/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.exoplatform.services.xml.transform.impl;

import org.exoplatform.commons.utils.PrivilegedSystemHelper;
import org.exoplatform.commons.utils.SecurityHelper;
import org.exoplatform.services.log.ExoLogger;
import org.exoplatform.services.log.Log;
import org.exoplatform.services.xml.resolving.XMLResolvingService;
import org.exoplatform.services.xml.transform.AbstractTransformer;
import org.exoplatform.services.xml.transform.NotSupportedIOTypeException;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLReaderFactory;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.PrivilegedExceptionAction;

import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.TransformerException;
import javax.xml.transform.sax.SAXResult;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.sax.TransformerHandler;
import javax.xml.transform.stream.StreamResult;

/**
 * Created by The eXo Platform SAS .
 * 
 * @author <a href="mailto:alex.kravchuk@gmail.com">Alexander Kravchuk</a>
 * @version $Id: TransformerBase.java 5799 2006-05-28 17:55:42Z geaz $
 */
public abstract class TransformerBase implements AbstractTransformer
{
   private Result result = null;

   protected static final Log LOG = ExoLogger.getLogger("exo.core.component.xml-processing.TransformerBase");

   protected SAXTransformerFactory tSAXFactory;

   protected XMLResolvingService resolvingService;

   public TransformerBase()
   {
      LOG.debug("Current javax.xml.parsers.SAXParserFactory sys property [ "
         + PrivilegedSystemHelper.getProperty("javax.xml.parsers.SAXParserFactory", "-Not set-") + "]");

      tSAXFactory = (SAXTransformerFactory)SAXTransformerFactory.newInstance();
   }

   /**
    * TODO change. Must no use explicit parser class name
    */
   static public XMLReader getXMLReader() throws SAXException
   {
      return SecurityHelper.doPrivilegedSAXExceptionAction(new PrivilegedExceptionAction<XMLReader>()
      {
         public XMLReader run() throws Exception
         {
            return XMLReaderFactory.createXMLReader();
         }
      });
   }

   public void setResolvingService(XMLResolvingService r)
   {
      resolvingService = r;
   }

   /**
    * override when need some operation after initialization result in
    * transformer
    */
   protected void afterInitResult()
   {
      LOG.debug("Result is set");
   }

   final public void initResult(Result result) throws NotSupportedIOTypeException
   {
      if (!isResultSupported(result))
      {
         throw new NotSupportedIOTypeException(result);
      }
      this.result = result;
      afterInitResult();
   }

   protected Result getResult()
   {
      return this.result;
   }

   protected boolean isSourceSupported(Source source)
   {
      return true;
   }

   protected boolean isResultSupported(Result result)
   {
      return true;
   }

   protected abstract void internalTransform(Source src) throws NotSupportedIOTypeException, TransformerException,
      IllegalStateException;

   final public void transform(Source source) throws NotSupportedIOTypeException, TransformerException,
      IllegalStateException
   {

      if (!isSourceSupported(source))
      {
         LOG.error("source of type " + source.getClass().getName() + " not supported");
         throw new NotSupportedIOTypeException(source);
      }

      if (this.result == null)
      {
         LOG.error("Result not set");
         throw new IllegalStateException("Result not specified. See initResult(Result)");
      }

      internalTransform(source);
   }

   /**
    * Tranform InputStream to specified result, according to type of result
    * 
    * @param input InputStream
    * @param result Result
    * @throws TransformerException
    */

   public void transformInputStream2Result(InputStream input, Result result) throws TransformerException
   {
      LOG.debug("Transform InputStream to result of type " + result.getClass().getName());

      // StreamResult - write data from InputStream to OutputStream
      if (result instanceof StreamResult)
      {
         OutputStream outputStream = ((StreamResult)result).getOutputStream();
         try
         {
            int counter = 0;
            while (input.available() > 0)
            {
               byte[] byteArray = new byte[input.available()];
               int readBytes = input.read(byteArray);
               counter += readBytes;
               outputStream.write(byteArray, 0, readBytes);
            }
            LOG.debug("Write " + counter + " bytes to ouput stream");
         }
         catch (IOException ex)
         {
            LOG.error("Error on read/write ", ex);
            throw new TransformerException(ex);
         }
      }
      // not StreamResult
      else
      {
         XMLReader xmlReader = null;
         try
         {
            xmlReader = getXMLReader();
            LOG.debug("xmlReader class is " + xmlReader.getClass().getName());

            // set default resolver
            if (resolvingService != null)
            {
               xmlReader.setEntityResolver(resolvingService.getEntityResolver());
               LOG.debug("Set entity resolver");
            }

            // SAXResult use XMLReader to parce InputStream to SAXEvents
            if (result instanceof SAXResult)
            {
               SAXResult saxResult = (SAXResult)result;
               xmlReader.setContentHandler(saxResult.getHandler());
               LOG.debug("Parse direct to result");
            }

            // not StreamResult, not SAXResult - create empty transformation
            else
            {
               LOG.debug("Create empty transformation");
               TransformerHandler transformerHandler = tSAXFactory.newTransformerHandler();
               transformerHandler.setResult(result);
               xmlReader.setContentHandler(transformerHandler);
               LOG.debug("Parse to result throw empty transformer");
            }
            xmlReader.parse(new InputSource(input));
            LOG.debug("Parse complete");
         }
         catch (SAXException ex)
         {
            throw new TransformerException(ex);
         }
         catch (IOException ex)
         {
            throw new TransformerException(ex);
         }
      }
   }

   /**
    * Transform javax.xml.transform.Source to java.io.InputStream if can't
    * transform throw exception
    * 
    * @param source Source
    * @return InputStream
    * @throws NotSupportedIOTypeException
    */
   protected InputStream sourceAsInputStream(Source source) throws NotSupportedIOTypeException
   {
      InputSource inputSource = SAXSource.sourceToInputSource(source);
      if (inputSource == null)
      {
         throw new NotSupportedIOTypeException(source);
      }
      return inputSource.getByteStream();
   }

   /**
    * TODO REMOVE!!!! For debug only!!!
    * @deprecated see Warning
    */
   protected void writeTofile(byte[] bytes, String postfix)
   {
      String POSTFIX = new java.text.SimpleDateFormat("yy-MM-DD_HH-mm-ss_").format(new java.util.Date());
      try
      {

         java.io.FileOutputStream fileLog =
            new java.io.FileOutputStream("c:/tmp/transf" + POSTFIX + postfix + ".xhtml");
         fileLog.write(bytes);
         fileLog.flush();
         fileLog.close();

      }
      catch (java.io.FileNotFoundException ex)
      {
         if (LOG.isTraceEnabled())
         {
            LOG.trace("An exception occurred: " + ex.getMessage());
         }
      }
      catch (IOException ex)
      {
         if (LOG.isTraceEnabled())
         {
            LOG.trace("An exception occurred: " + ex.getMessage());
         }
      }
   }

}
