Centralize default branch/HEAD resolution (issue 14)

If an object id was not specified Gitblit used HEAD to perform the
operation.  This breaks under some conditions like working with a
repository that does not have any commits on master but does have
commits on a vcs-import branch.

The new approach is to centralize the resolution of unspecified object
ids to a common method which resolves HEAD first but uses the most
recently modified branch if HEAD points to nothing.

This commit also includes a non-functional method for creating an empty
branch. I couldn't figure out how to make JGit create an orphaned
branch.

1 files changed, 23 insertions, 10 deletions

diff --git a/src/com/gitblit/utils/DiffUtils.java b/src/com/gitblit/utils/DiffUtils.java
index 9f0d04fc..04b5b0b1 100644
--- a/src/com/gitblit/utils/DiffUtils.java
+++ b/src/com/gitblit/utils/DiffUtils.java
@@ -25,7 +25,7 @@ import org.eclipse.jgit.diff.DiffEntry;
 import org.eclipse.jgit.diff.DiffFormatter;

 import org.eclipse.jgit.diff.RawText;

 import org.eclipse.jgit.diff.RawTextComparator;

-import org.eclipse.jgit.lib.Constants;

+import org.eclipse.jgit.lib.ObjectId;

 import org.eclipse.jgit.lib.Repository;

 import org.eclipse.jgit.revwalk.RevCommit;

 import org.eclipse.jgit.revwalk.RevTree;

@@ -147,10 +147,15 @@ public class DiffUtils {
 			RevTree commitTree = commit.getTree();

 			RevTree baseTree;

 			if (baseCommit == null) {

-				final RevWalk rw = new RevWalk(repository);

-				RevCommit parent = rw.parseCommit(commit.getParent(0).getId());

-				rw.dispose();

-				baseTree = parent.getTree();

+				if (commit.getParentCount() > 0) {

+					final RevWalk rw = new RevWalk(repository);

+					RevCommit parent = rw.parseCommit(commit.getParent(0).getId());

+					rw.dispose();

+					baseTree = parent.getTree();

+				} else {

+					// FIXME initial commit. no parent?!

+					baseTree = commitTree;

+				}

 			} else {

 				baseTree = baseCommit.getTree();

 			}

@@ -208,9 +213,14 @@ public class DiffUtils {
 			RevTree commitTree = commit.getTree();

 			RevTree baseTree;

 			if (baseCommit == null) {

-				final RevWalk rw = new RevWalk(repository);

-				RevCommit parent = rw.parseCommit(commit.getParent(0).getId());

-				baseTree = parent.getTree();

+				if (commit.getParentCount() > 0) {

+					final RevWalk rw = new RevWalk(repository);

+					RevCommit parent = rw.parseCommit(commit.getParent(0).getId());

+					baseTree = parent.getTree();

+				} else {

+					// FIXME initial commit. no parent?!

+					baseTree = commitTree;

+				}

 			} else {

 				baseTree = baseCommit.getTree();

 			}

@@ -246,12 +256,15 @@ public class DiffUtils {
 	public static List<AnnotatedLine> blame(Repository repository, String blobPath, String objectId) {

 		List<AnnotatedLine> lines = new ArrayList<AnnotatedLine>();

 		try {

+			ObjectId object;

 			if (StringUtils.isEmpty(objectId)) {

-				objectId = Constants.HEAD;

+				object = JGitUtils.getDefaultBranch(repository);

+			} else {

+				object = repository.resolve(objectId);

 			}

 			BlameCommand blameCommand = new BlameCommand(repository);

 			blameCommand.setFilePath(blobPath);

-			blameCommand.setStartCommit(repository.resolve(objectId));

+			blameCommand.setStartCommit(object);

 			BlameResult blameResult = blameCommand.call();

 			RawText rawText = blameResult.getResultContents();

 			int length = rawText.size();