/*
    * 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.model.superpom;
  
  import javax.inject.Inject;
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Objects;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.apache.maven.api.model.InputSource;
  import org.apache.maven.model.Model;
  import org.apache.maven.model.building.ModelProcessor;
  
  /**
   * Provides the super POM that all models implicitly inherit from.
   *
   */
  @Named
  @Singleton
  public class DefaultSuperPomProvider implements SuperPomProvider {
  
      private final ModelProcessor modelProcessor;
  
      /**
       * The cached super POM, lazily created.
       */
      private static final Map<String, Model> SUPER_MODELS = new ConcurrentHashMap<>();
  
      @Inject
      public DefaultSuperPomProvider(ModelProcessor modelProcessor) {
          this.modelProcessor = modelProcessor;
      }
  
      @Override
      public Model getSuperModel(String version) {
          return SUPER_MODELS.computeIfAbsent(Objects.requireNonNull(version), v -> {
              String resource = "/org/apache/maven/model/pom-" + v + ".xml";
  
              InputStream is = getClass().getResourceAsStream(resource);
  
              if (is == null) {
                  throw new IllegalStateException("The super POM " + resource + " was not found"
                          + ", please verify the integrity of your Maven installation");
              }
  
              try {
                  Map<String, Object> options = new HashMap<>(2);
                  options.put("xml:" + version, "xml:" + version);
  
                  String modelId = "org.apache.maven:maven-model-builder:" + version + "-"
                          + this.getClass().getPackage().getImplementationVersion() + ":super-pom";
                  InputSource inputSource = new InputSource(
                          modelId, getClass().getResource(resource).toExternalForm());
                  options.put(ModelProcessor.INPUT_SOURCE, new org.apache.maven.model.InputSource(inputSource));
  
                  return modelProcessor.read(is, options);
              } catch (IOException e) {
                  throw new IllegalStateException(
                          "The super POM " + resource + " is damaged"
                                  + ", please verify the integrity of your Maven installation",
                          e);
              }
          });
      }
  }