Initial commit of commit message length validation plugin

Replacing the checks that are removed from core Gerrit in
Ia0858b11e475c48f50ec63fbe0076239edf8f64b

Change-Id: I2b4bec03b0caefdf7c71606e7daa188c24b6c494
diff --git a/.gitignore b/.gitignore
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--- /dev/null
+++ b/.gitignore
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+.classpath
+.idea
+.project
+.settings
+target
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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diff --git a/pom.xml b/pom.xml
new file mode 100644
index 0000000..44b4248
--- /dev/null
+++ b/pom.xml
@@ -0,0 +1,82 @@
+<?xml version="1.0"?>
+<!--
+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.
+-->
+<project
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+  xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+
+  <artifactId>commit-message-length-validator</artifactId>
+  <groupId>com.googlesource.gerrit.plugins.validators</groupId>
+  <packaging>jar</packaging>
+  <version>1.0-SNAPSHOT</version>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <Gerrit-ApiType>plugin</Gerrit-ApiType>
+    <Gerrit-ApiVersion>2.6-SNAPSHOT</Gerrit-ApiVersion>
+  </properties>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-jar-plugin</artifactId>
+        <version>2.4</version>
+        <configuration>
+          <archive>
+            <manifestEntries>
+              <Implementation-Title>Plugin ${project.artifactId}</Implementation-Title>
+              <Implementation-Version>${project.version}</Implementation-Version>
+              <Implementation-Vendor>Gerrit Code Review</Implementation-Vendor>
+              <Implementation-Vendor-URL>http://code.google.com/p/gerrit/</Implementation-Vendor-URL>
+              <Gerrit-ApiType>${Gerrit-ApiType}</Gerrit-ApiType>
+              <Gerrit-ApiVersion>${Gerrit-ApiVersion}</Gerrit-ApiVersion>
+            </manifestEntries>
+          </archive>
+        </configuration>
+      </plugin>
+
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>2.3.2</version>
+        <configuration>
+          <source>1.6</source>
+          <target>1.6</target>
+          <encoding>UTF-8</encoding>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+
+  <dependencies>
+    <dependency>
+      <groupId>com.google.gerrit</groupId>
+      <artifactId>gerrit-${Gerrit-ApiType}-api</artifactId>
+      <version>${Gerrit-ApiVersion}</version>
+      <scope>provided</scope>
+    </dependency>
+  </dependencies>
+
+  <repositories>
+    <repository>
+      <id>gerrit-api-repository</id>
+      <url>https://gerrit-api.commondatastorage.googleapis.com/release/</url>
+    </repository>
+  </repositories>
+
+</project>
diff --git a/src/main/java/com/googlesource/gerrit/plugins/validators/CommitMessageLengthValidation.java b/src/main/java/com/googlesource/gerrit/plugins/validators/CommitMessageLengthValidation.java
new file mode 100644
index 0000000..a8f2969
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/validators/CommitMessageLengthValidation.java
@@ -0,0 +1,62 @@
+// 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.googlesource.gerrit.plugins.validators;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.eclipse.jgit.lib.AbbreviatedObjectId;
+import org.eclipse.jgit.revwalk.RevCommit;
+
+import com.google.gerrit.extensions.annotations.Listen;
+import com.google.gerrit.server.events.CommitReceivedEvent;
+import com.google.gerrit.server.git.validators.CommitValidationException;
+import com.google.gerrit.server.git.validators.CommitValidationListener;
+import com.google.gerrit.server.git.validators.CommitValidationMessage;
+import com.google.inject.Singleton;
+
+@Listen
+@Singleton
+public class CommitMessageLengthValidation implements CommitValidationListener {
+
+  @Override
+  public List<CommitValidationMessage> onCommitReceived(CommitReceivedEvent receiveEvent)
+      throws CommitValidationException {
+    final RevCommit commit = receiveEvent.commit;
+    final AbbreviatedObjectId id = commit.abbreviate(7);
+    List<CommitValidationMessage> messages = new ArrayList<CommitValidationMessage>();
+
+    if (65 < commit.getShortMessage().length()) {
+      messages.add(new CommitValidationMessage("(W) " + id.name() //
+         + ": commit subject >65 characters; use shorter first paragraph", false));
+    }
+
+    int longLineCnt = 0, nonEmptyCnt = 0;
+    for (String line : commit.getFullMessage().split("\n")) {
+      if (!line.trim().isEmpty()) {
+        nonEmptyCnt++;
+      }
+      if (70 < line.length()) {
+        longLineCnt++;
+      }
+    }
+
+    if (0 < longLineCnt && 33 < longLineCnt * 100 / nonEmptyCnt) {
+      messages.add(new CommitValidationMessage("(W) " + id.name() //
+          + ": commit message lines >70 characters; manually wrap lines", false));
+    }
+
+    return messages;
+  }
+}