package org.apache.maven.plugin.internal;
   
   /*
    * 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 org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.collection.DependencyCollectionContext;
  import org.eclipse.aether.collection.DependencySelector;
  import org.eclipse.aether.graph.Dependency;
  
  /**
   * Assists in detecting wagon providers brought into the plugin class path via legacy Maven core artifacts (e.g.
   * maven-core:2.0.6) and excluding them. A plugin should be able to explicitly declare dependencies on specific wagons
   * for its use. However, the (old) wagons pulled in transitively via legacy Maven core artifacts are usually not
   * intended as dependencies and more importantly screw up artifact resolution because they would get preferred over the
   * core wagon versions. This is a hack to provide backward-compat with Maven 2 (MNG-4528, MNG-4561).
   * 
   * @author Benjamin Bentmann
   */
  class WagonExcluder
      implements DependencySelector
  {
  
      private final boolean coreArtifact;
  
      public WagonExcluder()
      {
          this( false );
      }
  
      private WagonExcluder( boolean coreArtifact )
      {
          this.coreArtifact = coreArtifact;
      }
  
      public boolean selectDependency( Dependency dependency )
      {
          return !coreArtifact || !isWagonProvider( dependency.getArtifact() );
      }
  
      public DependencySelector deriveChildSelector( DependencyCollectionContext context )
      {
          if ( coreArtifact || !isLegacyCoreArtifact( context.getDependency().getArtifact() ) )
          {
              return this;
          }
          else
          {
              return new WagonExcluder( true );
          }
      }
  
      private boolean isLegacyCoreArtifact( Artifact artifact )
      {
          String version = artifact.getVersion();
          return version != null && version.startsWith( "2." ) && artifact.getArtifactId().startsWith( "maven-" )
              && artifact.getGroupId().equals( "org.apache.maven" );
      }
  
      private boolean isWagonProvider( Artifact artifact )
      {
          if ( "org.apache.maven.wagon".equals( artifact.getGroupId() ) )
          {
              return artifact.getArtifactId().startsWith( "wagon-" );
          }
          return false;
      }
  
      @Override
      public boolean equals( Object obj )
      {
          if ( obj == this )
          {
              return true;
          }
          else if ( obj == null || !getClass().equals( obj.getClass() ) )
          {
              return false;
          }
  
          WagonExcluder that = (WagonExcluder) obj;
          return coreArtifact == that.coreArtifact;
      }
 
     @Override
     public int hashCode()
     {
         int hash = getClass().hashCode();
         hash = hash * 31 + ( coreArtifact ? 1 : 0 );
         return hash;
     }
 
 }