/*
    * Copyright (C) 2010, Christian Halstrick <christian.halstrick@sap.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.IOException;
  import java.text.MessageFormat;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  
  import org.eclipse.jgit.api.MergeResult.MergeStatus;
  import org.eclipse.jgit.api.errors.ConcurrentRefUpdateException;
  import org.eclipse.jgit.api.errors.GitAPIException;
  import org.eclipse.jgit.api.errors.JGitInternalException;
  import org.eclipse.jgit.api.errors.MultipleParentsNotAllowedException;
  import org.eclipse.jgit.api.errors.NoHeadException;
  import org.eclipse.jgit.api.errors.NoMessageException;
  import org.eclipse.jgit.api.errors.UnmergedPathsException;
  import org.eclipse.jgit.api.errors.WrongRepositoryStateException;
  import org.eclipse.jgit.dircache.DirCacheCheckout;
  import org.eclipse.jgit.events.WorkingTreeModifiedEvent;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.NullProgressMonitor;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.ObjectIdRef;
  import org.eclipse.jgit.lib.ProgressMonitor;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.Ref.Storage;
  import org.eclipse.jgit.lib.Repository;
  import org.eclipse.jgit.merge.MergeMessageFormatter;
  import org.eclipse.jgit.merge.MergeStrategy;
  import org.eclipse.jgit.merge.ResolveMerger;
  import org.eclipse.jgit.merge.ResolveMerger.MergeFailureReason;
  import org.eclipse.jgit.revwalk.RevCommit;
  import org.eclipse.jgit.revwalk.RevWalk;
  import org.eclipse.jgit.treewalk.FileTreeIterator;
  
  /**
   * A class used to execute a {@code revert} command. It has setters for all
   * supported options and arguments of this command and a {@link #call()} method
   * to finally execute the command. Each instance of this class should only be
   * used for one invocation of the command (means: one call to {@link #call()})
   *
   * @see <a
   *      href="http://www.kernel.org/pub/software/scm/git/docs/git-revert.html"
   *      >Git documentation about revert</a>
   */
  public class RevertCommand extends GitCommand<RevCommit> {
  	private List<Ref> commits = new LinkedList<>();
  
  	private String ourCommitName = null;
  
  	private List<Ref> revertedRefs = new LinkedList<>();
  
  	private MergeResult failingResult;
  
  	private List<String> unmergedPaths;
  
  	private MergeStrategy strategy = MergeStrategy.RECURSIVE;
  
  	private ProgressMonitor monitor = NullProgressMonitor.INSTANCE;
  
  	/**
  	 * <p>
  	 * Constructor for RevertCommand.
  	 * </p>
  	 *
  	 * @param repo
  	 *            the {@link org.eclipse.jgit.lib.Repository}
  	 */
  	protected RevertCommand(Repository repo) {
  		super(repo);
  	}
  
  	/**
  	 * {@inheritDoc}
  	 * <p>
  	 * Executes the {@code revert} command with all the options and parameters
  	 * collected by the setter methods (e.g. {@link #include(Ref)} of this
  	 * class. Each instance of this class should only be used for one invocation
  	 * of the command. Don't call this method twice on an instance.
  	 */
  	@Override
  	public RevCommit call() throws NoMessageException, UnmergedPathsException,
  			ConcurrentRefUpdateException, WrongRepositoryStateException,
  			GitAPIException {
  		RevCommit newHead = null;
  		checkCallable();
  
  		try (RevWalklk.html#RevWalk">RevWalk revWalk = new RevWalk(repo)) {
 
 			// get the head commit
 			Ref headRef = repo.exactRef(Constants.HEAD);
 			if (headRef == null)
 				throw new NoHeadException(
 						JGitText.get().commitOnRepoWithoutHEADCurrentlyNotSupported);
 			RevCommit headCommit = revWalk.parseCommit(headRef.getObjectId());
 
 			newHead = headCommit;
 
 			// loop through all refs to be reverted
 			for (Ref src : commits) {
 				// get the commit to be reverted
 				// handle annotated tags
 				ObjectId srcObjectId = src.getPeeledObjectId();
 				if (srcObjectId == null)
 					srcObjectId = src.getObjectId();
 				RevCommit srcCommit = revWalk.parseCommit(srcObjectId);
 
 				// get the parent of the commit to revert
 				if (srcCommit.getParentCount() != 1)
 					throw new MultipleParentsNotAllowedException(
 							MessageFormat.format(
 									JGitText.get().canOnlyRevertCommitsWithOneParent,
 									srcCommit.name(),
 									Integer.valueOf(srcCommit.getParentCount())));
 
 				RevCommit srcParent = srcCommit.getParent(0);
 				revWalk.parseHeaders(srcParent);
 
 				String ourName = calculateOurName(headRef);
 				String revertName = srcCommit.getId().abbreviate(7).name()
 						+ " " + srcCommit.getShortMessage(); //$NON-NLS-1$
 
 				ResolveMerger merger = (ResolveMerger) strategy.newMerger(repo);
 				merger.setWorkingTreeIterator(new FileTreeIterator(repo));
 				merger.setBase(srcCommit.getTree());
 				merger.setCommitNames(new String[] {
 						"BASE", ourName, revertName }); //$NON-NLS-1$
 
 				String shortMessage = "Revert \"" + srcCommit.getShortMessage() //$NON-NLS-1$
 						+ "\""; //$NON-NLS-1$
 				String newMessage = shortMessage + "\n\n" //$NON-NLS-1$
 						+ "This reverts commit " + srcCommit.getId().getName() //$NON-NLS-1$
 						+ ".\n"; //$NON-NLS-1$
 				if (merger.merge(headCommit, srcParent)) {
 					if (!merger.getModifiedFiles().isEmpty()) {
 						repo.fireEvent(new WorkingTreeModifiedEvent(
 								merger.getModifiedFiles(), null));
 					}
 					if (AnyObjectId.isEqual(headCommit.getTree().getId(),
 							merger.getResultTreeId()))
 						continue;
 					DirCacheCheckout dco = new DirCacheCheckout(repo,
 							headCommit.getTree(), repo.lockDirCache(),
 							merger.getResultTreeId());
 					dco.setFailOnConflict(true);
 					dco.setProgressMonitor(monitor);
 					dco.checkout();
 					try (Gitit.html#Git">Git git = new Git(getRepository())) {
 						newHead = git.commit().setMessage(newMessage)
 								.setReflogComment("revert: " + shortMessage) //$NON-NLS-1$
 								.call();
 					}
 					revertedRefs.add(src);
 					headCommit = newHead;
 				} else {
 					unmergedPaths = merger.getUnmergedPaths();
 					Map<String, MergeFailureReason> failingPaths = merger
 							.getFailingPaths();
 					if (failingPaths != null)
 						failingResult = new MergeResult(null,
 								merger.getBaseCommitId(),
 								new ObjectId[] { headCommit.getId(),
 										srcParent.getId() },
 								MergeStatus.FAILED, strategy,
 								merger.getMergeResults(), failingPaths, null);
 					else
 						failingResult = new MergeResult(null,
 								merger.getBaseCommitId(),
 								new ObjectId[] { headCommit.getId(),
 										srcParent.getId() },
 								MergeStatus.CONFLICTING, strategy,
 								merger.getMergeResults(), failingPaths, null);
 					if (!merger.failed() && !unmergedPaths.isEmpty()) {
 						String message = new MergeMessageFormatter()
 						.formatWithConflicts(newMessage,
 								merger.getUnmergedPaths());
 						repo.writeRevertHead(srcCommit.getId());
 						repo.writeMergeCommitMsg(message);
 					}
 					return null;
 				}
 			}
 		} catch (IOException e) {
 			throw new JGitInternalException(
 					MessageFormat.format(
 									JGitText.get().exceptionCaughtDuringExecutionOfRevertCommand,
 							e), e);
 		}
 		return newHead;
 	}
 
 	/**
 	 * Include a {@code Ref} to a commit to be reverted
 	 *
 	 * @param commit
 	 *            a reference to a commit to be reverted into the current head
 	 * @return {@code this}
 	 */
 	public RevertCommand include(Ref commit) {
 		checkCallable();
 		commits.add(commit);
 		return this;
 	}
 
 	/**
 	 * Include a commit to be reverted
 	 *
 	 * @param commit
 	 *            the Id of a commit to be reverted into the current head
 	 * @return {@code this}
 	 */
 	public RevertCommand include(AnyObjectId commit) {
 		return include(commit.getName(), commit);
 	}
 
 	/**
 	 * Include a commit to be reverted
 	 *
 	 * @param name
 	 *            name of a {@code Ref} referring to the commit
 	 * @param commit
 	 *            the Id of a commit which is reverted into the current head
 	 * @return {@code this}
 	 */
 	public RevertCommand include(String name, AnyObjectId commit) {
 		return include(new ObjectIdRef.Unpeeled(Storage.LOOSE, name,
 				commit.copy()));
 	}
 
 	/**
 	 * Set the name to be used in the "OURS" place for conflict markers
 	 *
 	 * @param ourCommitName
 	 *            the name that should be used in the "OURS" place for conflict
 	 *            markers
 	 * @return {@code this}
 	 */
 	public RevertCommand setOurCommitName(String ourCommitName) {
 		this.ourCommitName = ourCommitName;
 		return this;
 	}
 
 	private String calculateOurName(Ref headRef) {
 		if (ourCommitName != null)
 			return ourCommitName;
 
 		String targetRefName = headRef.getTarget().getName();
 		String headName = Repository.shortenRefName(targetRefName);
 		return headName;
 	}
 
 	/**
 	 * Get the list of successfully reverted {@link org.eclipse.jgit.lib.Ref}'s.
 	 *
 	 * @return the list of successfully reverted
 	 *         {@link org.eclipse.jgit.lib.Ref}'s. Never <code>null</code> but
 	 *         maybe an empty list if no commit was successfully cherry-picked
 	 */
 	public List<Ref> getRevertedRefs() {
 		return revertedRefs;
 	}
 
 	/**
 	 * Get the result of a merge failure
 	 *
 	 * @return the result of a merge failure, <code>null</code> if no merge
 	 *         failure occurred during the revert
 	 */
 	public MergeResult getFailingResult() {
 		return failingResult;
 	}
 
 	/**
 	 * Get unmerged paths
 	 *
 	 * @return the unmerged paths, will be null if no merge conflicts
 	 */
 	public List<String> getUnmergedPaths() {
 		return unmergedPaths;
 	}
 
 	/**
 	 * Set the merge strategy to use for this revert command
 	 *
 	 * @param strategy
 	 *            The merge strategy to use for this revert command.
 	 * @return {@code this}
 	 * @since 3.4
 	 */
 	public RevertCommand setStrategy(MergeStrategy strategy) {
 		this.strategy = strategy;
 		return this;
 	}
 
 	/**
 	 * The progress monitor associated with the revert operation. By default,
 	 * this is set to <code>NullProgressMonitor</code>
 	 *
 	 * @see NullProgressMonitor
 	 * @param monitor
 	 *            a {@link org.eclipse.jgit.lib.ProgressMonitor}
 	 * @return {@code this}
 	 * @since 4.11
 	 */
 	public RevertCommand setProgressMonitor(ProgressMonitor monitor) {
 		if (monitor == null) {
 			monitor = NullProgressMonitor.INSTANCE;
 		}
 		this.monitor = monitor;
 		return this;
 	}
 }