Introduce feature for incoming changes

scm-core/src/main/java/sonia/scm/repository/Feature.java

@@ -45,5 +45,10 @@ public enum Feature
    * The default branch of the repository is a combined branch of all
    * repository branches.
    */
-  COMBINED_DEFAULT_BRANCH
+  COMBINED_DEFAULT_BRANCH,
+  /**
+   * The repository supports computation of incoming changes (either diff or list of changesets) of one branch
+   * in respect to another target branch.
+   */
+  INCOMING
 }

scm-core/src/main/java/sonia/scm/repository/api/DiffCommandBuilder.java

@@ -174,7 +174,8 @@ public final class DiffCommandBuilder
   }
 
   /**
-   * Show the difference only for the given revision.
+   * Show the difference only for the given revision or (using {@link #setAncestorChangeset(String)}) between this
+   * and another revision.
    *
    *
    * @param revision revision for difference
@@ -188,9 +189,9 @@ public final class DiffCommandBuilder
     return this;
   }
   /**
-   * Show the difference between the ancestor changeset and a revision.
-   *
-   * @param revision ancestor revision
+   * Compute the incoming changes of the branch set with {@link #setRevision(String)} in respect to the changeset given
+   * here. In other words: What changes would be new to the ancestor changeset given here when the branch would
+   * be merged into it. Requires feature {@link sonia.scm.repository.Feature#INCOMING}!
    *
    * @return {@code this}
    */

scm-core/src/main/java/sonia/scm/repository/api/LogCommandBuilder.java

@@ -397,6 +397,13 @@ public final class LogCommandBuilder
     return this;
   }
 
+  /**
+   * Compute the incoming changes of the branch set with {@link #setBranch(String)} in respect to the changeset given
+   * here. In other words: What changesets would be new to the ancestor changeset given here when the branch would
+   * be merged into it. Requires feature {@link sonia.scm.repository.Feature#INCOMING}!
+   *
+   * @return {@code this}
+   */
   public LogCommandBuilder setAncestorChangeset(String ancestorChangeset) {
     request.setAncestorChangeset(ancestorChangeset);
     return this;

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

@@ -33,12 +33,13 @@
 
 package sonia.scm.repository.spi;
 
-import com.google.common.collect.ImmutableSet;
+import sonia.scm.repository.Feature;
 import sonia.scm.repository.GitRepositoryHandler;
 import sonia.scm.repository.Repository;
 import sonia.scm.repository.api.Command;
 
 import java.io.IOException;
+import java.util.EnumSet;
 import java.util.Set;
 
 //~--- JDK imports ------------------------------------------------------------
@@ -52,7 +53,7 @@ public class GitRepositoryServiceProvider extends RepositoryServiceProvider
 
   /** Field description */
   //J-
-  public static final Set<Command> COMMANDS = ImmutableSet.of(
+  public static final Set<Command> COMMANDS = EnumSet.of(
     Command.BLAME,
     Command.BROWSE,
     Command.CAT,
@@ -66,6 +67,7 @@ public class GitRepositoryServiceProvider extends RepositoryServiceProvider
     Command.PULL,
     Command.MERGE
   );
+  public static final Set<Feature> FEATURES = EnumSet.of(Feature.INCOMING);
   //J+
 
   //~--- constructors ---------------------------------------------------------
@@ -246,6 +248,10 @@ public class GitRepositoryServiceProvider extends RepositoryServiceProvider
     return new GitMergeCommand(context, repository, handler.getWorkdirFactory());
   }
 
+  @Override
+  public Set<Feature> getSupportedFeatures() {
+    return FEATURES;
+  }
 //~--- fields ---------------------------------------------------------------
 
   /** Field description */

scm-webapp/src/main/java/sonia/scm/api/v2/resources/RepositoryResource.java

@@ -196,11 +196,15 @@ public class RepositoryResource {
     return permissionRootResource.get();
   }
 
- @Path("modifications/")
-  public ModificationsRootResource modifications() {return modificationsRootResource.get(); }
+  @Path("modifications/")
+  public ModificationsRootResource modifications() {
+    return modificationsRootResource.get();
+  }
 
- @Path("incoming/")
-  public IncomingRootResource incoming() {return incomingRootResource.get(); }
+  @Path("incoming/")
+  public IncomingRootResource incoming() {
+    return incomingRootResource.get();
+  }
 
   private Optional<Response> handleNotArchived(Throwable throwable) {
     if (throwable instanceof RepositoryIsNotArchivedException) {

scm-webapp/src/main/java/sonia/scm/api/v2/resources/RepositoryToRepositoryDtoMapper.java

@@ -6,6 +6,7 @@ import de.otto.edison.hal.Links;
 import org.mapstruct.AfterMapping;
 import org.mapstruct.Mapper;
 import org.mapstruct.MappingTarget;
+import sonia.scm.repository.Feature;
 import sonia.scm.repository.HealthCheckFailure;
 import sonia.scm.repository.Repository;
 import sonia.scm.repository.RepositoryPermissions;
@@ -55,11 +56,13 @@ public abstract class RepositoryToRepositoryDtoMapper extends BaseMapper<Reposit
       if (repositoryService.isSupported(Command.BRANCHES)) {
         linksBuilder.single(link("branches", resourceLinks.branchCollection().self(target.getNamespace(), target.getName())));
       }
+      if (repositoryService.isSupported(Feature.INCOMING)) {
+        linksBuilder.single(link("incomingChangesets", resourceLinks.incoming().changesets(target.getNamespace(), target.getName())));
+        linksBuilder.single(link("incomingDiff", resourceLinks.incoming().diff(target.getNamespace(), target.getName())));
+      }
     }
     linksBuilder.single(link("changesets", resourceLinks.changeset().all(target.getNamespace(), target.getName())));
     linksBuilder.single(link("sources", resourceLinks.source().selfWithoutRevision(target.getNamespace(), target.getName())));
-    linksBuilder.single(link("incomingChangesets", resourceLinks.incoming().changesets(target.getNamespace(), target.getName())));
-    linksBuilder.single(link("incomingDiff", resourceLinks.incoming().diff(target.getNamespace(), target.getName())));
     target.add(linksBuilder.build());
   }