OMEncoding.java

package org.uncertweb.ps.encoding.xml;

import java.io.ByteArrayInputStream;
import java.util.Iterator;

import org.jdom.Content;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.Namespace;
import org.jdom.filter.Filter;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;
import org.uncertweb.api.om.io.StaxObservationParser;
import org.uncertweb.api.om.io.XBObservationEncoder;
import org.uncertweb.api.om.observation.AbstractObservation;
import org.uncertweb.api.om.observation.collections.IObservationCollection;
import org.uncertweb.ps.encoding.EncodeException;
import org.uncertweb.ps.encoding.ParseException;

public class OMEncoding extends AbstractXMLEncoding {

	@Override
	public boolean isSupportedType(Class<?> type) {
		for (Class<?> interf : type.getInterfaces()) {
			if (interf.equals(IObservationCollection.class)) {
				return true;
			}
		}
		Class<?> superClass = type.getSuperclass();
		if (superClass != null) {
			return superClass.equals(AbstractObservation.class);
		}
		return false;
	}

	@Override
	public <T> T parse(Content content, Class<T> type) throws ParseException {
		try {
			// this is a workaround for broken parser
			Element element = (Element)content;
			Iterator<?> fois = element.getDescendants(new Filter() {
				private static final long serialVersionUID = 1L;
				public boolean matches(Object obj) {
					if (obj instanceof Element) {
						Element e = (Element)obj;
						return e.getName().equals("featureOfInterest");
					}
					return false;
				}				
			});
			
			while (fois.hasNext()) {
				Element e = (Element)fois.next();			
				Element ssf = e.getChild("SF_SpatialSamplingFeature", Namespace.getNamespace("http://www.opengis.net/samplingSpatial/2.0"));
				if (ssf != null) {
					Element shape = ssf.getChild("shape", Namespace.getNamespace("http://www.opengis.net/samplingSpatial/2.0"));
					shape.removeAttribute("type");
				}
			}			
			
			// convert to string for external parsing
			String om = new XMLOutputter().outputString(element);
			StaxObservationParser parser = new StaxObservationParser();			
			if (element.getName().endsWith("Collection")) {
				return type.cast(parser.parseObservationCollection(om));
			}
			else {
				return type.cast(parser.parseObservation(om));
			}
		}
		catch (Exception e) {
			throw new ParseException("Couldn't parse O&M: " + e.getMessage(), e);
		}
	}

	@Override
	public <T> Content encode(T object) throws EncodeException {
		try {
			// generate random char
			// to ensure we are encoding valid o&m, some instances will have multiple collections in one document
			char idPrefix = (char) (System.nanoTime() % 26 + 'a');
			
			// and encode
			XBObservationEncoder encoder = new XBObservationEncoder();
			String om;
			if (object instanceof IObservationCollection) {
				om = encoder.encodeObservationCollectionWithId((IObservationCollection)object, String.valueOf(idPrefix));
			}
			else {
				om = encoder.encodeObservationWithId((AbstractObservation)object, String.valueOf(idPrefix));
			}
			Document document = new SAXBuilder().build(new ByteArrayInputStream(om.getBytes()));
			return document.getRootElement();
		}
		catch (Exception e) {
			throw new EncodeException("Couldn't encode O&M: " + e.getMessage(), e);
		}
	}

	@Override
	public String getNamespace() {
		return "http://www.opengis.net/om/2.0";
	}

	@Override
	public String getSchemaLocation() {
		return "http://52north.org/schema/geostatistics/uncertweb/Profiles/OM/UncertWeb_OM.xsd";
	}

	@Override
	public Include getInclude(Class<?> type) {
		return new IncludeRef("OM_" + type.getSimpleName());
	}

}