package org.gcube.application.framework.core.util;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringWriter;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

import org.apache.xml.serialize.OutputFormat;
import org.apache.xml.serialize.XMLSerializer;
import org.w3c.dom.Document;

/**
 * @author Valia Tsagkalidou (KNUA)
 *
 */
public class TransformXSLT {
	/**
	 * Transforms an xml document based on the given xslt
	 * @param xslt the xslt for transforming the xml
	 * @param xml the xml to be transformed
	 * @return a string containing the transformed xml (output of the transformation)
	 */
	public static String transform(String xslt, String xml)
	{
		Transformer transformer;
		try
		{//Retrieve the XSLT from the DIS (generic resource), and create the transformer
			ByteArrayInputStream xsltStream = new ByteArrayInputStream(xslt.getBytes());
			TransformerFactory tFactory = TransformerFactory.newInstance();
			transformer = tFactory.newTransformer(new StreamSource(xsltStream));
		
			DocumentBuilderFactory dfactory = DocumentBuilderFactory.newInstance();
			Document doc = null;
			
			doc = dfactory.newDocumentBuilder().parse(xml);
			// Apply the transformation
			ByteArrayOutputStream ba_stream = new ByteArrayOutputStream();
			OutputFormat format = new OutputFormat(doc);
			format.setIndenting(false);
			format.setOmitDocumentType(true);
			format.setOmitXMLDeclaration(true);
			StringWriter writer = new StringWriter();
			XMLSerializer serial = new XMLSerializer(writer,format);
			serial.serialize(doc);
			transformer.transform(new StreamSource(new ByteArrayInputStream(writer.toString().getBytes())), new StreamResult(ba_stream));
			//Prepares the object to be returned
			    StringBuffer buffer = new StringBuffer();
			    try {
				InputStreamReader isr = new InputStreamReader( new ByteArrayInputStream(ba_stream.toByteArray()),
									      "UTF8");
				Reader in2 = new BufferedReader(isr);
				int ch;
				while ((ch = in2.read()) > -1) {
					buffer.append((char)ch);
				}
				in2.close();
				return buffer.toString();
			    } catch (Exception e) {
				e.printStackTrace();
			}
		}
		catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}
	
	/**
	 * Transforms an xml document based on the given transformer
	 * @param transformer the transformer based on which the transformation will be applied
	 * @param xml the xml document to be transformed
	 * @return a string containing the transformed xml (output of the transformation)
	 */
	public static String transform(Transformer transformer, String xml)
	{
		DocumentBuilderFactory dfactory = DocumentBuilderFactory.newInstance();
		Document doc = null;
		
		try
		{
			doc = dfactory.newDocumentBuilder().parse(xml);
			ByteArrayOutputStream ba_stream = new ByteArrayOutputStream();
			OutputFormat format = new OutputFormat(doc);
			format.setIndenting(false);
			format.setOmitDocumentType(true);
			format.setOmitXMLDeclaration(true);
			StringWriter writer = new StringWriter();
			XMLSerializer serial = new XMLSerializer(writer,format);
			serial.serialize(doc);
			transformer.transform(new StreamSource(new ByteArrayInputStream(writer.toString().getBytes())), new StreamResult(ba_stream));
			//Prepares the object to be returned
			    StringBuffer buffer = new StringBuffer();
			    try {
				InputStreamReader isr = new InputStreamReader( new ByteArrayInputStream(ba_stream.toByteArray()),
									      "UTF8");
				Reader in2 = new BufferedReader(isr);
				int ch;
				while ((ch = in2.read()) > -1) {
					buffer.append((char)ch);
				}
				in2.close();
				return buffer.toString();
			    } catch (Exception e) {
				e.printStackTrace();
			}
		}
		catch (Exception e) {
			e.printStackTrace();
		}
		return null;    
	}
}