grading-on-a-curve/code/szz/src/main/java/parser/GitParser.java

/*
 * MIT License
 *
 * Copyright (c) 2018 Axis Communications AB
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package parser;

import data.Issues;
import diff.JavaFileExtension;
import graph.AnnotationMap;
import graph.FileAnnotationGraph;
import org.eclipse.jgit.api.BlameCommand;
import org.eclipse.jgit.api.errors.GitAPIException;
import org.eclipse.jgit.blame.BlameResult;
import org.eclipse.jgit.diff.DiffEntry;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectLoader;
import org.eclipse.jgit.lib.ObjectReader;
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.eclipse.jgit.storage.file.FileRepositoryBuilder;
import org.eclipse.jgit.treewalk.TreeWalk;
import org.incava.diffj.lang.DiffJException;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import org.slf4j.Logger;
import util.CommitUtil;
import util.JSONUtil;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.*;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.stream.Collectors;

/**
 * A class which is capable to search and build line mapping graphs from a local repository. Uses
 * JGit to parse the repository and the revision trees.
 *
 * @author Oscar Svensson
 */
public class GitParser {

  private static final List<String> USELESS_FILE_EXTENSIONS = Arrays.asList(".md", ".txt", ".markdown");

  private CommitUtil util;
  private Repository repo;
  private RevWalk revWalk;
  private Issues issues;

  private String resultPath;

  private Logger logger;

  private int depth;

  private BlameCommand blameCommand;

  /**
   * The constructor for the GitParser class. It requires the repository to exist and will fail if
   * its not. The resultPath is also created if it's not existing.
   *
   * @param path the path to where the local repository can be found.
   * @param resultPath the path to where the JSON files will be written.
   */
  public GitParser(String path, String resultPath, int depth, int customContext)
      throws IOException {
    FileRepositoryBuilder builder = new FileRepositoryBuilder();
    builder.setMustExist(true);

    builder.addCeilingDirectory(new File(path));
    builder.findGitDir(new File(path));
    this.repo = builder.build();
    this.revWalk = new RevWalk(repo);
    this.blameCommand = new BlameCommand(this.repo);

    this.resultPath = resultPath;

    /*
     * Check if the resultpath exists otherwise create it.
     */

    if (this.resultPath != null) {
      File resDirectory = new File(resultPath);
      if (!resDirectory.exists()) resDirectory.mkdirs();
    } else {
      System.err.println("Resultpath not set! Using deafult directory instead.");
      this.resultPath = "./results";
    }

    this.util = new CommitUtil(this.repo, customContext);

    this.depth = depth;
  }

  public String getResultPath() {
    return this.resultPath;
  }

  public Repository getRepository() {
    return this.repo;
  }

  public Issues getIssues() {
    return this.issues;
  }

  public void useLogger(Logger logger) {
    this.logger = logger;
  }

  private int getSourceLine(BlameResult foundCommit, int index) throws IOException {
    foundCommit.computeAll();

    try {
      return foundCommit.getSourceLine(index);
    } catch (ArrayIndexOutOfBoundsException e) {
      return -1;
    }
  }

  /**
   * Traces a file change that have occured before a given commmit.
   *
   * @param filePath specifies which file to trace changes on.
   * @param source the source commit from which the trace should start at.
   */
  private FileAnnotationGraph traceFileChanges(String filePath, Commit source, int step)
          throws IOException, GitAPIException {

    if (step == 0 || !source.diffWithParent.containsKey(filePath)) return null;

    /*
     * Save all line numbers for the source commits deletions.
     */
    List<Integer> delIndexes = buildDelIndexes(filePath, source);

    FileAnnotationGraph graph = createEmptyGraph(filePath);
    graph.revisions.add(ObjectId.toString(source.commit.toObjectId()));

    BlameResult found = callBlameCommand(filePath, source.commit.getParent(0));
    if (found == null) return graph;

    Map<RevCommit, Map<Integer, Integer>> foundRevisions = linkRevisionsWithLineNumbers(delIndexes, found);
    populateGraphWithMappings(graph, foundRevisions);
    populateSubgraphs(filePath, step, graph, foundRevisions);

    return graph;
  }

  private List<Integer> buildDelIndexes(String filePath, Commit source) {
    List<Integer> delIndexes = source
            .diffWithParent
            .get(filePath)
            .deletions
            .stream()
            .map(s -> parseInt(s[0]))
            .collect(Collectors.toList());

    if(filePath.endsWith(".java")) {
      Set<Integer> changesFromDiffJ = changesFromDiffJ(filePath, source);
      delIndexes = delIndexes.stream().filter(changesFromDiffJ::contains).collect(Collectors.toList());
    }

    return delIndexes;
  }

  private Set<Integer> changesFromDiffJ(String filePath, Commit source) {
    try {
      JavaFileExtension revision = getFileContentAtRevision(filePath, source.commit);
      JavaFileExtension parentRev = getFileContentAtRevision(filePath, source.commit.getParent(0));
      // Converting line numbers to indexes.
      return revision.affectedLineNumbers(parentRev).stream().map(it ->
              it-1
      ).collect(Collectors.toSet());
    } catch (Exception e) {
      e.printStackTrace();
      return Collections.emptySet();
    }
  }

  private JavaFileExtension getFileContentAtRevision(String filePath, RevCommit revision) throws IOException, DiffJException {
    RevTree tree = revWalk.parseCommit(revision.getId()).getTree();
    TreeWalk treeWalk = TreeWalk.forPath(repo, filePath, tree);
    ObjectId blobId = treeWalk.getObjectId(0);
    ObjectReader objectReader = repo.newObjectReader();
    ObjectLoader objectLoader = objectReader.open(blobId);
    byte[] bytes = objectLoader.getBytes();

    return new JavaFileExtension(new String(bytes, StandardCharsets.UTF_8));
  }

  /*
   * Start building subgraphs.
   */
  private void populateSubgraphs(String filePath, int step, FileAnnotationGraph graph, Map<RevCommit, Map<Integer, Integer>> foundRevisions) throws IOException, GitAPIException {
    for (Map.Entry<RevCommit, Map<Integer, Integer>> rev : foundRevisions.entrySet()) {
      Commit subCommit = this.util.getCommitDiffingLines(rev.getKey());
      FileAnnotationGraph subGraph = traceFileChanges(filePath, subCommit, step - 1);

      if (subGraph == null) break;
      graph.sub_graphs.put(subCommit.getHashString(), subGraph);
    }
  }

  /*
   * Save all mappings in the annotationgraph.
   */
  private void populateGraphWithMappings(FileAnnotationGraph graph, Map<RevCommit, Map<Integer, Integer>> foundRevisions) {
    for (Map.Entry<RevCommit, Map<Integer, Integer>> rev : foundRevisions.entrySet()) {
      String revSha = ObjectId.toString(rev.getKey().toObjectId());

      if (!graph.mappings.containsKey(revSha)) {
        graph.revisions.add(revSha);
        graph.mappings.put(revSha, rev.getValue());
      } else {
        Map<Integer, Integer> linemapping = graph.mappings.get(revSha);
        // Add missing mappings.
        for (Map.Entry<Integer, Integer> entry : rev.getValue().entrySet()) {
          if (!linemapping.containsKey(entry.getKey())) {
            linemapping.put(entry.getKey(), entry.getValue());
          }
        }
      }
    }
  }

  /*
   * Grab the blamed commits and get the line numbers.
   */
  private Map<RevCommit, Map<Integer, Integer>> linkRevisionsWithLineNumbers(List<Integer> delIndexes, BlameResult found) {
    int index;
    Map<RevCommit, Map<Integer, Integer>> foundRevisions = new HashMap<>();

    for (Integer delIndex : delIndexes) {
      index = delIndex;
      if (index == -1) continue;
      try {
        RevCommit foundRev = found.getSourceCommit(index);

        if (!foundRevisions.containsKey(foundRev)) {
          Map<Integer, Integer> blamedLines = new LinkedHashMap<>();

          blamedLines.put(index, getSourceLine(found, index));
          foundRevisions.put(foundRev, blamedLines);
        } else {
          foundRevisions.get(foundRev).put(index, getSourceLine(found, index));
        }
      } catch (Exception e) {
        // This means that a row didn't exist in a previous revision..
      }
    }
    return foundRevisions;
  }

  private BlameResult callBlameCommand(String filePath, RevCommit startCommit) throws GitAPIException {
    blameCommand.setStartCommit(startCommit);
    blameCommand.setFilePath(filePath);
    return blameCommand.call();
  }

  /*
   * Create a graph to store line mappings in.
   */
  private FileAnnotationGraph createEmptyGraph(String filePath) {
    FileAnnotationGraph graph = new FileAnnotationGraph();
    graph.filePath = filePath;
    graph.revisions = new LinkedList<>();
    graph.mappings = new HashMap<>();
    graph.sub_graphs = new HashMap<>();
    return graph;
  }

  /**
   * With each revision, check all files and build their line mapping graphs for each changed line.
   *
   * @param commits list of commits that should be traced.
   * @return the map containing annotation graphs for each file change by a commit.
   */
  private AnnotationMap<String, List<FileAnnotationGraph>> buildLineMappingGraph(
      List<Commit> commits) throws IOException, GitAPIException {

    AnnotationMap<String, List<FileAnnotationGraph>> fileGraph = new AnnotationMap<>();
    for (Commit commit : commits) {
      List<FileAnnotationGraph> graphs = new LinkedList<>();
      for (Map.Entry<String, DiffEntry.ChangeType> file : commit.changeTypes.entrySet()) {
        String filePath = file.getKey();
        if (checkFileType(filePath)) {
          FileAnnotationGraph tracedCommits = traceFileChanges(filePath, commit, this.depth);
          graphs.add(tracedCommits);
        }
      }

      fileGraph.put(commit.getHashString(), graphs);
    }

    return fileGraph;
  }

  private boolean checkFileType(String filePath) {
    return !filePath.contains("/test/") && checkFileExtension(filePath);
  }

  private boolean checkFileExtension(String filePath) {
    AtomicBoolean validExtension = new AtomicBoolean(true);
    USELESS_FILE_EXTENSIONS.forEach(it -> {
      validExtension.set(!filePath.endsWith(it));
    });
    return validExtension.get();
  }

  /**
   * Wrapper method to catch a faulty value.
   *
   * @param value the string to convert to an int.
   * @return the value of the string as an int.
   */
  private int parseInt(String value) {
    try {
      return Integer.parseInt(value);
    } catch (Exception e) {
      return -1;
    }
  }

  /**
   * Searchs for commits that have certain keywords in their messages, indicating that they have
   * fiexd bugs.
   *
   * <p>It then saves the found commits and the line mapping graph to two JSON files.
   *
   * @param commits a set containing references to commits.
   */
  public AnnotationMap<String, List<FileAnnotationGraph>> annotateCommits(Set<RevCommit> commits)
      throws IOException, GitAPIException {
    this.logger.info("Parsing difflines for all found commits.");
    List<Commit> parsedCommits = this.util.getDiffingLines(commits);

    this.logger.info("Saving parsed commits to file");
    JSONUtil.saveFoundCommits(parsedCommits, this.resultPath);

    this.logger.info("Building line mapping graph.");
    AnnotationMap<String, List<FileAnnotationGraph>> mapping = buildLineMappingGraph(parsedCommits);

    this.logger.info("Saving results to file");
    mapping.saveToJSON(this.resultPath);

    return mapping;
  }

  /**
   * Use this method to use already found big fixing changes.
   *
   * @param path the path to the json file where the changes are stored.
   */
  public Set<RevCommit> readBugFixCommits(String path) throws IOException {
    if (repo == null) return Collections.emptySet();

    this.issues = new Issues();

    JSONParser commitParser = new JSONParser();
    try {
      JSONObject object = (JSONObject) commitParser.parse(new FileReader(path));

      this.issues.revisions = new HashSet<>();
      this.issues.dates = new HashMap<>();

      for (Object issue : object.keySet()) {
        Map<String, String> issueInfo = (Map<String, String>) object.get(issue);

        String rev = issueInfo.get("hash");
        RevCommit revCommit = this.repo.parseCommit(this.repo.resolve(rev));

        Map<String, String> dates = new HashMap<>();

        dates.put("resolutiondate", issueInfo.get("resolutiondate"));
        dates.put("commitdate", issueInfo.get("commitdate"));
        dates.put("creationdate", issueInfo.get("creationdate"));

        this.issues.dates.put(rev, dates);
        this.issues.revisions.add(revCommit);
      }

    } catch (FileNotFoundException | ParseException e) {
      return Collections.emptySet();
    }

    this.logger.info(String.format("Found %d number of commits.", this.issues.revisions.size()));

    if (this.issues.revisions.size() == 0) return Collections.emptySet();
    return this.issues.revisions;
  }

}