commit
	 *            the commit
	 * @param result
	 *            the failing result
	 */
	private static void showFailureDialog(final Shell shell,
			final RevCommit commit, final MergeResult result) {
		shell.getDisplay().syncExec(new Runnable() {
			@Override
			public void run() {
				RevertFailureDialog.show(shell, commit, result);
			}
		});
	}

	/**
	 * Shows the "No revert performed" dialog.
	 *
	 * @param shell
	 *            the shell to parent the dialog from
	 */
	private static void showRevertedDialog(final Shell shell) {
		PlatformUI.getWorkbench().getDisplay().syncExec(new Runnable() {
			@Override
			public void run() {
				MessageDialog.openWarning(shell,
						UIText.RevertHandler_NoRevertTitle,
						UIText.RevertHandler_AlreadyRevertedMessage);
			}
		});
	}
}