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.Collection;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  
  import org.apache.maven.api.settings.IdentifiableBase;
  import org.apache.maven.api.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 Settings merge( Settings dominant, Settings recessive, String recessiveSourceLevel )
      {
          if ( dominant == null )
          {
              return recessive;
          }
          else if ( recessive == null )
          {
              return dominant;
          }
  
          recessive.setSourceLevel( recessiveSourceLevel );
  
          Settings.Builder merged = Settings.newBuilder( dominant );
  
          List<String> dominantActiveProfiles = dominant.getActiveProfiles();
          List<String> recessiveActiveProfiles = recessive.getActiveProfiles();
          List<String> mergedActiveProfiles = Stream.of( dominantActiveProfiles, recessiveActiveProfiles )
                      .flatMap( Collection::stream )
                      .distinct()
                      .collect( Collectors.toList() );
          merged.activeProfiles( mergedActiveProfiles );
  
          List<String> dominantPluginGroupIds = dominant.getPluginGroups();
          List<String> recessivePluginGroupIds = recessive.getPluginGroups();
          List<String> mergedPluginGroupIds = Stream.of( dominantPluginGroupIds, recessivePluginGroupIds )
                  .flatMap( Collection::stream )
                  .distinct()
                  .collect( Collectors.toList() );
          merged.pluginGroups( mergedPluginGroupIds );
  
          String localRepository = StringUtils.isEmpty( dominant.getLocalRepository() )
                  ? recessive.getLocalRepository() : dominant.getLocalRepository();
          merged.localRepository( localRepository );
  
          merged.mirrors( shallowMergeById( dominant.getMirrors(), recessive.getMirrors(), recessiveSourceLevel ) );
          merged.servers( shallowMergeById( dominant.getServers(), recessive.getServers(), recessiveSourceLevel ) );
          merged.proxies( shallowMergeById( dominant.getProxies(), recessive.getProxies(), recessiveSourceLevel ) );
          merged.profiles( shallowMergeById( dominant.getProfiles(), recessive.getProfiles(), recessiveSourceLevel ) );
  
          return merged.build();
      }
  
      /**
       * @param dominant
       * @param recessive
       * @param recessiveSourceLevel
       */
      private static <T extends IdentifiableBase> List<T> shallowMergeById(
              List<T> dominant, List<T> recessive, String recessiveSourceLevel )
      {
          Set<String> dominantIds = dominant.stream().map( IdentifiableBase::getId ).collect( Collectors.toSet() );
          final List<T> merged = new ArrayList<>( dominant.size() + recessive.size() );
         merged.addAll( dominant );
         for ( T identifiable : recessive )
         {
             if ( !dominantIds.contains( identifiable.getId() ) )
             {
                 identifiable.setSourceLevel( recessiveSourceLevel );
                 merged.add( identifiable );
             }
         }
         return merged;
     }
 
     /**
      * @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;
     }
 
 }