Apaches DTM to Plaintext for css-querying

I am writing a XPath function expression to find elements by CSS query.

This is what I have:

import javax.xml.transform.TransformerException;    
import org.apache.xml.dtm.ref.dom2dtm.DOM2DTM;
import org.apache.xpath.XPathContext;
import org.apache.xpath.functions.FunctionOneArg;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.objects.XString;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

public class CSSFinder extends FunctionOneArg {
    @Override
    public XObject execute(XPathContext c) throws TransformerException {
        final DOM2DTM dtm = (DOM2DTM) c.getDTM(c.getContextNode());
        final Document parse = Jsoup.parse(dtm.toString()); // toString returns not html.
        final Elements parents = parse.select(getArg0().toString()).first().parents();
        String xpath = "/";
        for (final Element parent : parents) {
            xpath += "/*[" + parent.elementSiblingIndex() + "]";
        }
        // replace this later...
        return new XString("sc-login");
    }
}

The problem is that toString does not return html. How to get the complete parsed html?

Found the solution:

import java.io.IOException;
import java.util.Collections;

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.apache.commons.io.output.ByteArrayOutputStream;
import org.apache.xml.dtm.ref.dom2dtm.DOM2DTM;
import org.apache.xpath.XPathContext;
import org.apache.xpath.functions.FunctionOneArg;
import org.apache.xpath.objects.XNodeSetForDOM;
import org.apache.xpath.objects.XObject;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import org.w3c.dom.Node;

import com.gargoylesoftware.htmlunit.html.xpath.XPathUtils;

public class CSSFinder extends FunctionOneArg {
    @Override
    public XObject execute(XPathContext c) throws TransformerException {
        final DOM2DTM currentNode = (DOM2DTM) c.getDTM(c.getContextNode());
        final Node root = currentNode.getNode(currentNode.getDocumentRoot(c.getContextNode()));
        final Transformer transformer = TransformerFactory.newInstance().newTransformer();
        final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        transformer.transform(new DOMSource(root), new StreamResult(outputStream));
        try {
            outputStream.close();
        } catch (final IOException e) {
            e.printStackTrace();
        }
        final Document parse = Jsoup.parse(outputStream.toString());
        final Element current = parse.select(getArg0().toString()).first();
        final Elements parents = current.parents();
        Collections.reverse(parents);
        String xpath = "";
        for (final Element parent : parents) {
            final int index = parent.elementSiblingIndex() + 1;
            xpath += "/*[" + index + "]";
        }
        xpath += "/*[" + (current.elementSiblingIndex()+1) + "]";
        return new XNodeSetForDOM((Node) XPathUtils.getByXPath(root, xpath).get(0), c.getDTMManager());
    }
}

I must register the function

XPathHelper.registerGlobalFunction("http://webtest.canoo.com", "css", CSSFinder.class);

And here we go in canoo webtest:

<clickElement xpath="wt:css('button.sc-login')" />