/*
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 */
/*
 * $Id: DOMXPathTransform.java,v 1.16 2005/05/12 19:28:35 mullan Exp $
 */
package org.jcp.xml.dsig.internal.dom;

import javax.xml.crypto.*;
import javax.xml.crypto.dsig.*;
import javax.xml.crypto.dsig.spec.TransformParameterSpec;
import javax.xml.crypto.dsig.spec.XPathFilterParameterSpec;
import java.security.InvalidAlgorithmParameterException;
import java.util.Iterator;
import java.util.Map;
import java.util.HashMap;
import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;

/**
 * DOM-based implementation of XPath Filtering Transform.
 * (Uses Apache XML-Sec Transform implementation)
 *
 * @author Sean Mullan
 */
public final class DOMXPathTransform extends ApacheTransform {
 
    public void init(TransformParameterSpec params)
        throws InvalidAlgorithmParameterException {
        if (params == null) {
	    throw new InvalidAlgorithmParameterException("params are required");
	} else if (!(params instanceof XPathFilterParameterSpec)) {
	    throw new InvalidAlgorithmParameterException
		("params must be of type XPathFilterParameterSpec");
        }
	this.params = params;
    }

    public void init(XMLStructure parent, XMLCryptoContext context)
        throws InvalidAlgorithmParameterException {

	super.init(parent, context);
	unmarshalParams(DOMUtils.getFirstChildElement(transformElem));
    }

    private void unmarshalParams(Element paramsElem) {
        String xPath = paramsElem.getFirstChild().getNodeValue();
        // create a Map of namespace prefixes
        NamedNodeMap attributes = paramsElem.getAttributes();
        if (attributes != null) {
	    int length = attributes.getLength();
            Map namespaceMap = new HashMap(length);
	    for (int i = 0; i < length; i++) {
	        Attr attr = (Attr) attributes.item(i);
	        String prefix = attr.getPrefix();
	        if (prefix != null && prefix.equals("xmlns")) {
	            namespaceMap.put(attr.getLocalName(), attr.getValue());
	        }
	    }
	    this.params = new XPathFilterParameterSpec(xPath, namespaceMap);
	} else {
	    this.params = new XPathFilterParameterSpec(xPath);
	}
    }

    public void marshalParams(XMLStructure parent, XMLCryptoContext context)
        throws MarshalException {

	super.marshalParams(parent, context);
	XPathFilterParameterSpec xp = 
	    (XPathFilterParameterSpec) getParameterSpec();
	Element xpathElem = DOMUtils.createElement
	    (ownerDoc, "XPath", XMLSignature.XMLNS, 
	     DOMUtils.getSignaturePrefix(context));
	xpathElem.appendChild(ownerDoc.createTextNode(xp.getXPath()));

	// add namespace attributes, if necessary
	Iterator i = xp.getNamespaceMap().entrySet().iterator();
	while (i.hasNext()) {
	    Map.Entry entry = (Map.Entry) i.next();
	    xpathElem.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:" 
		+ (String) entry.getKey(), (String) entry.getValue());
	}
	    
	transformElem.appendChild(xpathElem);
    }
}