package com.dougkeen.bart.networktasks;

import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import android.util.Log;
import android.util.Xml;

public class ElevatorMessageConverter extends
		AbstractHttpMessageConverter<String> {

	private static final String TAG = "ElevatorMessageConverter";

	@Override
	protected String readInternal(Class<? extends String> clazz,
			HttpInputMessage inputMessage) throws IOException,
			HttpMessageNotReadableException {

		final ElevatorMessageHandler handler = new ElevatorMessageHandler();
		try {
			Xml.parse(new InputStreamReader(inputMessage.getBody()), handler);
		} catch (SAXException e) {
			Log.e(TAG, "Unable to parse elevator message", e);
			return null;
		}

		return handler.getMessage();
	}

	@Override
	protected boolean supports(Class<?> arg0) {
		return String.class.equals(arg0);
	}

	@Override
	public List<MediaType> getSupportedMediaTypes() {
		final List<MediaType> supportedMediaTypes = new ArrayList<MediaType>();
		supportedMediaTypes.add(MediaType.TEXT_HTML);
		supportedMediaTypes.add(MediaType.TEXT_XML);
		supportedMediaTypes.addAll(super.getSupportedMediaTypes());
		return supportedMediaTypes;
	}

	@Override
	protected void writeInternal(String arg0, HttpOutputMessage arg1)
			throws IOException, HttpMessageNotWritableException {
		throw new UnsupportedOperationException();
	}

	private static class ElevatorMessageHandler extends DefaultHandler {
		private String currentValue;
		private boolean isParsingTag;

		private String message;

		public String getMessage() {
			return message;
		}

		@Override
		public void characters(char[] ch, int start, int length)
				throws SAXException {
			if (isParsingTag) {
				currentValue = new String(ch, start, length);
			}
		}

		@Override
		public void startElement(String uri, String localName, String qName,
				Attributes attributes) throws SAXException {
			if ("description".equals(localName)) {
				isParsingTag = true;
			}
		}

		@Override
		public void endElement(String uri, String localName, String qName)
				throws SAXException {
			if ("description".equals(localName)) {
				message = currentValue;
			}
			isParsingTag = false;
			currentValue = null;
		}
	}

}