package org.apache.fulcrum.yaafi.framework.interceptor;
   
   /*
    * 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.lang.reflect.InvocationHandler;
  import java.lang.reflect.Proxy;
  import java.util.List;
  
  import org.apache.avalon.framework.service.ServiceException;
  import org.apache.avalon.framework.service.ServiceManager;
  import org.apache.fulcrum.yaafi.framework.constant.AvalonYaafiConstants;
  import org.apache.fulcrum.yaafi.framework.reflection.Clazz;
  import org.apache.fulcrum.yaafi.framework.util.Validate;
  
  
  /**
   * A factory for creating dynamic proxies for Avalon services.
   *
   * @author <a href="mailto:siegfried.goeschl@it20one.at">Siegfried Goeschl</a>
   */
  
  public class AvalonInterceptorFactory
  {
      /**
       * Creates a dynamic proxy wrapping a service instance.
       *
       * @param serviceName the name of the service
       * @param serviceShorthand the shorthand of the service being intercepted
       * @param serviceManager the corresponding service manager
       * @param serviceInterceptorList the list of interceptors to be installed
       * @param serviceDelegate the service implementation
       * @return a dynamic proxy
       * @throws ServiceException an interceptor was not found
       */
      public static Object create(
          String serviceName,
          String serviceShorthand,
          ServiceManager serviceManager,
          String[] serviceInterceptorList,
          Object serviceDelegate )
          throws ServiceException
      {
          Validate.notEmpty(serviceName,"serviceName");
          Validate.notEmpty(serviceShorthand,"serviceShorthand");
          Validate.notNull(serviceManager,"serviceManager");
          Validate.notNull(serviceInterceptorList,"serviceInterceptorList");
          Validate.notNull(serviceDelegate,"serviceDelegate");
  
          Object result;
  
          Class<? extends Object> clazz = serviceDelegate.getClass();
          ClassLoader classLoader = clazz.getClassLoader();
          List<?> interfaceList = Clazz.getAllInterfaces(clazz);
  
          // get the service interfaces to avoid look-ups
  
          AvalonInterceptorService[] avalonInterceptorServices = resolve(
              serviceManager,
              serviceInterceptorList
              );
  
          InvocationHandler invocationHandler = new AvalonInterceptorInvocationHandler(
              serviceName,
              serviceShorthand,
              serviceDelegate,
              avalonInterceptorServices
              );
  
          result = Proxy.newProxyInstance(
              classLoader,
              (Class[]) interfaceList.toArray(new Class[interfaceList.size()]),
              invocationHandler
              );
  
          return result;
      }
  
      /**
       * Resolve all interceptor service names to service interfaces.
       *
       * @param serviceManager to lookup the services
       * @param interceptorList the list of service names
      * @return a list of interceptor services
      * @throws ServiceException an interceptor service was not found
      */
     private static AvalonInterceptorService[] resolve( ServiceManager serviceManager, String[] interceptorList )
         throws ServiceException
     {
         String interceptorServiceName;
         AvalonInterceptorService[] result = new AvalonInterceptorService[interceptorList.length];
 
         for( int i=0; i<interceptorList.length; i++ )
         {
             interceptorServiceName = interceptorList[i];
             Object currService = serviceManager.lookup(interceptorServiceName);
 
             if (currService instanceof AvalonInterceptorService)
             {
                 result[i] = (AvalonInterceptorService) currService;
             }
             else
             {
                 String msg = "The following service is not an AvalonInterceptorService : " + interceptorServiceName;
                 throw new ServiceException(AvalonYaafiConstants.AVALON_CONTAINER_YAAFI,msg);
             }
         }
 
         return result;
     }
 }