/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Copyright 1999-2007 The Apache Software Foundation.

 *

 *  Licensed under the Apache License, Version 2.0 (the "License");

 *  you may not use this file except in compliance with the License.

 *  You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 *  Unless required by applicable law or agreed to in writing, software

 *  distributed under the License is distributed on an "AS IS" BASIS,

 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 *  See the License for the specific language governing permissions and

 *  limitations under the License.

 *

 */

package com.sun.org.apache.xml.internal.security.transforms.implementations;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.lang.reflect.Method;

import javax.xml.transform.Source;

import javax.xml.transform.Transformer;

import javax.xml.transform.TransformerConfigurationException;

import javax.xml.transform.TransformerException;

import javax.xml.transform.TransformerFactory;

import javax.xml.transform.dom.DOMSource;

import javax.xml.transform.stream.StreamResult;

import javax.xml.transform.stream.StreamSource;

import com.sun.org.apache.xml.internal.security.exceptions.XMLSecurityException;

import com.sun.org.apache.xml.internal.security.signature.XMLSignatureInput;

import com.sun.org.apache.xml.internal.security.transforms.Transform;

import com.sun.org.apache.xml.internal.security.transforms.TransformSpi;

import com.sun.org.apache.xml.internal.security.transforms.TransformationException;

import com.sun.org.apache.xml.internal.security.transforms.Transforms;

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

import org.w3c.dom.Element;

/**

 * Class TransformXSLT

 *

 * Implements the <CODE>http://www.w3.org/TR/1999/REC-xslt-19991116</CODE>

 * transform.

 *

 * @author Christian Geuer-Pollmann

 */

public class TransformXSLT extends TransformSpi {

   /** Field implementedTransformURI */

   public static final String implementedTransformURI =

      Transforms.TRANSFORM_XSLT;

   //J-

   static final String XSLTSpecNS              = "http://www.w3.org/1999/XSL/Transform";

   static final String defaultXSLTSpecNSprefix = "xslt";

   static final String XSLTSTYLESHEET          = "stylesheet";

   static java.util.logging.Logger log =

      java.util.logging.Logger.getLogger(

         TransformXSLT.class.getName());

   /**

    * Method engineGetURI

    *

    * @inheritDoc

    */

   protected String engineGetURI() {

      return implementedTransformURI;

   }

   /**

    * Method enginePerformTransform

    *

    * @param input the input for this transform

    * @return the result of this Transform

    * @throws IOException

    * @throws TransformationException

    */

   protected XMLSignatureInput enginePerformTransform

        (XMLSignatureInput input, Transform _transformObject)

           throws IOException,

                  TransformationException {

        return enginePerformTransform(input, null, _transformObject);

   }

    protected XMLSignatureInput enginePerformTransform(XMLSignatureInput input,OutputStream baos, Transform _transformObject)

    throws IOException,

           TransformationException {

      try {

         Element transformElement = _transformObject.getElement();

         Element _xsltElement =

            XMLUtils.selectNode(transformElement.getFirstChild(),

                                                XSLTSpecNS,"stylesheet", 0);

         if (_xsltElement == null) {

            Object exArgs[] = { "xslt:stylesheet", "Transform" };

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

         }

         TransformerFactory tFactory = TransformerFactory.newInstance();

         // Process XSLT stylesheets in a secure manner

         /*

          * This transform requires an octet stream as input. If the actual

          * input is an XPath node-set, then the signature application should

          * attempt to convert it to octets (apply Canonical XML]) as described

          * in the Reference Processing Model (section 4.3.3.2).

          */

         Source xmlSource =

            new StreamSource(new ByteArrayInputStream(input.getBytes()));

         Source stylesheet;

         /*

          * This complicated transformation of the stylesheet itself is necessary

          * because of the need to get the pure style sheet. If we simply say

          * Source stylesheet = new DOMSource(this._xsltElement);

          * whereby this._xsltElement is not the rootElement of the Document,

          * this causes problems;

          * so we convert the stylesheet to byte[] and use this as input stream

          */

         {

            ByteArrayOutputStream os = new ByteArrayOutputStream();

            Transformer transformer = tFactory.newTransformer();

            DOMSource source = new DOMSource(_xsltElement);

            StreamResult result = new StreamResult(os);

            transformer.transform(source, result);

            stylesheet =

               new StreamSource(new ByteArrayInputStream(os.toByteArray()));

         }

         Transformer transformer = tFactory.newTransformer(stylesheet);

         // Force Xalan to use \n as line separator on all OSes. This

         // avoids OS specific signature validation failures due to line

         // separator differences in the transformed output. Unfortunately,

         // this is not a standard JAXP property so will not work with non-Xalan

         // implementations.

         try {

            transformer.setOutputProperty

               ("{http://xml.apache.org/xalan}line-separator", "\n");

         } catch (Exception e) {

            log.log(java.util.logging.Level.WARNING, "Unable to set Xalan line-separator property: "

               + e.getMessage());

         }

         if (baos==null) {

            ByteArrayOutputStream baos1 = new ByteArrayOutputStream();

            StreamResult outputTarget = new StreamResult(baos1);

            transformer.transform(xmlSource, outputTarget);

            return new XMLSignatureInput(baos1.toByteArray());

         }

         StreamResult outputTarget = new StreamResult(baos);

         transformer.transform(xmlSource, outputTarget);

         XMLSignatureInput output=new XMLSignatureInput((byte[])null);

         output.setOutputStream(baos);

         return output;

      } catch (XMLSecurityException ex) {

         Object exArgs[] = { ex.getMessage() };

         throw new TransformationException("generic.EmptyMessage", exArgs, ex);

      } catch (TransformerConfigurationException ex) {

         Object exArgs[] = { ex.getMessage() };

         throw new TransformationException("generic.EmptyMessage", exArgs, ex);

      } catch (TransformerException ex) {

         Object exArgs[] = { ex.getMessage() };

         throw new TransformationException("generic.EmptyMessage", exArgs, ex);

      }

   }

}