// ========================================================================
// Copyright (c) 2002 Mort Bay Consulting (Australia) Pty. Ltd.
// $Id: MarshallingInterceptor.java,v 1.1.2.1 2002/08/04 02:37:15 jules_gosnell Exp $
// ========================================================================


package org.mortbay.j2ee.session;

//----------------------------------------

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectOutputStream;
import java.rmi.RemoteException;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionActivationListener;
import javax.servlet.http.HttpSessionEvent;
import org.apache.log4j.Category;

//----------------------------------------

// If we distributed instances via tiers that knew nothing about their
// type (EJB/DB) they would not be able to handle them, so we send
// them all as Strings. This involves marshalling them on the way out
// and demarshalling them on the way back. The relevant
// activation/passivation notifications are made during this process.

// I should probably separate Marshalling from ActivationNotifying in
// case someone knows that they are only using classes that will be
// present in the e.g. ejb tier and can avoid the marshalling
// overhead.

public class MarshallingInterceptor
  extends StateInterceptor
{
  class ObjectInputStream
    extends java.io.ObjectInputStream
  {
    ObjectInputStream(InputStream is)
      throws IOException
    {
      super(is);
    }

    protected Class resolveClass(java.io.ObjectStreamClass desc)
      throws IOException, ClassNotFoundException
    {
      return Class.forName(desc.getName(), false, Thread.currentThread().getContextClassLoader());
    }
  }

  Category _log=Category.getInstance(getClass().getName());

  public
    MarshallingInterceptor(Manager ignore, HttpSession session, State state)
  {
    super(session, state);
  }

/*


  protected String
    marshal(Object value)
    throws IOException
  {
    if (value==null)
      return null;

    ByteArrayOutputStream baos=new ByteArrayOutputStream();
    ObjectOutputStream    oos =new ObjectOutputStream(baos);
    oos.writeObject(value);
    oos.flush();
    return baos.toString();
  }

  protected Object
    demarshal (String buffer)
    throws IOException,ClassNotFoundException
  {
    if (buffer==null)
      return buffer;

    ByteArrayInputStream bais=new ByteArrayInputStream(buffer.getBytes());
    ObjectInputStream    ois =new ObjectInputStream(bais);
    return ois.readObject();
  }


*/


  protected byte[]
    marshal(Object value)
    throws IOException
  {
    if (value==null)
      return null;

    ByteArrayOutputStream baos=new ByteArrayOutputStream();
    ObjectOutputStream    oos =new ObjectOutputStream(baos);
    oos.writeObject(value);
    oos.flush();
    return baos.toByteArray();
  }

  protected Object
    demarshal (byte[] bytes)
    throws IOException,ClassNotFoundException
  {
    if (bytes==null)
      return bytes;

    ByteArrayInputStream bais=new ByteArrayInputStream(bytes);
    ObjectInputStream    ois =new ObjectInputStream(bais);
    return ois.readObject();
  }

  public Object
    getAttribute(String name)
    throws IllegalArgumentException, RemoteException
  {
    try
    {
      byte[] bytes = (byte[])super.getAttribute(name);
      Object tmp=demarshal(bytes);
//       if (tmp!=null && tmp instanceof HttpSessionActivationListener)
// 	((HttpSessionActivationListener)tmp).sessionDidActivate(new HttpSessionEvent(_session));

      return tmp;
    }
    catch (Exception e)
    {
      _log.error("could not get Attribute: "+name, e);
      throw new IllegalArgumentException("could not get Attribute");
    }
  }

  public Object
    setAttribute(String name, Object value)
    throws IllegalArgumentException
  {
    try
    {
      Object tmp=value;
      if (tmp!=null)
      {
// 	if (tmp instanceof HttpSessionActivationListener)
// 	  ((HttpSessionActivationListener)tmp).sessionWillPassivate(new HttpSessionEvent(_session));
 	tmp=marshal(tmp);
      }
      return demarshal((byte[])super.setAttribute(name, tmp));
    }
    catch (Exception e)
    {
      _log.error("could not set Attribute: "+name+":"+value, e);
      throw new IllegalArgumentException("could not set Attribute");
    }
  }

  // should an attribute be activated before it is removed ? How do we deal with the bind/unbind events... - TODO
  public Object
    removeAttribute(String name)
    throws IllegalArgumentException
  {
    try
    {
      // should this be activated - probably
      return demarshal((byte[])super.removeAttribute(name));
    }
    catch (Exception e)
    {
      _log.error("could not remove Attribute: "+name, e);
      throw new IllegalArgumentException("could not remove Attribute");
    }
  }
}