/*
 *    XMLTransformer.java
 *    Copyright (C) 2002 New Zealand Digital Library, http://www.nzdl.org
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
package org.greenstone.gsdl3.util;

// XML classes
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;

import javax.xml.transform.stream.StreamSource;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.dom.DOMResult;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

// other java classes
import java.io.StringReader;
import java.io.StringWriter;
import java.io.File;
import java.util.HashMap;
import java.util.Set;
import java.util.Map;
import java.util.Iterator;
/** XMLTransformer - utility class for greenstone
 *
 * transforms xml using xslt
 *
 * @author <a href="mailto:kjdon@cs.waikato.ac.nz">Katherine Don</a>
 * @version $Revision: 5142 $
 */
public class XMLTransformer {

  /** The transformer factory we're using */
    TransformerFactory t_factory=null;
  
  /**
   * The no-arguments constructor. 
   *
   * Any exceptions thrown are caught internally
   * 
   * @return a new transformer
   * @see javax.xml.transform.TransformerFactory
   */
    public XMLTransformer() {

	// make sure we are using the xalan transformer
	System.setProperty("javax.xml.transform.TransformerFactory", "org.apache.xalan.processor.TransformerFactoryImpl");
	try {
	    this.t_factory = org.apache.xalan.processor.TransformerFactoryImpl.newInstance();

	} catch (Exception e) {
	    System.err.println("XMLTransformer() exception "+e.getMessage());
	}
    }

 
	
  /**
   * Transform an XML document using a XSLT stylesheet
   * 
   * @param stylesheet a filename for an XSLT stylesheet
   * @param xml_in the XML to be transformed
   * @return the transformed XML
   */
    public String transform(String stylesheet, String xml_in) {
	
	try {
	    // Use the TransformerFactory to process the stylesheet Source and generate a Transformer.
	    Transformer transformer = this.t_factory.newTransformer(new StreamSource(stylesheet));

	    // Use the Transformer to transform an XML Source and send the output to a Result object.
	    StringWriter output = new StringWriter();

	    transformer.transform(new StreamSource(new StringReader(xml_in)), new StreamResult(output));
	    return output.toString();
	} catch (TransformerConfigurationException e) {
	    System.err.println("XMLTransformer: couldn't create transformer object: "+e.getMessageAndLocation());
	    System.err.println(e.getLocationAsString());  
	    return "";
	} catch (TransformerException e) {
	    System.err.println("XMLTransformer: couldn't transform the source: " + e.getMessage());
	    return "";
	}	
    }

    public String transformToString(Document stylesheet, Document source) {
	return transformToString(stylesheet, source, null);
    }
    
    public String transformToString(Document stylesheet, Document source, HashMap parameters) {
	
	try {
	    // Use the TransformerFactory to process the stylesheet Source and generate a Transformer.
	    Transformer transformer = this.t_factory.newTransformer(new DOMSource(stylesheet));
	    if (parameters != null) {
		Set params = parameters.entrySet();
		Iterator i = params.iterator();
		while (i.hasNext()) {
		    Map.Entry m = (Map.Entry)i.next();
		    transformer.setParameter((String)m.getKey(), m.getValue());
		}
	    }
	    //transformer.setParameter("page_lang", source.getDocumentElement().getAttribute(GSXML.LANG_ATT));

	    
	    // Use the Transformer to transform an XML Source and send the output to a Result object.
	    StringWriter output = new StringWriter();
	    
	    transformer.transform(new DOMSource(source), new StreamResult(output));
	    return output.toString();
	} catch (TransformerConfigurationException e) {
	    System.err.println("XMLTransformer: couldn't create transformer object: "+e.getMessageAndLocation());
	    System.err.println(e.getLocationAsString());  
	    return "";
	} catch (TransformerException e) {
	    System.err.println("XMLTransformer: couldn't transform the source: " + e.getMessage());
	    return "";
	}	
      }

    public Node transform(Document stylesheet, Document source) {
	return transform(stylesheet, source, null);
    }

    public Node transform(Document stylesheet, Document source, HashMap parameters) {

	try {
	    // Use the TransformerFactory to process the stylesheet Source and generate a Transformer.
	    Transformer transformer = this.t_factory.newTransformer(new DOMSource(stylesheet));
	    if (parameters != null) {
		Set params = parameters.entrySet();
		Iterator i = params.iterator();
		while (i.hasNext()) {
		    Map.Entry m = (Map.Entry)i.next();
		    transformer.setParameter((String)m.getKey(), m.getValue());
		}
	    }

	    DOMResult result = new DOMResult();
	    transformer.transform(new DOMSource(source), result);
	    return result.getNode().getFirstChild();
	} catch (TransformerConfigurationException e) {
	    System.err.println("XMLTransformer: couldn't create transformer object: "+e.getMessageAndLocation());
	    System.err.println(e.getLocationAsString());  
	    return null;
	} catch (TransformerException e) {
	    System.err.println("XMLTransformer: couldn't transform the source: " + e.getMessage());
	    return null;
	}	
	

    }

    public Node transform(File stylesheet, File source) {

	try {
	    Transformer transformer = this.t_factory.newTransformer(new StreamSource(stylesheet));
	    
	    DOMResult result = new DOMResult();
	    transformer.transform(new StreamSource(source), result);
	    return result.getNode().getFirstChild();
	} catch (TransformerConfigurationException e) {
	    System.err.println("XMLTransformer: couldn't create transformer object: "+e.getMessageAndLocation());
	    System.err.println(e.getLocationAsString());  
	    return null;
	} catch (TransformerException e) {
	    System.err.println("XMLTransformer: couldn't transform the source: " + e.getMessage());
	    return null;
	}	
    }
}