/*******************************************************************************
 * Copyright (C) 2016 Obeo.
 *
 * 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.synchronize;

import java.io.IOException;
import java.nio.file.Files;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.IPath;
import org.eclipse.egit.core.internal.storage.GitFileRevision;
import org.eclipse.egit.core.project.RepositoryMapping;
import org.eclipse.egit.core.synchronize.dto.GitSynchronizeData;
import org.eclipse.egit.core.synchronize.dto.GitSynchronizeDataSet;
import org.eclipse.egit.ui.Activator;
import org.eclipse.egit.ui.internal.CompareUtils;
import org.eclipse.egit.ui.internal.UIText;
import org.eclipse.egit.ui.internal.dialogs.CompareTreeView;
import org.eclipse.jgit.annotations.NonNull;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.osgi.util.NLS;
import org.eclipse.swt.widgets.Display;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.PlatformUI;

/**
 * This default implementation of a synchronizer does not take logical models
 * into account.
 */
public class DefaultGitSynchronizer implements GitSynchronizer {

	/**
	 * Indicates if it's OK to directly open a compare editor.
	 *
	 * @param resources
	 *            The resources to compare.
	 *
	 * @return <code>false</code> if the descriptor contains an empty array or
	 *         an array with more than one resource. If the array contains only
	 *         one resource, returns <code>false</code> unless either:
	 *         <ul>
	 *         <li>this resource is a symbolic link;</li>
	 *         <li>this resource is a file and
	 *         {@code this#canCompareDirectly(IFile)} returns <code>true</code>
	 *         on this file.</li> </lu>
	 */
	protected boolean canCompareDirectly(IResource[] resources) {
		if (resources.length == 1) {
			IResource resource = resources[0];
			if (resource instanceof IFile) {
				return canCompareDirectly((IFile) resource);
			} else {
				IPath location = resource.getLocation();
				if (location != null
						&& Files.isSymbolicLink(location.toFile().toPath())) {
					// for directory *link*, file compare must be used
					return true;
				}
			}
		}
		return false;
	}

	/**
	 * Indicates if it is OK to open the selected file directly in a compare
	 * editor. This default implementation always returns <code>true</code>.
	 *
	 * @param file
	 *            file the user is trying to compare
	 * @return Always <code>true</code>.
	 */
	protected boolean canCompareDirectly(@NonNull IFile file) {
		return true;
	}

	@Override
	public void compare(IResource[] resources, @NonNull Repository repository,
			String leftRev, String rightRev, boolean includeLocal,
			IWorkbenchPage page) throws IOException {
		if (canCompareDirectly(resources)) {
			if (includeLocal) {
				CompareUtils.compareWorkspaceWithRef(
						repository, resources[0], rightRev, page);
			} else {
				final IResource file = resources[0];
				Assert.isNotNull(file);
				final RepositoryMapping mapping = RepositoryMapping
						.getMapping(file);
				if (mapping == null) {
					Activator.error(
							NLS.bind(UIText.GitHistoryPage_errorLookingUpPath,
									file.getLocation(),
									repository),
							null);
					return;
				}
				final String gitPath = mapping.getRepoRelativePath(file);

				CompareUtils.compareBetween(repository, gitPath, leftRev,
						rightRev, page);
			}
		} else {
			synchronize(resources, repository, leftRev, rightRev, includeLocal);
		}
	}

	@Override
	public void compare(IFile file, Repository repository, String leftPath,
			String rightPath, String leftRev, String rightRev,
			boolean includeLocal, IWorkbenchPage page) throws IOException {
		if (canCompareDirectly(file)) {
			if (includeLocal) {
				CompareUtils.compareWorkspaceWithRef(repository, file, rightRev,
						page);
			} else {
				CompareUtils.compareBetween(repository, leftPath, rightPath,
						leftRev, rightRev, page);
			}
		} else {
			synchronize(new IResource[] { file }, repository, leftRev, rightRev,
					includeLocal);
		}
	}

	/**
	 * Synchronize the given descriptor.
	 *
	 * @param resources
	 *            The resources to compare, can be empty in which case the whole
	 *            repositpry will be synchronized.
	 * @param repository
	 *            The repository to use.
	 * @param leftRev
	 *            The left revision.
	 * @param rightRev
	 *            The right revision.
	 * @param includeLocal
	 *            Whether the local version of the file should be used, in which
	 *            case leftRev is ignored.
	 *
	 * @throws IOException
	 */
	protected void synchronize(IResource[] resources, Repository repository,
			String leftRev, String rightRev, boolean includeLocal)
			throws IOException {
		if (rightRev.equals(GitFileRevision.INDEX)) {
			openGitTreeCompare(resources, leftRev,
					CompareTreeView.INDEX_VERSION, includeLocal);
		} else if (leftRev.equals(GitFileRevision.INDEX)) {
			// Even git tree compare cannot handle index as source...
			// Synchronize using the local data for now.
			Set<IResource> resSet = new HashSet<>(
					Arrays.asList(resources));
			final GitSynchronizeData gsd = new GitSynchronizeData(
					repository, leftRev, rightRev, true, resSet);
			GitModelSynchronize.launch(new GitSynchronizeDataSet(gsd),
					resources);
		} else {
			Set<IResource> resSet = new HashSet<>(
					Arrays.asList(resources));
			final GitSynchronizeData gsd = new GitSynchronizeData(
					repository, leftRev, rightRev, includeLocal,
					resSet);
			GitModelSynchronize.launch(new GitSynchronizeDataSet(gsd),
					resources);
		}
	}

	/**
	 * Open the git tree compare view.
	 *
	 * @param resources
	 *            The resources to display
	 * @param leftRev
	 *            The left revision
	 * @param rightRev
	 *            The right revision
	 * @param includeLocal
	 *            Whether the local version must be used, if <code>true</code>
	 *            {@code leftRev} will be ignored
	 */
	protected void openGitTreeCompare(IResource[] resources, String leftRev,
			String rightRev, boolean includeLocal) {
		Display display = PlatformUI.getWorkbench().getDisplay();
		display.asyncExec(new Runnable() {

			@Override
			public void run() {
				CompareTreeView view;
				try {
					view = (CompareTreeView) PlatformUI.getWorkbench()
							.getActiveWorkbenchWindow().getActivePage()
							.showView(CompareTreeView.ID);
					if (includeLocal) {
						view.setInput(resources, rightRev);
					} else {
						view.setInput(resources, leftRev, rightRev);
					}
				} catch (PartInitException e) {
					Activator.handleError(e.getMessage(), e, true);
				}
			}
		});
	}

}