/**

  * Distribution License:

  * JSword is free software; you can redistribute it and/or modify it under

  * the terms of the GNU Lesser General Public License, version 2.1 or later

  * as published by the Free Software Foundation. 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 Lesser General Public License for more details.

  *

  * The License is available on the internet at:

  *      http://www.gnu.org/copyleft/lgpl.html

  * or by writing to:

  *      Free Software Foundation, Inc.

  *      59 Temple Place - Suite 330

  *      Boston, MA 02111-1307, USA

  *

  * © CrossWire Bible Society, 2005 - 2016

  *

  */

 package org.crosswire.common.xml;

 import java.io.IOException;

 import java.io.InputStream;

 import java.net.URI;

 import java.util.HashMap;

 import java.util.Map;

 import java.util.Properties;

 import javax.xml.transform.ErrorListener;

 import javax.xml.transform.Result;

 import javax.xml.transform.Source;

 import javax.xml.transform.Templates;

 import javax.xml.transform.Transformer;

 import javax.xml.transform.TransformerConfigurationException;

 import javax.xml.transform.TransformerException;

 import javax.xml.transform.TransformerFactory;

 import javax.xml.transform.URIResolver;

 import javax.xml.transform.sax.SAXResult;

 import javax.xml.transform.sax.SAXSource;

 import javax.xml.transform.stream.StreamSource;

 import org.crosswire.common.util.IOUtil;

 import org.crosswire.common.util.NetUtil;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 import org.xml.sax.ContentHandler;

 import org.xml.sax.SAXException;

 /**

  * A SAXEventProvider that gets its output data from an XSL stylesheet and

  * another SAXEventProvider (supplying input XML).

  * 

  * @see gnu.lgpl.License The GNU Lesser General Public License for details.

  * @author Joe Walker

  */

 public class TransformingSAXEventProvider extends Transformer implements SAXEventProvider {

     /**

      * Simple ctor

      * 

      * @param xsluri the URI of XSL

      * @param xmlsep a SAX Event Provider for an XML document

      */

     public TransformingSAXEventProvider(URI xsluri, SAXEventProvider xmlsep) {

         this.xsluri = xsluri;

         this.xmlsep = xmlsep;

         this.outputs = new Properties();

         this.params = new HashMap<String, Object>();

     }

     /**

      * Compile the XSL or retrieve it from the cache

      * 

      * @return the template information

      * @throws TransformerConfigurationException when there is a problem with configuring the transformer

      * @throws IOException when there is an I/O error

      */

     private TemplateInfo getTemplateInfo() throws TransformerConfigurationException, IOException {

         // we may have one cached

         TemplateInfo tinfo = txers.get(xsluri);

         long modtime = -1;

         if (TransformingSAXEventProvider.developmentMode) {

             if (tinfo != null) {

                 modtime = NetUtil.getLastModified(xsluri);

                 // But check it is up to date

                 if (modtime > tinfo.getModtime()) {

                     txers.remove(xsluri);

                     tinfo = null;

                     log.debug("updated style, re-caching. xsl={}", xsluri);

                 }

             }

         }

         if (tinfo == null) {

             log.debug("generating templates for {}", xsluri);

             InputStream xslStream = null;

             try {

                 xslStream = NetUtil.getInputStream(xsluri);

                 if (transfact == null) {

                     transfact = TransformerFactory.newInstance();

                 }

                 Templates templates = transfact.newTemplates(new StreamSource(xslStream));

                 if (modtime == -1) {

                     modtime = NetUtil.getLastModified(xsluri);

                 }

                 tinfo = new TemplateInfo(templates, modtime);

                 txers.put(xsluri, tinfo);

             } finally {

                 IOUtil.close(xslStream);

             }

         }

         return tinfo;

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#transform(javax.xml.transform.Source, javax.xml.transform.Result)

      */

     @Override

     public void transform(Source xmlSource, Result outputTarget) throws TransformerException {

         TemplateInfo tinfo;

         try {

             tinfo = getTemplateInfo();

         } catch (IOException e) {

             throw new TransformerException(e);

         }

         Transformer transformer = tinfo.getTemplates().newTransformer();

         for (Object obj : outputs.keySet()) {

             String key = (String) obj;

             String val = getOutputProperty(key);

             transformer.setOutputProperty(key, val);

         }

         for (String key : params.keySet()) {

             Object val = params.get(key);

             transformer.setParameter(key, val);

         }

         if (errors != null) {

             transformer.setErrorListener(errors);

         }

         if (resolver != null) {

             transformer.setURIResolver(resolver);

         }

         transformer.transform(xmlSource, outputTarget);

     }

     /* (non-Javadoc)

      * @see org.crosswire.common.xml.SAXEventProvider#provideSAXEvents(org.xml.sax.ContentHandler)

      */

     public void provideSAXEvents(ContentHandler handler) throws SAXException {

         try {

             Source xmlSource = new SAXSource(new SAXEventProviderXMLReader(xmlsep), new SAXEventProviderInputSource());

             SAXResult outputTarget = new SAXResult(handler);

             transform(xmlSource, outputTarget);

         } catch (TransformerException ex) {

             throw new SAXException(ex);

         }

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#getErrorListener()

      */

     @Override

     public ErrorListener getErrorListener() {

         return errors;

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#setErrorListener(javax.xml.transform.ErrorListener)

      */

     @Override

     public void setErrorListener(ErrorListener errors) throws IllegalArgumentException {

         this.errors = errors;

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#getURIResolver()

      */

     @Override

     public URIResolver getURIResolver() {

         return resolver;

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#setURIResolver(javax.xml.transform.URIResolver)

      */

     @Override

     public void setURIResolver(URIResolver resolver) {

         this.resolver = resolver;

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#getOutputProperties()

      */

     @Override

     public Properties getOutputProperties() {

         return outputs;

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#setOutputProperties(java.util.Properties)

      */

     @Override

     public void setOutputProperties(Properties outputs) throws IllegalArgumentException {

         this.outputs = outputs;

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#getOutputProperty(java.lang.String)

      */

     @Override

     public String getOutputProperty(String name) throws IllegalArgumentException {

         return outputs.getProperty(name);

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#setOutputProperty(java.lang.String, java.lang.String)

      */

     @Override

     public void setOutputProperty(String name, String value) throws IllegalArgumentException {

         outputs.setProperty(name, value);

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#clearParameters()

      */

     @Override

     public void clearParameters() {

         params.clear();

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#getParameter(java.lang.String)

      */

     @Override

     public Object getParameter(String name) {

         return params.get(name);

     }

     /* (non-Javadoc)

      * @see javax.xml.transform.Transformer#setParameter(java.lang.String, java.lang.Object)

      */

     @Override

     public void setParameter(String name, Object value) {

         params.put(name, value);

     }

     /**

      * In development mode the style sheet is checked for modifications before use and if so, it is recompiled.

      * 

      * @param developmentMode the developmentMode to set

      */

     public static void setDevelopmentMode(boolean developmentMode) {

         TransformingSAXEventProvider.developmentMode = developmentMode;

     }

     /**

      * In development mode the style sheet is checked for modifications before use and if so, it is recompiled.

      * 

      * @return the developmentMode

      */

     public static boolean isDevelopmentMode() {

         return developmentMode;

     }

     /**

      * A simple class to link modification times to Templates objects

      */

     private static class TemplateInfo {

         /**

          * Simple ctor

          * 

          * @param templates the compiled XSL

          * @param modtime the time the XSL was last modified

          */

         TemplateInfo(Templates templates, long modtime) {

             this.templates = templates;

             this.modtime = modtime;

         }

         /**

          * The transformer

          * 

          * @return the compiled XSL

          */

         Templates getTemplates() {

             return templates;

         }

         /**

          * The time the xsl file was last modified

          * 

          * @return when the xsl was last modified.

          */

         long getModtime() {

             return modtime;

         }

         private Templates templates;

         private long modtime;

     }

     /**

      * In development mode the style sheet is checked for modifications before use and if so, it is recompiled.

      */

     private static boolean developmentMode;

     /**

      * The remembered ErrorListener because the transformer has not been created

      */

     private ErrorListener errors;

     /**

      * The remembered URIResolver because the transformer has not been created

      */

     private URIResolver resolver;

     /**

      * The remembered OutputProperties because the transformer has not been

      * created

      */

     private Properties outputs;

     /**

      * The remembered Parameters because the transformer has not been created

      */

     private Map<String, Object> params;

     /**

      * The XSL stylesheet

      */

     private URI xsluri;

     /**

      * The XML input source

      */

     private SAXEventProvider xmlsep;

     /**

      * How we get the transformer objects

      */

     private TransformerFactory transfact;

     /**

      * A cache of transformers

      */

     private static Map<URI, TemplateInfo> txers = new HashMap<URI, TemplateInfo>();

     /**

      * The log stream

      */

     private static final Logger log = LoggerFactory.getLogger(TransformingSAXEventProvider.class);

 }