/*

  * Copyright 2007 The Kuali Foundation

  * 

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  * 

  * 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 org.kuali.rice.ken.util;

 import java.io.StringReader;

 import java.io.StringWriter;

 import java.util.HashMap;

 import java.util.Iterator;

 import javax.xml.transform.ErrorListener;

 import javax.xml.transform.Source;

 import javax.xml.transform.Transformer;

 import javax.xml.transform.TransformerException;

 import javax.xml.transform.TransformerFactory;

 import javax.xml.transform.stream.StreamResult;

 import javax.xml.transform.stream.StreamSource;

 import org.apache.log4j.Logger;

 /**

  * This class handles XSLT transformations.

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class ContentTransformer {

     private static final Logger LOG = Logger.getLogger(ContentTransformer.class);

     private static final class LoggingErrorListener implements ErrorListener {

         private final ErrorListener delegate;

         public LoggingErrorListener(ErrorListener delegate) {

             this.delegate = delegate;

         }

         public void error(TransformerException exception) throws TransformerException {

             LOG.error("Error transforming document", exception);

         }

         public void fatalError(TransformerException exception) throws TransformerException {

             if (delegate != null) {

                 delegate.fatalError(exception);

             } else {

                 throw exception;

             }

         }

         public void warning(TransformerException exception) throws TransformerException {

             LOG.warn("Error transforming document", exception);

         }

     };

     private Transformer transformer;

     /**

      * Constructs a ContentTransformer.java.

      * @param aStyleSheet

      * @throws Exception

      */

     public ContentTransformer(StreamSource aStyleSheet) throws Exception {

         // create transformer        

         TransformerFactory factory = TransformerFactory.newInstance();

         transformer = factory.newTransformer( aStyleSheet );

     }

     /**

      * Constructs a ContentTransformer.java.

      * @param aStyleSheet

      * @param parametermap

      * @throws Exception

      */

     public ContentTransformer(StreamSource aStyleSheet, HashMap parametermap) throws Exception {

        // create transformer

        TransformerFactory factory = TransformerFactory.newInstance();

        transformer = factory.newTransformer( aStyleSheet );

        Iterator iter = parametermap.keySet().iterator();

        while (iter.hasNext()) {

           Object o = iter.next();

           String param = o.toString();

           String value = (String) parametermap.get(param);

           transformer.setParameter(param, value);

        }

        transformer.setErrorListener(new LoggingErrorListener(transformer.getErrorListener()));

     }

     /**

      * This method performs the actual transformation.

      * @param xml

      * @return

      * @throws Exception

      */

     public String transform(String xml) throws Exception {

         // perform transformation

         Source xmlsource = new StreamSource(new StringReader(xml));

         StringWriter sout = new StringWriter();

         transformer.transform(xmlsource, new StreamResult(sout));

         // return resulting document

         return sout.toString();

     }

 }