Add support for creating a stashed commit

Adds a new command to stash the index and working directory
changes in a commit stored in refs/stash

Bug: 309355
Change-Id: I2ce85b1601b74b07e286a3f99feb358dfbdfe29c
Signed-off-by: Chris Aniszczyk <zx@twitter.com>

4 files changed, 329 insertions, 0 deletions

diff --git a/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties b/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties
index 8a5e023104..5a916f5a43 100644
--- a/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties
+++ b/org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties
@@ -205,6 +205,7 @@ flagIsDisposed={0} is disposed.
 flagNotFromThis={0} not from this.
 flagsAlreadyCreated={0} flags already created.
 funnyRefname=funny refname
+headRequiredToStash=HEAD required to stash local changes
 hoursAgo={0} hours ago
 hugeIndexesAreNotSupportedByJgitYet=Huge indexes are not supported by jgit, yet
 hunkBelongsToAnotherFile=Hunk belongs to another file
@@ -422,6 +423,7 @@ sourceRefDoesntResolveToAnyObject=Source ref {0} doesn't resolve to any object.
 sourceRefNotSpecifiedForRefspec=Source ref not specified for refspec: {0}
 staleRevFlagsOn=Stale RevFlags on {0}
 startingReadStageWithoutWrittenRequestDataPendingIsNotSupported=Starting read stage without written request data pending is not supported
+stashFailed=Stashing local changes did not successfully complete
 statelessRPCRequiresOptionToBeEnabled=stateless RPC requires {0} to be enabled
 submoduleExists=Submodule ''{0}'' already exists in the index
 submoduleParentRemoteUrlInvalid=Cannot remove segment from remote url ''{0}''
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/JGitText.java b/org.eclipse.jgit/src/org/eclipse/jgit/JGitText.java
index bcd14c6a4f..0276f68612 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/JGitText.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/JGitText.java
@@ -265,6 +265,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String flagNotFromThis;
 	/***/ public String flagsAlreadyCreated;
 	/***/ public String funnyRefname;
+	/***/ public String headRequiredToStash;
 	/***/ public String hoursAgo;
 	/***/ public String hugeIndexesAreNotSupportedByJgitYet;
 	/***/ public String hunkBelongsToAnotherFile;
@@ -482,6 +483,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String sourceRefNotSpecifiedForRefspec;
 	/***/ public String staleRevFlagsOn;
 	/***/ public String startingReadStageWithoutWrittenRequestDataPendingIsNotSupported;
+	/***/ public String stashFailed;
 	/***/ public String statelessRPCRequiresOptionToBeEnabled;
 	/***/ public String submoduleExists;
 	/***/ public String submodulesNotSupported;
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/Git.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/Git.java
index 7d34902e93..0c5b56a6cc 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/Git.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/Git.java
@@ -574,6 +574,15 @@ public class Git {
 	}
 
 	/**
+	 * Returns a command object used to create a stashed commit
+	 *
+	 * @return a {@link StashCreateCommand}
+	 */
+	public StashCreateCommand stashCreate() {
+		return new StashCreateCommand(repo);
+	}
+
+	/**
 	 * @return the git repository this class is interacting with
 	 */
 	public Repository getRepository() {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/StashCreateCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/StashCreateCommand.java
new file mode 100644
index 0000000000..8ead2b57fa
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/StashCreateCommand.java
@@ -0,0 +1,316 @@
+/*
+ * Copyright (C) 2012, GitHub Inc.
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.api;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.text.MessageFormat;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.eclipse.jgit.JGitText;
+import org.eclipse.jgit.api.ResetCommand.ResetType;
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.api.errors.JGitInternalException;
+import org.eclipse.jgit.api.errors.NoHeadException;
+import org.eclipse.jgit.dircache.DirCache;
+import org.eclipse.jgit.dircache.DirCacheEditor;
+import org.eclipse.jgit.dircache.DirCacheEditor.DeletePath;
+import org.eclipse.jgit.dircache.DirCacheEditor.PathEdit;
+import org.eclipse.jgit.dircache.DirCacheEntry;
+import org.eclipse.jgit.dircache.DirCacheIterator;
+import org.eclipse.jgit.lib.CommitBuilder;
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.MutableObjectId;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectInserter;
+import org.eclipse.jgit.lib.ObjectReader;
+import org.eclipse.jgit.lib.PersonIdent;
+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.treewalk.AbstractTreeIterator;
+import org.eclipse.jgit.treewalk.FileTreeIterator;
+import org.eclipse.jgit.treewalk.TreeWalk;
+import org.eclipse.jgit.treewalk.WorkingTreeIterator;
+import org.eclipse.jgit.treewalk.filter.AndTreeFilter;
+import org.eclipse.jgit.treewalk.filter.IndexDiffFilter;
+import org.eclipse.jgit.treewalk.filter.SkipWorkTreeFilter;
+
+/**
+ * Command class to stash changes in the working directory and index in a
+ * commit.
+ *
+ * @see <a href="http://www.kernel.org/pub/software/scm/git/docs/git-stash.html"
+ *      >Git documentation about Stash</a>
+ */
+public class StashCreateCommand extends GitCommand<RevCommit> {
+
+	private static final String MSG_INDEX = "index on {0}: {1} {2}";
+
+	private static final String MSG_WORKING_DIR = "WIP on {0}: {1} {2}";
+
+	private String indexMessage = MSG_INDEX;
+
+	private String workingDirectoryMessage = MSG_WORKING_DIR;
+
+	private String ref = Constants.R_STASH;
+
+	private PersonIdent person;
+
+	/**
+	 * Create a command to stash changes in the working directory and index
+	 *
+	 * @param repo
+	 */
+	public StashCreateCommand(Repository repo) {
+		super(repo);
+		person = new PersonIdent(repo);
+	}
+
+	/**
+	 * Set the message used when committing index changes
+	 * <p>
+	 * The message will be formatted with the current branch, abbreviated commit
+	 * id, and short commit message when used.
+	 *
+	 * @param message
+	 * @return {@code this}
+	 */
+	public StashCreateCommand setIndexMessage(String message) {
+		indexMessage = message;
+		return this;
+	}
+
+	/**
+	 * Set the message used when committing working directory changes
+	 * <p>
+	 * The message will be formatted with the current branch, abbreviated commit
+	 * id, and short commit message when used.
+	 *
+	 * @param message
+	 * @return {@code this}
+	 */
+	public StashCreateCommand setWorkingDirectoryMessage(String message) {
+		workingDirectoryMessage = message;
+		return this;
+	}
+
+	/**
+	 * Set the person to use as the author and committer in the commits made
+	 *
+	 * @param person
+	 */
+	public void setPerson(PersonIdent person) {
+		this.person = person;
+	}
+
+	/**
+	 * Set the reference to update with the stashed commit id
+	 * <p>
+	 * This value defaults to {@link Constants#R_STASH}
+	 *
+	 * @param ref
+	 */
+	public void setRef(String ref) {
+		this.ref = ref;
+	}
+
+	private RevCommit parseCommit(final ObjectReader reader,
+			final ObjectId headId) throws IOException {
+		final RevWalk walk = new RevWalk(reader);
+		walk.setRetainBody(true);
+		return walk.parseCommit(headId);
+	}
+
+	private CommitBuilder createBuilder(ObjectId headId) {
+		CommitBuilder builder = new CommitBuilder();
+		PersonIdent author = person;
+		if (author == null)
+			author = new PersonIdent(repo);
+		builder.setAuthor(author);
+		builder.setCommitter(author);
+		builder.setParentId(headId);
+		return builder;
+	}
+
+	private void updateStashRef(ObjectId commitId) throws IOException {
+		Ref currentRef = repo.getRef(ref);
+		RefUpdate refUpdate = repo.updateRef(ref);
+		refUpdate.setNewObjectId(commitId);
+		if (currentRef != null)
+			refUpdate.setExpectedOldObjectId(currentRef.getObjectId());
+		else
+			refUpdate.setExpectedOldObjectId(ObjectId.zeroId());
+		refUpdate.forceUpdate();
+	}
+
+	private Ref getHead() throws GitAPIException {
+		try {
+			Ref head = repo.getRef(Constants.HEAD);
+			if (head == null || head.getObjectId() == null)
+				throw new NoHeadException(JGitText.get().headRequiredToStash);
+			return head;
+		} catch (IOException e) {
+			throw new JGitInternalException(JGitText.get().stashFailed, e);
+		}
+	}
+
+	/**
+	 * Stash the contents on the working directory and index in separate commits
+	 * and reset to the current HEAD commit.
+	 *
+	 * @return stashed commit or null if no changes to stash
+	 */
+	public RevCommit call() throws GitAPIException, JGitInternalException {
+		checkCallable();
+
+		Ref head = getHead();
+		ObjectReader reader = repo.newObjectReader();
+		try {
+			RevCommit headCommit = parseCommit(reader, head.getObjectId());
+			DirCache cache = repo.lockDirCache();
+			ObjectInserter inserter = repo.newObjectInserter();
+			ObjectId commitId;
+			try {
+				TreeWalk treeWalk = new TreeWalk(reader);
+				treeWalk.setRecursive(true);
+				treeWalk.addTree(headCommit.getTree());
+				treeWalk.addTree(new DirCacheIterator(cache));
+				treeWalk.addTree(new FileTreeIterator(repo));
+				treeWalk.setFilter(AndTreeFilter.create(new SkipWorkTreeFilter(
+						1), new IndexDiffFilter(1, 2)));
+
+				// Return null if no local changes to stash
+				if (!treeWalk.next())
+					return null;
+
+				MutableObjectId id = new MutableObjectId();
+				List<PathEdit> wtEdits = new ArrayList<PathEdit>();
+				List<String> wtDeletes = new ArrayList<String>();
+				do {
+					AbstractTreeIterator headIter = treeWalk.getTree(0,
+							AbstractTreeIterator.class);
+					DirCacheIterator indexIter = treeWalk.getTree(1,
+							DirCacheIterator.class);
+					WorkingTreeIterator wtIter = treeWalk.getTree(2,
+							WorkingTreeIterator.class);
+					if (headIter != null && indexIter != null && wtIter != null) {
+						if (wtIter.idEqual(indexIter)
+								|| wtIter.idEqual(headIter))
+							continue;
+						treeWalk.getObjectId(id, 0);
+						final DirCacheEntry entry = new DirCacheEntry(
+								treeWalk.getRawPath());
+						entry.setLength(wtIter.getEntryLength());
+						entry.setLastModified(wtIter.getEntryLastModified());
+						entry.setFileMode(wtIter.getEntryFileMode());
+						InputStream in = wtIter.openEntryStream();
+						try {
+							entry.setObjectId(inserter.insert(
+									Constants.OBJ_BLOB,
+									wtIter.getEntryLength(), in));
+						} finally {
+							in.close();
+						}
+						wtEdits.add(new PathEdit(entry) {
+
+							public void apply(DirCacheEntry ent) {
+								ent.copyMetaData(entry);
+							}
+						});
+					} else if (indexIter == null)
+						wtDeletes.add(treeWalk.getPathString());
+					else if (wtIter == null && headIter != null)
+						wtDeletes.add(treeWalk.getPathString());
+				} while (treeWalk.next());
+
+				String branch = Repository.shortenRefName(head.getTarget()
+						.getName());
+
+				// Commit index changes
+				CommitBuilder builder = createBuilder(headCommit);
+				builder.setTreeId(cache.writeTree(inserter));
+				builder.setMessage(MessageFormat.format(indexMessage, branch,
+						headCommit.abbreviate(7).name(),
+						headCommit.getShortMessage()));
+				ObjectId indexCommit = inserter.insert(builder);
+
+				// Commit working tree changes
+				if (!wtEdits.isEmpty() || !wtDeletes.isEmpty()) {
+					DirCacheEditor editor = cache.editor();
+					for (PathEdit edit : wtEdits)
+						editor.add(edit);
+					for (String path : wtDeletes)
+						editor.add(new DeletePath(path));
+					editor.finish();
+				}
+				builder.addParentId(indexCommit);
+				builder.setMessage(MessageFormat.format(
+						workingDirectoryMessage, branch,
+						headCommit.abbreviate(7).name(),
+						headCommit.getShortMessage()));
+				builder.setTreeId(cache.writeTree(inserter));
+				commitId = inserter.insert(builder);
+				inserter.flush();
+
+				updateStashRef(commitId);
+			} finally {
+				inserter.release();
+				cache.unlock();
+			}
+
+			// Hard reset to HEAD
+			new ResetCommand(repo).setMode(ResetType.HARD).call();
+
+			// Return stashed commit
+			return parseCommit(reader, commitId);
+		} catch (IOException e) {
+			throw new JGitInternalException(JGitText.get().stashFailed, e);
+		} finally {
+			reader.release();
+		}
+	}
+}