/*
    * 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.
   */
  package org.apache.maven.plugin.plugin;
  
  import javax.lang.model.SourceVersion;
  
  import java.io.File;
  import java.util.Arrays;
  import java.util.stream.Collectors;
  
  import org.apache.maven.plugin.MojoExecutionException;
  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.tools.plugin.generator.GeneratorException;
  import org.apache.maven.tools.plugin.generator.PluginHelpGenerator;
  import org.codehaus.plexus.util.StringUtils;
  import org.codehaus.plexus.velocity.VelocityComponent;
  
  /**
   * Generates a <code>HelpMojo</code> class.
   * Relies at runtime on one output file from {@link DescriptorGeneratorMojo}.
   *
   * @author <a href="mailto:vincent.siveton@gmail.com">Vincent Siveton</a>
   * @since 2.4
   */
  @Mojo(
          name = "helpmojo",
          defaultPhase = LifecyclePhase.GENERATE_SOURCES,
          threadSafe = true,
          requiresDependencyResolution = ResolutionScope.COMPILE)
  public class HelpGeneratorMojo extends AbstractGeneratorMojo {
      /**
       * The directory where the generated <code>HelpMojo</code> file will be put.
       */
      @Parameter(defaultValue = "${project.build.directory}/generated-sources/plugin")
      protected File outputDirectory;
  
      /**
       * The name of the package for the generated <code>HelpMojo</code>.
       * <p>
       * By default, the package name will be calculated as <code>groupId + "." + artifactId</code> with additional
       * <ul>
       * <li><code>-</code> (dashes) will be replaced by <code>_</code> (underscores)</li>
       * <li><code>_</code> (underscore) will be added before each number or Java keyword at the beginning of name</li>
       * </ul>
       *
       * @since 2.6
       */
      @Parameter
      private String helpPackageName;
  
      /**
       * Velocity component.
       */
      @Component
      private VelocityComponent velocity;
  
      String getHelpPackageName() {
          String packageName = null;
          if (StringUtils.isNotBlank(helpPackageName)) {
              packageName = helpPackageName;
          }
  
          if (packageName == null) {
              packageName = project.getGroupId() + "." + project.getArtifactId();
              packageName = packageName.replace("-", "_");
  
              String[] packageItems = packageName.split("\\.");
              packageName =
                      Arrays.stream(packageItems).map(this::prefixSpecialCase).collect(Collectors.joining("."));
          }
  
          return packageName;
      }
  
      private String prefixSpecialCase(String name) {
          if (SourceVersion.isKeyword(name) || !Character.isJavaIdentifierStart(name.charAt(0))) {
              name = "_" + name;
          }
          return name;
     }
 
     @Override
     protected void generate() throws MojoExecutionException {
         PluginHelpGenerator pluginHelpGenerator = new PluginHelpGenerator()
                 .setMavenProject(project)
                 .setHelpPackageName(getHelpPackageName())
                 .setGoalPrefix(goalPrefix)
                 .setVelocityComponent(velocity);
 
         try {
             pluginHelpGenerator.execute(outputDirectory);
         } catch (GeneratorException e) {
             throw new MojoExecutionException(e.getMessage(), e);
         }
 
         if (!project.getCompileSourceRoots().contains(outputDirectory.getAbsolutePath())) {
             project.addCompileSourceRoot(outputDirectory.getAbsolutePath());
         }
     }
 }