James Moger
2015-11-22 ed552ba47c02779c270ffd62841d6d1048dade70
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/*
 * Copyright 2011 gitblit.com.
 *
 * 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.gitblit.utils;
 
import java.io.ByteArrayOutputStream;
import java.io.Serializable;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;
 
import org.eclipse.jgit.api.BlameCommand;
import org.eclipse.jgit.blame.BlameResult;
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.ObjectId;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevTree;
import org.eclipse.jgit.revwalk.RevWalk;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
 
import com.gitblit.models.AnnotatedLine;
import com.gitblit.models.PathModel.PathChangeModel;
 
/**
 * DiffUtils is a class of utility methods related to diff, patch, and blame.
 *
 * The diff methods support pluggable diff output types like Gitblit, Gitweb,
 * and Plain.
 *
 * @author James Moger
 *
 */
public class DiffUtils {
 
    private static final Logger LOGGER = LoggerFactory.getLogger(DiffUtils.class);
 
    /**
     * Callback interface for binary diffs. All the getDiff methods here take an optional handler;
     * if given and the {@link DiffOutputType} is {@link DiffOutputType#HTML HTML}, it is responsible
     * for displaying a binary diff.
     */
    public interface BinaryDiffHandler {
 
        /**
         * Renders a binary diff. The result must be valid HTML, it will be inserted into an HTML table cell.
         * May return {@code null} if the default behavior (which is typically just a textual note "Bnary
         * files differ") is desired.
         *
         * @param diffEntry
         *            current diff entry
         *
         * @return the rendered diff as HTML, or {@code null} if the default is desired.
         */
        public String renderBinaryDiff(final DiffEntry diffEntry);
 
    }
 
    /**
     * Enumeration for the diff output types.
     */
    public static enum DiffOutputType {
        PLAIN, HTML;
 
        public static DiffOutputType forName(String name) {
            for (DiffOutputType type : values()) {
                if (type.name().equalsIgnoreCase(name)) {
                    return type;
                }
            }
            return null;
        }
    }
 
    /**
     * Enumeration for the diff comparator types.
     */
    public static enum DiffComparator {
        SHOW_WHITESPACE(RawTextComparator.DEFAULT),
        IGNORE_WHITESPACE(RawTextComparator.WS_IGNORE_ALL),
        IGNORE_LEADING(RawTextComparator.WS_IGNORE_LEADING),
        IGNORE_TRAILING(RawTextComparator.WS_IGNORE_TRAILING),
        IGNORE_CHANGES(RawTextComparator.WS_IGNORE_CHANGE);
 
        public final RawTextComparator textComparator;
 
        DiffComparator(RawTextComparator textComparator) {
            this.textComparator = textComparator;
        }
 
        public DiffComparator getOpposite() {
            return this == SHOW_WHITESPACE ? IGNORE_WHITESPACE : SHOW_WHITESPACE;
        }
 
        public String getTranslationKey() {
            return "gb." + name().toLowerCase();
        }
 
        public static DiffComparator forName(String name) {
            for (DiffComparator type : values()) {
                if (type.name().equalsIgnoreCase(name)) {
                    return type;
                }
            }
            return null;
        }
    }
 
    /**
     * Encapsulates the output of a diff.
     */
    public static class DiffOutput implements Serializable {
        private static final long serialVersionUID = 1L;
 
        public final DiffOutputType type;
        public final String content;
        public final DiffStat stat;
 
        DiffOutput(DiffOutputType type, String content, DiffStat stat) {
            this.type = type;
            this.content = content;
            this.stat = stat;
        }
 
        public PathChangeModel getPath(String path) {
            if (stat == null) {
                return null;
            }
            return stat.getPath(path);
        }
    }
 
    /**
     * Class that represents the number of insertions and deletions from a
     * chunk.
     */
    public static class DiffStat implements Serializable {
 
        private static final long serialVersionUID = 1L;
 
        public final List<PathChangeModel> paths = new ArrayList<PathChangeModel>();
 
        private final String commitId;
 
        public DiffStat(String commitId) {
            this.commitId = commitId;
        }
 
        public PathChangeModel addPath(DiffEntry entry) {
            PathChangeModel pcm = PathChangeModel.from(entry, commitId);
            paths.add(pcm);
            return pcm;
        }
 
        public int getInsertions() {
            int val = 0;
            for (PathChangeModel entry : paths) {
                val += entry.insertions;
            }
            return val;
        }
 
        public int getDeletions() {
            int val = 0;
            for (PathChangeModel entry : paths) {
                val += entry.deletions;
            }
            return val;
        }
 
        public PathChangeModel getPath(String path) {
            PathChangeModel stat = null;
            for (PathChangeModel p : paths) {
                if (p.path.equals(path)) {
                    stat = p;
                    break;
                }
            }
            return stat;
        }
 
        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder();
            for (PathChangeModel entry : paths) {
                sb.append(entry.toString()).append('\n');
            }
            sb.setLength(sb.length() - 1);
            return sb.toString();
        }
    }
 
    public static class NormalizedDiffStat implements Serializable {
 
        private static final long serialVersionUID = 1L;
 
        public final int insertions;
        public final int deletions;
        public final int blanks;
 
        NormalizedDiffStat(int insertions, int deletions, int blanks) {
            this.insertions = insertions;
            this.deletions = deletions;
            this.blanks = blanks;
        }
    }
 
    /**
     * Returns the complete diff of the specified commit compared to its primary
     * parent.
     *
     * @param repository
     * @param commit
     * @param comparator
     * @param outputType
     * @param tabLength
     * @return the diff
     */
    public static DiffOutput getCommitDiff(Repository repository, RevCommit commit,
            DiffComparator comparator, DiffOutputType outputType, int tabLength) {
        return getDiff(repository, null, commit, null, comparator, outputType, tabLength);
    }
 
    /**
     * Returns the complete diff of the specified commit compared to its primary parent.
     *
     * @param repository
     * @param commit
     * @param comparator
     * @param outputType
     * @param handler
     *            to use for rendering binary diffs if {@code outputType} is {@link DiffOutputType#HTML HTML}.
     *            May be {@code null}, resulting in the default behavior.
     * @param tabLength
     * @return the diff
     */
    public static DiffOutput getCommitDiff(Repository repository, RevCommit commit,
            DiffComparator comparator, DiffOutputType outputType, BinaryDiffHandler handler, int tabLength) {
        return getDiff(repository, null, commit, null, comparator, outputType, handler, tabLength);
    }
 
 
    /**
     * Returns the diff for the specified file or folder from the specified
     * commit compared to its primary parent.
     *
     * @param repository
     * @param commit
     * @param path
     * @param comparator
     * @param outputType
     * @param tabLength
     * @return the diff
     */
    public static DiffOutput getDiff(Repository repository, RevCommit commit, String path,
            DiffComparator comparator, DiffOutputType outputType, int tabLength) {
        return getDiff(repository, null, commit, path, comparator, outputType, tabLength);
    }
 
    /**
     * Returns the diff for the specified file or folder from the specified
     * commit compared to its primary parent.
     *
     * @param repository
     * @param commit
     * @param path
     * @param comparator
     * @param outputType
     * @param handler
     *            to use for rendering binary diffs if {@code outputType} is {@link DiffOutputType#HTML HTML}.
     *            May be {@code null}, resulting in the default behavior.
     * @param tabLength
     * @return the diff
     */
    public static DiffOutput getDiff(Repository repository, RevCommit commit, String path,
            DiffComparator comparator, DiffOutputType outputType, BinaryDiffHandler handler, int tabLength) {
        return getDiff(repository, null, commit, path, comparator, outputType, handler, tabLength);
    }
 
    /**
     * Returns the complete diff between the two specified commits.
     *
     * @param repository
     * @param baseCommit
     * @param commit
     * @param comparator
     * @param outputType
     * @param tabLength
     *
     * @return the diff
     */
    public static DiffOutput getDiff(Repository repository, RevCommit baseCommit, RevCommit commit,
            DiffComparator comparator, DiffOutputType outputType, int tabLength) {
        return getDiff(repository, baseCommit, commit, null, comparator, outputType, tabLength);
    }
 
    /**
     * Returns the complete diff between the two specified commits.
     *
     * @param repository
     * @param baseCommit
     * @param commit
     * @param comparator
     * @param outputType
     * @param handler
     *            to use for rendering binary diffs if {@code outputType} is {@link DiffOutputType#HTML HTML}.
     *            May be {@code null}, resulting in the default behavior.
     * @param tabLength
     * @return the diff
     */
    public static DiffOutput getDiff(Repository repository, RevCommit baseCommit, RevCommit commit,
            DiffComparator comparator, DiffOutputType outputType, BinaryDiffHandler handler, int tabLength) {
        return getDiff(repository, baseCommit, commit, null, comparator, outputType, handler, tabLength);
    }
 
    /**
     * Returns the diff between two commits for the specified file.
     *
     * @param repository
     * @param baseCommit
     *            if base commit is null the diff is to the primary parent of
     *            the commit.
     * @param commit
     * @param path
     *            if the path is specified, the diff is restricted to that file
     *            or folder. if unspecified, the diff is for the entire commit.
     * @param outputType
     * @param diffComparator
     * @param tabLength
     * @return the diff
     */
    public static DiffOutput getDiff(Repository repository, RevCommit baseCommit, RevCommit commit,
            String path, DiffComparator diffComparator, DiffOutputType outputType, int tabLength) {
        return getDiff(repository, baseCommit, commit, path, diffComparator, outputType, null, tabLength);
    }
 
    /**
     * Returns the diff between two commits for the specified file.
     *
     * @param repository
     * @param baseCommit
     *            if base commit is null the diff is to the primary parent of
     *            the commit.
     * @param commit
     * @param path
     *            if the path is specified, the diff is restricted to that file
     *            or folder. if unspecified, the diff is for the entire commit.
     * @param comparator
     * @param outputType
     * @param handler
     *            to use for rendering binary diffs if {@code outputType} is {@link DiffOutputType#HTML HTML}.
     *            May be {@code null}, resulting in the default behavior.
     * @param tabLength
     * @return the diff
     */
    public static DiffOutput getDiff(Repository repository, RevCommit baseCommit, RevCommit commit, String path,
            DiffComparator comparator, DiffOutputType outputType, final BinaryDiffHandler handler, int tabLength) {
        DiffStat stat = null;
        String diff = null;
        try {
            ByteArrayOutputStream os = null;
 
            DiffFormatter df;
            switch (outputType) {
            case HTML:
                df = new GitBlitDiffFormatter(commit.getName(), path, handler, tabLength);
                break;
            case PLAIN:
            default:
                os = new ByteArrayOutputStream();
                df = new DiffFormatter(os);
                break;
            }
            df.setRepository(repository);
            df.setDiffComparator((comparator == null ? DiffComparator.SHOW_WHITESPACE : comparator).textComparator);
            df.setDetectRenames(true);
 
            RevTree commitTree = commit.getTree();
            RevTree baseTree;
            if (baseCommit == null) {
                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();
            }
 
            List<DiffEntry> diffEntries = df.scan(baseTree, commitTree);
            if (path != null && path.length() > 0) {
                for (DiffEntry diffEntry : diffEntries) {
                    if (diffEntry.getNewPath().equalsIgnoreCase(path)) {
                        df.format(diffEntry);
                        break;
                    }
                }
            } else {
                df.format(diffEntries);
            }
            df.flush();
            if (df instanceof GitBlitDiffFormatter) {
                // workaround for complex private methods in DiffFormatter
                diff = ((GitBlitDiffFormatter) df).getHtml();
                stat = ((GitBlitDiffFormatter) df).getDiffStat();
            } else {
                diff = os.toString();
            }
        } catch (Throwable t) {
            LOGGER.error("failed to generate commit diff!", t);
        }
 
        return new DiffOutput(outputType, diff, stat);
    }
 
    /**
     * Returns the diff between the two commits for the specified file or folder
     * formatted as a patch.
     *
     * @param repository
     * @param baseCommit
     *            if base commit is unspecified, the patch is generated against
     *            the primary parent of the specified commit.
     * @param commit
     * @param path
     *            if path is specified, the patch is generated only for the
     *            specified file or folder. if unspecified, the patch is
     *            generated for the entire diff between the two commits.
     * @return patch as a string
     */
    public static String getCommitPatch(Repository repository, RevCommit baseCommit,
            RevCommit commit, String path) {
        String diff = null;
        try {
            final ByteArrayOutputStream os = new ByteArrayOutputStream();
            RawTextComparator cmp = RawTextComparator.DEFAULT;
            PatchFormatter df = new PatchFormatter(os);
            df.setRepository(repository);
            df.setDiffComparator(cmp);
            df.setDetectRenames(true);
 
            RevTree commitTree = commit.getTree();
            RevTree baseTree;
            if (baseCommit == null) {
                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();
            }
 
            List<DiffEntry> diffEntries = df.scan(baseTree, commitTree);
            if (path != null && path.length() > 0) {
                for (DiffEntry diffEntry : diffEntries) {
                    if (diffEntry.getNewPath().equalsIgnoreCase(path)) {
                        df.format(diffEntry);
                        break;
                    }
                }
            } else {
                df.format(diffEntries);
            }
            diff = df.getPatch(commit);
            df.flush();
        } catch (Throwable t) {
            LOGGER.error("failed to generate commit diff!", t);
        }
        return diff;
    }
 
    /**
     * Returns the diffstat between the two commits for the specified file or folder.
     *
     * @param repository
     * @param base
     *            if base commit is unspecified, the diffstat is generated against
     *            the primary parent of the specified tip.
     * @param tip
     * @param path
     *            if path is specified, the diffstat is generated only for the
     *            specified file or folder. if unspecified, the diffstat is
     *            generated for the entire diff between the two commits.
     * @return patch as a string
     */
    public static DiffStat getDiffStat(Repository repository, String base, String tip) {
        RevCommit baseCommit = null;
        RevCommit tipCommit = null;
        RevWalk revWalk = new RevWalk(repository);
        try {
            tipCommit = revWalk.parseCommit(repository.resolve(tip));
            if (!StringUtils.isEmpty(base)) {
                baseCommit = revWalk.parseCommit(repository.resolve(base));
            }
            return getDiffStat(repository, baseCommit, tipCommit, null);
        } catch (Exception e) {
            LOGGER.error("failed to generate diffstat!", e);
        } finally {
            revWalk.dispose();
        }
        return null;
    }
 
    public static DiffStat getDiffStat(Repository repository, RevCommit commit) {
        return getDiffStat(repository, null, commit, null);
    }
 
    /**
     * Returns the diffstat between the two commits for the specified file or folder.
     *
     * @param repository
     * @param baseCommit
     *            if base commit is unspecified, the diffstat is generated against
     *            the primary parent of the specified commit.
     * @param commit
     * @param path
     *            if path is specified, the diffstat is generated only for the
     *            specified file or folder. if unspecified, the diffstat is
     *            generated for the entire diff between the two commits.
     * @return patch as a string
     */
    public static DiffStat getDiffStat(Repository repository, RevCommit baseCommit,
            RevCommit commit, String path) {
        DiffStat stat = null;
        try {
            RawTextComparator cmp = RawTextComparator.DEFAULT;
            DiffStatFormatter df = new DiffStatFormatter(commit.getName());
            df.setRepository(repository);
            df.setDiffComparator(cmp);
            df.setDetectRenames(true);
 
            RevTree commitTree = commit.getTree();
            RevTree baseTree;
            if (baseCommit == null) {
                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();
            }
 
            List<DiffEntry> diffEntries = df.scan(baseTree, commitTree);
            if (path != null && path.length() > 0) {
                for (DiffEntry diffEntry : diffEntries) {
                    if (diffEntry.getNewPath().equalsIgnoreCase(path)) {
                        df.format(diffEntry);
                        break;
                    }
                }
            } else {
                df.format(diffEntries);
            }
            stat = df.getDiffStat();
            df.flush();
        } catch (Throwable t) {
            LOGGER.error("failed to generate commit diff!", t);
        }
        return stat;
    }
 
    /**
     * Returns the list of lines in the specified source file annotated with the
     * source commit metadata.
     *
     * @param repository
     * @param blobPath
     * @param objectId
     * @return list of annotated lines
     */
    public static List<AnnotatedLine> blame(Repository repository, String blobPath, String objectId) {
        List<AnnotatedLine> lines = new ArrayList<AnnotatedLine>();
        try {
            ObjectId object;
            if (StringUtils.isEmpty(objectId)) {
                object = JGitUtils.getDefaultBranch(repository);
            } else {
                object = repository.resolve(objectId);
            }
            BlameCommand blameCommand = new BlameCommand(repository);
            blameCommand.setFilePath(blobPath);
            blameCommand.setStartCommit(object);
            BlameResult blameResult = blameCommand.call();
            RawText rawText = blameResult.getResultContents();
            int length = rawText.size();
            for (int i = 0; i < length; i++) {
                RevCommit commit = blameResult.getSourceCommit(i);
                AnnotatedLine line = new AnnotatedLine(commit, i + 1, rawText.getString(i));
                lines.add(line);
            }
        } catch (Throwable t) {
            LOGGER.error(MessageFormat.format("failed to generate blame for {0} {1}!", blobPath, objectId), t);
        }
        return lines;
    }
 
    /**
     * Normalizes a diffstat to an N-segment display.
     *
     * @params segments
     * @param insertions
     * @param deletions
     * @return a normalized diffstat
     */
    public static NormalizedDiffStat normalizeDiffStat(final int segments, final int insertions, final int deletions) {
        final int total = insertions + deletions;
        final float fi = ((float) insertions) / total;
        int si;
        int sd;
        int sb;
        if (deletions == 0) {
            // only addition
            si = Math.min(insertions, segments);
            sd = 0;
            sb = si < segments ? (segments - si) : 0;
        } else if (insertions == 0) {
            // only deletion
            si = 0;
            sd = Math.min(deletions, segments);
            sb = sd < segments ? (segments - sd) : 0;
        } else if (total <= segments) {
            // total churn fits in segment display
            si = insertions;
            sd = deletions;
            sb = segments - total;
        } else if ((segments % 2) > 0 && fi > 0.45f && fi < 0.55f) {
            // odd segment display, fairly even +/-, use even number of segments
            si = Math.round(((float) insertions)/total * (segments - 1));
            sd = segments - 1 - si;
            sb = 1;
        } else {
            si = Math.round(((float) insertions)/total * segments);
            sd = segments - si;
            sb = 0;
        }
 
        return new NormalizedDiffStat(si, sd, sb);
    }
}