package org.eclipse.aether.util.graph.version;

/*
 * 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.Iterator;

import org.eclipse.aether.collection.DependencyCollectionContext;
import org.eclipse.aether.collection.VersionFilter;
import org.eclipse.aether.version.Version;

/**
 * A version filter that excludes any version except the highest one.
 */
public final class HighestVersionFilter
    implements VersionFilter
{

    /**
     * Creates a new instance of this version filter.
     */
    public HighestVersionFilter()
    {
    }

    public void filterVersions( VersionFilterContext context )
    {
        Iterator<Version> it = context.iterator();
        for ( boolean hasNext = it.hasNext(); hasNext; )
        {
            it.next();
            if ( hasNext = it.hasNext() )
            {
                it.remove();
            }
        }
    }

    public VersionFilter deriveChildFilter( DependencyCollectionContext context )
    {
        return this;
    }

    @Override
    public boolean equals( Object obj )
    {
        if ( this == obj )
        {
            return true;
        }
        else if ( null == obj || !getClass().equals( obj.getClass() ) )
        {
            return false;
        }
        return true;
    }

    @Override
    public int hashCode()
    {
        return getClass().hashCode();
    }

}