package org.apache.fulcrum.yaafi.service.advice;
   
   /*
    * 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 org.apache.avalon.framework.configuration.Configuration;
  import org.apache.avalon.framework.configuration.ConfigurationException;
  import org.apache.avalon.framework.configuration.Reconfigurable;
  import org.apache.avalon.framework.context.Context;
  import org.apache.avalon.framework.context.ContextException;
  import org.apache.avalon.framework.context.Contextualizable;
  import org.apache.avalon.framework.logger.AbstractLogEnabled;
  import org.apache.avalon.framework.service.ServiceException;
  import org.apache.avalon.framework.service.ServiceManager;
  import org.apache.avalon.framework.service.Serviceable;
  import org.apache.fulcrum.yaafi.framework.interceptor.AvalonInterceptorFactory;
  import org.apache.fulcrum.yaafi.framework.interceptor.AvalonInterceptorInvocationHandler;
  import org.apache.fulcrum.yaafi.framework.util.Validate;
  
  /**
   * Simple service providing interceptor advices for ordinary POJOs. Since the
   * implementation uses Dynamic Proxies only methods invoked by an interface can
   * be advised.
   *
   * @author <a href="mailto:siegfried.goeschl@it20one.at">Siegfried Goeschl</a>
   */
  
  public class AdviceServiceImpl extends AbstractLogEnabled
  		implements AdviceService, Serviceable, Contextualizable, Reconfigurable {
  	/** the service manager supplied by the Avalon framework */
  	private ServiceManager serviceManager;
  
  	/** the list of default interceptors */
  	private String[] defaultInterceptorList;
  
  	/////////////////////////////////////////////////////////////////////////
  	// Avalon Service Lifecycle Implementation
  	/////////////////////////////////////////////////////////////////////////
  
  	/**
  	 * @see org.apache.avalon.framework.service.Serviceable#service(org.apache.avalon.framework.service.ServiceManager)
  	 */
  	public void service(ServiceManager serviceManager) throws ServiceException {
  		this.serviceManager = serviceManager;
  	}
  
  	/**
  	 * @see org.apache.avalon.framework.context.Contextualizable#contextualize(org.apache.avalon.framework.context.Context)
  	 */
  	public void contextualize(Context context) throws ContextException {
  		// nothing to do
  	}
  
  	/**
  	 * @see org.apache.avalon.framework.configuration.Configurable#configure(org.apache.avalon.framework.configuration.Configuration)
  	 */
  	public void configure(Configuration configuration) throws ConfigurationException {
  		Configuration[] interceptorConfigList = configuration.getChild("interceptors").getChildren("interceptor");
  		this.defaultInterceptorList = new String[interceptorConfigList.length];
  		for (int i = 0; i < interceptorConfigList.length; i++) {
  			this.defaultInterceptorList[i] = interceptorConfigList[i].getValue();
  		}
  	}
  
  	/**
  	 * @see org.apache.avalon.framework.configuration.Reconfigurable#reconfigure(org.apache.avalon.framework.configuration.Configuration)
  	 */
  	public void reconfigure(Configuration configuration) throws ConfigurationException {
  		this.configure(configuration);
  	}
  
  	/////////////////////////////////////////////////////////////////////////
  	// Service interface implementation
  	/////////////////////////////////////////////////////////////////////////
  
  	/**
  	 * @see org.apache.fulcrum.yaafi.service.advice.AdviceService#advice(java.lang.Object)
  	 */
  	public Object advice(Object object) {
  		Validate.notNull(object, "object");
 		return this.advice(this.getDefaultInterceptorList(), object);
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * 
 	 * @see org.apache.fulcrum.yaafi.service.advice.AdviceService#advice(java.lang.
 	 * String, java.lang.Object)
 	 */
 	public Object advice(String name, Object object) {
 		Validate.notNull(object, "object");
 		return this.doAdvice(name, this.getDefaultInterceptorList(), object);
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * 
 	 * @see
 	 * org.apache.fulcrum.yaafi.service.advice.AdviceService#advice(java.lang.String
 	 * [], java.lang.Object)
 	 */
 	public Object advice(String[] interceptorList, Object object) {
 		Validate.notNull(object, "object");
 		String className = object.getClass().getName();
 		return this.doAdvice(className, interceptorList, object);
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * 
 	 * @see org.apache.fulcrum.yaafi.service.advice.AdviceService#advice(java.lang.
 	 * String, java.lang.String[], java.lang.Object)
 	 */
 	public Object advice(String name, String[] interceptorList, Object object) {
 		Validate.notNull(object, "object");
 		return this.doAdvice(name, interceptorList, object);
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * 
 	 * @see
 	 * org.apache.fulcrum.yaafi.service.advice.AdviceService#isAdviced(java.lang.
 	 * Object)
 	 */
 	public boolean isAdviced(Object object) {
 		InvocationHandler invocationHandler = null;
 
 		if (object != null && Proxy.isProxyClass(object.getClass())) {
 			invocationHandler = Proxy.getInvocationHandler(object);
 			return invocationHandler instanceof AvalonInterceptorInvocationHandler;
 		}
 
 		return false;
 	}
 
 	/////////////////////////////////////////////////////////////////////////
 	// Service implementation
 	/////////////////////////////////////////////////////////////////////////
 
 	/**
 	 * Does the actual work of advising the object.
 	 *
 	 * @param name            the name of the object to be advised
 	 * @param interceptorList the list of interceptor services to advise the object
 	 * @param object          the object to be advised
 	 * @return the advised object.
 	 */
 	protected Object doAdvice(String name, String[] interceptorList, Object object) {
 		Validate.notEmpty(name, "name");
 		Validate.notNull(interceptorList, "interceptorList");
 		Validate.notNull(object, "object");
 
 		Object result = null;
 		String clazzName = object.getClass().getName();
 
 		// do nothing if no interceptor services are requested
 
 		if (interceptorList.length == 0) {
 			if (this.getLogger().isInfoEnabled()) {
 				String msg = "Skipping creation of dynamic proxy since no interceptors are requested : " + name;
 				this.getLogger().info(msg);
 			}
 
 			return object;
 		}
 
 		// skip creating a dynamic proxy if it is already advised
 
 		if (this.isAdviced(object)) {
 			if (this.getLogger().isInfoEnabled()) {
 				String msg = "Skipping creation of dynamic proxy since it is already advised : " + name;
 				this.getLogger().info(msg);
 			}
 
 			return object;
 		}
 
 		// create the advised object
 
 		try {
 			result = AvalonInterceptorFactory.create(clazzName, name, this.getServiceManager(), interceptorList,
 					object);
 		} catch (ServiceException e) {
 			String msg = "Unable to advice the object : " + name;
 			this.getLogger().error(msg, e);
 			throw new IllegalArgumentException(msg);
 		}
 
 		return result;
 	}
 
 	/**
 	 * @return Returns the serviceManager.
 	 */
 	private ServiceManager getServiceManager() {
 		return serviceManager;
 	}
 
 	/**
 	 * @return Returns the defaultInterceptorList.
 	 */
 	private String[] getDefaultInterceptorList() {
 		return defaultInterceptorList;
 	}
 }