added getter for commit information

src/de/uni_passau/fim/seibt/gitwrapper/repo/Commit.java

@@ -16,11 +16,19 @@ public class Commit {
 
     private static final Logger LOG = Logger.getLogger(Commit.class.getCanonicalName());
 
+    // since there is no porcelain format for this command, this regex is might depend on the git version
+    private static final Pattern commitInfoPattern = Pattern.compile("tree (.{40})\\nparent (.{40})\\nauthor (.*?)<(.*?)> (\\d+) ([+-]\\d{4})\\ncommitter (.*?)<(.*?)> (\\d+) ([+-]\\d{4})\\n.*?\\n(.*)");
+
     private GitWrapper git;
     private Repository repo;
 
     private String id;
 
+    private String author;
+    private String authorMail;
+    private Date authorTime;
+
+
     /**
      * Constructs a new {@link Commit} with the given <code>id</code> made in the <code>repo</code>.
      *
@@ -100,6 +108,67 @@ public class Commit {
         return id;
     }
 
+    /**
+     * Returns the author of this commit.
+     *
+     * @return the author
+     */
+    public String getAuthor() {
+        if (author == null) {
+            getCommitInfo();
+        }
+        return author;
+    }
+
+    /**
+     * Returns the author mail of this commit.
+     *
+     * @return the author mail
+     */
+    public String getAuthorMail() {
+        if (authorMail == null) {
+            getCommitInfo();
+        }
+        return authorMail;
+    }
+
+    /**
+     * Returns the author time of this commit in committer-local time
+     *
+     * @return the author time
+     */
+    public Date getAuthorTime() {
+        if (authorTime == null) {
+            getCommitInfo();
+        }
+        return authorTime;
+    }
+
+    /**
+     * Reads the author information (author, author mail, author time) about this commit and saves it in the
+     * {@link Commit}.
+     */
+    private void getCommitInfo() {
+        Optional<ExecRes> commitInfo = git.exec(repo.getDir(), "cat-file", "-p", id);
+        commitInfo.map(execRes -> {
+            if (git.failed(execRes)) {
+                LOG.warning(() -> String.format("Failed to obtain information about commit %s.", this));
+                return null;
+            }
+
+            String result = execRes.stdOut.trim();
+            Matcher matcher = commitInfoPattern.matcher(result);
+            if (!matcher.find()) {
+                LOG.warning(() -> String.format("Unexpected output while getting commit info for %s.", this));
+            } else {
+                author = matcher.group(3);
+                authorMail = matcher.group(4);
+                authorTime = new Date(Long.parseLong(matcher.group(5)));
+            }
+            return null;
+        });
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) {