/*
    * Copyright (C) 2010, 2021 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.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.errors.MissingObjectException;
  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.ContentMergeStrategy;
  import org.eclipse.jgit.merge.MergeMessageFormatter;
  import org.eclipse.jgit.merge.MergeStrategy;
  import org.eclipse.jgit.merge.Merger;
  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 cherry-pick} 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-cherry-pick.html"
   *      >Git documentation about cherry-pick</a>
   */
  public class CherryPickCommand extends GitCommand<CherryPickResult> {
  	private String reflogPrefix = "cherry-pick:"; //$NON-NLS-1$
  
  	private List<Ref> commits = new LinkedList<>();
  
  	private String ourCommitName = null;
  
  	private MergeStrategy strategy = MergeStrategy.RECURSIVE;
  
  	private ContentMergeStrategy contentStrategy;
  
  	private Integer mainlineParentNumber;
  
  	private boolean noCommit = false;
  
  	private ProgressMonitor monitor = NullProgressMonitor.INSTANCE;
  
  	/**
  	 * Constructor for CherryPickCommand
  	 *
  	 * @param repo
  	 *            the {@link org.eclipse.jgit.lib.Repository}
  	 */
  	protected CherryPickCommand(Repository repo) {
  		super(repo);
  	}
  
  	/**
  	 * {@inheritDoc}
  	 * <p>
  	 * Executes the {@code Cherry-Pick} 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 CherryPickResult call() throws GitAPIException, NoMessageException,
  			UnmergedPathsException, ConcurrentRefUpdateException,
  			WrongRepositoryStateException, NoHeadException {
  		RevCommit newHead = null;
  		List<Ref> cherryPickedRefs = new LinkedList<>();
 		checkCallable();
 
 		try (RevWalk revWalk = new RevWalk(repo)) {
 
 			// get the head commit
 			Ref headRef = repo.exactRef(Constants.HEAD);
 			if (headRef == null) {
 				throw new NoHeadException(
 						JGitText.get().commitOnRepoWithoutHEADCurrentlyNotSupported);
 			}
 
 			newHead = revWalk.parseCommit(headRef.getObjectId());
 
 			// loop through all refs to be cherry-picked
 			for (Ref src : commits) {
 				// get the commit to be cherry-picked
 				// 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 cherry-pick
 				final RevCommit srcParent = getParentCommit(srcCommit, revWalk);
 
 				String ourName = calculateOurName(headRef);
 				String cherryPickName = srcCommit.getId().abbreviate(7).name()
 						+ " " + srcCommit.getShortMessage(); //$NON-NLS-1$
 
 				Merger merger = strategy.newMerger(repo);
 				merger.setProgressMonitor(monitor);
 				boolean noProblems;
 				Map<String, MergeFailureReason> failingPaths = null;
 				List<String> unmergedPaths = null;
 				if (merger instanceof ResolveMerger) {
 					ResolveMerger resolveMerger = (ResolveMerger) merger;
 					resolveMerger.setContentMergeStrategy(contentStrategy);
 					resolveMerger.setCommitNames(
 							new String[] { "BASE", ourName, cherryPickName }); //$NON-NLS-1$
 					resolveMerger
 							.setWorkingTreeIterator(new FileTreeIterator(repo));
 					resolveMerger.setBase(srcParent.getTree());
 					noProblems = merger.merge(newHead, srcCommit);
 					failingPaths = resolveMerger.getFailingPaths();
 					unmergedPaths = resolveMerger.getUnmergedPaths();
 					if (!resolveMerger.getModifiedFiles().isEmpty()) {
 						repo.fireEvent(new WorkingTreeModifiedEvent(
 								resolveMerger.getModifiedFiles(), null));
 					}
 				} else {
 					noProblems = merger.merge(newHead, srcCommit);
 				}
 				if (noProblems) {
 					if (AnyObjectId.isEqual(newHead.getTree().getId(),
 							merger.getResultTreeId())) {
 						continue;
 					}
 					DirCacheCheckout dco = new DirCacheCheckout(repo,
 							newHead.getTree(), repo.lockDirCache(),
 							merger.getResultTreeId());
 					dco.setFailOnConflict(true);
 					dco.setProgressMonitor(monitor);
 					dco.checkout();
 					if (!noCommit) {
 						try (Git git = new Git(getRepository())) {
 							newHead = git.commit()
 									.setMessage(srcCommit.getFullMessage())
 									.setReflogComment(reflogPrefix + " " //$NON-NLS-1$
 											+ srcCommit.getShortMessage())
 									.setAuthor(srcCommit.getAuthorIdent())
 									.setNoVerify(true).call();
 						}
 					}
 					cherryPickedRefs.add(src);
 				} else {
 					if (failingPaths != null && !failingPaths.isEmpty()) {
 						return new CherryPickResult(failingPaths);
 					}
 
 					// there are merge conflicts
 
 					String message;
 					if (unmergedPaths != null) {
 						message = new MergeMessageFormatter()
 							.formatWithConflicts(srcCommit.getFullMessage(),
 										unmergedPaths);
 					} else {
 						message = srcCommit.getFullMessage();
 					}
 
 					if (!noCommit) {
 						repo.writeCherryPickHead(srcCommit.getId());
 					}
 					repo.writeMergeCommitMsg(message);
 
 					return CherryPickResult.CONFLICT;
 				}
 			}
 		} catch (IOException e) {
 			throw new JGitInternalException(
 					MessageFormat.format(
 							JGitText.get().exceptionCaughtDuringExecutionOfCherryPickCommand,
 							e), e);
 		}
 		return new CherryPickResult(newHead, cherryPickedRefs);
 	}
 
 	private RevCommit getParentCommit(RevCommit srcCommit, RevWalk revWalk)
 			throws MultipleParentsNotAllowedException, MissingObjectException,
 			IOException {
 		final RevCommit srcParent;
 		if (mainlineParentNumber == null) {
 			if (srcCommit.getParentCount() != 1)
 				throw new MultipleParentsNotAllowedException(
 						MessageFormat.format(
 								JGitText.get().canOnlyCherryPickCommitsWithOneParent,
 								srcCommit.name(),
 								Integer.valueOf(srcCommit.getParentCount())));
 			srcParent = srcCommit.getParent(0);
 		} else {
 			if (mainlineParentNumber.intValue() > srcCommit.getParentCount()) {
 				throw new JGitInternalException(MessageFormat.format(
 						JGitText.get().commitDoesNotHaveGivenParent, srcCommit,
 						mainlineParentNumber));
 			}
 			srcParent = srcCommit
 					.getParent(mainlineParentNumber.intValue() - 1);
 		}
 
 		revWalk.parseHeaders(srcParent);
 		return srcParent;
 	}
 
 	/**
 	 * Include a reference to a commit
 	 *
 	 * @param commit
 	 *            a reference to a commit which is cherry-picked to the current
 	 *            head
 	 * @return {@code this}
 	 */
 	public CherryPickCommand include(Ref commit) {
 		checkCallable();
 		commits.add(commit);
 		return this;
 	}
 
 	/**
 	 * Include a commit
 	 *
 	 * @param commit
 	 *            the Id of a commit which is cherry-picked to the current head
 	 * @return {@code this}
 	 */
 	public CherryPickCommand include(AnyObjectId commit) {
 		return include(commit.getName(), commit);
 	}
 
 	/**
 	 * Include a commit
 	 *
 	 * @param name
 	 *            a name given to the commit
 	 * @param commit
 	 *            the Id of a commit which is cherry-picked to the current head
 	 * @return {@code this}
 	 */
 	public CherryPickCommand include(String name, AnyObjectId commit) {
 		return include(new ObjectIdRef.Unpeeled(Storage.LOOSE, name,
 				commit.copy()));
 	}
 
 	/**
 	 * Set the name that should 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 CherryPickCommand setOurCommitName(String ourCommitName) {
 		this.ourCommitName = ourCommitName;
 		return this;
 	}
 
 	/**
 	 * Set the prefix to use in the reflog.
 	 * <p>
 	 * This is primarily needed for implementing rebase in terms of
 	 * cherry-picking
 	 *
 	 * @param prefix
 	 *            including ":"
 	 * @return {@code this}
 	 * @since 3.1
 	 */
 	public CherryPickCommand setReflogPrefix(String prefix) {
 		this.reflogPrefix = prefix;
 		return this;
 	}
 
 	/**
 	 * Set the {@code MergeStrategy}
 	 *
 	 * @param strategy
 	 *            The merge strategy to use during this Cherry-pick.
 	 * @return {@code this}
 	 * @since 3.4
 	 */
 	public CherryPickCommand setStrategy(MergeStrategy strategy) {
 		this.strategy = strategy;
 		return this;
 	}
 
 	/**
 	 * Sets the content merge strategy to use if the
 	 * {@link #setStrategy(MergeStrategy) merge strategy} is "resolve" or
 	 * "recursive".
 	 *
 	 * @param strategy
 	 *            the {@link ContentMergeStrategy} to be used
 	 * @return {@code this}
 	 * @since 5.12
 	 */
 	public CherryPickCommand setContentMergeStrategy(
 			ContentMergeStrategy strategy) {
 		this.contentStrategy = strategy;
 		return this;
 	}
 
 	/**
 	 * Set the (1-based) parent number to diff against
 	 *
 	 * @param mainlineParentNumber
 	 *            the (1-based) parent number to diff against. This allows
 	 *            cherry-picking of merges.
 	 * @return {@code this}
 	 * @since 3.4
 	 */
 	public CherryPickCommand setMainlineParentNumber(int mainlineParentNumber) {
 		this.mainlineParentNumber = Integer.valueOf(mainlineParentNumber);
 		return this;
 	}
 
 	/**
 	 * Allows cherry-picking changes without committing them.
 	 * <p>
 	 * NOTE: The behavior of cherry-pick is undefined if you pick multiple
 	 * commits or if HEAD does not match the index state before cherry-picking.
 	 *
 	 * @param noCommit
 	 *            true to cherry-pick without committing, false to commit after
 	 *            each pick (default)
 	 * @return {@code this}
 	 * @since 3.5
 	 */
 	public CherryPickCommand setNoCommit(boolean noCommit) {
 		this.noCommit = noCommit;
 		return this;
 	}
 
 	/**
 	 * The progress monitor associated with the cherry-pick 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 CherryPickCommand setProgressMonitor(ProgressMonitor monitor) {
 		if (monitor == null) {
 			monitor = NullProgressMonitor.INSTANCE;
 		}
 		this.monitor = monitor;
 		return this;
 	}
 
 	private String calculateOurName(Ref headRef) {
 		if (ourCommitName != null)
 			return ourCommitName;
 
 		String targetRefName = headRef.getTarget().getName();
 		String headName = Repository.shortenRefName(targetRefName);
 		return headName;
 	}
 
 	/** {@inheritDoc} */
 	@SuppressWarnings("nls")
 	@Override
 	public String toString() {
 		return "CherryPickCommand [repo=" + repo + ",\ncommits=" + commits
 				+ ",\nmainlineParentNumber=" + mainlineParentNumber
 				+ ", noCommit=" + noCommit + ", ourCommitName=" + ourCommitName
 				+ ", reflogPrefix=" + reflogPrefix + ", strategy=" + strategy
 				+ "]";
 	}
 
 }