/*
    * 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.
   */
  package org.apache.maven.toolchain.merge;
  
  import java.util.ArrayList;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import org.apache.maven.api.toolchain.PersistedToolchains;
  import org.apache.maven.api.toolchain.ToolchainModel;
  import org.apache.maven.api.xml.Dom;
  
  /**
   *
   * @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;
      }
  }