package org.eclipse.aether.util.graph.manager;
   
   /*
    * 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.LinkedHashSet;
  import java.util.Map;
  import java.util.Objects;
  
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.artifact.ArtifactProperties;
  import org.eclipse.aether.collection.DependencyCollectionContext;
  import org.eclipse.aether.collection.DependencyManagement;
  import org.eclipse.aether.collection.DependencyManager;
  import org.eclipse.aether.graph.Dependency;
  import org.eclipse.aether.graph.Exclusion;
  import org.eclipse.aether.util.artifact.JavaScopes;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * A dependency manager managing transitive dependencies supporting transitive dependency management.
   *
   * @author Christian Schulte
   * @since 1.4.0
   */
  public final class TransitiveDependencyManager
      implements DependencyManager
  {
  
      private final Map<Object, String> managedVersions;
  
      private final Map<Object, String> managedScopes;
  
      private final Map<Object, Boolean> managedOptionals;
  
      private final Map<Object, String> managedLocalPaths;
  
      private final Map<Object, Collection<Exclusion>> managedExclusions;
  
      private final int depth;
  
      private int hashCode;
  
      /**
       * Creates a new dependency manager without any management information.
       */
      public TransitiveDependencyManager()
      {
          this( 0, Collections.<Object, String>emptyMap(), Collections.<Object, String>emptyMap(),
                Collections.<Object, Boolean>emptyMap(), Collections.<Object, String>emptyMap(),
                Collections.<Object, Collection<Exclusion>>emptyMap() );
      }
  
      private TransitiveDependencyManager( final int depth,
                                           final Map<Object, String> managedVersions,
                                           final Map<Object, String> managedScopes,
                                           final Map<Object, Boolean> managedOptionals,
                                           final Map<Object, String> managedLocalPaths,
                                           final Map<Object, Collection<Exclusion>> managedExclusions )
      {
          super();
          this.depth = depth;
          this.managedVersions = managedVersions;
          this.managedScopes = managedScopes;
          this.managedOptionals = managedOptionals;
          this.managedLocalPaths = managedLocalPaths;
          this.managedExclusions = managedExclusions;
      }
  
      public DependencyManager deriveChildManager( final DependencyCollectionContext context )
      {
          requireNonNull( context, "context cannot be null" );
          Map<Object, String> versions = managedVersions;
          Map<Object, String> scopes = managedScopes;
          Map<Object, Boolean> optionals = managedOptionals;
          Map<Object, String> localPaths = managedLocalPaths;
          Map<Object, Collection<Exclusion>> exclusions = managedExclusions;
  
          for ( Dependency managedDependency : context.getManagedDependencies() )
         {
             Artifact artifact = managedDependency.getArtifact();
             Object key = getKey( artifact );
 
             String version = artifact.getVersion();
             if ( version.length() > 0 && !versions.containsKey( key ) )
             {
                 if ( versions == managedVersions )
                 {
                     versions = new HashMap<>( managedVersions );
                 }
                 versions.put( key, version );
             }
 
             String scope = managedDependency.getScope();
             if ( scope.length() > 0 && !scopes.containsKey( key ) )
             {
                 if ( scopes == this.managedScopes )
                 {
                     scopes = new HashMap<>( this.managedScopes );
                 }
                 scopes.put( key, scope );
             }
 
             Boolean optional = managedDependency.getOptional();
             if ( optional != null && !optionals.containsKey( key ) )
             {
                 if ( optionals == managedOptionals )
                 {
                     optionals = new HashMap<>( managedOptionals );
                 }
                 optionals.put( key, optional );
             }
 
             String localPath = managedDependency.getArtifact().getProperty( ArtifactProperties.LOCAL_PATH, null );
             if ( localPath != null && !localPaths.containsKey( key ) )
             {
                 if ( localPaths == this.managedLocalPaths )
                 {
                     localPaths = new HashMap<>( managedLocalPaths );
                 }
                 localPaths.put( key, localPath );
             }
 
             if ( !managedDependency.getExclusions().isEmpty() )
             {
                 if ( exclusions == managedExclusions )
                 {
                     exclusions = new HashMap<>( managedExclusions );
                 }
                 Collection<Exclusion> managed = exclusions.computeIfAbsent( key, k -> new LinkedHashSet<>() );
                 managed.addAll( managedDependency.getExclusions() );
             }
         }
 
         return new TransitiveDependencyManager( depth + 1, versions, scopes, optionals, localPaths,
                                                 exclusions );
 
     }
 
     public DependencyManagement manageDependency( Dependency dependency )
     {
         requireNonNull( dependency, "dependency cannot be null" );
         DependencyManagement management = null;
 
         Object key = getKey( dependency.getArtifact() );
 
         if ( depth >= 2 )
         {
             String version = managedVersions.get( key );
             if ( version != null )
             {
                 management = new DependencyManagement();
                 management.setVersion( version );
             }
 
             String scope = managedScopes.get( key );
             if ( scope != null )
             {
                 if ( management == null )
                 {
                     management = new DependencyManagement();
                 }
                 management.setScope( scope );
 
                 if ( !JavaScopes.SYSTEM.equals( scope ) && dependency.getArtifact().getProperty(
                         ArtifactProperties.LOCAL_PATH, null ) != null )
                 {
                     Map<String, String> properties = new HashMap<>( dependency.getArtifact().getProperties() );
                     properties.remove( ArtifactProperties.LOCAL_PATH );
                     management.setProperties( properties );
                 }
             }
 
             if ( ( JavaScopes.SYSTEM.equals( scope ) )
                      || ( scope == null && JavaScopes.SYSTEM.equals( dependency.getScope() ) ) )
             {
                 String localPath = managedLocalPaths.get( key );
                 if ( localPath != null )
                 {
                     if ( management == null )
                     {
                         management = new DependencyManagement();
                     }
                     Map<String, String> properties = new HashMap<>( dependency.getArtifact().getProperties() );
                     properties.put( ArtifactProperties.LOCAL_PATH, localPath );
                     management.setProperties( properties );
                 }
             }
 
             Boolean optional = managedOptionals.get( key );
             if ( optional != null )
             {
                 if ( management == null )
                 {
                     management = new DependencyManagement();
                 }
                 management.setOptional( optional );
             }
         }
 
         Collection<Exclusion> exclusions = managedExclusions.get( key );
         if ( exclusions != null )
         {
             if ( management == null )
             {
                 management = new DependencyManagement();
             }
             Collection<Exclusion> result = new LinkedHashSet<>( dependency.getExclusions() );
             result.addAll( exclusions );
             management.setExclusions( result );
         }
 
         return management;
     }
 
     private Object getKey( Artifact a )
     {
         return new Key( a );
     }
 
     @Override
     public boolean equals( final Object obj )
     {
         boolean equal = obj instanceof TransitiveDependencyManager;
 
         if ( equal )
         {
             final TransitiveDependencyManager that = (TransitiveDependencyManager) obj;
             return depth == that.depth
                        && Objects.equals( managedVersions, that.managedVersions )
                        && Objects.equals( managedScopes, that.managedScopes )
                        && Objects.equals( managedOptionals, that.managedOptionals )
                        && Objects.equals( managedExclusions, that.managedExclusions );
         }
 
         return false;
     }
 
     @Override
     public int hashCode()
     {
         if ( hashCode == 0 )
         {
             hashCode = Objects.hash( depth, managedVersions, managedScopes, managedOptionals, managedExclusions );
         }
         return hashCode;
     }
 
     static class Key
     {
         private final Artifact artifact;
 
         private final int hashCode;
 
         Key( final Artifact artifact )
         {
             this.artifact = artifact;
             this.hashCode = Objects.hash( artifact.getGroupId(), artifact.getArtifactId() );
         }
 
         @Override
         public boolean equals( final Object obj )
         {
             boolean equal = obj instanceof Key;
 
             if ( equal )
             {
                 final Key that = (Key) obj;
                 return Objects.equals( artifact.getArtifactId(), that.artifact.getArtifactId() )
                            && Objects.equals( artifact.getGroupId(), that.artifact.getGroupId() )
                            && Objects.equals( artifact.getExtension(), that.artifact.getExtension() )
                            && Objects.equals( artifact.getClassifier(), that.artifact.getClassifier() );
             }
 
             return false;
         }
 
         @Override
         public int hashCode()
         {
             return this.hashCode;
         }
 
     }
 
 }