package org.eclipse.aether.util.graph.selector;
   
   /*
    * 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.collection.DependencyCollectionContext;
  import org.eclipse.aether.collection.DependencySelector;
  import org.eclipse.aether.graph.Dependency;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * A dependency selector that excludes optional dependencies which occur beyond level one of the dependency graph.
   * 
   * @see Dependency#isOptional()
   */
  public final class OptionalDependencySelector
      implements DependencySelector
  {
  
      private final int depth;
  
      /**
       * Creates a new selector to exclude optional transitive dependencies.
       */
      public OptionalDependencySelector()
      {
          depth = 0;
      }
  
      private OptionalDependencySelector( int depth )
      {
          this.depth = depth;
      }
  
      public boolean selectDependency( Dependency dependency )
      {
          requireNonNull( dependency, "dependency cannot be null" );
          return depth < 2 || !dependency.isOptional();
      }
  
      public DependencySelector deriveChildSelector( DependencyCollectionContext context )
      {
          requireNonNull( context, "context cannot be null" );
          if ( depth >= 2 )
          {
              return this;
          }
  
          return new OptionalDependencySelector( depth + 1 );
      }
  
      @Override
      public boolean equals( Object obj )
      {
          if ( this == obj )
          {
              return true;
          }
          else if ( null == obj || !getClass().equals( obj.getClass() ) )
          {
              return false;
          }
  
          OptionalDependencySelector that = (OptionalDependencySelector) obj;
          return depth == that.depth;
      }
  
      @Override
      public int hashCode()
      {
          int hash = getClass().hashCode();
          hash = hash * 31 + depth;
          return hash;
      }
  
      @Override
      public String toString()
      {
          return String.format( "%s(depth: %d)", this.getClass().getSimpleName(), this.depth );
      }
  
  }