Implemented diff-to-current.

This is for history where we specify two revs to diff, not just a
commit against its parent.

src/com/gitblit/utils/JGitUtils.java

 	}
 
 	public static String getCommitDiff(Repository r, RevCommit commit, boolean outputHtml) {
-		return getCommitDiff(r, commit, null, outputHtml);
+		return getCommitDiff(r, null, commit, null, outputHtml);
 	}
 
 	public static String getCommitDiff(Repository r, RevCommit commit, String path, boolean outputHtml) {
+		return getCommitDiff(r, null, commit, path, outputHtml);
+	}
+
+	public static String getCommitDiff(Repository r, RevCommit baseCommit, RevCommit commit, boolean outputHtml) {
+		return getCommitDiff(r, baseCommit, commit, null, outputHtml);
+	}
+
+	public static String getCommitDiff(Repository r, RevCommit baseCommit, RevCommit commit, String path, boolean outputHtml) {
 		try {
-			final RevWalk rw = new RevWalk(r);
-			RevCommit parent = rw.parseCommit(commit.getParent(0).getId());
-			RevTree parentTree = parent.getTree();
+			RevTree baseTree;
+			if (baseCommit == null) {
+				final RevWalk rw = new RevWalk(r);
+				RevCommit parent = rw.parseCommit(commit.getParent(0).getId());
+				rw.dispose();
+				baseTree = parent.getTree();	
+			} else {
+				baseTree = baseCommit.getTree();
+			}
+
 			RevTree commitTree = commit.getTree();
 
 			final TreeWalk walk = new TreeWalk(r);
 			walk.reset();
 			walk.setRecursive(true);
-			walk.addTree(parentTree);
+			walk.addTree(baseTree);
 			walk.addTree(commitTree);
 			walk.setFilter(TreeFilter.ANY_DIFF);
 
 			df.setRepository(r);
 			df.setDiffComparator(cmp);
 			df.setDetectRenames(true);
-			List<DiffEntry> diffs = df.scan(parentTree, commitTree);
+			List<DiffEntry> diffs = df.scan(baseTree, commitTree);
 			if (path != null && path.length() > 0) {
 				for (DiffEntry diff : diffs) {
 					if (diff.getNewPath().equalsIgnoreCase(path)) {

src/com/gitblit/wicket/WicketUtils.java

 
 import com.gitblit.GitBlit;
 import com.gitblit.Keys;
+import com.gitblit.utils.StringUtils;
 import com.gitblit.utils.TimeUtils;
 
 public class WicketUtils {
 	}
 
 	public static PageParameters newObjectParameter(String repositoryName, String objectId) {
-		if (objectId == null || objectId.trim().length() == 0) {
+		if (StringUtils.isEmpty(objectId)) {
 			return newRepositoryParameter(repositoryName);
 		}
 		return new PageParameters("r=" + repositoryName + ",h=" + objectId);
 	}
 
 	public static PageParameters newPathParameter(String repositoryName, String objectId, String path) {
-		if (path == null || path.trim().length() == 0) {
+		if (StringUtils.isEmpty(path)) {
 			return newObjectParameter(repositoryName, objectId);
 		}
 		return new PageParameters("r=" + repositoryName + ",h=" + objectId + ",f=" + path);
 		return new PageParameters("r=" + repositoryName + ",h=" + objectId + ",f=" + path + ",page=" + pageNumber);
 	}
 
+	public static PageParameters newBlobDiffParameter(String repositoryName, String baseCommitId, String commitId, String path) {
+		return new PageParameters("r=" + repositoryName + ",h=" + commitId + ",f=" + path + ",hb=" + baseCommitId);
+	}
+
+	
 	public static String getRepositoryName(PageParameters params) {
 		return params.getString("r", "");
 	}
 	public static String getPath(PageParameters params) {
 		return params.getString("f", null);
 	}
+	
+	public static String getBaseObjectId(PageParameters params) {
+		return params.getString("hb", null);
+	}
 
 	public static int getPage(PageParameters params) {
 		return params.getInt("page", 1); // index from 1

src/com/gitblit/wicket/pages/BlobDiffPage.java

 import org.eclipse.jgit.revwalk.RevCommit;
 
 import com.gitblit.utils.JGitUtils;
+import com.gitblit.utils.StringUtils;
 import com.gitblit.wicket.LinkPanel;
 import com.gitblit.wicket.RepositoryPage;
 import com.gitblit.wicket.WicketUtils;
 		super(params);
 
 		final String blobPath = WicketUtils.getPath(params);
+		final String baseObjectId = WicketUtils.getBaseObjectId(params);
 
 		Repository r = getRepository();
 		RevCommit commit = JGitUtils.getCommit(r, objectId);
-		String diff = JGitUtils.getCommitDiff(r, commit, blobPath, true);
+		
+		String diff;
+		if (StringUtils.isEmpty(baseObjectId)) {
+			// use first parent
+			diff = JGitUtils.getCommitDiff(r, commit, blobPath, true);
+		} else {
+			// base commit specified
+			RevCommit baseCommit = JGitUtils.getCommit(r, baseObjectId);
+			diff = JGitUtils.getCommitDiff(r, baseCommit, commit, blobPath, true);
+		}
+		
 		add(new BookmarkablePageLink<Void>("patchLink", PatchPage.class, WicketUtils.newPathParameter(repositoryName, objectId, blobPath)));
 		add(new BookmarkablePageLink<Void>("commitLink", CommitPage.class, WicketUtils.newObjectParameter(repositoryName, objectId)));
 		add(new BookmarkablePageLink<Void>("commitDiffLink", CommitDiffPage.class, WicketUtils.newObjectParameter(repositoryName, objectId)));

src/com/gitblit/wicket/panels/HistoryPanel.java

 	
 	private boolean hasMore = false;
 
-	public HistoryPanel(String wicketId, final String repositoryName, String objectId, final String path, Repository r, int limit, int pageOffset) {
+	public HistoryPanel(String wicketId, final String repositoryName, final String objectId, final String path, Repository r, int limit, int pageOffset) {
 		super(wicketId);
 		boolean pageResults = limit <= 0;
 		int itemsPerPage = GitBlit.self().settings().getInteger(Keys.web.logPageCommitCount, 50);
 				// TODO links for folder
 				item.add(new BookmarkablePageLink<Void>("view", CommitPage.class, WicketUtils.newObjectParameter(repositoryName, entry.getName())));
 				item.add(new BookmarkablePageLink<Void>("commitdiff", CommitDiffPage.class, WicketUtils.newObjectParameter(repositoryName, entry.getName())));
-				item.add(new BookmarkablePageLink<Void>("difftocurrent", BlobDiffPage.class, WicketUtils.newPathParameter(repositoryName, entry.getName(), path)).setEnabled(counter > 0));
+				item.add(new BookmarkablePageLink<Void>("difftocurrent", BlobDiffPage.class, WicketUtils.newBlobDiffParameter(repositoryName, entry.getName(), objectId, path)).setEnabled(counter > 0));
 
 				WicketUtils.setAlternatingBackground(item, counter);
 				counter++;