/*
    * Copyright (C) 2007 the original author or authors.
    *
    * Licensed 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.codehaus.plexus.metadata;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import org.codehaus.plexus.component.repository.ComponentDescriptor;
  
  /**
   * Support for {@link ComponentDescriptorExtractor} implementations.
   *
   */
  public abstract class ComponentDescriptorExtractorSupport implements ComponentDescriptorExtractor {
      protected Map<String, ComponentDescriptor<?>> getDefaultsByRole(final ComponentDescriptor<?>[] roleDefaults) {
          Map<String, ComponentDescriptor<?>> defaultsByRole = new HashMap<String, ComponentDescriptor<?>>();
  
          if (roleDefaults != null) {
              for (ComponentDescriptor<?> roleDefault : roleDefaults) {
                  String role = roleDefault.getRole();
  
                  if (role == null) {
                      throw new IllegalArgumentException("Invalid role defaults; found null role in: " + roleDefault);
                  }
  
                  defaultsByRole.put(role, roleDefault);
              }
          }
  
          return defaultsByRole;
      }
  
      protected void applyDefaults(
              ComponentDescriptor<?> descriptor, Map<String, ComponentDescriptor<?>> defaultsByRole) {
          assert descriptor != null;
          assert defaultsByRole != null;
  
          if (defaultsByRole.containsKey(descriptor.getRole())) {
              ComponentDescriptor<?> defaults = defaultsByRole.get(descriptor.getRole());
  
              if (descriptor.getInstantiationStrategy() == null) {
                  descriptor.setInstantiationStrategy(defaults.getInstantiationStrategy());
              }
          }
      }
  }