package org.apache.maven.toolchain.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.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.maven.api.xml.Dom;
  import org.apache.maven.api.toolchain.PersistedToolchains;
  import org.apache.maven.api.toolchain.ToolchainModel;
  
  /**
   *
   * @author Robert Scholte
   * @since 3.2.4
   */
  public class MavenToolchainMerger
  {
  
      public PersistedToolchains merge( PersistedToolchains dominant, PersistedToolchains recessive,
                                        String recessiveSourceLevel )
      {
          if ( dominant == null || recessive == null )
          {
              return dominant;
          }
  
          recessive.setSourceLevel( recessiveSourceLevel );
  
          return shallowMerge( dominant.getToolchains(), recessive.getToolchains(), recessiveSourceLevel );
      }
  
      private PersistedToolchains shallowMerge( List<ToolchainModel> dominant, List<ToolchainModel> recessive,
                                 String recessiveSourceLevel )
      {
          Map<Object, ToolchainModel> merged = new LinkedHashMap<>();
  
          for ( ToolchainModel dominantModel : dominant )
          {
              Object key = getToolchainModelKey( dominantModel );
  
              merged.put( key, dominantModel );
          }
  
          for ( ToolchainModel recessiveModel : recessive )
          {
              Object key = getToolchainModelKey( recessiveModel );
  
              ToolchainModel dominantModel = merged.get( key );
              if ( dominantModel == null )
              {
                  recessiveModel.setSourceLevel( recessiveSourceLevel );
                  merged.put( key, recessiveModel );
              }
              else
              {
                  merged.put( key, mergeToolchainModelConfiguration( dominantModel, recessiveModel ) );
              }
          }
          return PersistedToolchains.newBuilder()
                  .toolchains( new ArrayList<>( merged.values() ) )
                  .build();
      }
  
      protected ToolchainModel mergeToolchainModelConfiguration( ToolchainModel target,
                                                                 ToolchainModel source )
      {
          Dom src = source.getConfiguration();
          Dom tgt = target.getConfiguration();
          Dom merged = Dom.merge( tgt, src );
          return target.withConfiguration( merged );
      }
  
      protected Object getToolchainModelKey( ToolchainModel model )
      {
          return model;
      }
  
  }