/*
Wotonomy: OpenStep design patterns for pure Java applications.
Copyright (C) 2000 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.IOException;
import java.io.InputStream;
import java.net.URL;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import net.wotonomy.foundation.internal.WotonomyException;
import net.wotonomy.foundation.xml.XMLDecoder;

import org.xml.sax.SAXException;

/**
* An implementation of XMLDecoder that reads objects from 
* XMLRPC format. 
* This implementation is not thread-safe, so a new instances
* should be created to accomodate multiple threads.
*/
public class XMLRPCDecoder implements XMLDecoder
{
    XMLRPCDecoderHelper helper = new XMLRPCDecoderHelper();
    
    /**
    * Decodes an object in XML-RPC format from the specified input stream.
    * @param anInputStream The input stream from which to read.
    * The stream will be read fully.
    * @param aDescription A description to accompany error messages
    * for the stream, typically a file name.
    * @param aURL A URL against which relative references within the
    * XML will be resolved.
    * @return The object that was constructed from the XML content,
    * or null if no object could be constructed.
    */ 
    public Object decode( 
        InputStream anInputStream, String aDescription, URL aURL )
    {
    	Object result = null;
    	
        try {
        	SAXParser sparser = SAXParserFactory.newInstance().newSAXParser();
        	sparser.parse(anInputStream,helper,aURL.toExternalForm());
        	result = helper.getResult();
        } catch (ParserConfigurationException e) {
            throw new WotonomyException("Problem in parser configuration", e );
        } catch (IOException e) {
            throw new WotonomyException("IOException thrown while parsing", e );
        } catch (SAXException e) {
            throw new WotonomyException("SAXException thrown while parsing", e );
        }
        helper.reset();
        return result;
    }

    /**
    * Decodes an XML-RPC message from the specified input stream.
    * Stand-alone values not wrapped in "methodCall" or "param"
    * tags will be treated as a response.
    * @param anInputStream The input stream from which to read.
    * The stream will be read fully.
    * @param aReceiver an XMLRPCReceiver that will be invoked with
    * the appropriate method: request, response, or fault.
    */ 
    public void decode( 
        InputStream anInputStream, XMLRPCReceiver aReceiver )
    {
        try
        {
        	SAXParser sparser = SAXParserFactory.newInstance().newSAXParser();
        	sparser.parse(anInputStream,helper);
        	
            if ( helper.isRequest() )
            {
                aReceiver.request( helper.getMethodName(), helper.getParameters() );
            }
            else
            if ( helper.isFault() )
            {
                aReceiver.fault( helper.getFaultCode(), helper.getFaultString() );
            }
            else // all else is considered a response
            {
                aReceiver.response( helper.getResult() );
            }
	    } catch (ParserConfigurationException e) {
	        throw new WotonomyException("Problem in parser configuration", e );
	    } catch (IOException e) {
	        throw new WotonomyException("IOException thrown while parsing", e );
	    } catch (SAXException e) {
	        throw new WotonomyException("SAXException thrown while parsing", e );
        }
        helper.reset();
    }
}