log, diff: Add rename detection support

Implement rename detection in the command line diff and log commands.
Also support --name-status, -p and -U flags, as these can be quite
useful to view more detail.

All of the Git patch file formatting code is now moved over to the
DiffFormatter class.  This permits us to reuse it in any context,
including inside of IDEs.

Change-Id: I687ccba34e18105a07e0a439d2181c323209d96c
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

5 files changed, 300 insertions, 70 deletions

diff --git a/org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/CLIText.properties b/org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/CLIText.properties
index d13c47d297..67357be1da 100644
--- a/org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/CLIText.properties
+++ b/org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/CLIText.properties
@@ -66,6 +66,7 @@ metaVar_directory=DIRECTORY
 metaVar_file=FILE
 metaVar_gitDir=GIT_DIR
 metaVar_hostName=HOSTNAME
+metaVar_linesOfContext=lines
 metaVar_message=message
 metaVar_name=name
 metaVar_object=object
@@ -139,6 +140,7 @@ usage_cloneRepositoryIntoNewDir=Clone a repository into a new directory
 usage_configureTheServiceInDaemonServicename=configure the service in daemon.servicename
 usage_deleteBranchEvenIfNotMerged=delete branch (even if not merged)
 usage_deleteFullyMergedBranch=delete fully merged branch
+usage_detectRenames=detect renamed files
 usage_directoriesToExport=directories to export
 usage_disableTheServiceInAllRepositories=disable the service in all repositories
 usage_displayAListOfAllRegisteredJgitCommands=Display a list of all registered jgit commands
@@ -160,6 +162,7 @@ usage_listBothRemoteTrackingAndLocalBranches=list both remote-tracking and local
 usage_listCreateOrDeleteBranches=List, create, or delete branches
 usage_logAllPretty=format:%H %ct %P' output=log --all '--pretty=format:%H %ct %P' output
 usage_moveRenameABranch=move/rename a branch
+usage_nameStatus=show only name and status of files
 usage_outputFile=Output file
 usage_path=path
 usage_performFsckStyleChecksOnReceive=perform fsck style checks on receive
@@ -170,6 +173,7 @@ usage_recurseIntoSubtrees=recurse into subtrees
 usage_recordChangesToRepository=Record changes to the repository
 usage_setTheGitRepositoryToOperateOn=set the git repository to operate on
 usage_showRefNamesMatchingCommits=Show ref names matching commits
+usage_showPatch=display patch
 usage_symbolicVersionForTheProject=Symbolic version for the project
 usage_synchronizeIPZillaData=Synchronize IPZilla data
 usage_tagMessage=tag message
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Diff.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Diff.java
index fc1e400ab0..a3fca638b5 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Diff.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Diff.java
@@ -45,28 +45,28 @@
 
 package org.eclipse.jgit.pgm;
 
+import java.io.BufferedOutputStream;
 import java.io.IOException;
-import java.io.PrintStream;
+import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.List;
 
-import org.kohsuke.args4j.Argument;
-import org.kohsuke.args4j.Option;
-
+import org.eclipse.jgit.diff.DiffEntry;
 import org.eclipse.jgit.diff.DiffFormatter;
-import org.eclipse.jgit.diff.MyersDiff;
 import org.eclipse.jgit.diff.RawText;
 import org.eclipse.jgit.diff.RawTextIgnoreAllWhitespace;
 import org.eclipse.jgit.diff.RawTextIgnoreLeadingWhitespace;
 import org.eclipse.jgit.diff.RawTextIgnoreTrailingWhitespace;
 import org.eclipse.jgit.diff.RawTextIgnoreWhitespaceChange;
-import org.eclipse.jgit.lib.FileMode;
-import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.diff.RenameDetector;
+import org.eclipse.jgit.lib.TextProgressMonitor;
 import org.eclipse.jgit.pgm.opt.PathTreeFilterHandler;
 import org.eclipse.jgit.treewalk.AbstractTreeIterator;
 import org.eclipse.jgit.treewalk.TreeWalk;
 import org.eclipse.jgit.treewalk.filter.AndTreeFilter;
 import org.eclipse.jgit.treewalk.filter.TreeFilter;
+import org.kohsuke.args4j.Argument;
+import org.kohsuke.args4j.Option;
 
 @Command(common = true, usage = "usage_ShowDiffs")
 class Diff extends TextBuiltin {
@@ -78,9 +78,15 @@ class Diff extends TextBuiltin {
 	@Argument(index = 1, metaVar = "metaVar_treeish", required = true)
 	private final List<AbstractTreeIterator> trees = new ArrayList<AbstractTreeIterator>();
 
-	@Option(name = "--", metaVar = "metaVar_port", multiValued = true, handler = PathTreeFilterHandler.class)
+	@Option(name = "--", metaVar = "metaVar_paths", multiValued = true, handler = PathTreeFilterHandler.class)
 	private TreeFilter pathFilter = TreeFilter.ALL;
 
+	@Option(name = "-M", usage = "usage_detectRenames")
+	private boolean detectRenames;
+
+	@Option(name = "--name-status", usage = "usage_nameStatus")
+	private boolean showNameAndStatusOnly;
+
 	@Option(name = "--ignore-space-at-eol")
 	private boolean ignoreWsTrailing;
 
@@ -93,10 +99,69 @@ class Diff extends TextBuiltin {
 	@Option(name = "-w", aliases = { "--ignore-all-space" })
 	private boolean ignoreWsAll;
 
-	private DiffFormatter fmt = new DiffFormatter();
+	@Option(name = "-U", aliases = { "--unified" }, metaVar = "metaVar_linesOfContext")
+	void unified(int lines) {
+		fmt.setContext(lines);
+	}
+
+	private DiffFormatter fmt = new DiffFormatter() {
+		@Override
+		protected RawText newRawText(byte[] raw) {
+			if (ignoreWsAll)
+				return new RawTextIgnoreAllWhitespace(raw);
+			else if (ignoreWsTrailing)
+				return new RawTextIgnoreTrailingWhitespace(raw);
+			else if (ignoreWsChange)
+				return new RawTextIgnoreWhitespaceChange(raw);
+			else if (ignoreWsLeading)
+				return new RawTextIgnoreLeadingWhitespace(raw);
+			else
+				return new RawText(raw);
+		}
+	};
 
 	@Override
 	protected void run() throws Exception {
+		List<DiffEntry> files = scan();
+
+		if (showNameAndStatusOnly) {
+			nameStatus(out, files);
+			out.flush();
+
+		} else {
+			BufferedOutputStream o = new BufferedOutputStream(System.out);
+			fmt.format(o, db, files);
+			o.flush();
+		}
+	}
+
+	static void nameStatus(PrintWriter out, List<DiffEntry> files) {
+		for (DiffEntry ent : files) {
+			switch (ent.getChangeType()) {
+			case ADD:
+				out.println("A\t" + ent.getNewName());
+				break;
+			case DELETE:
+				out.println("D\t" + ent.getOldName());
+				break;
+			case MODIFY:
+				out.println("M\t" + ent.getNewName());
+				break;
+			case COPY:
+				out.format("C%1$03d\t%2$s\t%3$s", ent.getScore(), //
+						ent.getOldName(), ent.getNewName());
+				out.println();
+				break;
+			case RENAME:
+				out.format("R%1$03d\t%2$s\t%3$s", ent.getScore(), //
+						ent.getOldName(), ent.getNewName());
+				out.println();
+				break;
+			}
+		}
+	}
+
+	private List<DiffEntry> scan() throws IOException {
 		final TreeWalk walk = new TreeWalk(db);
 		walk.reset();
 		walk.setRecursive(true);
@@ -104,65 +169,12 @@ class Diff extends TextBuiltin {
 			walk.addTree(i);
 		walk.setFilter(AndTreeFilter.create(TreeFilter.ANY_DIFF, pathFilter));
 
-		while (walk.next())
-			outputDiff(System.out, walk.getPathString(),
-				walk.getObjectId(0), walk.getFileMode(0),
-				walk.getObjectId(1), walk.getFileMode(1));
-	}
-
-	protected void outputDiff(PrintStream out, String path,
-			ObjectId id1, FileMode mode1, ObjectId id2, FileMode mode2) throws IOException {
-		String name1 = "a/" + path;
-		String name2 =  "b/" + path;
-		out.println("diff --git " + name1 + " " + name2);
-		boolean isNew=false;
-		boolean isDelete=false;
-		if (id1.equals(ObjectId.zeroId())) {
-			out.println("new file mode " + mode2);
-			isNew=true;
-		} else if (id2.equals(ObjectId.zeroId())) {
-			out.println("deleted file mode " + mode1);
-			isDelete=true;
-		} else if (!mode1.equals(mode2)) {
-			out.println("old mode " + mode1);
-			out.println("new mode " + mode2);
+		List<DiffEntry> files = DiffEntry.scan(walk);
+		if (detectRenames) {
+			RenameDetector rd = new RenameDetector(db);
+			rd.addAll(files);
+			files = rd.compute(new TextProgressMonitor());
 		}
-		out.println("index " + id1.abbreviate(db, 7).name()
-			+ ".." + id2.abbreviate(db, 7).name()
-			+ (mode1.equals(mode2) ? " " + mode1 : ""));
-		out.println("--- " + (isNew ?  "/dev/null" : name1));
-		out.println("+++ " + (isDelete ?  "/dev/null" : name2));
-
-		byte[] aRaw = getRawBytes(id1);
-		byte[] bRaw = getRawBytes(id2);
-
-		if (RawText.isBinary(aRaw) || RawText.isBinary(bRaw)) {
-			out.println("Binary files differ");
-			return;
-		}
-
-		RawText a = getRawText(aRaw);
-		RawText b = getRawText(bRaw);
-		MyersDiff diff = new MyersDiff(a, b);
-		fmt.formatEdits(out, a, b, diff.getEdits());
-	}
-
-	private byte[] getRawBytes(ObjectId id) throws IOException {
-		if (id.equals(ObjectId.zeroId()))
-			return new byte[] {};
-		return db.openBlob(id).getCachedBytes();
-	}
-
-	private RawText getRawText(byte[] raw) {
-		if (ignoreWsAll)
-			return new RawTextIgnoreAllWhitespace(raw);
-		else if (ignoreWsTrailing)
-			return new RawTextIgnoreTrailingWhitespace(raw);
-		else if (ignoreWsChange)
-			return new RawTextIgnoreWhitespaceChange(raw);
-		else if (ignoreWsLeading)
-			return new RawTextIgnoreLeadingWhitespace(raw);
-		else
-			return new RawText(raw);
+		return files;
 	}
 }
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Log.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Log.java
index 9aa197e4ab..511da44984 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Log.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Log.java
@@ -45,22 +45,32 @@
 
 package org.eclipse.jgit.pgm;
 
+import java.io.BufferedOutputStream;
+import java.io.IOException;
 import java.text.DateFormat;
 import java.text.MessageFormat;
 import java.text.SimpleDateFormat;
 import java.util.Collection;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.TimeZone;
 
-import org.kohsuke.args4j.Option;
+import org.eclipse.jgit.diff.DiffEntry;
+import org.eclipse.jgit.diff.DiffFormatter;
+import org.eclipse.jgit.diff.RenameDetector;
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.PersonIdent;
 import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.lib.TextProgressMonitor;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.treewalk.TreeWalk;
+import org.eclipse.jgit.treewalk.filter.AndTreeFilter;
+import org.eclipse.jgit.treewalk.filter.TreeFilter;
+import org.kohsuke.args4j.Option;
 
 @Command(common = true, usage = "usage_viewCommitHistory")
 class Log extends RevWalkTextBuiltin {
@@ -73,6 +83,22 @@ class Log extends RevWalkTextBuiltin {
 	@Option(name="--decorate", usage="usage_showRefNamesMatchingCommits")
 	private boolean decorate;
 
+	@Option(name = "-M", usage = "usage_detectRenames")
+	private boolean detectRenames;
+
+	@Option(name = "--name-status", usage = "usage_nameStatus")
+	private boolean showNameAndStatusOnly;
+
+	@Option(name = "-p", usage = "usage_showPatch")
+	private boolean showPatch;
+
+	@Option(name = "-U", aliases = { "--unified" }, metaVar = "metaVar_linesOfContext")
+	void unified(int lines) {
+		diffFmt.setContext(lines);
+	}
+
+	private DiffFormatter diffFmt = new DiffFormatter();
+
 	Log() {
 		fmt = new SimpleDateFormat("EEE MMM dd HH:mm:ss yyyy ZZZZZ", Locale.US);
 	}
@@ -120,6 +146,34 @@ class Log extends RevWalkTextBuiltin {
 		}
 
 		out.println();
+		if (c.getParentCount() > 0 && (showNameAndStatusOnly || showPatch))
+			showDiff(c);
 		out.flush();
 	}
+
+	private void showDiff(RevCommit c) throws IOException {
+		final TreeWalk tw = new TreeWalk(db);
+		tw.reset();
+		tw.setRecursive(true);
+		tw.addTree(c.getParent(0).getTree());
+		tw.addTree(c.getTree());
+		tw.setFilter(AndTreeFilter.create(TreeFilter.ANY_DIFF, pathFilter));
+
+		List<DiffEntry> files = DiffEntry.scan(tw);
+		if (detectRenames) {
+			RenameDetector rd = new RenameDetector(db);
+			rd.addAll(files);
+			files = rd.compute(new TextProgressMonitor());
+		}
+
+		if (showNameAndStatusOnly) {
+			Diff.nameStatus(out, files);
+
+		} else {
+			out.flush();
+			BufferedOutputStream o = new BufferedOutputStream(System.out);
+			diffFmt.format(o, db, files);
+			o.flush();
+		}
+	}
 }
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/RevWalkTextBuiltin.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/RevWalkTextBuiltin.java
index ea6eeb102c..beb961d99c 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/RevWalkTextBuiltin.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/RevWalkTextBuiltin.java
@@ -114,7 +114,7 @@ abstract class RevWalkTextBuiltin extends TextBuiltin {
 	private final List<RevCommit> commits = new ArrayList<RevCommit>();
 
 	@Option(name = "--", metaVar = "metaVar_path", multiValued = true, handler = PathTreeFilterHandler.class)
-	private TreeFilter pathFilter = TreeFilter.ALL;
+	protected TreeFilter pathFilter = TreeFilter.ALL;
 
 	private final List<RevFilter> revLimiter = new ArrayList<RevFilter>();
 
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/diff/DiffFormatter.java b/org.eclipse.jgit/src/org/eclipse/jgit/diff/DiffFormatter.java
index c40d3b7000..b08d1cb502 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/diff/DiffFormatter.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/diff/DiffFormatter.java
@@ -44,6 +44,7 @@
 
 package org.eclipse.jgit.diff;
 
+import static org.eclipse.jgit.lib.Constants.encode;
 import static org.eclipse.jgit.lib.Constants.encodeASCII;
 
 import java.io.IOException;
@@ -51,7 +52,13 @@ import java.io.OutputStream;
 import java.util.List;
 
 import org.eclipse.jgit.JGitText;
+import org.eclipse.jgit.lib.AbbreviatedObjectId;
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.FileMode;
+import org.eclipse.jgit.lib.ObjectLoader;
+import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.patch.FileHeader;
+import org.eclipse.jgit.util.QuotedString;
 
 /**
  * Format an {@link EditList} as a Git style unified patch script.
@@ -81,6 +88,159 @@ public class DiffFormatter {
 	}
 
 	/**
+	 * Format a patch script from a list of difference entries.
+	 *
+	 * @param out
+	 *            stream to write the patch script out to.
+	 * @param src
+	 *            repository the file contents can be read from.
+	 * @param entries
+	 *            entries describing the affected files.
+	 * @throws IOException
+	 *             a file's content cannot be read, or the output stream cannot
+	 *             be written to.
+	 */
+	public void format(final OutputStream out, Repository src,
+			List<? extends DiffEntry> entries) throws IOException {
+		for(DiffEntry ent : entries) {
+			if (ent instanceof FileHeader) {
+				format(
+						out,
+						(FileHeader) ent, //
+						newRawText(open(src, ent.getOldMode(), ent.getOldId())),
+						newRawText(open(src, ent.getNewMode(), ent.getNewId())));
+			} else {
+				format(out, src, ent);
+			}
+		}
+	}
+
+	private void format(OutputStream out, Repository src, DiffEntry ent)
+			throws IOException {
+		String oldName = quotePath("a/" + ent.getOldName());
+		String newName = quotePath("b/" + ent.getNewName());
+		out.write(encode("diff --git " + oldName + " " + newName + "\n"));
+
+		switch(ent.getChangeType()) {
+		case ADD:
+			out.write(encodeASCII("new file mode "));
+			ent.getNewMode().copyTo(out);
+			out.write('\n');
+			break;
+
+		case DELETE:
+			out.write(encodeASCII("deleted file mode "));
+			ent.getOldMode().copyTo(out);
+			out.write('\n');
+			break;
+
+		case RENAME:
+			out.write(encode("similarity index " + ent.getScore() + "%"));
+			out.write('\n');
+
+			out.write(encode("rename from " + quotePath(ent.getOldName())));
+			out.write('\n');
+
+			out.write(encode("rename to " + quotePath(ent.getNewName())));
+			out.write('\n');
+			break;
+
+		case COPY:
+			out.write(encode("similarity index " + ent.getScore() + "%"));
+			out.write('\n');
+
+			out.write(encode("copy from " + quotePath(ent.getOldName())));
+			out.write('\n');
+
+			out.write(encode("copy to " + quotePath(ent.getNewName())));
+			out.write('\n');
+
+			if (!ent.getOldMode().equals(ent.getNewMode())) {
+				out.write(encodeASCII("new file mode "));
+				ent.getNewMode().copyTo(out);
+				out.write('\n');
+			}
+			break;
+		}
+
+		switch (ent.getChangeType()) {
+		case RENAME:
+		case MODIFY:
+			if (!ent.getOldMode().equals(ent.getNewMode())) {
+				out.write(encodeASCII("old mode "));
+				ent.getOldMode().copyTo(out);
+				out.write('\n');
+
+				out.write(encodeASCII("new mode "));
+				ent.getNewMode().copyTo(out);
+				out.write('\n');
+			}
+		}
+
+		out.write(encodeASCII("index " //
+				+ format(src, ent.getOldId()) //
+				+ ".." //
+				+ format(src, ent.getNewId())));
+		if (ent.getOldMode().equals(ent.getNewMode())) {
+			out.write(' ');
+			ent.getNewMode().copyTo(out);
+		}
+		out.write('\n');
+		out.write(encode("--- " + oldName + '\n'));
+		out.write(encode("+++ " + newName + '\n'));
+
+		byte[] aRaw = open(src, ent.getOldMode(), ent.getOldId());
+		byte[] bRaw = open(src, ent.getNewMode(), ent.getNewId());
+
+		if (RawText.isBinary(aRaw) || RawText.isBinary(bRaw)) {
+			out.write(encodeASCII("Binary files differ\n"));
+
+		} else {
+			RawText a = newRawText(aRaw);
+			RawText b = newRawText(bRaw);
+			formatEdits(out, a, b, new MyersDiff(a, b).getEdits());
+		}
+	}
+
+	/**
+	 * Construct a RawText sequence for use with {@link MyersDiff}.
+	 *
+	 * @param content
+	 *            text to be compared.
+	 * @return the raw text instance to handle the content.
+	 */
+	protected RawText newRawText(byte[] content) {
+		return new RawText(content);
+	}
+
+	private String format(Repository db, AbbreviatedObjectId oldId) {
+		if (oldId.isComplete())
+			oldId = oldId.toObjectId().abbreviate(db, 8);
+		return oldId.name();
+	}
+
+	private static String quotePath(String name) {
+		String q = QuotedString.GIT_PATH.quote(name);
+		return ('"' + name + '"').equals(q) ? name : q;
+	}
+
+	private byte[] open(Repository src, FileMode mode, AbbreviatedObjectId id)
+			throws IOException {
+		if (mode == FileMode.MISSING)
+			return new byte[] {};
+
+		if (mode.getObjectType() != Constants.OBJ_BLOB)
+			return new byte[] {};
+
+		if (id.isComplete()) {
+			ObjectLoader ldr = src.openObject(id.toObjectId());
+			return ldr.getCachedBytes();
+		}
+
+		return new byte[] {};
+	}
+
+	/**
 	 * Format a patch script, reusing a previously parsed FileHeader.
 	 * <p>
 	 * This formatter is primarily useful for editing an existing patch script