Add command line support for "git difftool"

see: http://git-scm.com/docs/git-difftool

* add command line support for "jgit difftool"
* show supported commands with "jgit difftool --help"
* added "git difftool --tool-help" to show the tools (empty now)
* prepare for all other commands

Bug: 356832
Change-Id: Ice0c13ef7953a20feaf25e7746d62b94ff4e89e5
Signed-off-by: Andre Bossert <andre.bossert@siemens.com>
Signed-off-by: Simeon Andreev <simeon.danailov.andreev@gmail.com>

5 files changed, 274 insertions, 0 deletions

diff --git a/org.eclipse.jgit.pgm/META-INF/MANIFEST.MF b/org.eclipse.jgit.pgm/META-INF/MANIFEST.MF
index 1ebd3a3e4c..fa0f452c59 100644
--- a/org.eclipse.jgit.pgm/META-INF/MANIFEST.MF
+++ b/org.eclipse.jgit.pgm/META-INF/MANIFEST.MF
@@ -24,6 +24,7 @@ Import-Package: javax.servlet;version="[3.1.0,5.0.0)",
  org.eclipse.jgit.errors;version="[6.1.0,6.2.0)",
  org.eclipse.jgit.gitrepo;version="[6.1.0,6.2.0)",
  org.eclipse.jgit.internal.storage.file;version="[6.1.0,6.2.0)",
+ org.eclipse.jgit.internal.diffmergetool;version="[6.1.0,6.2.0)",
  org.eclipse.jgit.internal.storage.io;version="[6.1.0,6.2.0)",
  org.eclipse.jgit.internal.storage.pack;version="[6.1.0,6.2.0)",
  org.eclipse.jgit.internal.storage.reftable;version="[6.1.0,6.2.0)",
@@ -33,6 +34,7 @@ Import-Package: javax.servlet;version="[3.1.0,5.0.0)",
  org.eclipse.jgit.lfs.server.s3;version="[6.1.0,6.2.0)",
  org.eclipse.jgit.lib;version="[6.1.0,6.2.0)",
  org.eclipse.jgit.merge;version="[6.1.0,6.2.0)",
+ org.eclipse.jgit.lib.internal;version="[6.1.0,6.2.0)",
  org.eclipse.jgit.nls;version="[6.1.0,6.2.0)",
  org.eclipse.jgit.notes;version="[6.1.0,6.2.0)",
  org.eclipse.jgit.revplot;version="[6.1.0,6.2.0)",
diff --git a/org.eclipse.jgit.pgm/META-INF/services/org.eclipse.jgit.pgm.TextBuiltin b/org.eclipse.jgit.pgm/META-INF/services/org.eclipse.jgit.pgm.TextBuiltin
index e645255e96..8c44764c63 100644
--- a/org.eclipse.jgit.pgm/META-INF/services/org.eclipse.jgit.pgm.TextBuiltin
+++ b/org.eclipse.jgit.pgm/META-INF/services/org.eclipse.jgit.pgm.TextBuiltin
@@ -12,6 +12,7 @@ org.eclipse.jgit.pgm.ConvertRefStorage
 org.eclipse.jgit.pgm.Daemon
 org.eclipse.jgit.pgm.Describe
 org.eclipse.jgit.pgm.Diff
+org.eclipse.jgit.pgm.DiffTool
 org.eclipse.jgit.pgm.DiffTree
 org.eclipse.jgit.pgm.Fetch
 org.eclipse.jgit.pgm.Gc
diff --git a/org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/internal/CLIText.properties b/org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/internal/CLIText.properties
index 97450033ee..d51daafde3 100644
--- a/org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/internal/CLIText.properties
+++ b/org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/internal/CLIText.properties
@@ -58,6 +58,9 @@ couldNotCreateBranch=Could not create branch {0}: {1}
 dateInfo=Date:   {0}
 deletedBranch=Deleted branch {0}
 deletedRemoteBranch=Deleted remote branch {0}
+diffToolHelpSetToFollowing='git difftool --tool=<tool>' may be set to one of the following:\n{0}\n\tuser-defined:\n{1}\nThe following tools are valid, but not currently available:\n{2}\nSome of the tools listed above only work in a windowed\nenvironment. If run in a terminal-only session, they will fail.
+diffToolLaunch=Viewing ({0}/{1}): '{2}'\nLaunch '{3}' [Y/n]?
+diffToolDied=external diff died, stopping at {0}
 doesNotExist={0} does not exist
 dontOverwriteLocalChanges=error: Your local changes to the following file would be overwritten by merge:
 everythingUpToDate=Everything up-to-date
@@ -145,6 +148,7 @@ metaVar_s3StorageClass=STORAGE-CLASS
 metaVar_seconds=SECONDS
 metaVar_service=SERVICE
 metaVar_tagLocalUser=<GPG key ID>
+metaVar_tool=TOOL
 metaVar_treeish=tree-ish
 metaVar_uriish=uri-ish
 metaVar_url=URL
@@ -249,6 +253,8 @@ usage_DiffAlgorithms=Test performance of jgit's diff algorithms
 usage_DisplayTheVersionOfJgit=Display the version of jgit
 usage_Gc=Cleanup unnecessary files and optimize the local repository
 usage_Glog=View commit history as a graph
+usage_DiffGuiTool=When git-difftool is invoked with the -g or --gui option the default diff tool will be read from the configured diff.guitool variable instead of diff.tool.
+usage_noGui=The --no-gui option can be used to override -g or --gui setting.
 usage_IndexPack=Build pack index file for an existing packed archive
 usage_LFSDirectory=Directory to store large objects
 usage_LFSPort=Server http port
@@ -295,6 +301,7 @@ usage_ShowRef=List references in a local repository
 usage_Status=Show the working tree status
 usage_StopTrackingAFile=Stop tracking a file
 usage_TextHashFunctions=Scan repository to compute maximum number of collisions for hash functions
+usage_ToolForDiff=Use the diff tool specified by <tool>. Run git difftool --tool-help for the list of valid <tool> settings.\nIf a diff tool is not specified, git difftool will use the configuration variable diff.tool.
 usage_UpdateRemoteRepositoryFromLocalRefs=Update remote repository from local refs
 usage_UseAll=Use all refs found in refs/
 usage_UseTags=Use any tag including lightweight tags
@@ -341,6 +348,7 @@ usage_deleteFullyMergedBranch=delete fully merged branch
 usage_date=date format, one of default, rfc, local, iso, short, raw (as defined by git-log(1) ), locale or localelocal (jgit extensions)
 usage_detectRenames=detect renamed files
 usage_diffAlgorithm=the diff algorithm to use. Currently supported are: 'myers', 'histogram'
+usage_DiffTool=git difftool is a Git command that allows you to compare and edit files between revisions using common diff tools.\ngit difftool is a frontend to git diff and accepts the same options and arguments.
 usage_directoriesToExport=directories to export
 usage_disableTheServiceInAllRepositories=disable the service in all repositories
 usage_displayAListOfAllRegisteredJgitCommands=Display a list of all registered jgit commands
@@ -395,6 +403,8 @@ usage_pathToXml=path to the repo manifest XML file
 usage_performFsckStyleChecksOnReceive=perform fsck style checks on receive
 usage_portNumberToListenOn=port number to listen on
 usage_printOnlyBranchesThatContainTheCommit=print only branches that contain the commit
+usage_prompt=Prompt before each invocation of the diff tool. This is the default behaviour; the option is provided to override any configuration settings.
+usage_noPrompt=Do not prompt before launching a diff tool.
 usage_pruneStaleTrackingRefs=prune stale tracking refs
 usage_pushUrls=push URLs are manipulated
 usage_quiet=don't show progress messages
@@ -422,6 +432,8 @@ usage_srcPrefix=show the source prefix instead of "a/"
 usage_sshDriver=Selects the built-in ssh library to use, JSch or Apache MINA sshd.
 usage_symbolicVersionForTheProject=Symbolic version for the project
 usage_tags=fetch all tags
+usage_trustExitCode=git-difftool invokes a diff tool individually on each file. Errors reported by the diff tool are ignored by default. Use --trust-exit-code to make git-difftool exit when an invoked diff tool returns a non-zero exit code.\ngit-difftool will forward the exit code of the invoked tool when --trust-exit-code is used.
+usage_noTrustExitCode=This option can be used to override --trust-exit-code setting.
 usage_notags=do not fetch tags
 usage_tagAnnotated=create an annotated tag, unsigned unless -s or -u are given, or config tag.gpgSign is true
 usage_tagDelete=delete tag
@@ -430,6 +442,7 @@ usage_tagMessage=create an annotated tag with the given message, unsigned unless
 usage_tagSign=create a signed annotated tag
 usage_tagNoSign=suppress signing the tag
 usage_tagVerify=Verify the GPG signature
+usage_toolHelp=Print a list of diff tools that may be used with --tool.
 usage_untrackedFilesMode=show untracked files
 usage_updateRef=reference to update
 usage_updateRemoteRefsFromAnotherRepository=Update remote refs from another repository
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/DiffTool.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/DiffTool.java
new file mode 100644
index 0000000000..9fc26c9356
--- /dev/null
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/DiffTool.java
@@ -0,0 +1,255 @@
+/*
+ * Copyright (C) 2018-2021, Andre Bossert <andre.bossert@siemens.com>
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+package org.eclipse.jgit.pgm;
+
+import static org.eclipse.jgit.lib.Constants.HEAD;
+
+import java.io.BufferedOutputStream;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.text.MessageFormat;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+import org.eclipse.jgit.diff.DiffEntry;
+import org.eclipse.jgit.diff.DiffFormatter;
+import org.eclipse.jgit.dircache.DirCacheIterator;
+import org.eclipse.jgit.errors.AmbiguousObjectException;
+import org.eclipse.jgit.errors.IncorrectObjectTypeException;
+import org.eclipse.jgit.errors.RevisionSyntaxException;
+import org.eclipse.jgit.internal.diffmergetool.DiffTools;
+import org.eclipse.jgit.internal.diffmergetool.ExternalDiffTool;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectReader;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.lib.TextProgressMonitor;
+import org.eclipse.jgit.lib.internal.BooleanTriState;
+import org.eclipse.jgit.pgm.internal.CLIText;
+import org.eclipse.jgit.pgm.opt.PathTreeFilterHandler;
+import org.eclipse.jgit.treewalk.AbstractTreeIterator;
+import org.eclipse.jgit.treewalk.CanonicalTreeParser;
+import org.eclipse.jgit.treewalk.FileTreeIterator;
+import org.eclipse.jgit.treewalk.filter.TreeFilter;
+import org.eclipse.jgit.util.StringUtils;
+import org.kohsuke.args4j.Argument;
+import org.kohsuke.args4j.Option;
+
+@Command(name = "difftool", common = true, usage = "usage_DiffTool")
+class DiffTool extends TextBuiltin {
+	private DiffFormatter diffFmt;
+
+	private DiffTools diffTools;
+
+	@Argument(index = 0, metaVar = "metaVar_treeish")
+	private AbstractTreeIterator oldTree;
+
+	@Argument(index = 1, metaVar = "metaVar_treeish")
+	private AbstractTreeIterator newTree;
+
+	@Option(name = "--tool", aliases = {
+			"-t" }, metaVar = "metaVar_tool", usage = "usage_ToolForDiff")
+	private String toolName;
+
+	@Option(name = "--cached", aliases = { "--staged" }, usage = "usage_cached")
+	private boolean cached;
+
+	private BooleanTriState prompt = BooleanTriState.UNSET;
+
+	@Option(name = "--prompt", usage = "usage_prompt")
+	void setPrompt(@SuppressWarnings("unused") boolean on) {
+		prompt = BooleanTriState.TRUE;
+	}
+
+	@Option(name = "--no-prompt", aliases = { "-y" }, usage = "usage_noPrompt")
+	void noPrompt(@SuppressWarnings("unused") boolean on) {
+		prompt = BooleanTriState.FALSE;
+	}
+
+	@Option(name = "--tool-help", usage = "usage_toolHelp")
+	private boolean toolHelp;
+
+	private BooleanTriState gui = BooleanTriState.UNSET;
+
+	@Option(name = "--gui", aliases = { "-g" }, usage = "usage_DiffGuiTool")
+	void setGui(@SuppressWarnings("unused") boolean on) {
+		gui = BooleanTriState.TRUE;
+	}
+
+	@Option(name = "--no-gui", usage = "usage_noGui")
+	void noGui(@SuppressWarnings("unused") boolean on) {
+		gui = BooleanTriState.FALSE;
+	}
+
+	private BooleanTriState trustExitCode = BooleanTriState.UNSET;
+
+	@Option(name = "--trust-exit-code", usage = "usage_trustExitCode")
+	void setTrustExitCode(@SuppressWarnings("unused") boolean on) {
+		trustExitCode = BooleanTriState.TRUE;
+	}
+
+	@Option(name = "--no-trust-exit-code", usage = "usage_noTrustExitCode")
+	void noTrustExitCode(@SuppressWarnings("unused") boolean on) {
+		trustExitCode = BooleanTriState.FALSE;
+	}
+
+	@Option(name = "--", metaVar = "metaVar_paths", handler = PathTreeFilterHandler.class)
+	private TreeFilter pathFilter = TreeFilter.ALL;
+
+	@Override
+	protected void init(Repository repository, String gitDir) {
+		super.init(repository, gitDir);
+		diffFmt = new DiffFormatter(new BufferedOutputStream(outs));
+		diffTools = new DiffTools(repository);
+	}
+
+	@Override
+	protected void run() {
+		try {
+			if (toolHelp) {
+				showToolHelp();
+			} else {
+				boolean showPrompt = diffTools.isInteractive();
+				if (prompt != BooleanTriState.UNSET) {
+					showPrompt = prompt == BooleanTriState.TRUE;
+				}
+				String toolNamePrompt = toolName;
+				if (showPrompt) {
+					if (StringUtils.isEmptyOrNull(toolNamePrompt)) {
+						toolNamePrompt = diffTools.getDefaultToolName(gui);
+					}
+				}
+				// get the changed files
+				List<DiffEntry> files = getFiles();
+				if (files.size() > 0) {
+					compare(files, showPrompt, toolNamePrompt);
+				}
+			}
+			outw.flush();
+		} catch (RevisionSyntaxException | IOException e) {
+			throw die(e.getMessage(), e);
+		} finally {
+			diffFmt.close();
+		}
+	}
+
+	private void compare(List<DiffEntry> files, boolean showPrompt,
+			String toolNamePrompt) throws IOException {
+		for (int fileIndex = 0; fileIndex < files.size(); fileIndex++) {
+			DiffEntry ent = files.get(fileIndex);
+			String mergedFilePath = ent.getNewPath();
+			if (mergedFilePath.equals(DiffEntry.DEV_NULL)) {
+				mergedFilePath = ent.getOldPath();
+			}
+			// check if user wants to launch compare
+			boolean launchCompare = true;
+			if (showPrompt) {
+				launchCompare = isLaunchCompare(fileIndex + 1, files.size(),
+						mergedFilePath, toolNamePrompt);
+			}
+			if (launchCompare) {
+				switch (ent.getChangeType()) {
+				case MODIFY:
+					outw.println("M\t" + ent.getNewPath() //$NON-NLS-1$
+							+ " (" + ent.getNewId().name() + ")" //$NON-NLS-1$ //$NON-NLS-2$
+							+ "\t" + ent.getOldPath() //$NON-NLS-1$
+							+ " (" + ent.getOldId().name() + ")"); //$NON-NLS-1$ //$NON-NLS-2$
+					int ret = diffTools.compare(ent.getNewPath(),
+							ent.getOldPath(), ent.getNewId().name(),
+							ent.getOldId().name(), toolName, prompt, gui,
+							trustExitCode);
+					if (ret != 0) {
+						throw die(MessageFormat.format(
+								CLIText.get().diffToolDied, mergedFilePath));
+					}
+					break;
+				default:
+					break;
+				}
+			} else {
+				break;
+			}
+		}
+	}
+
+	@SuppressWarnings("boxing")
+	private boolean isLaunchCompare(int fileIndex, int fileCount,
+			String fileName, String toolNamePrompt) throws IOException {
+		boolean launchCompare = true;
+		outw.println(MessageFormat.format(CLIText.get().diffToolLaunch,
+				fileIndex, fileCount, fileName, toolNamePrompt));
+		outw.flush();
+		BufferedReader br = new BufferedReader(new InputStreamReader(ins));
+		String line = null;
+		if ((line = br.readLine()) != null) {
+			if (!line.equalsIgnoreCase("Y")) { //$NON-NLS-1$
+				launchCompare = false;
+			}
+		}
+		return launchCompare;
+	}
+
+	private void showToolHelp() throws IOException {
+		String availableToolNames = new String();
+		for (String name : diffTools.getAvailableTools().keySet()) {
+			availableToolNames += String.format("\t\t{0}\n", name); //$NON-NLS-1$
+		}
+		String notAvailableToolNames = new String();
+		for (String name : diffTools.getNotAvailableTools().keySet()) {
+			notAvailableToolNames += String.format("\t\t{0}\n", name); //$NON-NLS-1$
+		}
+		String userToolNames = new String();
+		Map<String, ExternalDiffTool> userTools = diffTools
+				.getUserDefinedTools();
+		for (String name : userTools.keySet()) {
+			availableToolNames += String.format("\t\t{0}.cmd {1}\n", //$NON-NLS-1$
+					name, userTools.get(name).getCommand());
+		}
+		outw.println(MessageFormat.format(
+				CLIText.get().diffToolHelpSetToFollowing, availableToolNames,
+				userToolNames, notAvailableToolNames));
+	}
+
+	private List<DiffEntry> getFiles()
+			throws RevisionSyntaxException, AmbiguousObjectException,
+			IncorrectObjectTypeException, IOException {
+		diffFmt.setRepository(db);
+		if (cached) {
+			if (oldTree == null) {
+				ObjectId head = db.resolve(HEAD + "^{tree}"); //$NON-NLS-1$
+				if (head == null) {
+					die(MessageFormat.format(CLIText.get().notATree, HEAD));
+				}
+				CanonicalTreeParser p = new CanonicalTreeParser();
+				try (ObjectReader reader = db.newObjectReader()) {
+					p.reset(reader, head);
+				}
+				oldTree = p;
+			}
+			newTree = new DirCacheIterator(db.readDirCache());
+		} else if (oldTree == null) {
+			oldTree = new DirCacheIterator(db.readDirCache());
+			newTree = new FileTreeIterator(db);
+		} else if (newTree == null) {
+			newTree = new FileTreeIterator(db);
+		}
+
+		TextProgressMonitor pm = new TextProgressMonitor(errw);
+		pm.setDelayStart(2, TimeUnit.SECONDS);
+		diffFmt.setProgressMonitor(pm);
+		diffFmt.setPathFilter(pathFilter);
+
+		List<DiffEntry> files = diffFmt.scan(oldTree, newTree);
+		return files;
+	}
+
+}
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/internal/CLIText.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/internal/CLIText.java
index 8e49a76a33..7fe5b0fa45 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/internal/CLIText.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/internal/CLIText.java
@@ -136,6 +136,9 @@ public class CLIText extends TranslationBundle {
 	/***/ public String dateInfo;
 	/***/ public String deletedBranch;
 	/***/ public String deletedRemoteBranch;
+	/***/ public String diffToolHelpSetToFollowing;
+	/***/ public String diffToolLaunch;
+	/***/ public String diffToolDied;
 	/***/ public String doesNotExist;
 	/***/ public String dontOverwriteLocalChanges;
 	/***/ public String everythingUpToDate;