Add BranchTrackingStatus for getting remote tracking statusrefs/changes/32/4732/4

This is used by EGit change I1e1caca561d1b0a0c194bfc42e64b698f42c6e6a to
show branch status in decoration.

It can also be used for providing the same output as C Git in "git
status".

Change-Id: I8d2b108c89905c3f0496f3d517879596740787c0
Signed-off-by: Robin Stocker <robin@nibor.org>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

2 files changed, 244 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/BranchTrackingStatusTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/BranchTrackingStatusTest.java
new file mode 100644
index 0000000..bc18d5f
--- a/dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/BranchTrackingStatusTest.java
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2011, Robin Stocker <robin@nibor.org>
+ * 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.lib;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+import org.eclipse.jgit.junit.TestRepository;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.junit.Test;
+
+public class BranchTrackingStatusTest extends RepositoryTestCase {
+	private TestRepository<Repository> util;
+
+	protected RevWalk rw;
+
+	@Override
+	public void setUp() throws Exception {
+		super.setUp();
+		util = new TestRepository<Repository>(db);
+		StoredConfig config = util.getRepository().getConfig();
+		config.setString(ConfigConstants.CONFIG_BRANCH_SECTION, "master",
+				ConfigConstants.CONFIG_KEY_REMOTE, "origin");
+		config.setString(ConfigConstants.CONFIG_BRANCH_SECTION, "master",
+				ConfigConstants.CONFIG_KEY_MERGE, "refs/heads/master");
+		config.setString(ConfigConstants.CONFIG_REMOTE_SECTION, "origin",
+				"fetch", "+refs/heads/*:refs/remotes/origin/*");
+	}
+
+	@Test
+	public void shouldWorkInNormalCase() throws Exception {
+		RevCommit remoteTracking = util.branch("refs/remotes/origin/master")
+				.commit().create();
+		util.branch("master").commit().parent(remoteTracking).create();
+		util.branch("master").commit().create();
+
+		BranchTrackingStatus status = BranchTrackingStatus.of(
+				util.getRepository(), "master");
+		assertEquals(2, status.getAheadCount());
+		assertEquals(0, status.getBehindCount());
+		assertEquals("refs/remotes/origin/master",
+				status.getRemoteTrackingBranch());
+	}
+
+	@Test
+	public void shouldWorkWithoutMergeBase() throws Exception {
+		util.branch("refs/remotes/origin/master").commit().create();
+		util.branch("master").commit().create();
+
+		BranchTrackingStatus status = BranchTrackingStatus.of(util.getRepository(), "master");
+		assertEquals(1, status.getAheadCount());
+		assertEquals(1, status.getBehindCount());
+	}
+
+	@Test
+	public void shouldReturnNullWhenBranchDoesntExist() throws Exception {
+		BranchTrackingStatus status = BranchTrackingStatus.of(
+				util.getRepository(), "doesntexist");
+
+		assertNull(status);
+	}
+}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/BranchTrackingStatus.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/BranchTrackingStatus.java
new file mode 100644
index 0000000..4d69e60
--- a/dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/BranchTrackingStatus.java
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2011, Robin Stocker <robin@nibor.org>
+ * 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.lib;
+
+import java.io.IOException;
+
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.revwalk.RevWalkUtils;
+import org.eclipse.jgit.revwalk.filter.RevFilter;
+
+/**
+ * Status of a branch's relation to its remote-tracking branch.
+ */
+public class BranchTrackingStatus {
+
+	/**
+	 * Compute the tracking status for the <code>branchName</code> in
+	 * <code>repository</code>.
+	 *
+	 * @param repository
+	 *            the git repository to compute the status from
+	 * @param branchName
+	 *            the local branch
+	 * @return the tracking status, or null if it is not known
+	 * @throws IOException
+	 */
+	public static BranchTrackingStatus of(Repository repository, String branchName)
+			throws IOException {
+
+		BranchConfig branchConfig = new BranchConfig(repository.getConfig(),
+				branchName);
+
+		String remoteTrackingBranch = branchConfig.getRemoteTrackingBranch();
+		if (remoteTrackingBranch == null)
+			return null;
+
+		Ref tracking = repository.getRef(remoteTrackingBranch);
+		if (tracking == null)
+			return null;
+
+		Ref local = repository.getRef(branchName);
+		if (local == null)
+			return null;
+
+		RevWalk walk = new RevWalk(repository);
+
+		RevCommit localCommit = walk.parseCommit(local.getObjectId());
+		RevCommit trackingCommit = walk.parseCommit(tracking.getObjectId());
+
+		walk.setRevFilter(RevFilter.MERGE_BASE);
+		walk.markStart(localCommit);
+		walk.markStart(trackingCommit);
+		RevCommit mergeBase = walk.next();
+
+		walk.reset();
+		walk.setRevFilter(RevFilter.ALL);
+		int aheadCount = RevWalkUtils.count(walk, localCommit, mergeBase);
+		int behindCount = RevWalkUtils.count(walk, trackingCommit, mergeBase);
+
+		return new BranchTrackingStatus(remoteTrackingBranch, aheadCount, behindCount);
+	}
+
+	private final String remoteTrackingBranch;
+
+	private final int aheadCount;
+
+	private final int behindCount;
+
+	private BranchTrackingStatus(String remoteTrackingBranch, int aheadCount,
+			int behindCount) {
+		this.remoteTrackingBranch = remoteTrackingBranch;
+		this.aheadCount = aheadCount;
+		this.behindCount = behindCount;
+	}
+
+	/**
+	 * @return full remote-tracking branch name
+	 */
+	public String getRemoteTrackingBranch() {
+		return remoteTrackingBranch;
+	}
+
+	/**
+	 * @return number of commits that the local branch is ahead of the
+	 *         remote-tracking branch
+	 */
+	public int getAheadCount() {
+		return aheadCount;
+	}
+
+	/**
+	 * @return number of commits that the local branch is behind of the
+	 *         remote-tracking branch
+	 */
+	public int getBehindCount() {
+		return behindCount;
+	}
+}