package org.apache.maven.plugins.enforcer;
   
   /*
    * 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.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  
  import org.apache.commons.lang3.SystemUtils;
  import org.apache.maven.enforcer.rule.api.EnforcerRuleException;
  import org.apache.maven.enforcer.rule.api.EnforcerRuleHelper;
  import org.apache.maven.execution.MavenSession;
  import org.apache.maven.model.Dependency;
  import org.apache.maven.plugin.logging.Log;
  import org.apache.maven.project.MavenProject;
  import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluationException;
  import org.codehaus.plexus.util.StringUtils;
  
  /**
   * This rule will check if a multi module build will follow the best practices.
   * 
   * @author Karl-Heinz Marbaise
   * @since 1.4
   */
  public class ReactorModuleConvergence
      extends AbstractNonCacheableEnforcerRule
  {
      private boolean ignoreModuleDependencies = false;
  
      private Log logger;
  
      @Override
      public void execute( EnforcerRuleHelper helper )
          throws EnforcerRuleException
      {
          logger = helper.getLog();
  
          MavenSession session;
          try
          {
              session = (MavenSession) helper.evaluate( "${session}" );
          }
          catch ( ExpressionEvaluationException eee )
          {
              throw new EnforcerRuleException( "Unable to retrieve the MavenSession: ", eee );
          }
  
          List<MavenProject> sortedProjects = session.getProjectDependencyGraph().getSortedProjects();
          if ( sortedProjects != null && !sortedProjects.isEmpty() )
          {
              checkReactor( sortedProjects );
              checkParentsInReactor( sortedProjects );
              checkMissingParentsInReactor( sortedProjects );
              checkParentsPartOfTheReactor( sortedProjects );
              if ( !isIgnoreModuleDependencies() )
              {
                  checkDependenciesWithinReactor( sortedProjects );
              }
          }
  
      }
  
      private void checkParentsPartOfTheReactor( List<MavenProject> sortedProjects )
          throws EnforcerRuleException
      {
          List<MavenProject> parentsWhichAreNotPartOfTheReactor =
              existParentsWhichAreNotPartOfTheReactor( sortedProjects );
          if ( !parentsWhichAreNotPartOfTheReactor.isEmpty() )
          {
              StringBuilder sb = new StringBuilder().append( SystemUtils.LINE_SEPARATOR );
              addMessageIfExist( sb );
              for ( MavenProject mavenProject : parentsWhichAreNotPartOfTheReactor )
              {
                  sb.append( " module: " );
                  sb.append( mavenProject.getId() );
                  sb.append( SystemUtils.LINE_SEPARATOR );
              }
              throw new EnforcerRuleException( "Module parents have been found which could not be found in the reactor."
                  + sb.toString() );
          }
     }
 
     /**
      * Convenience method to create a user readable message.
      * 
      * @param sortedProjects The list of reactor projects.
      * @throws EnforcerRuleException In case of a violation.
      */
     private void checkMissingParentsInReactor( List<MavenProject> sortedProjects )
         throws EnforcerRuleException
     {
         List<MavenProject> modulesWithoutParentsInReactor = existModulesWithoutParentsInReactor( sortedProjects );
         if ( !modulesWithoutParentsInReactor.isEmpty() )
         {
             StringBuilder sb = new StringBuilder().append( SystemUtils.LINE_SEPARATOR );
             addMessageIfExist( sb );
             for ( MavenProject mavenProject : modulesWithoutParentsInReactor )
             {
                 sb.append( " module: " );
                 sb.append( mavenProject.getId() );
                 sb.append( SystemUtils.LINE_SEPARATOR );
             }
             throw new EnforcerRuleException( "Reactor contains modules without parents." + sb.toString() );
         }
     }
 
     private void checkDependenciesWithinReactor( List<MavenProject> sortedProjects )
         throws EnforcerRuleException
     {
         // After we are sure having consistent version we can simply use the first one?
         String reactorVersion = sortedProjects.get( 0 ).getVersion();
 
         Map<MavenProject, List<Dependency>> areThereDependenciesWhichAreNotPartOfTheReactor =
             areThereDependenciesWhichAreNotPartOfTheReactor( reactorVersion, sortedProjects );
         if ( !areThereDependenciesWhichAreNotPartOfTheReactor.isEmpty() )
         {
             StringBuilder sb = new StringBuilder().append( SystemUtils.LINE_SEPARATOR );
             addMessageIfExist( sb );
             // CHECKSTYLE_OFF: LineLength
             for ( Entry<MavenProject, List<Dependency>> item : areThereDependenciesWhichAreNotPartOfTheReactor.entrySet() )
             {
                 sb.append( " module: " );
                 sb.append( item.getKey().getId() );
                 sb.append( SystemUtils.LINE_SEPARATOR );
                 for ( Dependency dependency : item.getValue() )
                 {
                     String id =
                         dependency.getGroupId() + ":" + dependency.getArtifactId() + ":" + dependency.getVersion();
                     sb.append( "    dependency: " );
                     sb.append( id );
                     sb.append( SystemUtils.LINE_SEPARATOR );
                 }
             }
             throw new EnforcerRuleException(
                                              "Reactor modules contains dependencies which do not reference the reactor."
                                                  + sb.toString() );
             // CHECKSTYLE_ON: LineLength
         }
     }
 
     /**
      * Convenience method to create a user readable message.
      * 
      * @param sortedProjects The list of reactor projects.
      * @throws EnforcerRuleException In case of a violation.
      */
     private void checkParentsInReactor( List<MavenProject> sortedProjects )
         throws EnforcerRuleException
     {
         // After we are sure having consistent version we can simply use the first one?
         String reactorVersion = sortedProjects.get( 0 ).getVersion();
 
         List<MavenProject> areParentsFromTheReactor = areParentsFromTheReactor( reactorVersion, sortedProjects );
         if ( !areParentsFromTheReactor.isEmpty() )
         {
             StringBuilder sb = new StringBuilder().append( SystemUtils.LINE_SEPARATOR );
             addMessageIfExist( sb );
             for ( MavenProject mavenProject : areParentsFromTheReactor )
             {
                 sb.append( " --> " );
                 sb.append( mavenProject.getId() );
                 sb.append( " parent:" );
                 sb.append( mavenProject.getParent().getId() );
                 sb.append( SystemUtils.LINE_SEPARATOR );
             }
             throw new EnforcerRuleException( "Reactor modules have parents which contain a wrong version."
                 + sb.toString() );
         }
     }
 
     /**
      * Convenience method to create user readable message.
      * 
      * @param sortedProjects The list of reactor projects.
      * @throws EnforcerRuleException In case of a violation.
      */
     private void checkReactor( List<MavenProject> sortedProjects )
         throws EnforcerRuleException
     {
         List<MavenProject> consistenceCheckResult = isReactorVersionConsistent( sortedProjects );
         if ( !consistenceCheckResult.isEmpty() )
         {
             StringBuilder sb = new StringBuilder().append( SystemUtils.LINE_SEPARATOR );
             addMessageIfExist( sb );
             for ( MavenProject mavenProject : consistenceCheckResult )
             {
                 sb.append( " --> " );
                 sb.append( mavenProject.getId() );
                 sb.append( SystemUtils.LINE_SEPARATOR );
             }
             throw new EnforcerRuleException( "The reactor contains different versions." + sb.toString() );
         }
     }
 
     private List<MavenProject> areParentsFromTheReactor( String reactorVersion, List<MavenProject> sortedProjects )
     {
         List<MavenProject> result = new ArrayList<MavenProject>();
 
         for ( MavenProject mavenProject : sortedProjects )
         {
             logger.debug( "Project: " + mavenProject.getId() );
             if ( hasParent( mavenProject ) )
             {
                 if ( !mavenProject.isExecutionRoot() )
                 {
                     MavenProject parent = mavenProject.getParent();
                     if ( !reactorVersion.equals( parent.getVersion() ) )
                     {
                         logger.debug( "The project: " + mavenProject.getId()
                             + " has a parent which version does not match the other elements in reactor" );
                         result.add( mavenProject );
                     }
                 }
             }
             else
             {
                 // This situation is currently ignored, cause it's handled by existModulesWithoutParentsInReactor()
             }
         }
 
         return result;
     }
 
     private List<MavenProject> existParentsWhichAreNotPartOfTheReactor( List<MavenProject> sortedProjects )
     {
         List<MavenProject> result = new ArrayList<MavenProject>();
 
         for ( MavenProject mavenProject : sortedProjects )
         {
             logger.debug( "Project: " + mavenProject.getId() );
             if ( hasParent( mavenProject ) )
             {
                 if ( !mavenProject.isExecutionRoot() )
                 {
                     MavenProject parent = mavenProject.getParent();
                     if ( !isProjectPartOfTheReactor( parent, sortedProjects ) )
                     {
                         result.add( mavenProject );
                     }
                 }
             }
         }
 
         return result;
     }
 
     /**
      * This will check of the groupId/artifactId can be found in any reactor project. The version will be ignored cause
      * versions are checked before.
      * 
      * @param project The project which should be checked if it is contained in the sortedProjects.
      * @param sortedProjects The list of existing projects.
      * @return true if the project has been found within the list false otherwise.
      */
     private boolean isProjectPartOfTheReactor( MavenProject project, List<MavenProject> sortedProjects )
     {
         return isGAPartOfTheReactor( project.getGroupId(), project.getArtifactId(), sortedProjects );
     }
 
     private boolean isDependencyPartOfTheReactor( Dependency dependency, List<MavenProject> sortedProjects )
     {
         return isGAPartOfTheReactor( dependency.getGroupId(), dependency.getArtifactId(), sortedProjects );
     }
 
     /**
      * This will check if the given <code>groupId/artifactId</code> is part of the current reactor.
      * 
      * @param groupId The groupId
      * @param artifactId The artifactId
      * @param sortedProjects The list of projects within the reactor.
      * @return true if the groupId/artifactId is part of the reactor false otherwise.
      */
     private boolean isGAPartOfTheReactor( String groupId, String artifactId, List<MavenProject> sortedProjects )
     {
         boolean result = false;
         for ( MavenProject mavenProject : sortedProjects )
         {
             String parentId = groupId + ":" + artifactId;
             String projectId = mavenProject.getGroupId() + ":" + mavenProject.getArtifactId();
             if ( parentId.equals( projectId ) )
             {
                 result = true;
             }
         }
         return result;
     }
 
     /**
      * Assume we have a module which is a child of a multi module build but this child does not have a parent. This
      * method will exactly search for such cases.
      * 
      * @param sortedProjects The sorted list of the reactor modules.
      * @return The resulting list will contain the modules in the reactor which do not have a parent. The list will
      *         never null. If the list is empty no violation have happened.
      */
     private List<MavenProject> existModulesWithoutParentsInReactor( List<MavenProject> sortedProjects )
     {
         List<MavenProject> result = new ArrayList<MavenProject>();
 
         for ( MavenProject mavenProject : sortedProjects )
         {
             logger.debug( "Project: " + mavenProject.getId() );
             if ( !hasParent( mavenProject ) )
             {
                 // TODO: Should add an option to force having a parent?
                 if ( mavenProject.isExecutionRoot() )
                 {
                     logger.debug( "The root does not need having a parent." );
                 }
                 else
                 {
                     logger.debug( "The module: " + mavenProject.getId() + " has no parent." );
                     result.add( mavenProject );
                 }
             }
         }
 
         return result;
     }
 
     /**
      * Convenience method to handle adding a dependency to the Map of List.
      * 
      * @param result The result List which should be handled.
      * @param project The MavenProject which will be added.
      * @param dependency The dependency which will be added.
      */
     private void addDep( Map<MavenProject, List<Dependency>> result, MavenProject project, Dependency dependency )
     {
         if ( result.containsKey( project ) )
         {
             List<Dependency> list = result.get( project );
             if ( list == null )
             {
                 list = new ArrayList<Dependency>();
             }
             list.add( dependency );
             result.put( project, list );
         }
         else
         {
             List<Dependency> list = new ArrayList<Dependency>();
             list.add( dependency );
             result.put( project, list );
         }
     }
 
     /**
      * Go through the list of modules in the builds and check if we have dependencies. If yes we will check every
      * dependency based on groupId/artifactId if it belongs to the multi module build. In such a case it will be checked
      * if the version does fit the version in the rest of build.
      * 
      * @param reactorVersion The version of the reactor.
      * @param sortedProjects The list of existing projects within this build.
      * @return List of violations. Never null. If the list is empty than no violation has happened.
      */
     // CHECKSTYLE_OFF: LineLength
     private Map<MavenProject, List<Dependency>> areThereDependenciesWhichAreNotPartOfTheReactor( String reactorVersion,
                                                                                                  List<MavenProject> sortedProjects )
     // CHECKSTYLE_ON: LineLength
     {
         Map<MavenProject, List<Dependency>> result = new HashMap<MavenProject, List<Dependency>>();
         for ( MavenProject mavenProject : sortedProjects )
         {
             logger.debug( "Project: " + mavenProject.getId() );
 
             List<Dependency> dependencies = mavenProject.getDependencies();
             if ( hasDependencies( dependencies ) )
             {
                 for ( Dependency dependency : dependencies )
                 {
                     logger.debug( " -> Dep:" + dependency.getGroupId() + ":" + dependency.getArtifactId() + ":"
                         + dependency.getVersion() );
                     if ( isDependencyPartOfTheReactor( dependency, sortedProjects ) )
                     {
                         if ( !dependency.getVersion().equals( reactorVersion ) )
                         {
                             addDep( result, mavenProject, dependency );
                         }
                     }
                 }
             }
         }
 
         return result;
     }
 
     /**
      * This method will check the following situation within a multi-module build.
      * 
      * <pre>
      *  &lt;parent&gt;
      *    &lt;groupId&gt;...&lt;/groupId&gt;
      *    &lt;artifactId&gt;...&lt;/artifactId&gt;
      *    &lt;version&gt;1.0-SNAPSHOT&lt;/version&gt;
      *  &lt;/parent&gt;
      *  
      *  &lt;version&gt;1.1-SNAPSHOT&lt;/version&gt;
      * </pre>
      * 
      * @param projectList The sorted list of the reactor modules.
      * @return The resulting list will contain the modules in the reactor which do the thing in the example above. The
      *         list will never null. If the list is empty no violation have happened.
      */
     private List<MavenProject> isReactorVersionConsistent( List<MavenProject> projectList )
     {
         List<MavenProject> result = new ArrayList<MavenProject>();
 
         if ( projectList != null && !projectList.isEmpty() )
         {
             String version = projectList.get( 0 ).getVersion();
             logger.debug( "First version:" + version );
             for ( MavenProject mavenProject : projectList )
             {
                 logger.debug( " -> checking " + mavenProject.getId() );
                 if ( !version.equals( mavenProject.getVersion() ) )
                 {
                     result.add( mavenProject );
                 }
             }
         }
         return result;
     }
 
     private boolean hasDependencies( List<Dependency> dependencies )
     {
         return dependencies != null && !dependencies.isEmpty();
     }
 
     private boolean hasParent( MavenProject mavenProject )
     {
         return mavenProject.getParent() != null;
     }
 
     public boolean isIgnoreModuleDependencies()
     {
         return ignoreModuleDependencies;
     }
 
     public void setIgnoreModuleDependencies( boolean ignoreModuleDependencies )
     {
         this.ignoreModuleDependencies = ignoreModuleDependencies;
     }
 
     /**
      * This will add the given user message to the output.
      * 
      * @param sb The already initialized exception message part.
      */
     private void addMessageIfExist( StringBuilder sb )
     {
         if ( !StringUtils.isEmpty( getMessage() ) )
         {
             sb.append( getMessage() );
             sb.append( SystemUtils.LINE_SEPARATOR );
         }
     }
 
 }