sendemail.includeDiff: Enable $email.UnifiedDiff in NewChange.vm

Instead of making site administrators hack the email template,
allow admins to enable the diff feature by setting a configuration
variable in gerrit.config.

Change-Id: I378485ca076cd9c56bc5149a0aaa202b20ba82d4

Documentation/config-gerrit.txt

@@ -1879,6 +1879,14 @@ email from Gerrit.
 +
 By default, unset, permitting delivery to any email address.
 
+[[sendemail.includeDiff]]sendemail.includeDiff::
++
+If true, new change emails from Gerrit will include the complete
+unified diff of the change. There is no upper limit on how large
+the email can get when this option is enabled.
++
+By default, false.
+
 [[sendemail.importance]]sendemail.importance::
 +
 If present, emails sent from Gerrit will have the given level

gerrit-server/src/main/java/com/google/gerrit/server/mail/EmailArguments.java

@@ -55,6 +55,7 @@ class EmailArguments {
   final Provider<ChangeQueryRewriter> queryRewriter;
   final Provider<ReviewDb> db;
   final RuntimeInstance velocityRuntime;
+  final EmailSettings settings;
 
   @Inject
   EmailArguments(GitRepositoryManager server, ProjectCache projectCache,
@@ -68,7 +69,8 @@ class EmailArguments {
       AllProjectsName allProjectsName,
       ChangeQueryBuilder.Factory queryBuilder,
       Provider<ChangeQueryRewriter> queryRewriter, Provider<ReviewDb> db,
-      RuntimeInstance velocityRuntime) {
+      RuntimeInstance velocityRuntime,
+      EmailSettings settings) {
     this.server = server;
     this.projectCache = projectCache;
     this.groupBackend = groupBackend;
@@ -86,5 +88,6 @@ class EmailArguments {
     this.queryRewriter = queryRewriter;
     this.db = db;
     this.velocityRuntime = velocityRuntime;
+    this.settings = settings;
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/mail/EmailSettings.java

@@ -0,0 +1,31 @@
+// Copyright (C) 2012 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.mail;
+
+import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+
+import org.eclipse.jgit.lib.Config;
+
+@Singleton
+class EmailSettings {
+  final boolean includeDiff;
+
+  @Inject
+  EmailSettings(@GerritServerConfig Config cfg) {
+    includeDiff = cfg.getBoolean("sendemail", "includeDiff", false);
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/mail/NewChangeSender.java

@@ -101,6 +101,10 @@ public abstract class NewChangeSender extends ChangeEmail {
     return host;
   }
 
+  public boolean getIncludeDiff() {
+    return args.settings.includeDiff;
+  }
+
   /** Show patch set as unified difference.  */
   public String getUnifiedDiff() {
     ByteArrayOutputStream out = new ByteArrayOutputStream();

gerrit-server/src/main/resources/com/google/gerrit/server/mail/NewChange.vm

@@ -52,6 +52,7 @@ $email.changeDetail
 #if($email.sshHost)
   git pull ssh://$email.sshHost/$projectName $patchSet.refName
 #end
+#if($email.includeDiff)
 
-## It is possible to include the patch as a unified diff in the email:
-#$email.UnifiedDiff
+$email.UnifiedDiff
+#end