package org.apache.maven.tools.plugin.generator;
   
   /*
    * 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.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.OutputStreamWriter;
  import java.io.StringWriter;
  import java.io.Writer;
  
  import org.apache.maven.project.MavenProject;
  import org.apache.velocity.VelocityContext;
  import org.codehaus.plexus.logging.AbstractLogEnabled;
  import org.codehaus.plexus.logging.Logger;
  import org.codehaus.plexus.logging.console.ConsoleLogger;
  import org.codehaus.plexus.util.StringUtils;
  import org.codehaus.plexus.util.io.CachingOutputStream;
  import org.codehaus.plexus.velocity.VelocityComponent;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  
  /**
   * Generates an <code>HelpMojo</code> class from <code>help-class-source.vm</code> template.
   * The generated mojo reads help content from <code>META-INF/maven/${groupId}/${artifactId}/plugin-help.xml</code>
   * resource, which is generated by this {@link PluginDescriptorFilesGenerator}.
   *
   * @author <a href="mailto:vincent.siveton@gmail.com">Vincent Siveton</a>
   * @since 2.4
   */
  public class PluginHelpGenerator
      extends AbstractLogEnabled
  {
      /**
       * Default generated class name
       */
      private static final String HELP_MOJO_CLASS_NAME = "HelpMojo";
  
      private String helpPackageName;
      private String goalPrefix;
      private MavenProject mavenProject;
      private VelocityComponent velocityComponent;
  
      /**
       * Default constructor
       */
      public PluginHelpGenerator()
      {
          this.enableLogging( new ConsoleLogger( Logger.LEVEL_INFO, "PluginHelpGenerator" ) );
      }
  
      // ----------------------------------------------------------------------
      // Public methods
      // ----------------------------------------------------------------------
  
      public void execute( File destinationDirectory )
          throws GeneratorException
      {
          String helpImplementation = getImplementation();
  
          try
          {
              String sourcePath = helpImplementation.replace( '.', File.separatorChar ) + ".java";
  
              File helpClass = new File( destinationDirectory, sourcePath );
              helpClass.getParentFile().mkdirs();
  
              String helpClassSources =
                  getHelpClassSources( getPluginHelpPath( mavenProject ) );
  
              try ( Writer w = new OutputStreamWriter( new CachingOutputStream( helpClass ), UTF_8 ) )
              {
                  w.write( helpClassSources );
              }
          }
          catch ( IOException e )
          {
              throw new GeneratorException( e.getMessage(), e );
          }
      }
  
     public PluginHelpGenerator setHelpPackageName( String helpPackageName )
     {
         this.helpPackageName = helpPackageName;
         return this;
     }
 
     public PluginHelpGenerator setVelocityComponent( VelocityComponent velocityComponent )
     {
         this.velocityComponent = velocityComponent;
         return this;
     }
 
     public PluginHelpGenerator setGoalPrefix( String goalPrefix )
     {
         this.goalPrefix = goalPrefix;
         return this;
     }
 
     public PluginHelpGenerator setMavenProject( MavenProject mavenProject )
     {
         this.mavenProject = mavenProject;
         return this;
     }
 
     // ----------------------------------------------------------------------
     // Private methods
     // ----------------------------------------------------------------------
 
     private String getHelpClassSources( String pluginHelpPath )
         throws IOException
     {
         VelocityContext context = new VelocityContext();
         boolean useAnnotations = mavenProject.getArtifactMap().containsKey(
             "org.apache.maven.plugin-tools:maven-plugin-annotations" );
 
         context.put( "helpPackageName", helpPackageName );
         context.put( "pluginHelpPath", pluginHelpPath );
         context.put( "artifactId", mavenProject.getArtifactId() );
         // TODO: evaluate prefix from deserialized plugin
         context.put( "goalPrefix", goalPrefix );
         context.put( "useAnnotations", useAnnotations );
 
         StringWriter stringWriter = new StringWriter();
 
         // plugin-tools sources are UTF-8 (and even ASCII in this case))
         try ( InputStream is = //
                  Thread.currentThread().getContextClassLoader().getResourceAsStream( "help-class-source.vm" ); //
              InputStreamReader isReader = new InputStreamReader( is, UTF_8 ) )
         {
             //isReader =
             velocityComponent.getEngine().evaluate( context, stringWriter, "", isReader );
         }
         // Apply OS lineSeparator instead of template's lineSeparator to have consistent separators for
         // all source files.
         return stringWriter.toString().replaceAll( "(\r\n|\n|\r)", System.lineSeparator() );
     }
 
     /**
      * @return The implementation.
      */
     private String getImplementation( )
     {
         return StringUtils.isEmpty( helpPackageName )
             ? HELP_MOJO_CLASS_NAME
             : helpPackageName + '.' + HELP_MOJO_CLASS_NAME;
     }
 
     static String getPluginHelpPath( MavenProject mavenProject )
     {
         return mavenProject.getGroupId() + "/" + mavenProject.getArtifactId() + "/plugin-help.xml";
     }
 }