Add git-reset to the Git API

Bug: 334764
Change-Id: Ice404629687d7f2a595d8d4eccf471b12f7e32ec
Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com>

1 files changed, 258 insertions, 0 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/ResetCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/ResetCommand.java
new file mode 100644
index 0000000000..d55767d3a6
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/ResetCommand.java
@@ -0,0 +1,258 @@
+/*
+ * Copyright (C) 2011, Chris Aniszczyk <caniszczyk@gmail.com>
+ * 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.text.MessageFormat;
+
+import org.eclipse.jgit.JGitText;
+import org.eclipse.jgit.api.errors.JGitInternalException;
+import org.eclipse.jgit.dircache.DirCache;
+import org.eclipse.jgit.dircache.DirCacheBuilder;
+import org.eclipse.jgit.dircache.DirCacheCheckout;
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.lib.RefUpdate;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.lib.RepositoryState;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
+
+/**
+ * A class used to execute a {@code Reset} 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-reset.html"
+ *      >Git documentation about Reset</a>
+ */
+public class ResetCommand extends GitCommand<Ref> {
+
+	/**
+	 * Kind of reset
+	 */
+	public enum ResetType {
+		/**
+		 * Just change the ref, the index and workdir are not changed.
+		 */
+		SOFT,
+
+		/**
+		 * Change the ref and the index, the workdir is not changed.
+		 */
+		MIXED,
+
+		/**
+		 * Change the ref, the index and the workdir
+		 */
+		HARD,
+
+		/**
+		 * Resets the index and updates the files in the working tree that are
+		 * different between respective commit and HEAD, but keeps those which
+		 * are different between the index and working tree
+		 */
+		MERGE, // TODO not implemented yet
+
+		/**
+		 * Change the ref, the index and the workdir that are different between
+		 * respective commit and HEAD
+		 */
+		KEEP // TODO not implemented yet
+	}
+
+	private String ref;
+
+	private ResetType mode;
+
+	/**
+	 *
+	 * @param repo
+	 */
+	public ResetCommand(Repository repo) {
+		super(repo);
+	}
+
+	/**
+	 * Executes the {@code Reset} command. Each instance of this class should
+	 * only be used for one invocation of the command. Don't call this method
+	 * twice on an instance.
+	 *
+	 * @return the Ref after reset
+	 */
+	public Ref call() throws IOException {
+		checkCallable();
+
+		Ref r;
+		RevCommit commit;
+
+		try {
+			boolean merging = false;
+			if (repo.getRepositoryState().equals(RepositoryState.MERGING)
+					|| repo.getRepositoryState().equals(
+							RepositoryState.MERGING_RESOLVED))
+				merging = true;
+
+			// resolve the ref to a commit
+			final ObjectId commitId;
+			try {
+				commitId = repo.resolve(ref);
+			} catch (IOException e) {
+				throw new JGitInternalException(
+						MessageFormat.format(JGitText.get().cannotRead, ref),
+						e);
+			}
+			RevWalk rw = new RevWalk(repo);
+			try {
+				commit = rw.parseCommit(commitId);
+			} catch (IOException e) {
+				throw new JGitInternalException(
+						MessageFormat.format(
+						JGitText.get().cannotReadCommit, commitId.toString()),
+						e);
+			} finally {
+				rw.release();
+			}
+
+			// write the ref
+			final RefUpdate ru = repo.updateRef(Constants.HEAD);
+			ru.setNewObjectId(commitId);
+
+			String refName = Repository.shortenRefName(ref);
+			String message = "reset --" //$NON-NLS-1$
+					+ mode.toString().toLowerCase() + " " + refName; //$NON-NLS-1$
+			ru.setRefLogMessage(message, false);
+			if (ru.forceUpdate() == RefUpdate.Result.LOCK_FAILURE)
+				throw new JGitInternalException(MessageFormat.format(
+						JGitText.get().cannotLock, ru.getName()));
+
+			switch (mode) {
+				case HARD:
+					checkoutIndex(commit);
+					break;
+				case MIXED:
+					resetIndex(commit);
+					break;
+				case SOFT: // do nothing, only the ref was changed
+					break;
+				case KEEP: // TODO
+				case MERGE: // TODO
+					throw new UnsupportedOperationException();
+
+			}
+
+			if (mode != ResetType.SOFT && merging)
+				resetMerge();
+
+			setCallable(false);
+			r = ru.getRef();
+		} catch (IOException e) {
+			throw new JGitInternalException(
+					JGitText.get().exceptionCaughtDuringExecutionOfResetCommand,
+					e);
+		}
+
+		return r;
+	}
+
+	/**
+	 * @param ref
+	 *            the ref to reset to
+	 * @return this instance
+	 */
+	public ResetCommand setRef(String ref) {
+		this.ref = ref;
+		return this;
+	}
+
+	/**
+	 * @param mode
+	 *            the mode of the reset command
+	 * @return this instance
+	 */
+	public ResetCommand setMode(ResetType mode) {
+		this.mode = mode;
+		return this;
+	}
+
+	private void resetIndex(RevCommit commit) throws IOException {
+		DirCache dc = null;
+		try {
+			dc = repo.lockDirCache();
+			dc.clear();
+			DirCacheBuilder dcb = dc.builder();
+			dcb.addTree(new byte[0], 0, repo.newObjectReader(),
+					commit.getTree());
+			dcb.commit();
+		} catch (IOException e) {
+			throw e;
+		} finally {
+			if (dc != null)
+				dc.unlock();
+		}
+	}
+
+	private void checkoutIndex(RevCommit commit) throws IOException {
+		DirCache dc = null;
+		try {
+			dc = repo.lockDirCache();
+			DirCacheCheckout checkout = new DirCacheCheckout(repo, dc,
+					commit.getTree());
+			checkout.setFailOnConflict(false);
+			checkout.checkout();
+		} catch (IOException e) {
+			throw e;
+		} finally {
+			if (dc != null)
+				dc.unlock();
+		}
+	}
+
+	private void resetMerge() throws IOException {
+		repo.writeMergeHeads(null);
+		repo.writeMergeCommitMsg(null);
+	}
+
+}