Don't show error on ACL modification if a section is added more than once

Even if the RPC to change the access rights of a project returns
successfully it might be that not all ACL modifications were saved
successfully since modifications to refs which are not owned are
ignored. This is why on client side there is a check to verify if all
modifications were successfully saved and if not the user is informed
about failed modifications with an error message.

This error message was incorrectly displayed if multiple sections for
the same ref were added. This is now fixed by merging the expected
sections before doing the verification.

Change-Id: I8236bfa33ab5cdf215770b2cf5f47bd798ee0b94
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

gerrit-common/src/main/java/com/google/gerrit/common/ProjectAccessUtil.java

@@ -0,0 +1,68 @@
+// 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.common;
+
+import com.google.gerrit.common.data.AccessSection;
+import com.google.gerrit.common.data.Permission;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+public class ProjectAccessUtil {
+  public static List<AccessSection> mergeSections(final List<AccessSection> src) {
+    final Map<String, AccessSection> map =
+        new LinkedHashMap<String, AccessSection>();
+    for (final AccessSection section : src) {
+      if (section.getPermissions().isEmpty()) {
+        continue;
+      }
+
+      final AccessSection prior = map.get(section.getName());
+      if (prior != null) {
+        prior.mergeFrom(section);
+      } else {
+        map.put(section.getName(), section);
+      }
+    }
+    return new ArrayList<AccessSection>(map.values());
+  }
+
+  public static List<AccessSection> removeEmptyPermissionsAndSections(
+      final List<AccessSection> src) {
+    final Set<AccessSection> sectionsToRemove = new HashSet<AccessSection>();
+    for (final AccessSection section : src) {
+      final Set<Permission> permissionsToRemove = new HashSet<Permission>();
+      for (final Permission permission : section.getPermissions()) {
+        if (permission.getRules().isEmpty()) {
+          permissionsToRemove.add(permission);
+        }
+      }
+      for (final Permission permissionToRemove : permissionsToRemove) {
+        section.remove(permissionToRemove);
+      }
+      if (section.getPermissions().isEmpty()) {
+        sectionsToRemove.add(section);
+      }
+    }
+    for (final AccessSection sectionToRemove : sectionsToRemove) {
+      src.remove(sectionToRemove);
+    }
+    return src;
+  }
+}