Add method to retrieve branch name from repository

scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/GitUtil.java

@@ -499,6 +499,33 @@ public final class GitUtil
     return ref;
   }
 
+  public static String getRepositoryHeadBranchName(org.eclipse.jgit.lib.Repository repo) {
+    Map<String, Ref> refs = repo.getAllRefs();
+    Ref lastHeadRef = null;
+
+    for (Map.Entry<String, Ref> e : refs.entrySet()) {
+      String key = e.getKey();
+
+      if (REF_HEAD.equals(key)) {
+        if (e.getValue().isSymbolic() && isBranch(e.getValue().getTarget().getName())) {
+          return getBranch(e.getValue().getTarget());
+        }
+      } else if (key.startsWith(REF_HEAD_PREFIX)) {
+        if (REF_MASTER.equals(key.substring(REF_HEAD_PREFIX.length()))) {
+          return REF_MASTER;
+        } else {
+          lastHeadRef = e.getValue();
+        }
+      }
+    }
+
+    if (lastHeadRef == null) {
+      return null;
+    } else {
+      return getBranch(lastHeadRef);
+    }
+  }
+
   /**
    * Method description
    *

scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/AbstractGitCommand.java

@@ -97,9 +97,9 @@ public class AbstractGitCommand
     return commit;
   }
 
-  protected String getBranchNameOrDefault(String requestedBranch) {
+  protected String getBranchNameOrDefault(Repository gitRepository, String requestedBranch) {
     if ( Strings.isNullOrEmpty(requestedBranch) ) {
-      return getDefaultBranchName();
+      return getDefaultBranchName(gitRepository);
     } else {
       return requestedBranch;
     }
@@ -115,12 +115,12 @@ public class AbstractGitCommand
     return head;
   }
 
-  protected String getDefaultBranchName() {
+  protected String getDefaultBranchName(Repository gitRepository) {
     String defaultBranchName = repository.getProperty(GitConstants.PROPERTY_DEFAULT_BRANCH);
     if (!Strings.isNullOrEmpty(defaultBranchName)) {
       return defaultBranchName;
     } else {
-      return null;
+      return GitUtil.getRepositoryHeadBranchName(gitRepository);
     }
   }
 

scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitLogCommand.java

@@ -208,7 +208,7 @@ public class GitLogCommand extends AbstractGitCommand implements LogCommand
         }
 
         ObjectId head = getBranchOrDefault(repository, request.getBranch());
-        String branch = getBranchNameOrDefault(request.getBranch());
+        String branch = getBranchNameOrDefault(repository,request.getBranch());
 
         if (head != null) {
           if (startId != null) {

scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitLogCommandTest.java

@@ -1,3 +1,4 @@
+
 /**
  * Copyright (c) 2010, Sebastian Sdorra
  * All rights reserved.
@@ -33,24 +34,24 @@
 
 package sonia.scm.repository.spi;
 
-//~--- non-JDK imports --------------------------------------------------------
+import com.google.common.io.Files;
-
 import org.junit.Test;
 import sonia.scm.repository.Changeset;
 import sonia.scm.repository.ChangesetPagingResult;
 import sonia.scm.repository.GitConstants;
 import sonia.scm.repository.Modifications;
 
+import java.io.File;
+import java.io.IOException;
+
+import static java.nio.charset.Charset.defaultCharset;
 import static org.hamcrest.Matchers.contains;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 
-//~--- JDK imports ------------------------------------------------------------
-
 /**
  * Unit tests for {@link GitLogCommand}.
  *
@@ -73,7 +74,7 @@ public class GitLogCommandTest extends AbstractGitCommandTestBase
     assertEquals("86a6645eceefe8b9a247db5eb16e3d89a7e6e6d1", result.getChangesets().get(1).getId());
     assertEquals("592d797cd36432e591416e8b2b98154f4f163411", result.getChangesets().get(2).getId());
     assertEquals("435df2f061add3589cb326cc64be9b9c3897ceca", result.getChangesets().get(3).getId());
-    assertNull(result.getBranchName());
+    assertEquals("master", result.getBranchName());
     assertTrue(result.getChangesets().stream().allMatch(r -> r.getBranches().isEmpty()));
 
     // set default branch and fetch again
@@ -215,6 +216,32 @@ public class GitLogCommandTest extends AbstractGitCommandTestBase
     assertEquals("435df2f061add3589cb326cc64be9b9c3897ceca", c2.getId());
   }
 
+  @Test
+  public void shouldFindDefaultBranchFromHEAD() throws Exception {
+    setRepositoryHeadReference("ref: refs/heads/test-branch");
+
+    ChangesetPagingResult changesets = createCommand().getChangesets(new LogCommandRequest());
+
+    assertEquals("test-branch", changesets.getBranchName());
+  }
+
+  @Test
+  public void shouldFindMasterBranchWhenHEADisNoRef() throws Exception {
+    setRepositoryHeadReference("592d797cd36432e591416e8b2b98154f4f163411");
+
+    ChangesetPagingResult changesets = createCommand().getChangesets(new LogCommandRequest());
+
+    assertEquals("master", changesets.getBranchName());
+  }
+
+  private void setRepositoryHeadReference(String s) throws IOException {
+    Files.write(s, repositoryHeadReferenceFile(), defaultCharset());
+  }
+
+  private File repositoryHeadReferenceFile() {
+    return new File(repositoryDirectory, "HEAD");
+  }
+
   private GitLogCommand createCommand()
   {
     return new GitLogCommand(createContext(), repository);