import java.util.HashMap;

import com.sun.org.apache.xml.internal.security.utils.XMLUtils;

 * This <code>Transform</code>(Factory) class acts as the Factory and Proxy of

 * the implementing class that supports the functionality of <a

    /** {@link java.util.logging} logging facility */

    /** Field _alreadyInitialized */

    private static boolean alreadyInitialized = false;

    /** All available Transform classes are registered here */

    private static HashMap transformClassHash = null;

    private static HashMap transformSpiHash = new HashMap();

    private TransformSpi transformSpi = null;

    /**

     * Constructs {@link Transform}

     *

     * @param doc the {@link Document} in which <code>Transform</code> will be

     * placed

     * @param algorithmURI URI representation of

     * <code>Transform algorithm</code> which will be specified as parameter of

     * {@link #getInstance(Document, String)}, when generated. </br>

     * @param contextNodes the child node list of <code>Transform</code> element

     * @throws InvalidTransformException

     */

    public Transform(Document doc, String algorithmURI, NodeList contextNodes)

        throws InvalidTransformException {

        super(doc);

        this._constructionElement.setAttributeNS

            (null, Constants._ATT_ALGORITHM, algorithmURI);

        transformSpi = getTransformSpi(algorithmURI);

        if (transformSpi == null) {

        }

        if (log.isLoggable(java.util.logging.Level.FINE)) {

            log.log(java.util.logging.Level.FINE, "Create URI \"" + algorithmURI + "\" class \""

                   + transformSpi.getClass() + "\"");

            log.log(java.util.logging.Level.FINE, "The NodeList is " + contextNodes);

        }

        // give it to the current document

        if (contextNodes != null) {

            for (int i = 0; i < contextNodes.getLength(); i++) {

               this._constructionElement.appendChild

                   (contextNodes.item(i).cloneNode(true));

        }

    }

    /**

     * This constructor can only be called from the {@link Transforms} object,

     * so it's protected.

     *

     * @param element <code>ds:Transform</code> element

     * @param BaseURI the URI of the resource where the XML instance was stored

     * @throws InvalidTransformException

     * @throws TransformationException

     * @throws XMLSecurityException

     */

    public Transform(Element element, String BaseURI)

        throws InvalidTransformException, TransformationException,

               XMLSecurityException {

        super(element, BaseURI);

        // retrieve Algorithm Attribute from ds:Transform

        String algorithmURI = element.getAttributeNS(null, Constants._ATT_ALGORITHM);

        if (algorithmURI == null || algorithmURI.length() == 0) {

            Object exArgs[] = { Constants._ATT_ALGORITHM,

                                Constants._TAG_TRANSFORM };

            throw new TransformationException("xml.WrongContent", exArgs);

        }

        transformSpi = getTransformSpi(algorithmURI);

        if (transformSpi == null) {

            Object exArgs[] = { algorithmURI };

            throw new InvalidTransformException(

                "signature.Transform.UnknownTransform", exArgs);

        }

    }

    /**

     * Generates a Transform object that implements the specified

     * <code>Transform algorithm</code> URI.

     *

     * @param algorithmURI <code>Transform algorithm</code> URI representation,

     * such as specified in

     * <a href=http://www.w3.org/TR/xmldsig-core/#sec-TransformAlg>Transform algorithm </a>

     * @param doc the proxy {@link Document}

     * @return <code>{@link Transform}</code> object

     * @throws InvalidTransformException

     */

    public static Transform getInstance(

        Document doc, String algorithmURI) throws InvalidTransformException {

        return getInstance(doc, algorithmURI, (NodeList) null);

    }

    /**

     * Generates a Transform object that implements the specified

     * <code>Transform algorithm</code> URI.

     *

     * @param algorithmURI <code>Transform algorithm</code> URI representation,

     * such as specified in

     * <a href=http://www.w3.org/TR/xmldsig-core/#sec-TransformAlg>Transform algorithm </a>

     * @param contextChild the child element of <code>Transform</code> element

     * @param doc the proxy {@link Document}

     * @return <code>{@link Transform}</code> object

     * @throws InvalidTransformException

     */

    public static Transform getInstance(

        Document doc, String algorithmURI, Element contextChild)

        throws InvalidTransformException {

        HelperNodeList contextNodes = new HelperNodeList();

        XMLUtils.addReturnToElement(doc, contextNodes);

        contextNodes.appendChild(contextChild);

        XMLUtils.addReturnToElement(doc, contextNodes);

        return getInstance(doc, algorithmURI, contextNodes);

    }

    /**

     * Generates a Transform object that implements the specified

     * <code>Transform algorithm</code> URI.

     *

     * @param algorithmURI <code>Transform algorithm</code> URI form, such as

     * specified in <a href=http://www.w3.org/TR/xmldsig-core/#sec-TransformAlg>

     * Transform algorithm </a>

     * @param contextNodes the child node list of <code>Transform</code> element

     * @param doc the proxy {@link Document}

     * @return <code>{@link Transform}</code> object

     * @throws InvalidTransformException

     */

    public static Transform getInstance(

        Document doc, String algorithmURI, NodeList contextNodes)

        throws InvalidTransformException {

        return new Transform(doc, algorithmURI, contextNodes);

    }

    /**

     * Initalizes for this {@link Transform}.

     */

    public static void init() {

        if (!alreadyInitialized) {

            transformClassHash = new HashMap(10);

            alreadyInitialized = true;

        }

    }

    /**

     * Registers implementing class of the Transform algorithm with algorithmURI

     *

     * @param algorithmURI algorithmURI URI representation of

     * <code>Transform algorithm</code> will be specified as parameter of

     * {@link #getInstance(Document, String)}, when generate. </br>

     * @param implementingClass <code>implementingClass</code> the implementing

     * class of {@link TransformSpi}

     * @throws AlgorithmAlreadyRegisteredException if specified algorithmURI

     * is already registered

     */

    public static void register(String algorithmURI, String implementingClass)

        throws AlgorithmAlreadyRegisteredException {

        // are we already registered?

        Class registeredClass = getImplementingClass(algorithmURI);

        if ((registeredClass != null) ) {

        }

        ClassLoader cl = (ClassLoader) AccessController.doPrivileged(

            new PrivilegedAction() {

                public Object run() {

                    return Thread.currentThread().getContextClassLoader();

                }

            });

        try {

            transformClassHash.put

                (algorithmURI, Class.forName(implementingClass, true, cl));

        } catch (ClassNotFoundException e) {

            throw new RuntimeException(e);

        }

    }

    /**

     * Returns the URI representation of Transformation algorithm

     *

     * @return the URI representation of Transformation algorithm

     */

    public String getURI() {

        return this._constructionElement.getAttributeNS

            (null, Constants._ATT_ALGORITHM);

    }

    /**

     * Transforms the input, and generates {@link XMLSignatureInput} as output.

     *

     * @param input input {@link XMLSignatureInput} which can supplied Octet

     * Stream and NodeSet as Input of Transformation

     * @return the {@link XMLSignatureInput} class as the result of

     * transformation

     * @throws CanonicalizationException

     * @throws IOException

     * @throws InvalidCanonicalizerException

     * @throws TransformationException

     */

    public XMLSignatureInput performTransform(XMLSignatureInput input)

         throws IOException, CanonicalizationException,

                InvalidCanonicalizerException, TransformationException {

        XMLSignatureInput result = null;

        try {

            result = transformSpi.enginePerformTransform(input, this);

        } catch (ParserConfigurationException ex) {

            Object exArgs[] = { this.getURI(), "ParserConfigurationException" };

            throw new CanonicalizationException(

                "signature.Transform.ErrorDuringTransform", exArgs, ex);

        } catch (SAXException ex) {

            Object exArgs[] = { this.getURI(), "SAXException" };

            throw new CanonicalizationException(

                "signature.Transform.ErrorDuringTransform", exArgs, ex);

        }

        return result;

    }

    /**

     * Transforms the input, and generates {@link XMLSignatureInput} as output.

     *

     * @param input input {@link XMLSignatureInput} which can supplied Octet

     * Stream and NodeSet as Input of Transformation

     * @param os where to output the result of the last transformation

     * @return the {@link XMLSignatureInput} class as the result of

     * transformation

     * @throws CanonicalizationException

     * @throws IOException

     * @throws InvalidCanonicalizerException

     * @throws TransformationException

     */

    public XMLSignatureInput performTransform(XMLSignatureInput input,

        OutputStream os) throws IOException, CanonicalizationException,

        InvalidCanonicalizerException, TransformationException {

        XMLSignatureInput result = null;

        try {

            result = transformSpi.enginePerformTransform(input, os, this);

        } catch (ParserConfigurationException ex) {

            Object exArgs[] = { this.getURI(), "ParserConfigurationException" };

            throw new CanonicalizationException(

                "signature.Transform.ErrorDuringTransform", exArgs, ex);

        } catch (SAXException ex) {

            Object exArgs[] = { this.getURI(), "SAXException" };

            throw new CanonicalizationException(

                "signature.Transform.ErrorDuringTransform", exArgs, ex);

        }

        return result;

    }

    /**

     * Method getImplementingClass

     *

     * @param URI

     * @return The name of the class implementing the URI.

     */

    private static Class getImplementingClass(String URI) {

        return (Class) transformClassHash.get(URI);

    }

    private static TransformSpi getTransformSpi(String URI)

        throws InvalidTransformException {

        try {

            Object value = transformSpiHash.get(URI);

            if (value != null) {

                return (TransformSpi) value;

            }

            Class cl = (Class) transformClassHash.get(URI);

            if (cl != null) {

                TransformSpi tr = (TransformSpi) cl.newInstance();

                transformSpiHash.put(URI, tr);

                return tr;

            }

        } catch (InstantiationException ex) {

            Object exArgs[] = { URI };

            throw new InvalidTransformException(

                "signature.Transform.UnknownTransform", exArgs, ex);

        } catch (IllegalAccessException ex) {

            Object exArgs[] = { URI };

            throw new InvalidTransformException(

                "signature.Transform.UnknownTransform", exArgs, ex);

        }

        return null;

    }

    /** @inheritDoc */

    public String getBaseLocalName() {

        return Constants._TAG_TRANSFORM;

    }