/*
    * Copyright (C) 2011, 2017 Chris Aniszczyk <caniszczyk@gmail.com> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
    */
  package org.eclipse.jgit.api;
  
  import java.io.File;
  import java.io.IOException;
  import java.net.URISyntaxException;
  import java.text.MessageFormat;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  
  import org.eclipse.jgit.annotations.Nullable;
  import org.eclipse.jgit.api.errors.GitAPIException;
  import org.eclipse.jgit.api.errors.InvalidRemoteException;
  import org.eclipse.jgit.api.errors.JGitInternalException;
  import org.eclipse.jgit.dircache.DirCache;
  import org.eclipse.jgit.dircache.DirCacheCheckout;
  import org.eclipse.jgit.errors.IncorrectObjectTypeException;
  import org.eclipse.jgit.errors.MissingObjectException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.BranchConfig.BranchRebaseMode;
  import org.eclipse.jgit.lib.ConfigConstants;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.NullProgressMonitor;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.ProgressMonitor;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.RefUpdate;
  import org.eclipse.jgit.lib.Repository;
  import org.eclipse.jgit.revwalk.RevCommit;
  import org.eclipse.jgit.revwalk.RevWalk;
  import org.eclipse.jgit.submodule.SubmoduleWalk;
  import org.eclipse.jgit.transport.FetchResult;
  import org.eclipse.jgit.transport.RefSpec;
  import org.eclipse.jgit.transport.RemoteConfig;
  import org.eclipse.jgit.transport.TagOpt;
  import org.eclipse.jgit.transport.URIish;
  import org.eclipse.jgit.util.FS;
  import org.eclipse.jgit.util.FileUtils;
  
  /**
   * Clone a repository into a new working directory
   *
   * @see <a href="http://www.kernel.org/pub/software/scm/git/docs/git-clone.html"
   *      >Git documentation about Clone</a>
   */
  public class CloneCommand extends TransportCommand<CloneCommand, Git> {
  
  	private String uri;
  
  	private File directory;
  
  	private File gitDir;
  
  	private boolean bare;
  
  	private FS fs;
  
  	private String remote = Constants.DEFAULT_REMOTE_NAME;
  
  	private String branch = Constants.HEAD;
  
  	private ProgressMonitor monitor = NullProgressMonitor.INSTANCE;
  
  	private boolean cloneAllBranches;
  
  	private boolean mirror;
  
  	private boolean cloneSubmodules;
  
  	private boolean noCheckout;
  
  	private Collection<String> branchesToClone;
  
  	private Callback callback;
  
  	private boolean directoryExistsInitially;
  
  	private boolean gitDirExistsInitially;
  
  	private FETCH_TYPE fetchType;
  
  	private TagOpt tagOption;
  
  	private enum FETCH_TYPE {
  		MULTIPLE_BRANCHES, ALL_BRANCHES, MIRROR
  	}
  
  	/**
  	 * Callback for status of clone operation.
 	 *
 	 * @since 4.8
 	 */
 	public interface Callback {
 		/**
 		 * Notify initialized submodules.
 		 *
 		 * @param submodules
 		 *            the submodules
 		 *
 		 */
 		void initializedSubmodules(Collection<String> submodules);
 
 		/**
 		 * Notify starting to clone a submodule.
 		 *
 		 * @param path
 		 *            the submodule path
 		 */
 		void cloningSubmodule(String path);
 
 		/**
 		 * Notify checkout of commit
 		 *
 		 * @param commit
 		 *            the id of the commit being checked out
 		 * @param path
 		 *            the submodule path
 		 */
 		void checkingOut(AnyObjectId commit, String path);
 	}
 
 	/**
 	 * Create clone command with no repository set
 	 */
 	public CloneCommand() {
 		super(null);
 	}
 
 	/**
 	 * Get the git directory. This is primarily used for tests.
 	 *
 	 * @return the git directory
 	 */
 	@Nullable
 	File getDirectory() {
 		return directory;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 * <p>
 	 * Executes the {@code Clone} command.
 	 *
 	 * The Git instance returned by this command needs to be closed by the
 	 * caller to free resources held by the underlying {@link Repository}
 	 * instance. It is recommended to call this method as soon as you don't need
 	 * a reference to this {@link Git} instance and the underlying
 	 * {@link Repository} instance anymore.
 	 */
 	@Override
 	public Git call() throws GitAPIException, InvalidRemoteException,
 			org.eclipse.jgit.api.errors.TransportException {
 		URIish u = null;
 		try {
 			u = new URIish(uri);
 			verifyDirectories(u);
 		} catch (URISyntaxException e) {
 			throw new InvalidRemoteException(
 					MessageFormat.format(JGitText.get().invalidURL, uri), e);
 		}
 		setFetchType();
 		@SuppressWarnings("resource") // Closed by caller
 		Repository repository = init();
 		FetchResult fetchResult = null;
 		Thread cleanupHook = new Thread(() -> cleanup());
 		Runtime.getRuntime().addShutdownHook(cleanupHook);
 		try {
 			fetchResult = fetch(repository, u);
 		} catch (IOException ioe) {
 			if (repository != null) {
 				repository.close();
 			}
 			cleanup();
 			throw new JGitInternalException(ioe.getMessage(), ioe);
 		} catch (URISyntaxException e) {
 			if (repository != null) {
 				repository.close();
 			}
 			cleanup();
 			throw new InvalidRemoteException(
 					MessageFormat.format(JGitText.get().invalidRemote, remote),
 					e);
 		} catch (GitAPIException | RuntimeException e) {
 			if (repository != null) {
 				repository.close();
 			}
 			cleanup();
 			throw e;
 		} finally {
 			Runtime.getRuntime().removeShutdownHook(cleanupHook);
 		}
 		if (!noCheckout) {
 			try {
 				checkout(repository, fetchResult);
 			} catch (IOException ioe) {
 				repository.close();
 				throw new JGitInternalException(ioe.getMessage(), ioe);
 			} catch (GitAPIException | RuntimeException e) {
 				repository.close();
 				throw e;
 			}
 		}
 		return new Git(repository, true);
 	}
 
 	private void setFetchType() {
 		if (mirror) {
 			fetchType = FETCH_TYPE.MIRROR;
 			setBare(true);
 		} else if (cloneAllBranches) {
 			fetchType = FETCH_TYPE.ALL_BRANCHES;
 		} else if (branchesToClone != null && !branchesToClone.isEmpty()) {
 			fetchType = FETCH_TYPE.MULTIPLE_BRANCHES;
 		} else {
 			// Default: neither mirror nor all nor specific refs given
 			fetchType = FETCH_TYPE.ALL_BRANCHES;
 		}
 	}
 
 	private static boolean isNonEmptyDirectory(File dir) {
 		if (dir != null && dir.exists()) {
 			File[] files = dir.listFiles();
 			return files != null && files.length != 0;
 		}
 		return false;
 	}
 
 	void verifyDirectories(URIish u) {
 		if (directory == null && gitDir == null) {
 			directory = new File(u.getHumanishName() + (bare ? Constants.DOT_GIT_EXT : "")); //$NON-NLS-1$
 		}
 		directoryExistsInitially = directory != null && directory.exists();
 		gitDirExistsInitially = gitDir != null && gitDir.exists();
 		validateDirs(directory, gitDir, bare);
 		if (isNonEmptyDirectory(directory)) {
 			throw new JGitInternalException(MessageFormat.format(
 					JGitText.get().cloneNonEmptyDirectory, directory.getName()));
 		}
 		if (isNonEmptyDirectory(gitDir)) {
 			throw new JGitInternalException(MessageFormat.format(
 					JGitText.get().cloneNonEmptyDirectory, gitDir.getName()));
 		}
 	}
 
 	private Repository init() throws GitAPIException {
 		InitCommand command = Git.init();
 		command.setBare(bare);
 		if (fs != null) {
 			command.setFs(fs);
 		}
 		if (directory != null) {
 			command.setDirectory(directory);
 		}
 		if (gitDir != null) {
 			command.setGitDir(gitDir);
 		}
 		return command.call().getRepository();
 	}
 
 	private FetchResult fetch(Repository clonedRepo, URIish u)
 			throws URISyntaxException,
 			org.eclipse.jgit.api.errors.TransportException, IOException,
 			GitAPIException {
 		// create the remote config and save it
 		RemoteConfig config = new RemoteConfig(clonedRepo.getConfig(), remote);
 		config.addURI(u);
 
 		boolean fetchAll = fetchType == FETCH_TYPE.ALL_BRANCHES
 				|| fetchType == FETCH_TYPE.MIRROR;
 
 		config.setFetchRefSpecs(calculateRefSpecs(fetchType, config.getName()));
 		config.setMirror(fetchType == FETCH_TYPE.MIRROR);
 		if (tagOption != null) {
 			config.setTagOpt(tagOption);
 		}
 		config.update(clonedRepo.getConfig());
 
 		clonedRepo.getConfig().save();
 
 		// run the fetch command
 		FetchCommand command = new FetchCommand(clonedRepo);
 		command.setRemote(remote);
 		command.setProgressMonitor(monitor);
 		if (tagOption != null) {
 			command.setTagOpt(tagOption);
 		} else {
 			command.setTagOpt(
 					fetchAll ? TagOpt.FETCH_TAGS : TagOpt.AUTO_FOLLOW);
 		}
 		configure(command);
 
 		return command.call();
 	}
 
 	private List<RefSpec> calculateRefSpecs(FETCH_TYPE type,
 			String remoteName) {
 		List<RefSpec> specs = new ArrayList<>();
 		if (type == FETCH_TYPE.MIRROR) {
 			specs.add(new RefSpec().setForceUpdate(true).setSourceDestination(
 					Constants.R_REFS + '*', Constants.R_REFS + '*'));
 		} else {
 			RefSpec heads = new RefSpec();
 			heads = heads.setForceUpdate(true);
 			final String dst = (bare ? Constants.R_HEADS
 					: Constants.R_REMOTES + remoteName + '/') + '*';
 			heads = heads.setSourceDestination(Constants.R_HEADS + '*', dst);
 			if (type == FETCH_TYPE.MULTIPLE_BRANCHES) {
 				RefSpec tags = new RefSpec().setForceUpdate(true)
 						.setSourceDestination(Constants.R_TAGS + '*',
 								Constants.R_TAGS + '*');
 				for (String selectedRef : branchesToClone) {
 					if (heads.matchSource(selectedRef)) {
 						specs.add(heads.expandFromSource(selectedRef));
 					} else if (tags.matchSource(selectedRef)) {
 						specs.add(tags.expandFromSource(selectedRef));
 					}
 				}
 			} else {
 				// We'll fetch the tags anyway.
 				specs.add(heads);
 			}
 		}
 		return specs;
 	}
 
 	private void checkout(Repository clonedRepo, FetchResult result)
 			throws MissingObjectException, IncorrectObjectTypeException,
 			IOException, GitAPIException {
 
 		Ref head = null;
 		if (branch.equals(Constants.HEAD)) {
 			Ref foundBranch = findBranchToCheckout(result);
 			if (foundBranch != null)
 				head = foundBranch;
 		}
 		if (head == null) {
 			head = result.getAdvertisedRef(branch);
 			if (head == null)
 				head = result.getAdvertisedRef(Constants.R_HEADS + branch);
 			if (head == null)
 				head = result.getAdvertisedRef(Constants.R_TAGS + branch);
 		}
 
 		if (head == null || head.getObjectId() == null)
 			return; // TODO throw exception?
 
 		if (head.getName().startsWith(Constants.R_HEADS)) {
 			final RefUpdate newHead = clonedRepo.updateRef(Constants.HEAD);
 			newHead.disableRefLog();
 			newHead.link(head.getName());
 			addMergeConfig(clonedRepo, head);
 		}
 
 		final RevCommit commit = parseCommit(clonedRepo, head);
 
 		boolean detached = !head.getName().startsWith(Constants.R_HEADS);
 		RefUpdate u = clonedRepo.updateRef(Constants.HEAD, detached);
 		u.setNewObjectId(commit.getId());
 		u.forceUpdate();
 
 		if (!bare) {
 			DirCache dc = clonedRepo.lockDirCache();
 			DirCacheCheckout co = new DirCacheCheckout(clonedRepo, dc,
 					commit.getTree());
 			co.setProgressMonitor(monitor);
 			co.checkout();
 			if (cloneSubmodules)
 				cloneSubmodules(clonedRepo);
 		}
 	}
 
 	private void cloneSubmodules(Repository clonedRepo) throws IOException,
 			GitAPIException {
 		SubmoduleInitCommand init = new SubmoduleInitCommand(clonedRepo);
 		Collection<String> submodules = init.call();
 		if (submodules.isEmpty()) {
 			return;
 		}
 		if (callback != null) {
 			callback.initializedSubmodules(submodules);
 		}
 
 		SubmoduleUpdateCommand update = new SubmoduleUpdateCommand(clonedRepo);
 		configure(update);
 		update.setProgressMonitor(monitor);
 		update.setCallback(callback);
 		if (!update.call().isEmpty()) {
 			SubmoduleWalk walk = SubmoduleWalk.forIndex(clonedRepo);
 			while (walk.next()) {
 				try (Repository subRepo = walk.getRepository()) {
 					if (subRepo != null) {
 						cloneSubmodules(subRepo);
 					}
 				}
 			}
 		}
 	}
 
 	private Ref findBranchToCheckout(FetchResult result) {
 		final Ref idHEAD = result.getAdvertisedRef(Constants.HEAD);
 		ObjectId headId = idHEAD != null ? idHEAD.getObjectId() : null;
 		if (headId == null) {
 			return null;
 		}
 
 		if (idHEAD != null && idHEAD.isSymbolic()) {
 			return idHEAD.getTarget();
 		}
 
 		Ref master = result.getAdvertisedRef(Constants.R_HEADS
 				+ Constants.MASTER);
 		ObjectId objectId = master != null ? master.getObjectId() : null;
 		if (headId.equals(objectId)) {
 			return master;
 		}
 
 		Ref foundBranch = null;
 		for (Ref r : result.getAdvertisedRefs()) {
 			final String n = r.getName();
 			if (!n.startsWith(Constants.R_HEADS))
 				continue;
 			if (headId.equals(r.getObjectId())) {
 				foundBranch = r;
 				break;
 			}
 		}
 		return foundBranch;
 	}
 
 	private void addMergeConfig(Repository clonedRepo, Ref head)
 			throws IOException {
 		String branchName = Repository.shortenRefName(head.getName());
 		clonedRepo.getConfig().setString(ConfigConstants.CONFIG_BRANCH_SECTION,
 				branchName, ConfigConstants.CONFIG_KEY_REMOTE, remote);
 		clonedRepo.getConfig().setString(ConfigConstants.CONFIG_BRANCH_SECTION,
 				branchName, ConfigConstants.CONFIG_KEY_MERGE, head.getName());
 		String autosetupRebase = clonedRepo.getConfig().getString(
 				ConfigConstants.CONFIG_BRANCH_SECTION, null,
 				ConfigConstants.CONFIG_KEY_AUTOSETUPREBASE);
 		if (ConfigConstants.CONFIG_KEY_ALWAYS.equals(autosetupRebase)
 				|| ConfigConstants.CONFIG_KEY_REMOTE.equals(autosetupRebase))
 			clonedRepo.getConfig().setEnum(
 					ConfigConstants.CONFIG_BRANCH_SECTION, branchName,
 					ConfigConstants.CONFIG_KEY_REBASE, BranchRebaseMode.REBASE);
 		clonedRepo.getConfig().save();
 	}
 
 	private RevCommit parseCommit(Repository clonedRepo, Ref ref)
 			throws MissingObjectException, IncorrectObjectTypeException,
 			IOException {
 		final RevCommit commit;
 		try (RevWalkRevWalk.html#RevWalk">RevWalk rw = new RevWalk(clonedRepo)) {
 			commit = rw.parseCommit(ref.getObjectId());
 		}
 		return commit;
 	}
 
 	/**
 	 * Set the URI to clone from
 	 *
 	 * @param uri
 	 *            the URI to clone from, or {@code null} to unset the URI. The
 	 *            URI must be set before {@link #call} is called.
 	 * @return this instance
 	 */
 	public CloneCommand setURI(String uri) {
 		this.uri = uri;
 		return this;
 	}
 
 	/**
 	 * The optional directory associated with the clone operation. If the
 	 * directory isn't set, a name associated with the source uri will be used.
 	 *
 	 * @see URIish#getHumanishName()
 	 * @param directory
 	 *            the directory to clone to, or {@code null} if the directory
 	 *            name should be taken from the source uri
 	 * @return this instance
 	 * @throws java.lang.IllegalStateException
 	 *             if the combination of directory, gitDir and bare is illegal.
 	 *             E.g. if for a non-bare repository directory and gitDir point
 	 *             to the same directory of if for a bare repository both
 	 *             directory and gitDir are specified
 	 */
 	public CloneCommand setDirectory(File directory) {
 		validateDirs(directory, gitDir, bare);
 		this.directory = directory;
 		return this;
 	}
 
 	/**
 	 * Set the repository meta directory (.git)
 	 *
 	 * @param gitDir
 	 *            the repository meta directory, or {@code null} to choose one
 	 *            automatically at clone time
 	 * @return this instance
 	 * @throws java.lang.IllegalStateException
 	 *             if the combination of directory, gitDir and bare is illegal.
 	 *             E.g. if for a non-bare repository directory and gitDir point
 	 *             to the same directory of if for a bare repository both
 	 *             directory and gitDir are specified
 	 * @since 3.6
 	 */
 	public CloneCommand setGitDir(File gitDir) {
 		validateDirs(directory, gitDir, bare);
 		this.gitDir = gitDir;
 		return this;
 	}
 
 	/**
 	 * Set whether the cloned repository shall be bare
 	 *
 	 * @param bare
 	 *            whether the cloned repository is bare or not
 	 * @return this instance
 	 * @throws java.lang.IllegalStateException
 	 *             if the combination of directory, gitDir and bare is illegal.
 	 *             E.g. if for a non-bare repository directory and gitDir point
 	 *             to the same directory of if for a bare repository both
 	 *             directory and gitDir are specified
 	 */
 	public CloneCommand setBare(boolean bare) throws IllegalStateException {
 		validateDirs(directory, gitDir, bare);
 		this.bare = bare;
 		return this;
 	}
 
 	/**
 	 * Set the file system abstraction to be used for repositories created by
 	 * this command.
 	 *
 	 * @param fs
 	 *            the abstraction.
 	 * @return {@code this} (for chaining calls).
 	 * @since 4.10
 	 */
 	public CloneCommand setFs(FS fs) {
 		this.fs = fs;
 		return this;
 	}
 
 	/**
 	 * The remote name used to keep track of the upstream repository for the
 	 * clone operation. If no remote name is set, the default value of
 	 * <code>Constants.DEFAULT_REMOTE_NAME</code> will be used.
 	 *
 	 * @see Constants#DEFAULT_REMOTE_NAME
 	 * @param remote
 	 *            name that keeps track of the upstream repository.
 	 *            {@code null} means to use DEFAULT_REMOTE_NAME.
 	 * @return this instance
 	 */
 	public CloneCommand setRemote(String remote) {
 		if (remote == null) {
 			remote = Constants.DEFAULT_REMOTE_NAME;
 		}
 		this.remote = remote;
 		return this;
 	}
 
 	/**
 	 * Set the initial branch
 	 *
 	 * @param branch
 	 *            the initial branch to check out when cloning the repository.
 	 *            Can be specified as ref name (<code>refs/heads/master</code>),
 	 *            branch name (<code>master</code>) or tag name
 	 *            (<code>v1.2.3</code>). The default is to use the branch
 	 *            pointed to by the cloned repository's HEAD and can be
 	 *            requested by passing {@code null} or <code>HEAD</code>.
 	 * @return this instance
 	 */
 	public CloneCommand setBranch(String branch) {
 		if (branch == null) {
 			branch = Constants.HEAD;
 		}
 		this.branch = branch;
 		return this;
 	}
 
 	/**
 	 * The progress monitor associated with the clone operation. By default,
 	 * this is set to <code>NullProgressMonitor</code>
 	 *
 	 * @see NullProgressMonitor
 	 * @param monitor
 	 *            a {@link org.eclipse.jgit.lib.ProgressMonitor}
 	 * @return {@code this}
 	 */
 	public CloneCommand setProgressMonitor(ProgressMonitor monitor) {
 		if (monitor == null) {
 			monitor = NullProgressMonitor.INSTANCE;
 		}
 		this.monitor = monitor;
 		return this;
 	}
 
 	/**
 	 * Set whether all branches have to be fetched.
 	 * <p>
 	 * If {@code false}, use {@link #setBranchesToClone(Collection)} to define
 	 * what will be cloned. If neither are set, all branches will be cloned.
 	 * </p>
 	 *
 	 * @param cloneAllBranches
 	 *            {@code true} when all branches have to be fetched (indicates
 	 *            wildcard in created fetch refspec), {@code false} otherwise.
 	 * @return {@code this}
 	 */
 	public CloneCommand setCloneAllBranches(boolean cloneAllBranches) {
 		this.cloneAllBranches = cloneAllBranches;
 		return this;
 	}
 
 	/**
 	 * Set up a mirror of the source repository. This implies that a bare
 	 * repository will be created. Compared to {@link #setBare},
 	 * {@code #setMirror} not only maps local branches of the source to local
 	 * branches of the target, it maps all refs (including remote-tracking
 	 * branches, notes etc.) and sets up a refspec configuration such that all
 	 * these refs are overwritten by a git remote update in the target
 	 * repository.
 	 *
 	 * @param mirror
 	 *            whether to mirror all refs from the source repository
 	 *
 	 * @return {@code this}
 	 * @since 5.6
 	 */
 	public CloneCommand setMirror(boolean mirror) {
 		this.mirror = mirror;
 		return this;
 	}
 
 	/**
 	 * Set whether to clone submodules
 	 *
 	 * @param cloneSubmodules
 	 *            true to initialize and update submodules. Ignored when
 	 *            {@link #setBare(boolean)} is set to true.
 	 * @return {@code this}
 	 */
 	public CloneCommand setCloneSubmodules(boolean cloneSubmodules) {
 		this.cloneSubmodules = cloneSubmodules;
 		return this;
 	}
 
 	/**
 	 * Set the branches or tags to clone.
 	 * <p>
 	 * This is ignored if {@link #setCloneAllBranches(boolean)
 	 * setCloneAllBranches(true)} or {@link #setMirror(boolean) setMirror(true)}
 	 * is used. If {@code branchesToClone} is {@code null} or empty, it's also
 	 * ignored.
 	 * </p>
 	 *
 	 * @param branchesToClone
 	 *            collection of branches to clone. Must be specified as full ref
 	 *            names (e.g. {@code refs/heads/master} or
 	 *            {@code refs/tags/v1.0.0}).
 	 * @return {@code this}
 	 */
 	public CloneCommand setBranchesToClone(Collection<String> branchesToClone) {
 		this.branchesToClone = branchesToClone;
 		return this;
 	}
 
 	/**
 	 * Set the tag option used for the remote configuration explicitly.
 	 *
 	 * @param tagOption
 	 *            tag option to be used for the remote config
 	 * @return {@code this}
 	 * @since 5.8
 	 */
 	public CloneCommand setTagOption(TagOpt tagOption) {
 		this.tagOption = tagOption;
 		return this;
 	}
 
 	/**
 	 * Set the --no-tags option. Tags are not cloned now and the remote
 	 * configuration is initialized with the --no-tags option as well.
 	 *
 	 * @return {@code this}
 	 * @since 5.8
 	 */
 	public CloneCommand setNoTags() {
 		return setTagOption(TagOpt.NO_TAGS);
 	}
 
 	/**
 	 * Set whether to skip checking out a branch
 	 *
 	 * @param noCheckout
 	 *            if set to <code>true</code> no branch will be checked out
 	 *            after the clone. This enhances performance of the clone
 	 *            command when there is no need for a checked out branch.
 	 * @return {@code this}
 	 */
 	public CloneCommand setNoCheckout(boolean noCheckout) {
 		this.noCheckout = noCheckout;
 		return this;
 	}
 
 	/**
 	 * Register a progress callback.
 	 *
 	 * @param callback
 	 *            the callback
 	 * @return {@code this}
 	 * @since 4.8
 	 */
 	public CloneCommand setCallback(Callback callback) {
 		this.callback = callback;
 		return this;
 	}
 
 	private static void validateDirs(File directory, File gitDir, boolean bare)
 			throws IllegalStateException {
 		if (directory != null) {
 			if (directory.exists() && !directory.isDirectory()) {
 				throw new IllegalStateException(MessageFormat.format(
 						JGitText.get().initFailedDirIsNoDirectory, directory));
 			}
 			if (gitDir != null && gitDir.exists() && !gitDir.isDirectory()) {
 				throw new IllegalStateException(MessageFormat.format(
 						JGitText.get().initFailedGitDirIsNoDirectory,
 						gitDir));
 			}
 			if (bare) {
 				if (gitDir != null && !gitDir.equals(directory))
 					throw new IllegalStateException(MessageFormat.format(
 							JGitText.get().initFailedBareRepoDifferentDirs,
 							gitDir, directory));
 			} else {
 				if (gitDir != null && gitDir.equals(directory))
 					throw new IllegalStateException(MessageFormat.format(
 							JGitText.get().initFailedNonBareRepoSameDirs,
 							gitDir, directory));
 			}
 		}
 	}
 
 	private void cleanup() {
 		try {
 			if (directory != null) {
 				if (!directoryExistsInitially) {
 					FileUtils.delete(directory, FileUtils.RECURSIVE
 							| FileUtils.SKIP_MISSING | FileUtils.IGNORE_ERRORS);
 				} else {
 					deleteChildren(directory);
 				}
 			}
 			if (gitDir != null) {
 				if (!gitDirExistsInitially) {
 					FileUtils.delete(gitDir, FileUtils.RECURSIVE
 							| FileUtils.SKIP_MISSING | FileUtils.IGNORE_ERRORS);
 				} else {
 					deleteChildren(gitDir);
 				}
 			}
 		} catch (IOException e) {
 			// Ignore; this is a best-effort cleanup in error cases, and
 			// IOException should not be raised anyway
 		}
 	}
 
 	private void deleteChildren(File file) throws IOException {
 		File[] files = file.listFiles();
 		if (files == null) {
 			return;
 		}
 		for (File child : files) {
 			FileUtils.delete(child, FileUtils.RECURSIVE | FileUtils.SKIP_MISSING
 					| FileUtils.IGNORE_ERRORS);
 		}
 	}
 }