/*
    * 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.jetspeed.ajax;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.Reader;
  import java.io.StringWriter;
  import java.lang.reflect.Method;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Properties;
  
  import javax.servlet.ServletOutputStream;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.velocity.VelocityContext;
  import org.apache.velocity.app.VelocityEngine;
  import org.apache.velocity.context.Context;
  import org.springframework.beans.BeansException;
  import org.springframework.beans.factory.BeanFactory;
  import org.springframework.beans.factory.BeanFactoryAware;
  
  /***
   * Performs invocation of the actual AJAX request and returns
   * a result object to converted into XML.
   * 
   * @author <href a="mailto:weaver@apache.org">Scott T. Weaver</a>
   *
   */
  public class AJAXServiceImpl implements AJAXService, BeanFactoryAware
  {
      private Map serviceToBeans;
      private Map serviceToTemplates;
  
      private BeanFactory beanFactory;
      private VelocityEngine engine;
  
      public AJAXServiceImpl(Map serviceToBeans)
      {
          this.serviceToBeans = serviceToBeans;        
      }
  
      public AJAXServiceImpl(Map serviceToBeans, VelocityEngine engine, Map serviceToTemplates)
      {
          this.serviceToBeans = serviceToBeans; 
          this.engine = engine;
          this.serviceToTemplates = serviceToTemplates;
      }
  
      public AJAXResponse processRequest(AJAXRequest request)
              throws AJAXException
      {
          final String serviceName = request.getServiceName();
          final String methodName = request.getMethodName();
   //       final String templateName = request.getServletRequest().getServletPath();
  
          final String mappedServiceName = (serviceName+"."+methodName).trim();
          try
          {
              if(engine == null)
              {
                  engine = new VelocityEngine();
                  Properties props = new Properties();
                  props.load(request.getContext().getResourceAsStream("/WEB-INF/velocity.properties"));
                  props.setProperty("file.resource.loader.path", request.getContext().getRealPath("/"));
                  engine.init();
              }
              
              
              if(!serviceToBeans.containsKey(mappedServiceName))
              {
                  throw new AJAXException("There is no AJAX service named '"+mappedServiceName+"' defined.  "+ 
                          "Please make sure that your ajax.xml is set up correctly.");
              }
              
              String beanId = ((String)serviceToBeans.get(mappedServiceName)).trim();
              Object targetService = beanFactory.getBean(beanId);
              final List parameters = request.getParameters();
              Method method = targetService.getClass().getMethod(methodName, getTypes(parameters));
              Object result = method.invoke(targetService, getValues(parameters));
              Context context = new VelocityContext();
              context.put("ajaxRequest", request);
             context.put("result", result);            
    
             String templateName =  ((String)serviceToTemplates.get(mappedServiceName)).trim();
             final InputStream templateResource = request.getContext().getResourceAsStream(templateName);
             
             if(templateResource == null)
             {
                 request.getServletResponse().sendError(404, templateName+" ajax template could not be found.");
                 throw new IOException(templateName+" does not exist");
             }
             Reader template = new InputStreamReader(templateResource);
             
             StringWriter stringWriter = new StringWriter();
 
             AJAXResponse ajaxResponse = new AJAXResponseImpl(context, engine, template, stringWriter);            
             ajaxResponse.complete();
     
             String buffer = stringWriter.getBuffer().toString();
 
             // Put the response XML on the response object            
             HttpServletResponse response = request.getServletResponse();
             ServletOutputStream sos = response.getOutputStream();
             sos.print(buffer);
             sos.flush();
             return ajaxResponse;
         }
         catch(AJAXException ae)
         {
             throw ae;
         }
         catch (Exception e)
         {
             throw new AJAXException("Unable to process service" + mappedServiceName + ": " + e.getMessage(), e);
         }
 
     }
 
     /*
      * (non-Javadoc)
      * 
      * @see org.springframework.beans.factory.BeanFactoryAware#setBeanFactory(org.springframework.beans.factory.BeanFactory)
      */
     public void setBeanFactory(BeanFactory beanFactory) throws BeansException
     {
         this.beanFactory = beanFactory;
     }
 
     protected Class[] getTypes(List objects)
     {
         Class[] args = new Class[objects.size()];
         Iterator itr = objects.iterator();
         int i = 0;
         while (itr.hasNext())
         {
             args[i] = ((AJAXRequestImpl.AJAXParameter)itr.next()).getValue().getClass();
             i++;
         }
         return args;
     }
     
     protected Object[] getValues(List objects)
     {
         Object[] args = new Object[objects.size()];
         Iterator itr = objects.iterator();
         int i = 0;
         while (itr.hasNext())
         {
             args[i] = ((AJAXRequestImpl.AJAXParameter)itr.next()).getValue();
             i++;
         }
         return args;
     }
 
 }