package org.apache.maven.plugin.checkstyle;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.
   */
  
  import java.io.BufferedReader;
  import java.io.ByteArrayOutputStream;
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.Reader;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.maven.artifact.Artifact;
  import org.apache.maven.model.Dependency;
  import org.apache.maven.model.Plugin;
  import org.apache.maven.model.PluginManagement;
  import org.apache.maven.model.Resource;
  import org.apache.maven.plugin.AbstractMojo;
  import org.apache.maven.plugin.MojoExecution;
  import org.apache.maven.plugin.MojoExecutionException;
  import org.apache.maven.plugin.MojoFailureException;
  import org.apache.maven.plugin.checkstyle.exec.CheckstyleExecutor;
  import org.apache.maven.plugin.checkstyle.exec.CheckstyleExecutorException;
  import org.apache.maven.plugin.checkstyle.exec.CheckstyleExecutorRequest;
  import org.apache.maven.plugin.descriptor.PluginDescriptor;
  import org.apache.maven.plugins.annotations.Component;
  import org.apache.maven.plugins.annotations.LifecyclePhase;
  import org.apache.maven.plugins.annotations.Mojo;
  import org.apache.maven.plugins.annotations.Parameter;
  import org.apache.maven.plugins.annotations.ResolutionScope;
  import org.apache.maven.project.MavenProject;
  import org.codehaus.plexus.configuration.PlexusConfiguration;
  import org.codehaus.plexus.util.FileUtils;
  import org.codehaus.plexus.util.IOUtil;
  import org.codehaus.plexus.util.PathTool;
  import org.codehaus.plexus.util.ReaderFactory;
  import org.codehaus.plexus.util.StringUtils;
  import org.codehaus.plexus.util.xml.pull.MXParser;
  import org.codehaus.plexus.util.xml.pull.XmlPullParser;
  import org.codehaus.plexus.util.xml.pull.XmlPullParserException;
  
  import com.puppycrawl.tools.checkstyle.DefaultLogger;
  import com.puppycrawl.tools.checkstyle.XMLLogger;
  import com.puppycrawl.tools.checkstyle.api.AuditListener;
  import com.puppycrawl.tools.checkstyle.api.CheckstyleException;
  
  /**
   * Performs Checkstyle analysis and outputs violations or a count of violations
   * to the console, potentially failing the build.
   * It can also be configured to re-use an earlier analysis.
   *
   * @author <a href="mailto:joakim@erdfelt.net">Joakim Erdfelt</a>
   * @version $Id: CheckstyleViolationCheckMojo.html 959038 2015-07-20 17:14:24Z dennisl $
   */
  @Mojo( name = "check", defaultPhase = LifecyclePhase.VERIFY, requiresDependencyResolution = ResolutionScope.TEST,
         threadSafe = true )
  public class CheckstyleViolationCheckMojo
      extends AbstractMojo
  {
  
      private static final String JAVA_FILES = "**\\/*.java";
  
      private static final String CHECKSTYLE_FILE_HEADER = "<?xml version=\"1.0\"?>\n"
              + "<!DOCTYPE module PUBLIC \"-//Puppy Crawl//DTD Check Configuration 1.2//EN\"\n"
              + "        \"http://www.puppycrawl.com/dtds/configuration_1_2.dtd\">\n";
  
      /**
       * Specifies the path and filename to save the Checkstyle output. The format
       * of the output file is determined by the <code>outputFileFormat</code>
       * parameter.
       */
      @Parameter( property = "checkstyle.output.file", defaultValue = "${project.build.directory}/checkstyle-result.xml" )
      private File outputFile;
  
      /**
       * Specifies the format of the output to be used when writing to the output
       * file. Valid values are "<code>plain</code>" and "<code>xml</code>".
      */
     @Parameter( property = "checkstyle.output.format", defaultValue = "xml" )
     private String outputFileFormat;
 
     /**
      * Fail the build on a violation. The goal checks for the violations
      * after logging them (if {@link #logViolationsToConsole} is 'true').
      * Compare this to {@link #failsOnError} which fails the build immediately
      * before examining the output log.
      */
     @Parameter( property = "checkstyle.failOnViolation", defaultValue = "true" )
     private boolean failOnViolation;
 
     /**
      * The maximum number of allowed violations. The execution fails only if the
      * number of violations is above this limit.
      *
      * @since 2.3
      */
     @Parameter( property = "checkstyle.maxAllowedViolations", defaultValue = "0" )
     private int maxAllowedViolations;
 
     /**
      * The lowest severity level that is considered a violation.
      * Valid values are "<code>error</code>", "<code>warning</code>" and "<code>info</code>".
      *
      * @since 2.2
      */
     @Parameter( property = "checkstyle.violationSeverity", defaultValue = "error" )
     private String violationSeverity = "error";
 
     /**
      * Violations to ignore. This is a comma-separated list, each value being either
      * a rule name, a rule category or a java package name of rule class.
      *
      * @since 2.13
      */
     @Parameter( property = "checkstyle.violation.ignore" )
     private String violationIgnore;
 
     /**
      * Skip entire check.
      *
      * @since 2.2
      */
     @Parameter( property = "checkstyle.skip", defaultValue = "false" )
     private boolean skip;
 
     /**
      * Skip Checkstyle execution will only scan the outputFile.
      *
      * @since 2.5
      */
     @Parameter( property = "checkstyle.skipExec", defaultValue = "false" )
     private boolean skipExec;
 
     /**
      * Output the detected violations to the console.
      *
      * @since 2.3
      */
     @Parameter( property = "checkstyle.console", defaultValue = "true" )
     private boolean logViolationsToConsole;
 
     /**
      * Specifies the location of the resources to be used for Checkstyle.
      *
      * @since 2.11
      */
     @Parameter( defaultValue = "${project.resources}", readonly = true )
     protected List<Resource> resources;
     
     /**
      * Specifies the location of the test resources to be used for Checkstyle.
      *
      * @since 2.16
      */
     @Parameter( defaultValue = "${project.testResources}", readonly = true )
     protected List<Resource> testResources;
 
     /**
      * <p>
      * Specifies the location of the XML configuration to use.
      * </p>
      * <p/>
      * <p>
      * Potential values are a filesystem path, a URL, or a classpath resource.
      * This parameter expects that the contents of the location conform to the
      * xml format (Checkstyle <a
      * href="http://checkstyle.sourceforge.net/config.html#Modules">Checker
      * module</a>) configuration of rulesets.
      * </p>
      * <p/>
      * <p>
      * This parameter is resolved as resource, URL, then file. If successfully
      * resolved, the contents of the configuration is copied into the
      * <code>${project.build.directory}/checkstyle-configuration.xml</code>
      * file before being passed to Checkstyle as a configuration.
      * </p>
      * <p/>
      * <p>
      * There are 2 predefined rulesets.
      * </p>
      * <ul>
      * <li><code>sun_checks.xml</code>: Sun Checks.</li>
      * <li><code>google_checks.xml</code>: Google Checks.</li>
      * </ul>
      *
      * @since 2.5
      */
     @Parameter( property = "checkstyle.config.location", defaultValue = "sun_checks.xml" )
     private String configLocation;
 
     /**
      * <p>
      * Specifies the location of the properties file.
      * </p>
      * <p/>
      * <p>
      * This parameter is resolved as URL, File then resource. If successfully
      * resolved, the contents of the properties location is copied into the
      * <code>${project.build.directory}/checkstyle-checker.properties</code>
      * file before being passed to Checkstyle for loading.
      * </p>
      * <p/>
      * <p>
      * The contents of the <code>propertiesLocation</code> will be made
      * available to Checkstyle for specifying values for parameters within the
      * xml configuration (specified in the <code>configLocation</code>
      * parameter).
      * </p>
      *
      * @since 2.5
      */
     @Parameter( property = "checkstyle.properties.location" )
     private String propertiesLocation;
 
     /**
      * Allows for specifying raw property expansion information.
      */
     @Parameter
     private String propertyExpansion;
 
     /**
      * <p>
      * Specifies the location of the License file (a.k.a. the header file) that
      * can be used by Checkstyle to verify that source code has the correct
      * license header.
      * </p>
      * <p>
      * You need to use ${checkstyle.header.file} in your Checkstyle xml
      * configuration to reference the name of this header file.
      * </p>
      * <p>
      * For instance:
      * </p>
      * <p>
      * <code>
      * &lt;module name="RegexpHeader">
      * &lt;property name="headerFile" value="${checkstyle.header.file}"/>
      * &lt;/module>
      * </code>
      * </p>
      *
      * @since 2.0-beta-2
      */
     @Parameter( property = "checkstyle.header.file", defaultValue = "LICENSE.txt" )
     private String headerLocation;
 
     /**
      * Specifies the cache file used to speed up Checkstyle on successive runs.
      */
     @Parameter( defaultValue = "${project.build.directory}/checkstyle-cachefile" )
     private String cacheFile;
 
     /**
      * The key to be used in the properties for the suppressions file.
      *
      * @since 2.1
      */
     @Parameter( property = "checkstyle.suppression.expression", defaultValue = "checkstyle.suppressions.file" )
     private String suppressionsFileExpression;
 
     /**
      * <p>
      * Specifies the location of the suppressions XML file to use.
      * </p>
      * <p/>
      * <p>
      * This parameter is resolved as resource, URL, then file. If successfully
      * resolved, the contents of the suppressions XML is copied into the
      * <code>${project.build.directory}/checkstyle-suppressions.xml</code> file
      * before being passed to Checkstyle for loading.
      * </p>
      * <p/>
      * <p>
      * See <code>suppressionsFileExpression</code> for the property that will
      * be made available to your Checkstyle configuration.
      * </p>
      *
      * @since 2.0-beta-2
      */
     @Parameter( property = "checkstyle.suppressions.location" )
     private String suppressionsLocation;
 
     /**
      * The file encoding to use when reading the source files. If the property <code>project.build.sourceEncoding</code>
      * is not set, the platform default encoding is used. <strong>Note:</strong> This parameter always overrides the
      * property <code>charset</code> from Checkstyle's <code>TreeWalker</code> module.
      *
      * @since 2.2
      */
     @Parameter( property = "encoding", defaultValue = "${project.build.sourceEncoding}" )
     private String encoding;
 
     /**
      * @since 2.5
      */
     @Component( role = CheckstyleExecutor.class, hint = "default" )
     protected CheckstyleExecutor checkstyleExecutor;
 
     /**
      * Output errors to console.
      */
     @Parameter( property = "checkstyle.consoleOutput", defaultValue = "false" )
     private boolean consoleOutput;
 
     /**
      * The Maven Project Object.
      */
     @Parameter ( defaultValue = "${project}", readonly = true, required = true )
     protected MavenProject project;
     
     /**
      * The Plugin Descriptor
      */
     @Parameter( defaultValue = "${plugin}", readonly = true, required = true )
     private PluginDescriptor plugin;
 
     // remove when requiring Maven 3.x, just use #plugin 
     @Parameter( defaultValue = "${mojoExecution}", readonly = true, required = true )
     private MojoExecution mojoExecution;
 
     /**
      * If <code>null</code>, the Checkstyle plugin will display violations on stdout.
      * Otherwise, a text file will be created with the violations.
      */
     @Parameter
     private File useFile;
 
     /**
      * Specifies the names filter of the source files to be excluded for
      * Checkstyle.
      */
     @Parameter( property = "checkstyle.excludes" )
     private String excludes;
 
     /**
      * Specifies the names filter of the source files to be used for Checkstyle.
      */
     @Parameter( property = "checkstyle.includes", defaultValue = JAVA_FILES, required = true )
     private String includes;
 
     /**
      * Specifies the names filter of the files to be excluded for
      * Checkstyle when checking resources.
      * @since 2.11
      */
     @Parameter( property = "checkstyle.resourceExcludes" )
     private String resourceExcludes;
 
     /**
      * Specifies the names filter of the files to be used for Checkstyle when checking resources.
      * @since 2.11
      */
     @Parameter( property = "checkstyle.resourceIncludes", defaultValue = "**/*.properties", required = true )
     private String resourceIncludes;
 
     /**
      * If this is true, and Checkstyle reported any violations or errors,
      * the build fails immediately after running Checkstyle, before checking the log
      * for {@link #logViolationsToConsole}. If you want to use {@link #logViolationsToConsole},
      * use {@link #failOnViolation} instead of this.
      */
     @Parameter( defaultValue = "false" )
     private boolean failsOnError;
 
     /**
      * Specifies the location of the test source directory to be used for
      * Checkstyle.
      *
      * @since 2.2
      * @deprecated instead use {@link #testSourceDirectories} 
      */
     @Deprecated
     @Parameter
     private File testSourceDirectory;
 
     /**
      * Specifies the location of the test source directories to be used for
      * Checkstyle.
      * @since 2.13
      */
     @Parameter( defaultValue = "${project.testCompileSourceRoots}" )
     private List<String> testSourceDirectories;
 
     /**
      * Include or not the test source directory to be used for Checkstyle.
      *
      * @since 2.2
      */
     @Parameter( defaultValue = "false" )
     private boolean includeTestSourceDirectory;
 
     /**
      * Specifies the location of the source directory to be used for Checkstyle.
      * 
      * @deprecated instead use {@link #sourceDirectories}
      */
     @Deprecated
     @Parameter
     private File sourceDirectory;
 
     /**
      * Specifies the location of the source directories to be used for Checkstyle.
      * @since 2.13
      */
     @Parameter( defaultValue = "${project.compileSourceRoots}" )
     private List<String> sourceDirectories;
 
     /**
      * Whether to apply Checkstyle to resource directories.
      * @since 2.11
      */
     @Parameter( property = "checkstyle.includeResources", defaultValue = "true", required = true )
     private boolean includeResources = true;
 
     /**
      * Whether to apply Checkstyle to test resource directories.
      * @since 2.11
      */
     @Parameter( property = "checkstyle.includeTestResources", defaultValue = "true", required = true )
     private boolean includeTestResources = true;
 
     /**
      * By using this property, you can specify the whole Checkstyle rules
      * inline directly inside this pom.
      *
      * <pre>
      * &lt;plugin&gt;
      *   ...
      *   &lt;configuration&gt;
      *     &lt;checkstyleRules&gt;
      *       &lt;module name="Checker"&gt;
      *         &lt;module name="FileTabCharacter"&gt;
      *           &lt;property name="eachLine" value="true" /&gt;
      *         &lt;/module&gt;
      *         &lt;module name="TreeWalker"&gt;
      *           &lt;module name="EmptyBlock"/&gt;
      *         &lt;/module&gt;
      *       &lt;/module&gt;
      *     &lt;/checkstyleRules&gt;
      *   &lt;/configuration&gt;
      *   ...
      * </pre>
      *
      * @since 2.12
      */
     @Parameter
     private PlexusConfiguration checkstyleRules;
 
     /**
      * dump file for inlined Checkstyle rules 
      */
     @Parameter( property = "checkstyle.output.rules.file",
                     defaultValue = "${project.build.directory}/checkstyle-rules.xml" )
     private File rulesFiles;
 
     private ByteArrayOutputStream stringOutputStream;
 
     /** {@inheritDoc} */
     public void execute()
         throws MojoExecutionException, MojoFailureException
     {
         if ( skip )
         {
             return;
         }
 
         if ( !skipExec )
         {
             if ( checkstyleRules != null )
             {
                 if ( !"sun_checks.xml".equals( configLocation ) )
                 {
                     throw new MojoExecutionException( "If you use inline configuration for rules, don't specify "
                         + "a configLocation" );
                 }
                 if ( checkstyleRules.getChildCount() > 1 )
                 {
                     throw new MojoExecutionException( "Currently only one root module is supported" );
                 }
 
                 PlexusConfiguration checkerModule = checkstyleRules.getChild( 0 );
 
                 try
                 {
                     FileUtils.forceMkdir( rulesFiles.getParentFile() );
                     FileUtils.fileWrite( rulesFiles, CHECKSTYLE_FILE_HEADER + checkerModule.toString() );
                 }
                 catch ( final IOException e )
                 {
                     throw new MojoExecutionException( e.getMessage(), e );
                 }
                 configLocation = rulesFiles.getAbsolutePath();
             }
 
             ClassLoader currentClassLoader = Thread.currentThread().getContextClassLoader();
 
             try
             {
                 CheckstyleExecutorRequest request = new CheckstyleExecutorRequest();
                 request.setConsoleListener( getConsoleListener() ).setConsoleOutput( consoleOutput )
                     .setExcludes( excludes ).setFailsOnError( failsOnError ).setIncludes( includes )
                     .setResourceIncludes( resourceIncludes )
                     .setResourceExcludes( resourceExcludes )
                     .setIncludeResources( includeResources )
                     .setIncludeTestResources( includeTestResources )
                     .setIncludeTestSourceDirectory( includeTestSourceDirectory ).setListener( getListener() )
                     .setProject( project ).setSourceDirectories( getSourceDirectories() )
                     .setResources( resources ).setTestResources( testResources )
                     .setStringOutputStream( stringOutputStream ).setSuppressionsLocation( suppressionsLocation )
                     .setTestSourceDirectories( getTestSourceDirectories() ).setConfigLocation( configLocation )
                     .setConfigurationArtifacts( collectArtifacts( "config" ) )
                     .setPropertyExpansion( propertyExpansion )
                     .setHeaderLocation( headerLocation ).setLicenseArtifacts( collectArtifacts( "license" ) )
                     .setCacheFile( cacheFile ).setSuppressionsFileExpression( suppressionsFileExpression )
                     .setEncoding( encoding ).setPropertiesLocation( propertiesLocation );
                 checkstyleExecutor.executeCheckstyle( request );
 
             }
             catch ( CheckstyleException e )
             {
                 throw new MojoExecutionException( "Failed during checkstyle configuration", e );
             }
             catch ( CheckstyleExecutorException e )
             {
                 throw new MojoExecutionException( "Failed during checkstyle execution", e );
             }
             finally
             {
                 //be sure to restore original context classloader
                 Thread.currentThread().setContextClassLoader( currentClassLoader );
             }
         }
 
         if ( !"xml".equals( outputFileFormat ) )
         {
             throw new MojoExecutionException( "Output format is '" + outputFileFormat
                 + "', checkstyle:check requires format to be 'xml'." );
         }
 
         if ( !outputFile.exists() )
         {
             getLog().info( "Unable to perform checkstyle:check, unable to find checkstyle:checkstyle outputFile." );
             return;
         }
 
         Reader reader = null;
         try
         {
             reader = new BufferedReader( ReaderFactory.newXmlReader( outputFile ) );
 
             XmlPullParser xpp = new MXParser();
             xpp.setInput( reader );
 
             int violations = countViolations( xpp );
 
             if ( violations > maxAllowedViolations )
             {
                 if ( failOnViolation )
                 {
                     String msg =
                         "You have " + violations + " Checkstyle violation" + ( ( violations > 1 ) ? "s" : "" ) + ".";
                     if ( maxAllowedViolations > 0 )
                     {
                         msg += " The maximum number of allowed violations is " + maxAllowedViolations + ".";
                     }
                     throw new MojoFailureException( msg );
                 }
 
                 getLog().warn( "checkstyle:check violations detected but failOnViolation set to false" );
             }
         }
         catch ( IOException | XmlPullParserException e )
         {
             throw new MojoExecutionException( "Unable to read Checkstyle results xml: " + outputFile.getAbsolutePath(),
                                               e );
         }
         finally
         {
             IOUtil.close( reader );
         }
     }
 
     private int countViolations( XmlPullParser xpp )
         throws XmlPullParserException, IOException
     {
         int count = 0;
         int ignoreCount = 0;
         RuleUtil.Matcher[] ignores =
             ( violationIgnore == null ) ? null : RuleUtil.parseMatchers( violationIgnore.split( "," ) );
 
         String basedir = project.getBasedir().getAbsolutePath();
         String file = "";
         for ( int eventType = xpp.getEventType(); eventType != XmlPullParser.END_DOCUMENT; eventType = xpp.next() )
         {
             if ( eventType != XmlPullParser.START_TAG )
             {
                 continue;
             }
             else if ( "file".equals( xpp.getName() ) )
             {
                 file = PathTool.getRelativeFilePath( basedir, xpp.getAttributeValue( "", "name" ) );
                 //file = file.substring( file.lastIndexOf( File.separatorChar ) + 1 );
             }
             else if ( "error".equals( xpp.getName() ) )
             {
                 String severity = xpp.getAttributeValue( "", "severity" );
 
                 if ( !isViolation( severity ) )
                 {
                     continue;
                 }
 
                 String source = xpp.getAttributeValue( "", "source" );
 
                 if ( ignore( ignores, source ) )
                 {
                     ignoreCount++;
                 }
                 else
                 {
                     count++;
 
                     if ( logViolationsToConsole )
                     {
                         String line = xpp.getAttributeValue( "", "line" );
                         String column = xpp.getAttributeValue( "", "column" );
                         String message = xpp.getAttributeValue( "", "message" );
                         String rule = RuleUtil.getName( source );
                         String category = RuleUtil.getCategory( source );
 
                         log( severity, file + '[' + line + ( ( column == null ) ? "" : ( ':' + column ) ) + "] ("
                             + category + ") " + rule + ": " + message );
                     }
                 }
             }
         }
 
         if ( ignoreCount > 0 )
         {
             getLog().info( "Ignored " + ignoreCount + " error" + ( ( ignoreCount > 1 ) ? "s" : "" ) + ", " + count
                                + " violation" + ( ( count > 1 ) ? "s" : "" ) + " remaining." );
         }
 
         return count;
     }
 
     private void log( String severity, String message )
     {
         if ( "info".equals( severity ) )
         {
             getLog().info( message );
         }
         else if ( "warning".equals( severity ) )
         {
             getLog().warn( message );
         }
         else
         {
             getLog().error( message );
         }
     }
 
     /**
      * Checks if the given severity is considered a violation.
      *
      * @param severity The severity to check
      * @return <code>true</code> if the given severity is a violation, otherwise <code>false</code>
      */
     private boolean isViolation( String severity )
     {
         if ( "error".equals( severity ) )
         {
             return "error".equals( violationSeverity ) || "warning".equals( violationSeverity )
                 || "info".equals( violationSeverity );
         }
         else if ( "warning".equals( severity ) )
         {
             return "warning".equals( violationSeverity ) || "info".equals( violationSeverity );
         }
         else if ( "info".equals( severity ) )
         {
             return "info".equals( violationSeverity );
         }
         else
         {
             return false;
         }
     }
 
     private boolean ignore( RuleUtil.Matcher[] ignores, String source )
     {
         if ( ignores != null )
         {
             for ( RuleUtil.Matcher ignore : ignores )
             {
                 if ( ignore.match( source ) )
                 {
                     return true;
                 }
             }
         }
 
         return false;
     }
 
     private DefaultLogger getConsoleListener()
         throws MojoExecutionException
     {
         DefaultLogger consoleListener;
 
         if ( useFile == null )
         {
             stringOutputStream = new ByteArrayOutputStream();
             consoleListener = new DefaultLogger( stringOutputStream, false );
         }
         else
         {
             OutputStream out = getOutputStream( useFile );
 
             consoleListener = new DefaultLogger( out, true );
         }
 
         return consoleListener;
     }
 
     private OutputStream getOutputStream( File file )
         throws MojoExecutionException
     {
         File parentFile = file.getAbsoluteFile().getParentFile();
 
         if ( !parentFile.exists() )
         {
             parentFile.mkdirs();
         }
 
         FileOutputStream fileOutputStream;
         try
         {
             fileOutputStream = new FileOutputStream( file );
         }
         catch ( FileNotFoundException e )
         {
             throw new MojoExecutionException( "Unable to create output stream: " + file, e );
         }
         return fileOutputStream;
     }
 
     private AuditListener getListener()
         throws MojoFailureException, MojoExecutionException
     {
         AuditListener listener = null;
 
         if ( StringUtils.isNotEmpty( outputFileFormat ) )
         {
             File resultFile = outputFile;
 
             OutputStream out = getOutputStream( resultFile );
 
             if ( "xml".equals( outputFileFormat ) )
             {
                 listener = new XMLLogger( out, true );
             }
             else if ( "plain".equals( outputFileFormat ) )
             {
                 listener = new DefaultLogger( out, true );
             }
             else
             {
                 throw new MojoFailureException( "Invalid output file format: (" + outputFileFormat
                     + "). Must be 'plain' or 'xml'." );
             }
         }
 
         return listener;
     }
     
     @SuppressWarnings( "unchecked" )
     private List<Artifact> collectArtifacts( String hint )
     {
         if ( plugin == null || plugin.getGroupId() == null )
         {
             // Maven 2.x workaround
             plugin = mojoExecution.getMojoDescriptor().getPluginDescriptor();
         }
         
         List<Artifact> artifacts = new ArrayList<>();
 
         PluginManagement pluginManagement = project.getBuild().getPluginManagement();
         if ( pluginManagement != null )
         {
             artifacts.addAll( getCheckstylePluginDependenciesAsArtifacts( pluginManagement.getPluginsAsMap(), hint ) );
         }
 
         artifacts.addAll( getCheckstylePluginDependenciesAsArtifacts( project.getBuild().getPluginsAsMap(), hint ) );
 
         return artifacts;
     }
 
     private List<Artifact> getCheckstylePluginDependenciesAsArtifacts( Map<String, Plugin> plugins, String hint )
     {
         List<Artifact> artifacts = new ArrayList<>();
         
         Plugin checkstylePlugin = plugins.get( plugin.getGroupId() + ":" + plugin.getArtifactId() );
         if ( checkstylePlugin != null )
         {
             for ( Dependency dep : checkstylePlugin.getDependencies() )
             {
              // @todo if we can filter on hints, it should be done here...
                 String depKey = dep.getGroupId() + ":" + dep.getArtifactId();
                 artifacts.add( (Artifact) plugin.getArtifactMap().get( depKey ) );
             }
         }
         return artifacts;
     }
     
     private List<File> getSourceDirectories()
     {
         List<File> sourceDirs = null;
         // if sourceDirectory is explicitly set, use it
         if ( sourceDirectory != null )
         {
             sourceDirs = Collections.singletonList( sourceDirectory );
         }
         else
         {
             sourceDirs = new ArrayList<>( sourceDirectories.size() );
             for ( String sourceDir : sourceDirectories )
             {
                 sourceDirs.add( FileUtils.resolveFile( project.getBasedir(), sourceDir ) );
             }
         }
         
         return sourceDirs;
     }
     
     private List<File> getTestSourceDirectories()
     {
         List<File> testSourceDirs = null;
         // if testSourceDirectory is explicitly set, use it
         if ( testSourceDirectory != null )
         {
             testSourceDirs = Collections.singletonList( testSourceDirectory );
         }
         // probably null-check only required due to MavenProjectStubs
         else if ( testSourceDirectories != null )
         {
             testSourceDirs = new ArrayList<>( testSourceDirectories.size() );
             for ( String testSourceDir : testSourceDirectories )
             {
                 testSourceDirs.add( FileUtils.resolveFile( project.getBasedir(), testSourceDir ) );
             }
         }
         
         return testSourceDirs;
     }
     
 }