/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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 org.apache.any23.extractor.rdfa;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.w3c.dom.Document;
  
  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 java.io.InputStream;
  import java.io.Writer;
  import java.util.HashMap;
  import java.util.Map;
  
  /**
   * An XSLT stylesheet loaded from an InputStream, can be applied
   * to DOM trees and writes the result to a {@link Writer}.
   *
   * @author Gabriele Renzi
   * @author Richard Cyganiak (richard@cyganiak.de)
   */
  public class XSLTStylesheet {
  
      private final static Logger log = LoggerFactory.getLogger(XSLTStylesheet.class);
  
      private final Transformer transformer;
  
      public XSLTStylesheet(InputStream xsltFile) {
          try {
              transformer = TransformerFactory.newInstance().newTransformer(new StreamSource(xsltFile));
          } catch (TransformerConfigurationException e) {
              throw new RuntimeException("Should not happen, we use the default configuration", e);
          }
      }
  
      /**
       * Applies the XSLT transformation
       * @param document where apply the transformation
       * @param output the {@link java.io.Writer} where write on
       */
      public synchronized void applyTo(Document document, Writer output)
              throws XSLTStylesheetException {
          this.applyTo(document, output, new HashMap<String, String>());
      }
  
      /**
       * Applies the XSLT transformation
       * @param document where apply the transformation
       * @param output the {@link java.io.Writer} where write on
       * @param parameters the parameters to be passed to {@link Transformer}.
       *              Pass an empty {@link Map} if no parameters are foreseen.
       */
      public synchronized void applyTo(Document document, Writer output,
                                       Map<String, String> parameters) throws XSLTStylesheetException {
          for(String parameterKey : parameters.keySet()) {
              transformer.setParameter(parameterKey, parameters.get(parameterKey));
          }
          try {
              transformer.transform(
                      new DOMSource(
                              document,
                              document.getBaseURI()
                      ),
                      new StreamResult(output)
              );
          } catch (TransformerException te) {
              log.error("------ BEGIN XSLT Transformer Exception ------");
              log.error("Exception in XSLT Stylesheet transformation.", te);
              log.error("Input DOM node:", document);
              log.error("Input DOM node getBaseURI:", document.getBaseURI());
              log.error("Output writer:", output);
              log.error("------ END XSLT Transformer Exception ------");
              throw new XSLTStylesheetException(" An error occurred during the XSLT transformation", te);
          }
      }
      
  }