package org.eclipse.aether.internal.impl;
   
   /*
    * 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.Collections;
  import java.util.ConcurrentModificationException;
  import java.util.Iterator;
  import java.util.List;
  import java.util.NoSuchElementException;
  
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.collection.VersionFilter;
  import org.eclipse.aether.graph.Dependency;
  import org.eclipse.aether.repository.ArtifactRepository;
  import org.eclipse.aether.repository.RemoteRepository;
  import org.eclipse.aether.resolution.VersionRangeResult;
  import org.eclipse.aether.version.Version;
  import org.eclipse.aether.version.VersionConstraint;
  
  /**
   * @see DefaultDependencyCollector
   */
  final class DefaultVersionFilterContext
      implements VersionFilter.VersionFilterContext
  {
  
      private final Iterator<Version> EMPTY = Collections.<Version>emptySet().iterator();
  
      private final RepositorySystemSession session;
  
      private Dependency dependency;
  
      VersionRangeResult result;
  
      int count;
  
      byte[] deleted = new byte[64];
  
      DefaultVersionFilterContext( RepositorySystemSession session )
      {
          this.session = session;
      }
  
      public void set( Dependency dependency, VersionRangeResult result )
      {
          this.dependency = dependency;
          this.result = result;
          count = result.getVersions().size();
          if ( deleted.length < count )
          {
              deleted = new byte[count];
          }
          else
          {
              for ( int i = count - 1; i >= 0; i-- )
              {
                  deleted[i] = (byte) 0;
              }
          }
      }
  
      public List<Version> get()
      {
          if ( count == result.getVersions().size() )
          {
              return result.getVersions();
          }
          if ( count <= 1 )
          {
              if ( count <= 0 )
              {
                  return Collections.emptyList();
              }
              return Collections.singletonList( iterator().next() );
          }
          List<Version> versions = new ArrayList<Version>( count );
          for ( Version version : this )
          {
              versions.add( version );
          }
          return versions;
     }
 
     public RepositorySystemSession getSession()
     {
         return session;
     }
 
     public Dependency getDependency()
     {
         return dependency;
     }
 
     public VersionConstraint getVersionConstraint()
     {
         return result.getVersionConstraint();
     }
 
     public int getCount()
     {
         return count;
     }
 
     public ArtifactRepository getRepository( Version version )
     {
         return result.getRepository( version );
     }
 
     public List<RemoteRepository> getRepositories()
     {
         return Collections.unmodifiableList( result.getRequest().getRepositories() );
     }
 
     public Iterator<Version> iterator()
     {
         return ( count > 0 ) ? new VersionIterator() : EMPTY;
     }
 
     @Override
     public String toString()
     {
         return dependency + " " + result.getVersions();
     }
 
     private class VersionIterator
         implements Iterator<Version>
     {
 
         private final List<Version> versions;
 
         private final int size;
 
         private int count;
 
         private int index;
 
         private int next;
 
         VersionIterator()
         {
             count = DefaultVersionFilterContext.this.count;
             index = -1;
             next = 0;
             versions = result.getVersions();
             size = versions.size();
             advance();
         }
 
         private void advance()
         {
             for ( next = index + 1; next < size && deleted[next] != (byte) 0; next++ )
             {
                 // just advancing index
             }
         }
 
         public boolean hasNext()
         {
             return next < size;
         }
 
         public Version next()
         {
             if ( count != DefaultVersionFilterContext.this.count )
             {
                 throw new ConcurrentModificationException();
             }
             if ( next >= size )
             {
                 throw new NoSuchElementException();
             }
             index = next;
             advance();
             return versions.get( index );
         }
 
         public void remove()
         {
             if ( count != DefaultVersionFilterContext.this.count )
             {
                 throw new ConcurrentModificationException();
             }
             if ( index < 0 || deleted[index] == (byte) 1 )
             {
                 throw new IllegalStateException();
             }
             deleted[index] = (byte) 1;
             count = --DefaultVersionFilterContext.this.count;
         }
 
         @Override
         public String toString()
         {
             return ( index < 0 ) ? "null" : String.valueOf( versions.get( index ) );
         }
 
     }
 
 }