/*
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.
	 */
	@Override
	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();
	}
}