// Copyright (C) 2009 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
package com.google.gerrit.server.patch;
import com.google.gerrit.reviewdb.Patch;
import com.google.gerrit.reviewdb.AccountDiffPreference.Whitespace;
import com.google.gerrit.server.cache.EntryCreator;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.inject.Inject;
import org.eclipse.jgit.diff.DiffEntry;
import org.eclipse.jgit.diff.DiffFormatter;
import org.eclipse.jgit.diff.Edit;
import org.eclipse.jgit.diff.EditList;
import org.eclipse.jgit.diff.HistogramDiff;
import org.eclipse.jgit.diff.RawText;
import org.eclipse.jgit.diff.RawTextComparator;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.FileMode;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectInserter;
import org.eclipse.jgit.lib.ObjectReader;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.patch.FileHeader;
import org.eclipse.jgit.patch.FileHeader.PatchType;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevObject;
import org.eclipse.jgit.revwalk.RevTree;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.treewalk.TreeWalk;
import org.eclipse.jgit.treewalk.filter.TreeFilter;
import org.eclipse.jgit.util.io.DisabledOutputStream;
import java.io.IOException;
import java.util.Collections;
import java.util.List;
class PatchListLoader extends EntryCreator<PatchListKey, PatchList> {
private final GitRepositoryManager repoManager;
@Inject
PatchListLoader(GitRepositoryManager mgr) {
repoManager = mgr;
}
@Override
public PatchList createEntry(final PatchListKey key) throws Exception {
final Repository repo = repoManager.openRepository(key.projectKey);
try {
return readPatchList(key, repo);
} finally {
repo.close();
}
}
private static RawTextComparator comparatorFor(Whitespace ws) {
switch (ws) {
case IGNORE_ALL_SPACE:
return RawTextComparator.WS_IGNORE_ALL;
case IGNORE_SPACE_AT_EOL:
return RawTextComparator.WS_IGNORE_TRAILING;
case IGNORE_SPACE_CHANGE:
return RawTextComparator.WS_IGNORE_CHANGE;
case IGNORE_NONE:
default:
return RawTextComparator.DEFAULT;
}
}
private PatchList readPatchList(final PatchListKey key,
final Repository repo) throws IOException {
// TODO(jeffschu) correctly handle merge commits
final RawTextComparator cmp = comparatorFor(key.getWhitespace());
final ObjectReader reader = repo.newObjectReader();
try {
final RevWalk rw = new RevWalk(reader);
final RevCommit b = rw.parseCommit(key.getNewId());
final RevObject a = aFor(key, repo, rw, b);
if (a == null) {
// This is a merge commit, compared to its ancestor.
//
final PatchListEntry[] entries = new PatchListEntry[1];
entries[0] = newCommitMessage(cmp, repo, reader, null, b);
return new PatchList(a, b, true, entries);
}
final boolean againstParent =
b.getParentCount() > 0 && b.getParent(0) == a;
RevCommit aCommit;
RevTree aTree;
if (a instanceof RevCommit) {
aCommit = (RevCommit) a;
aTree = aCommit.getTree();
} else if (a instanceof RevTree) {
aCommit = null;
aTree = (RevTree) a;
} else {
throw new IOException("Unexpected type: " + a.getClass());
}
RevTree bTree = b.getTree();
final TreeWalk walk = new TreeWalk(reader);
walk.reset();
walk.setRecursive(true);
walk.addTree(aTree);
walk.addTree(bTree);
walk.setFilter(TreeFilter.ANY_DIFF);
DiffFormatter df = new DiffFormatter(DisabledOutputStream.INSTANCE);
df.setRepository(repo);
df.setDiffComparator(cmp);
df.setDetectRenames(true);
List<DiffEntry> diffEntries = df.scan(aTree, bTree);
final int cnt = diffEntries.size();
final PatchListEntry[] entries = new PatchListEntry[1 + cnt];
entries[0] = newCommitMessage(cmp, repo, reader, //
againstParent ? null : aCommit, b);
for (int i = 0; i < cnt; i++) {
FileHeader fh = df.toFileHeader(diffEntries.get(i));
entries[1 + i] = newEntry(aTree, fh);
}
return new PatchList(a, b, againstParent, entries);
} finally {
reader.release();
}
}
private PatchListEntry newCommitMessage(final RawTextComparator cmp,
final Repository db, final ObjectReader reader,
final RevCommit aCommit, final RevCommit bCommit) throws IOException {
StringBuilder hdr = new StringBuilder();
hdr.append("diff --git");
if (aCommit != null) {
hdr.append(" a/" + Patch.COMMIT_MSG);
} else {
hdr.append(" " + FileHeader.DEV_NULL);
}
hdr.append(" b/" + Patch.COMMIT_MSG);
hdr.append("\n");
if (aCommit != null) {
hdr.append("--- a/" + Patch.COMMIT_MSG + "\n");
} else {
hdr.append("--- " + FileHeader.DEV_NULL + "\n");
}
hdr.append("+++ b/" + Patch.COMMIT_MSG + "\n");
Text aText =
aCommit != null ? Text.forCommit(db, reader, aCommit) : Text.EMPTY;
Text bText = Text.forCommit(db, reader, bCommit);
byte[] rawHdr = hdr.toString().getBytes("UTF-8");
RawText aRawText = new RawText(aText.getContent());
RawText bRawText = new RawText(bText.getContent());
EditList edits = new HistogramDiff().diff(cmp, aRawText, bRawText);
FileHeader fh = new FileHeader(rawHdr, edits, PatchType.UNIFIED);
return new PatchListEntry(fh, edits);
}
private PatchListEntry newEntry(RevTree aTree, FileHeader fileHeader) {
final FileMode oldMode = fileHeader.getOldMode();
final FileMode newMode = fileHeader.getNewMode();
if (oldMode == FileMode.GITLINK || newMode == FileMode.GITLINK) {
return new PatchListEntry(fileHeader, Collections.<Edit> emptyList());
}
if (aTree == null // want combined diff
|| fileHeader.getPatchType() != PatchType.UNIFIED
|| fileHeader.getHunks().isEmpty()) {
return new PatchListEntry(fileHeader, Collections.<Edit> emptyList());
}
List<Edit> edits = fileHeader.toEditList();
if (edits.isEmpty()) {
return new PatchListEntry(fileHeader, Collections.<Edit> emptyList());
} else {
return new PatchListEntry(fileHeader, edits);
}
}
private static RevObject aFor(final PatchListKey key,
final Repository repo, final RevWalk rw, final RevCommit b)
throws IOException {
if (key.getOldId() != null) {
return rw.parseAny(key.getOldId());
}
switch (b.getParentCount()) {
case 0:
return rw.parseAny(emptyTree(repo));
case 1: {
RevCommit r = b.getParent(0);
rw.parseBody(r);
return r;
}
default:
// merge commit, return null to force combined diff behavior
return null;
}
}
private static ObjectId emptyTree(final Repository repo) throws IOException {
ObjectInserter oi = repo.newObjectInserter();
try {
ObjectId id = oi.insert(Constants.OBJ_TREE, new byte[] {});
oi.flush();
return id;
} finally {
oi.release();
}
}
}