/*
Wotonomy: OpenStep design patterns for pure Java applications.
Copyright (C) 2003 Intersect Software Corp.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see http://www.gnu.org
*/

package net.wotonomy.web;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamClass;

import javax.servlet.http.HttpSession;


/**
* An implementation of WOSessionStore that stores WOSessions
* inside of HttpSessions, to take advantage of the servlet 
* containers built-in distribution capabilities.
*
* @author michael@mpowers.net
* @author $Author: cgruber $
* @version $Revision: 905 $
*/
public class WOServletSessionStore extends WOSessionStore
{
    private static final String ServletSessionKey = "WOServletSessionStoreKey";

    /**
    * This implementation currently does nothing and returns null, as we rely on the 
    * servlet container to dispose of the HttpSession which contains our WOSession.
    */                                              
    public WOSession removeSessionWithID(String sessionID)
    {
        return null;
    }
    
    /**
    * Returns the WOSession for the specified ID from the store.
    * The sessionID parameter is ignored, and the session is removed from
    * the store until saveSessionForContext is called.
    */
    public WOSession restoreSessionWithID(String sessionID, WORequest aRequest)
    {
        WOSession result = null;
        HttpSession servletSession = aRequest.servletRequest().getSession();
        if ( servletSession != null )
        {
            try
            {
                result = (WOSession) servletSession.getAttribute( ServletSessionKey );
                if ( result != null )
                {
                    // if the servlet's class loader has changed, we need to reload
                    if ( result.getClass().getClassLoader() != 
                        WOApplication.application().getClass().getClassLoader() )
                    {
                        throw new ClassCastException( result.getClass().toString() );
                    }
                }
            } 
            catch ( ClassCastException exc )
            {
                // we're having an issue with the container's class loader:
                // try serializing and deserializing to see if it is reloaded correctly
                try
                {
                    
                    ByteArrayOutputStream bytes = new ByteArrayOutputStream();
                    ObjectOutputStream output = new ObjectOutputStream( bytes );
                    Object o = servletSession.getAttribute( ServletSessionKey );
                    output.writeObject( o );
                    output.flush();
                    output.close();
                    
                    System.out.println( 
                        "WOServletSessionStore: reloaded session with size: " +
                        bytes.toByteArray().length );                
    
                    ObjectInputStream input = new CustomObjectInputStream( 
                        new ByteArrayInputStream( bytes.toByteArray() ),
                        WOApplication.application().getClass().getClassLoader() );
                    
                    o = input.readObject();
                    input.close();
                    
                    // try it again
                    result = (WOSession) o;
                }
                catch ( Exception e )
                {
                    e.printStackTrace();
                    // give up: remove the attribute and allow a new session
                    servletSession.removeAttribute( ServletSessionKey );
                }
            }
            
            if ( result != null ) 
            {
                servletSession.removeAttribute( ServletSessionKey );
            }
        }
        //System.out.println( "restoreSessionWithID: " + sessionID + " : " + result );        
        return result;
    }
                                                   
    /**
    * Places the context's session into the store.
    */
    public void saveSessionForContext(WOContext context)
    {
        //System.out.println( "saveSessionForContext: " + context + " : " + context.session() );        
        context.request().servletRequest().getSession( true ).setAttribute(
            ServletSessionKey, context.session() );
    }
    
    /**
    * Needed to specify a class loader which may be different that the
    * one used to load the ObjectInputStream class.
    */ 
    private static class CustomObjectInputStream extends ObjectInputStream
    {
        ClassLoader loader;
        
        public CustomObjectInputStream( 
            InputStream anInputStream, ClassLoader aClassLoader )
        throws java.io.IOException, java.io.StreamCorruptedException
        {
            super( anInputStream );
            loader = aClassLoader;
        }
        
        protected Class resolveClass(ObjectStreamClass v)
             throws IOException, ClassNotFoundException 
        {
            return loader.loadClass( v.getName() );
        }
    }
}

/*
 * $Log$
 * Revision 1.2  2006/02/19 01:44:02  cgruber
 * Add xmlrpc files
 * Remove jclark and replace with dom4j and javax.xml.sax stuff
 * Re-work dependencies and imports so it all compiles.
 *
 * Revision 1.1  2006/02/16 13:22:22  cgruber
 * Check in all sources in eclipse-friendly maven-enabled packages.
 *
 * Revision 1.7  2003/01/22 23:00:32  mpowers
 * Now keeping the most recent page around.
 *
 * Revision 1.6  2003/01/21 17:53:16  mpowers
 * Now handling reloading when wotonomy is on the system class path.
 *
 * Revision 1.5  2003/01/15 19:50:49  mpowers
 * Fixed issues with WOSession and Serializable.
 * Can now persist sessions between classloaders (hot swap of class impls).
 *
 * Revision 1.3  2003/01/14 16:05:19  mpowers
 * Removed extraneous printlns.
 *
 * Revision 1.2  2003/01/13 22:25:07  mpowers
 * Request-response cycle is working with session and page persistence.
 *
 * Revision 1.1  2003/01/07 20:48:24  mpowers
 * Implemented WOSessionStore and WOServletSessionStore.
 *
 *
 */