/*
    * Copyright 2009 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.ksb.messaging;
  
  import java.lang.reflect.InvocationHandler;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.lang.reflect.Proxy;
  
  import javax.xml.namespace.QName;
  
  import org.apache.log4j.Logger;
  import org.kuali.rice.core.resourceloader.GlobalResourceLoader;
  import org.kuali.rice.core.util.ExceptionUtils;
  
  /**
   * This class creates a proxy for services deployed on KSB. A 
   * reference to the service is obtained only upon the first method
   * invocation.
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
   *
   */
  public class KSBClientProxy implements InvocationHandler {
  
  private static final Logger LOG = Logger.getLogger(KSBClientProxy.class);
      
      QName serviceName;
      Object service;
  
      @SuppressWarnings("unchecked")
      public static <T> T newInstance(String serviceQName, Class<T> interfaceClass) throws InstantiationException, IllegalAccessException {
          return (T)Proxy.newProxyInstance(interfaceClass.getClassLoader(), new Class[] { interfaceClass }, new KSBClientProxy(serviceQName));
      }
  
      public KSBClientProxy(String serviceQName){
          this.serviceName = QName.valueOf(serviceQName);
      }
      
      public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
          if (this.service == null){
              LOG.info("Getting service using GRL for: " + serviceName);
              service = GlobalResourceLoader.getService(serviceName);
              LOG.info("Obtained service using GRL for: " + serviceName);
          }
          try {
  	        return method.invoke(service, args);
  	    } catch (InvocationTargetException e) {
  	        throw ExceptionUtils.unwrapActualCause(e);
  	    }
      }
  
  }