Support changing the group owner via REST

A new owner group for a group can now be set by PUT on
'/groups/<group>/owner'.

The WebUI was adapted to use this new REST endpoint.

Change-Id: I1c921d65855f9ade91aa9b5db91a6001570d1c6d
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

gerrit-server/src/main/java/com/google/gerrit/server/group/PutOwner.java

@@ -0,0 +1,96 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// 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.google.gerrit.server.group;
+
+import com.google.common.base.Strings;
+import com.google.gerrit.common.data.GroupReference;
+import com.google.gerrit.common.errors.NoSuchGroupException;
+import com.google.gerrit.extensions.restapi.AuthException;
+import com.google.gerrit.extensions.restapi.BadRequestException;
+import com.google.gerrit.extensions.restapi.DefaultInput;
+import com.google.gerrit.extensions.restapi.MethodNotAllowedException;
+import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
+import com.google.gerrit.extensions.restapi.RestModifyView;
+import com.google.gerrit.reviewdb.client.AccountGroup;
+import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.account.GroupBackend;
+import com.google.gerrit.server.account.GroupBackends;
+import com.google.gerrit.server.account.GroupCache;
+import com.google.gerrit.server.account.GroupControl;
+import com.google.gerrit.server.group.PutOwner.Input;
+import com.google.gwtorm.server.OrmException;
+import com.google.inject.Inject;
+
+import java.util.Collections;
+
+public class PutOwner implements RestModifyView<GroupResource, Input> {
+  static class Input {
+    @DefaultInput
+    String owner;
+  }
+
+  private final GroupBackend groupBackend;
+  private final GroupCache groupCache;
+  private final GroupControl.Factory controlFactory;
+  private final ReviewDb db;
+
+  @Inject
+  PutOwner(GroupBackend groupBackend, GroupCache groupCache,
+      GroupControl.Factory controlFactory, ReviewDb db) {
+    this.groupBackend = groupBackend;
+    this.groupCache = groupCache;
+    this.controlFactory = controlFactory;
+    this.db = db;
+  }
+
+  @Override
+  public GroupInfo apply(GroupResource resource, Input input)
+      throws MethodNotAllowedException, AuthException, BadRequestException,
+      ResourceNotFoundException, OrmException {
+    AccountGroup group = resource.toAccountGroup();
+    if (group == null) {
+      throw new MethodNotAllowedException();
+    } else if (!resource.getControl().isOwner()) {
+      throw new AuthException("Not group owner");
+    }
+
+    if (input == null || Strings.isNullOrEmpty(input.owner)) {
+      throw new BadRequestException("owner is required");
+    }
+
+    GroupReference owner =
+        GroupBackends.findExactSuggestion(groupBackend, input.owner);
+    if (owner == null) {
+      throw new BadRequestException(String.format("No such group: %s", input.owner));
+    }
+
+    try {
+      GroupControl c = controlFactory.validateFor(owner.getUUID());
+      group = db.accountGroups().get(group.getId());
+      if (group == null) {
+        throw new ResourceNotFoundException();
+      }
+
+      if (!group.getOwnerGroupUUID().equals(owner.getUUID())) {
+        group.setOwnerGroupUUID(owner.getUUID());
+        db.accountGroups().update(Collections.singleton(group));
+        groupCache.evict(group);
+      }
+      return new GroupInfo(c.getGroup());
+    } catch (NoSuchGroupException e) {
+      throw new BadRequestException(String.format("No such group: %s", input.owner));
+    }
+  }
+}