/*
Wotonomy: OpenStep design patterns for pure Java applications.
Copyright (C) 2001 Intersect Software Corporation

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.xml;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Hashtable;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.wotonomy.foundation.NSSelector;
import net.wotonomy.foundation.internal.WotonomyException;

/**
* A servlet that can make any java object into an XML-RPC server.
* Simply pass in the object to the constructor and XML-RPC requests
* to this servlet will call the appropriate methods and convert
* the results to an XML-RPC response. <br><br>
*
* Depending on your servlet container, it may be necessary to 
* create a simple subclass that creates your handler object
* in its constructor and then calls setHandler(). <br><br>
*
* Responses are in the specification's standard response format.<br><br>
*
* Faults are returned if any exception is thrown in the method,
* or if the specified method is not found on the object.
* The fault string is the toString value of the exception,
* and the fault code is the hasCode value of the exception. <br><br>
*
* Remember that this servlet only responds to POSTs, 
* per the XML-RPC spec.  
*/
public class XMLRPCServlet extends HttpServlet 
{
    protected Object handler;
    protected boolean synchronizing;
    private Hashtable selectorCache = new Hashtable(); // thread safe
    private boolean copyStream = false;
    
    /**
    * Default constructor initializes internal state.
    */
    public XMLRPCServlet()
    {
        handler = null;
        synchronizing = false;
    }
    
    /**
    * Constructor takes any java object and allows its methods
    * to be invoked via XMLRPC requests to this servlet.
    * Simply calls setHandler().
    */
    public XMLRPCServlet( Object aHandler )
    {
        this();
        setHandler( aHandler );
    }
    
    /**
    * Gets the object whose methods will be invoked to
    * handle incoming requests.
    */
    public Object getHandler()
    {
        return handler;
    }
    
    /**
    * Sets the object whose methods will be invoked to
    * handle incoming requests.
    */
    public void setHandler( Object aHandler )
    {
        handler = aHandler;
    }
    
    /**
    * Gets whether the servlet should synchonize on the
    * object before invoking methods on it.
    * Defaults to false.
    */
    public boolean isSynchronizing()
    {
        return synchronizing;
    }
    
    /**
    * Sets whether the servlet should synchonize on the
    * object before invoking methods on it.
    * Defaults to false.
    */
    public void setSynchronizing( boolean willSynchronize )
    {
        synchronizing = willSynchronize;
    }
    
    /**
    * Overridden to service the request.
    */
    protected void doPost(
        HttpServletRequest req, HttpServletResponse resp) 
    throws ServletException, IOException
    {
        if ( getHandler() != null )
        {
            InputStream input = req.getInputStream();
            byte[] copyOfRequest = null;

            if ( copyStream )
            {
                ByteArrayOutputStream byteArray =
                    new ByteArrayOutputStream();
                int b;
                while ( ( b = input.read() ) != -1 )
                {
                    byteArray.write( b );
                }
                copyOfRequest = byteArray.toByteArray();
                input = new ByteArrayInputStream( copyOfRequest );
            }
            
            try
            {
                new XMLRPCDecoder().decode( input, 
                    new Receiver( this, resp ) );
            }
            catch ( WotonomyException exc )
            {
                if ( copyOfRequest != null )
                {
                    System.out.println( new String( copyOfRequest ) );
                    exc.printStackTrace();
                }
                // catches io exceptions thrown in handleRequest.
                Throwable t = exc.getWrappedThrowable();
                if ( t instanceof IOException )
                {
                    throw (IOException)t;
                }
                throw exc;
            }
        }
    }
    
    /**
    * Called by doPost after parsing an incoming request,
    * and is responsible for invoking the specified method
    * with the specified parameters on the handler object.
    * (This implementation calls getOutputStream() on the response.)
    * Override to customize the handling of the request.
    */
    protected void handleRequest( String aMethodName, 
        Object[] aParameterArray, HttpServletResponse aResponse )
    {
        OutputStream output = null;
        
        try 
        {
            output = aResponse.getOutputStream();
            aResponse.setStatus( HttpServletResponse.SC_OK ); // always 200
            aResponse.setContentType( "text/xml" );
        }
        catch ( IOException exc )
        {
            // caught in doPost
            throw new WotonomyException( exc );   
        }
        
        // get the array of types
        XMLRPCEncoder encoder = new XMLRPCEncoder();
        Class[] types = new Class[ aParameterArray.length ];
        for ( int i = 0; i < aParameterArray.length; i++ )
        {
            types[i] = aParameterArray[i].getClass();
        }
        
        //TODO: selectors should be cached if possible
        
        Object handler = getHandler();
        if ( isSynchronizing() )
        {
            synchronized ( handler )
            {
                execute( encoder, handler, output,
                    new NSSelector( aMethodName, types ), aParameterArray );
            }
        }
        else
        {
            execute( encoder, handler, output,
                new NSSelector( aMethodName, types ), aParameterArray );
        }
    }
    
    private void execute( XMLRPCEncoder anEncoder, Object aHandler, 
        OutputStream output, NSSelector aSelector, Object[] aParameterArray )
    {
        try 
        {
            Object result = 
                aSelector.invoke( aHandler, aParameterArray );
            anEncoder.encodeResponse( result, output );
        }
        catch ( Exception exc )
        {
            anEncoder.encodeFault( 
                exc.hashCode(), exc.toString(), output );
        }
    }
    
    private class Receiver implements XMLRPCReceiver
    {
        XMLRPCServlet controller;
        HttpServletResponse response;
        
        public Receiver( 
            XMLRPCServlet aController,
            HttpServletResponse aResponse )
        {
            controller = aController;
            response = aResponse;
        }
        
        public void request( 
            String aMethodName, Object[] aParameterArray )
        {
            controller.handleRequest( 
                aMethodName, aParameterArray, response );
        }
        
        public void response( 
            Object aResult ) 
        {
            // does nothing
        }
        
        public void fault( 
            int aFaultCode, String aFaultString)
        {
            // does nothing
        }
    }
}

/*
 * $Log$
 * Revision 1.1  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 1.1  2001/02/07 19:24:28  mpowers
 * Moved XML classes to separate package.
 *
 */