package org.eclipse.aether.graph;
   
   /*
    * 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.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import static java.util.Objects.requireNonNull;
  
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.repository.RemoteRepository;
  import org.eclipse.aether.version.Version;
  import org.eclipse.aether.version.VersionConstraint;
  
  /**
   * A node within a dependency graph.
   */
  public final class DefaultDependencyNode
      implements DependencyNode
  {
  
      private List<DependencyNode> children;
  
      private Dependency dependency;
  
      private Artifact artifact;
  
      private List<? extends Artifact> relocations;
  
      private Collection<? extends Artifact> aliases;
  
      private VersionConstraint versionConstraint;
  
      private Version version;
  
      private byte managedBits;
  
      private List<RemoteRepository> repositories;
  
      private String context;
  
      private Map<Object, Object> data;
  
      /**
       * Creates a new node with the specified dependency.
       * 
       * @param dependency The dependency associated with this node, may be {@code null} for a root node.
       */
      public DefaultDependencyNode( Dependency dependency )
      {
          this.dependency = dependency;
          artifact = ( dependency != null ) ? dependency.getArtifact() : null;
          children = new ArrayList<>( 0 );
          aliases = Collections.emptyList();
          relocations = Collections.emptyList();
          repositories = Collections.emptyList();
          context = "";
          data = Collections.emptyMap();
      }
  
      /**
       * Creates a new root node with the specified artifact as its label. Note that the new node has no dependency, i.e.
       * {@link #getDependency()} will return {@code null}. Put differently, the specified artifact will not be subject to
       * dependency collection/resolution.
       * 
       * @param artifact The artifact to use as label for this node, may be {@code null}.
       */
      public DefaultDependencyNode( Artifact artifact )
      {
          this.artifact = artifact;
          children = new ArrayList<>( 0 );
          aliases = Collections.emptyList();
          relocations = Collections.emptyList();
          repositories = Collections.emptyList();
          context = "";
          data = Collections.emptyMap();
      }
  
      /**
      * Creates a mostly shallow clone of the specified node. The new node has its own copy of any custom data and
      * initially no children.
      * 
      * @param node The node to copy, must not be {@code null}.
      */
     public DefaultDependencyNode( DependencyNode node )
     {
         dependency = node.getDependency();
         artifact = node.getArtifact();
         children = new ArrayList<>( 0 );
         setAliases( node.getAliases() );
         setRequestContext( node.getRequestContext() );
         setManagedBits( node.getManagedBits() );
         setRelocations( node.getRelocations() );
         setRepositories( node.getRepositories() );
         setVersion( node.getVersion() );
         setVersionConstraint( node.getVersionConstraint() );
         Map<?, ?> data = node.getData();
         setData( data.isEmpty() ? null : new HashMap<>( data ) );
     }
 
     public List<DependencyNode> getChildren()
     {
         return children;
     }
 
     public void setChildren( List<DependencyNode> children )
     {
         if ( children == null )
         {
             this.children = new ArrayList<>( 0 );
         }
         else
         {
             this.children = children;
         }
     }
 
     public Dependency getDependency()
     {
         return dependency;
     }
 
     public Artifact getArtifact()
     {
         return artifact;
     }
 
     public void setArtifact( Artifact artifact )
     {
         if ( dependency == null )
         {
             throw new IllegalStateException( "node does not have a dependency" );
         }
         dependency = dependency.setArtifact( artifact );
         this.artifact = dependency.getArtifact();
     }
 
     public List<? extends Artifact> getRelocations()
     {
         return relocations;
     }
 
     /**
      * Sets the sequence of relocations that was followed to resolve this dependency's artifact.
      * 
      * @param relocations The sequence of relocations, may be {@code null}.
      */
     public void setRelocations( List<? extends Artifact> relocations )
     {
         if ( relocations == null || relocations.isEmpty() )
         {
             this.relocations = Collections.emptyList();
         }
         else
         {
             this.relocations = relocations;
         }
     }
 
     public Collection<? extends Artifact> getAliases()
     {
         return aliases;
     }
 
     /**
      * Sets the known aliases for this dependency's artifact.
      * 
      * @param aliases The known aliases, may be {@code null}.
      */
     public void setAliases( Collection<? extends Artifact> aliases )
     {
         if ( aliases == null || aliases.isEmpty() )
         {
             this.aliases = Collections.emptyList();
         }
         else
         {
             this.aliases = aliases;
         }
     }
 
     public VersionConstraint getVersionConstraint()
     {
         return versionConstraint;
     }
 
     /**
      * Sets the version constraint that was parsed from the dependency's version declaration.
      * 
      * @param versionConstraint The version constraint for this node, may be {@code null}.
      */
     public void setVersionConstraint( VersionConstraint versionConstraint )
     {
         this.versionConstraint = versionConstraint;
     }
 
     public Version getVersion()
     {
         return version;
     }
 
     /**
      * Sets the version that was selected for the dependency's target artifact.
      * 
      * @param version The parsed version, may be {@code null}.
      */
     public void setVersion( Version version )
     {
         this.version = version;
     }
 
     public void setScope( String scope )
     {
         if ( dependency == null )
         {
             throw new IllegalStateException( "node does not have a dependency" );
         }
         dependency = dependency.setScope( scope );
     }
 
     public void setOptional( Boolean optional )
     {
         if ( dependency == null )
         {
             throw new IllegalStateException( "node does not have a dependency" );
         }
         dependency = dependency.setOptional( optional );
     }
 
     public int getManagedBits()
     {
         return managedBits;
     }
 
     /**
      * Sets a bit field indicating which attributes of this node were subject to dependency management.
      * 
      * @param managedBits The bit field indicating the managed attributes or {@code 0} if dependency management wasn't
      *            applied.
      */
     public void setManagedBits( int managedBits )
     {
         this.managedBits = (byte) ( managedBits & 0x1F );
     }
 
     public List<RemoteRepository> getRepositories()
     {
         return repositories;
     }
 
     /**
      * Sets the remote repositories from which this node's artifact shall be resolved.
      * 
      * @param repositories The remote repositories to use for artifact resolution, may be {@code null}.
      */
     public void setRepositories( List<RemoteRepository> repositories )
     {
         if ( repositories == null || repositories.isEmpty() )
         {
             this.repositories = Collections.emptyList();
         }
         else
         {
             this.repositories = repositories;
         }
     }
 
     public String getRequestContext()
     {
         return context;
     }
 
     public void setRequestContext( String context )
     {
         this.context = ( context != null ) ? context : "";
     }
 
     public Map<Object, Object> getData()
     {
         return data;
     }
 
     public void setData( Map<Object, Object> data )
     {
         if ( data == null )
         {
             this.data = Collections.emptyMap();
         }
         else
         {
             this.data = data;
         }
     }
 
     public void setData( Object key, Object value )
     {
         requireNonNull( key, "key cannot be null" );
 
         if ( value == null )
         {
             if ( !data.isEmpty() )
             {
                 data.remove( key );
 
                 if ( data.isEmpty() )
                 {
                     data = Collections.emptyMap();
                 }
             }
         }
         else
         {
             if ( data.isEmpty() )
             {
                 data = new HashMap<>( 1, 2 ); // nodes can be numerous so let's be space conservative
             }
             data.put( key, value );
         }
     }
 
     public boolean accept( DependencyVisitor visitor )
     {
         if ( visitor.visitEnter( this ) )
         {
             for ( DependencyNode child : children )
             {
                 if ( !child.accept( visitor ) )
                 {
                     break;
                 }
             }
         }
 
         return visitor.visitLeave( this );
     }
 
     @Override
     public String toString()
     {
         Dependency dep = getDependency();
         if ( dep == null )
         {
             return String.valueOf( getArtifact() );
         }
         return dep.toString();
     }
 
 }