package com.atlassian.plugin.servlet;
   
   import com.atlassian.plugin.servlet.descriptors.ServletModuleDescriptor;
   import com.atlassian.plugin.servlet.util.ClassLoaderStack;
   
   import java.io.IOException;
   import java.util.Enumeration;
   
   import javax.servlet.ServletConfig;
  import javax.servlet.ServletContext;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  /**
   * We are wrapping the plugins servlet in another servlet so that we can set some things up before
   * the plugins servlet is called. Currently we do the following:
   *      <ul>
   *        <li>the Threads classloader to the plugins classloader)</li>
   *        <li>wrap the request so that path info is right for the servlets</li>
   *      </ul>
   */
  public class DelegatingPluginServlet extends HttpServlet
  {
      private final ServletModuleDescriptor descriptor;
  
      private final HttpServlet servlet;
  
      public DelegatingPluginServlet(final ServletModuleDescriptor descriptor)
      {
          this.descriptor = descriptor;
          servlet = descriptor.getModule();
      }
  
      @Override
      public void service(final HttpServletRequest req, final HttpServletResponse res) throws ServletException, IOException
      {
          ClassLoaderStack.push(descriptor.getPlugin().getClassLoader());
          try
          {
              servlet.service(new PluginHttpRequestWrapper(req, descriptor), res);
          }
          finally
          {
              ClassLoaderStack.pop();
          }
      }
  
      @Override
      public void init(final ServletConfig config) throws ServletException
      {
          ClassLoaderStack.push(descriptor.getPlugin().getClassLoader());
          try
          {
              servlet.init(config);
          }
          finally
          {
              ClassLoaderStack.pop();
          }
      }
  
      @Override
      public void destroy()
      {
          ClassLoaderStack.push(descriptor.getPlugin().getClassLoader());
          try
          {
              servlet.destroy();
          }
          finally
          {
              ClassLoaderStack.pop();
          }
      }
  
      @Override
      public boolean equals(final Object obj)
      {
          return servlet.equals(obj);
      }
  
      @Override
      public String getInitParameter(final String name)
      {
          return servlet.getInitParameter(name);
      }
  
      @Override
      public Enumeration<String> getInitParameterNames()
      {
          @SuppressWarnings("unchecked")
          final Enumeration<String> initParameterNames = servlet.getInitParameterNames();
          return initParameterNames;
      }
  
      @Override
      public ServletConfig getServletConfig()
     {
         return servlet.getServletConfig();
     }
 
     @Override
     public ServletContext getServletContext()
     {
         return servlet.getServletContext();
     }
 
     @Override
     public String getServletInfo()
     {
         return servlet.getServletInfo();
     }
 
     @Override
     public String getServletName()
     {
         return servlet.getServletName();
     }
 
     @Override
     public int hashCode()
     {
         return servlet.hashCode();
     }
 
     @Override
     public void init() throws ServletException
     {
         servlet.init();
     }
 
     @Override
     public void log(final String message, final Throwable t)
     {
         servlet.log(message, t);
     }
 
     @Override
     public void log(final String msg)
     {
         servlet.log(msg);
     }
 
     @Override
     public String toString()
     {
         return servlet.toString();
     }
 
     public ServletModuleDescriptor getModuleDescriptor()
     {
         return descriptor;
     }
 
     HttpServlet getDelegatingServlet()
     {
         return servlet;
     }
 }