package org.opendaylight.controller.sal.rest.impl;

import static org.opendaylight.controller.sal.restconf.impl.MediaTypes.API;

import java.io.IOException;
import java.io.OutputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;

import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.Response;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.opendaylight.controller.sal.rest.api.RestconfService;
import org.opendaylight.controller.sal.restconf.impl.StructuredData;
import org.opendaylight.yangtools.yang.data.api.CompositeNode;
import org.opendaylight.yangtools.yang.data.impl.NodeUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;

@Provider
@Produces({API+RestconfService.XML})
public enum StructuredDataToXmlProvider implements MessageBodyWriter<StructuredData> {
    INSTANCE;
    
    private final static Logger logger = LoggerFactory.getLogger(StructuredDataToXmlProvider.class);

    @Override
    public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return true;
    }

    @Override
    public long getSize(StructuredData t, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return -1;
    }

    @Override
    public void writeTo(StructuredData t, Class<?> type, Type genericType, Annotation[] annotations,
            MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream)
            throws IOException, WebApplicationException {
        CompositeNode data = t.getData();
        Document domTree = NodeUtils.buildShadowDomTree(data);
        
        try {
            TransformerFactory tf = TransformerFactory.newInstance();
            Transformer transformer = tf.newTransformer();
            transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
            transformer.setOutputProperty(OutputKeys.METHOD, "xml");
            transformer.setOutputProperty(OutputKeys.INDENT, "yes");
            transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
            transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
            transformer.transform(new DOMSource(domTree), new StreamResult(entityStream));
        } catch (TransformerException e) {
            logger.error("Error during translation of Document to OutputStream", e);
            new WebApplicationException(Response.status(Response.Status.INTERNAL_SERVER_ERROR).build());
        }
    }

}