Default diff preferences GET REST endpoint

Change-Id: I36dc51d9d5b576b39aa8befd296dc4dda29fb31b

gerrit-server/src/main/java/com/google/gerrit/server/config/GetDiffPreferences.java

@@ -0,0 +1,67 @@
+// Copyright (C) 2016 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.config;
+
+import static com.google.gerrit.server.config.ConfigUtil.loadSection;
+
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
+import com.google.gerrit.extensions.restapi.BadRequestException;
+import com.google.gerrit.extensions.restapi.ResourceConflictException;
+import com.google.gerrit.extensions.restapi.RestReadView;
+import com.google.gerrit.server.account.VersionedAccountPreferences;
+import com.google.gerrit.server.git.GitRepositoryManager;
+import com.google.gerrit.server.git.UserConfigSections;
+
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+import org.eclipse.jgit.errors.ConfigInvalidException;
+import org.eclipse.jgit.errors.RepositoryNotFoundException;
+import org.eclipse.jgit.lib.Repository;
+
+import java.io.IOException;
+
+@Singleton
+public class GetDiffPreferences implements RestReadView<ConfigResource> {
+
+  private final AllUsersName allUsersName;
+  private final GitRepositoryManager gitManager;
+
+  @Inject
+  GetDiffPreferences(GitRepositoryManager gitManager,
+      AllUsersName allUsersName) {
+    this.allUsersName = allUsersName;
+    this.gitManager = gitManager;
+  }
+
+  @Override
+  public DiffPreferencesInfo apply(ConfigResource configResource)
+      throws BadRequestException, ResourceConflictException, Exception {
+    return readFromGit(gitManager, allUsersName, null);
+  }
+
+  static DiffPreferencesInfo readFromGit(GitRepositoryManager gitMgr,
+             AllUsersName allUsersName, DiffPreferencesInfo in)
+      throws IOException, ConfigInvalidException, RepositoryNotFoundException {
+    try (Repository git = gitMgr.openRepository(allUsersName)) {
+      // Load all users prefs.
+      VersionedAccountPreferences dp =
+          VersionedAccountPreferences.forDefault();
+      dp.load(git);
+      DiffPreferencesInfo allUserPrefs = new DiffPreferencesInfo();
+      loadSection(dp.getConfig(), UserConfigSections.DIFF, null, allUserPrefs,
+          DiffPreferencesInfo.defaults(), in);
+      return allUserPrefs;
+    }
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/config/Module.java

@@ -38,6 +38,7 @@ public class Module extends RestApiModule {
     get(CONFIG_KIND, "info").to(GetServerInfo.class);
     get(CONFIG_KIND, "preferences").to(GetPreferences.class);
     put(CONFIG_KIND, "preferences").to(SetPreferences.class);
+    get(CONFIG_KIND, "preferences.diff").to(GetDiffPreferences.class);
     put(CONFIG_KIND, "email.confirm").to(ConfirmEmail.class);
   }
 }