package org.apache.maven.project;
   
   /*
    * 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.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.stream.Collectors;
  
  import org.apache.maven.api.model.Build;
  import org.apache.maven.artifact.ArtifactUtils;
  import org.apache.maven.api.model.Dependency;
  import org.apache.maven.api.model.Extension;
  import org.apache.maven.api.model.Parent;
  import org.apache.maven.api.model.Plugin;
  import org.codehaus.plexus.util.StringUtils;
  import org.codehaus.plexus.util.dag.CycleDetectedException;
  import org.codehaus.plexus.util.dag.DAG;
  import org.codehaus.plexus.util.dag.TopologicalSorter;
  import org.codehaus.plexus.util.dag.Vertex;
  
  /**
   * ProjectSorter
   */
  public class ProjectSorter
  {
      private DAG dag;
  
      private List<MavenProject> sortedProjects;
  
      private Map<String, MavenProject> projectMap;
  
      /**
       * Sort a list of projects.
       * <ul>
       * <li>collect all the vertices for the projects that we want to build.</li>
       * <li>iterate through the deps of each project and if that dep is within
       * the set of projects we want to build then add an edge, otherwise throw
       * the edge away because that dependency is not within the set of projects
       * we are trying to build. we assume a closed set.</li>
       * <li>do a topo sort on the graph that remains.</li>
       * </ul>
       * @throws DuplicateProjectException if any projects are duplicated by id
       */
      // MAVENAPI FIXME: the DAG used is NOT only used to represent the dependency relation,
      // but also for <parent>, <build><plugin>, <reports>. We need multiple DAG's
      // since a DAG can only handle 1 type of relationship properly.
      // Use case:  This is detected as a cycle:
      // org.apache.maven:maven-plugin-api                -(PARENT)->
      // org.apache.maven:maven                           -(inherited REPORTING)->
      // org.apache.maven.plugins:maven-checkstyle-plugin -(DEPENDENCY)->
      // org.apache.maven:maven-plugin-api
      // In this case, both the verify and the report goals are called
      // in a different lifecycle. Though the compiler-plugin has a valid use case, although
      // that seems to work fine. We need to take versions and lifecycle into account.
      public ProjectSorter( Collection<MavenProject> projects )
          throws CycleDetectedException, DuplicateProjectException
      {
          dag = new DAG();
  
          // groupId:artifactId:version -> project
          projectMap = new HashMap<>( projects.size() * 2 );
  
          // groupId:artifactId -> (version -> vertex)
          Map<String, Map<String, Vertex>> vertexMap = new HashMap<>( projects.size() * 2 );
  
          for ( MavenProject project : projects )
          {
              String projectId = getId( project );
  
              MavenProject conflictingProject = projectMap.put( projectId, project );
  
              if ( conflictingProject != null )
              {
                  throw new DuplicateProjectException( projectId, conflictingProject.getFile(), project.getFile(),
                                                       "Project '" + projectId + "' is duplicated in the reactor" );
              }
  
              String projectKey = ArtifactUtils.versionlessKey( project.getGroupId(), project.getArtifactId() );
  
             Map<String, Vertex> vertices = vertexMap.computeIfAbsent( projectKey, k -> new HashMap<>( 2, 1 ) );
 
             vertices.put( project.getVersion(), dag.addVertex( projectId ) );
         }
 
         for ( Vertex projectVertex : dag.getVertices() )
         {
             String projectId = projectVertex.getLabel();
 
             MavenProject project = projectMap.get( projectId );
 
             for ( Dependency dependency : project.getModel().getDelegate().getDependencies() )
             {
                 addEdge( projectMap, vertexMap, project, projectVertex, dependency.getGroupId(),
                          dependency.getArtifactId(), dependency.getVersion(), false, false );
             }
 
             Parent parent = project.getModel().getDelegate().getParent();
 
             if ( parent != null )
             {
                 // Parent is added as an edge, but must not cause a cycle - so we remove any other edges it has
                 // in conflict
                 addEdge( projectMap, vertexMap, null, projectVertex, parent.getGroupId(), parent.getArtifactId(),
                          parent.getVersion(), true, false );
             }
 
             Build build = project.getModel().getDelegate().getBuild();
             if ( build != null )
             {
                 for ( Plugin plugin : build.getPlugins() )
                 {
                     addEdge( projectMap, vertexMap, project, projectVertex, plugin.getGroupId(),
                              plugin.getArtifactId(), plugin.getVersion(), false, true );
 
                     for ( Dependency dependency : plugin.getDependencies() )
                     {
                         addEdge( projectMap, vertexMap, project, projectVertex, dependency.getGroupId(),
                                  dependency.getArtifactId(), dependency.getVersion(), false, true );
                     }
                 }
 
                 for ( Extension extension : build.getExtensions() )
                 {
                     addEdge( projectMap, vertexMap, project, projectVertex, extension.getGroupId(),
                              extension.getArtifactId(), extension.getVersion(), false, true );
                 }
             }
         }
 
         List<String> sortedProjectLabels = TopologicalSorter.sort( dag );
 
         this.sortedProjects = sortedProjectLabels.stream().map( id -> projectMap.get( id ) )
                 .collect( Collectors.collectingAndThen( Collectors.toList(), Collections::unmodifiableList ) );
     }
     @SuppressWarnings( "checkstyle:parameternumber" )
     private void addEdge( Map<String, MavenProject> projectMap, Map<String, Map<String, Vertex>> vertexMap,
                           MavenProject project, Vertex projectVertex, String groupId, String artifactId,
                           String version, boolean force, boolean safe )
         throws CycleDetectedException
     {
         String projectKey = ArtifactUtils.versionlessKey( groupId, artifactId );
 
         Map<String, Vertex> vertices = vertexMap.get( projectKey );
 
         if ( vertices != null )
         {
             if ( isSpecificVersion( version ) )
             {
                 Vertex vertex = vertices.get( version );
                 if ( vertex != null )
                 {
                     addEdge( projectVertex, vertex, project, projectMap, force, safe );
                 }
             }
             else
             {
                 for ( Vertex vertex : vertices.values() )
                 {
                     addEdge( projectVertex, vertex, project, projectMap, force, safe );
                 }
             }
         }
     }
 
     private void addEdge( Vertex fromVertex, Vertex toVertex, MavenProject fromProject,
                           Map<String, MavenProject> projectMap, boolean force, boolean safe )
         throws CycleDetectedException
     {
         if ( fromVertex.equals( toVertex ) )
         {
             return;
         }
 
         if ( fromProject != null )
         {
             MavenProject toProject = projectMap.get( toVertex.getLabel() );
             fromProject.addProjectReference( toProject );
         }
 
         if ( force && toVertex.getChildren().contains( fromVertex ) )
         {
             dag.removeEdge( toVertex, fromVertex );
         }
 
         try
         {
             dag.addEdge( fromVertex, toVertex );
         }
         catch ( CycleDetectedException e )
         {
             if ( !safe )
             {
                 throw e;
             }
         }
     }
 
     private boolean isSpecificVersion( String version )
     {
         return !( StringUtils.isEmpty( version ) || version.startsWith( "[" ) || version.startsWith( "(" ) );
     }
 
     // TODO !![jc; 28-jul-2005] check this; if we're using '-r' and there are aggregator tasks, this will result in weirdness.
     public MavenProject getTopLevelProject()
     {
         return sortedProjects.stream().filter( MavenProject::isExecutionRoot ).findFirst()
                 .orElse( null );
     }
 
     public List<MavenProject> getSortedProjects()
     {
         return sortedProjects;
     }
 
     public boolean hasMultipleProjects()
     {
         return sortedProjects.size() > 1;
     }
 
     public List<String> getDependents( String id )
     {
         return dag.getParentLabels( id );
     }
 
     public List<String> getDependencies( String id )
     {
         return dag.getChildLabels( id );
     }
 
     public static String getId( MavenProject project )
     {
         return ArtifactUtils.key( project.getGroupId(), project.getArtifactId(), project.getVersion() );
     }
 
     public DAG getDAG()
     {
         return dag;
     }
 
     public Map<String, MavenProject> getProjectMap()
     {
         return projectMap;
     }
 
 }