maven-settings-builder/src/main/java/org/apache/maven/settings/merge/MavenSettingsMerger.java

package org.apache.maven.settings.merge;

/*
 * 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.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.maven.settings.IdentifiableBase;
import org.apache.maven.settings.Settings;
import org.codehaus.plexus.util.StringUtils;

/**
 * @author <a href="mailto:vincent.siveton@gmail.com">Vincent Siveton</a>
 * @author Benjamin Bentmann
 */
public class MavenSettingsMerger
{

    /**
     * @param dominant
     * @param recessive
     * @param recessiveSourceLevel
     */
    public void merge( Settings dominant, Settings recessive, String recessiveSourceLevel )
    {
        if ( dominant == null || recessive == null )
        {
            return;
        }

        recessive.setSourceLevel( recessiveSourceLevel );

        List<String> dominantActiveProfiles = dominant.getActiveProfiles();
        List<String> recessiveActiveProfiles = recessive.getActiveProfiles();

        if ( recessiveActiveProfiles != null )
        {
            if ( dominantActiveProfiles == null )
            {
                dominantActiveProfiles = new ArrayList<>();
                dominant.setActiveProfiles( dominantActiveProfiles );
            }

            for ( String profileId : recessiveActiveProfiles )
            {
                if ( !dominantActiveProfiles.contains( profileId ) )
                {
                    dominantActiveProfiles.add( profileId );
                }
            }
        }

        List<String> dominantPluginGroupIds = dominant.getPluginGroups();

        List<String> recessivePluginGroupIds = recessive.getPluginGroups();

        if ( recessivePluginGroupIds != null )
        {
            if ( dominantPluginGroupIds == null )
            {
                dominantPluginGroupIds = new ArrayList<>();
                dominant.setPluginGroups( dominantPluginGroupIds );
            }

            for ( String pluginGroupId : recessivePluginGroupIds )
            {
                if ( !dominantPluginGroupIds.contains( pluginGroupId ) )
                {
                    dominantPluginGroupIds.add( pluginGroupId );
                }
            }
        }

        if ( StringUtils.isEmpty( dominant.getLocalRepository() ) )
        {
            dominant.setLocalRepository( recessive.getLocalRepository() );
        }

        shallowMergeById( dominant.getMirrors(), recessive.getMirrors(), recessiveSourceLevel );
        shallowMergeById( dominant.getServers(), recessive.getServers(), recessiveSourceLevel );
        shallowMergeById( dominant.getProxies(), recessive.getProxies(), recessiveSourceLevel );
        shallowMergeById( dominant.getProfiles(), recessive.getProfiles(), recessiveSourceLevel );

    }

    /**
     * @param dominant
     * @param recessive
     * @param recessiveSourceLevel
     */
    private static <T extends IdentifiableBase> void shallowMergeById( List<T> dominant, List<T> recessive,
                                                                       String recessiveSourceLevel )
    {
        Map<String, T> dominantById = mapById( dominant );
        final List<T> identifiables = new ArrayList<>( recessive.size() );

        for ( T identifiable : recessive )
        {
            if ( !dominantById.containsKey( identifiable.getId() ) )
            {
                identifiable.setSourceLevel( recessiveSourceLevel );

                identifiables.add( identifiable );
            }
        }

        dominant.addAll( 0, identifiables );
    }

    /**
     * @param identifiables
     * @return a map
     */
    private static <T extends IdentifiableBase> Map<String, T> mapById( List<T> identifiables )
    {
        Map<String, T> byId = new HashMap<>();

        for ( T identifiable : identifiables )
        {
            byId.put( identifiable.getId(), identifiable );
        }

        return byId;
    }

}