/* Copyright (20072008) Schibsted Søk AS

  * This file is part of SESAT.

  *

  *   SESAT is free software: you can redistribute it and/or modify

  *   it under the terms of the GNU Affero General Public License as published by

  *   the Free Software Foundation, either version 3 of the License, or

  *   (at your option) any later version.

  *

  *   SESAT 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 Affero General Public License for more details.

  *

  *   You should have received a copy of the GNU Affero General Public License

  *   along with SESAT.  If not, see <http://www.gnu.org/licenses/>.

  */

 package no.sesat.search.view.velocity;

 import java.io.*;

 import javax.xml.parsers.DocumentBuilderFactory;

 import javax.xml.parsers.ParserConfigurationException;

 import javax.xml.transform.OutputKeys;

 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 no.sesat.Interpreter;

 import org.apache.log4j.Logger;

 import org.apache.velocity.exception.ResourceNotFoundException;

 import org.w3c.dom.Document;

 import org.w3c.dom.Element;

 /**

  *

  * Load templates and adds debuginformation if VELOCITY_DEBUG is set to true.

  *

  * @see URLResourceLoader

  *

  *

  *

  *

  */

 public class URLVelocityTemplateLoader extends URLResourceLoader {

     private static final Logger LOG = Logger.getLogger(URLVelocityTemplateLoader.class);

     private static final String DIV_TAG = "div";

     private static final String STYLE_ATTRIB = "style";

     private static final String STYLE_BORDER = "margin:3px;border:1px solid #C0C0C0";

     private static final String STYLE_HEADING="text-decoration:underline;font-size:10px";

     private static final String ONMOUSEOVER = "this.style.border='1px solid #C0C0C0';this.style.margin='4px'";

     private static final String ONMOUSEOUT = "this.style.border='none'";

     private static final String VELOCITY_DEBUG = "VELOCITY_DEBUG";

     private static final String VELOCITY_DEBUG_ON = "VELOCITY_DEBUG_ON";

     private static final String VELOCITY_DEBUG_STYLE = "VELOCITY_DEBUG_STYLE";

     private static final String VELOCITY_DEVELOP_BASEDIR = "VELOCITY_DEVELOP_BASEDIR";

     /**

      * getResourceStream() loads resource from url. Then add border around the

      * template so its easy to see wich templates are loaded.

      * @throws org.apache.velocity.exception.ResourceNotFoundException

      */

     @Override

     public InputStream getResourceStream(final String url) throws ResourceNotFoundException {

         // Enable/disable velocity debug

         final boolean velocityDebug = Boolean.getBoolean(VELOCITY_DEBUG);

         // Activate debug (Show borders/debuginfo)

         final boolean velocityDebugOn = Boolean.getBoolean(VELOCITY_DEBUG_ON);

         // Onmouseover style

         final boolean styleOnmouseover ="onmouseover".equals(System.getProperty(VELOCITY_DEBUG_STYLE));

         // Silent style

         final boolean styleSilent ="silent".equals(System.getProperty(VELOCITY_DEBUG_STYLE));

         // Indicates if we found file local.(Can be edited)

         boolean foundLocal = false;

         if(velocityDebug) {

             final String templatesDir = System.getProperty(VELOCITY_DEVELOP_BASEDIR);

             // Get the file equivalece of the URL by removing the host as well as the web application context path.

             final String filePath = url.replaceAll("http://(.*?)/[^/]+/", "/").replace("localhost/", "");

             final File file = getFile(templatesDir, filePath);

             foundLocal = file.exists();

             final InputStream stream = file.exists() ? getStream(file) : super.getResourceStream(url);

             if(velocityDebugOn && -1 == url.indexOf("rss")){

                 StringBuilder  content = this.readTemplateFrom(stream);

                 // Create html

                 final StringBuilder template= new  StringBuilder();

                 template.append("\n");

                 template.append(content);

                 template.append("\n");

                 final StringWriter writer = new StringWriter();

                 final Document doc = createDocument();

                 final Element div = doc.createElement(DIV_TAG);

                 if(styleOnmouseover) {

                     div.setAttribute("onmouseover", ONMOUSEOVER);

                     div.setAttribute("onmouseout", ONMOUSEOUT);

                 }else if(styleSilent){

                         // Just print title as popup.

                 }else {

                     final Element divHeader = doc.createElement(DIV_TAG);

                     divHeader.setAttribute(STYLE_ATTRIB, STYLE_HEADING);

                     divHeader.appendChild(doc.createTextNode(filePath));

                     div.appendChild(divHeader);

                     div.setAttribute("style", STYLE_BORDER);

                 }

                 div.setAttribute("title", file.getName() + (foundLocal ? "(Editable)" : "(Not editable)"));

                 div.appendChild(doc.createCDATASection(template.toString()));

                 doc.appendChild(div);

                 internalWriteDocument(doc, writer);

                 final String result = writer.getBuffer().toString()

                         .replace("<![CDATA[", "")

                         .replace("]]>", "");

                 return new ByteArrayInputStream(result.getBytes());

             }else{

                 // If debug is not currently activated OR If rss, means the output is xml.

                 return stream;

             }

         }

         return super.getResourceStream(url);

     }

     /**

      * Read template utf8.

      * @param is to read from

      * @return template as StringBuilder object

      */

     private StringBuilder readTemplateFrom(final InputStream is) {

         StringBuilder builder = new StringBuilder();

         try {

             InputStreamReader isr = new InputStreamReader(is, "UTF8");

             Reader in = new BufferedReader(isr);

             int ch;

             while ((ch = in.read()) > -1) {

                 builder.append((char)ch);

             }

             in.close();

         } catch (IOException e) {

             LOG.error(e);

         }

         return builder;

     }

     /**

      * Create file object

      */

     private File getFile(final String templatesDir, final String filePath) {

         File result = null;

         if(null == templatesDir) {

             result = new File("null" + filePath);

         }else{

             for(String p : templatesDir.split(",")) {

                 final File file = new File(p + filePath);

                 if(file.exists()) {

                     result = file;

                     break;

                 }

             }

         }

         return null == result ? new File(filePath) : result;

     }

     /*

      * Get stream from file of or url.

      */

     private InputStream getStream(final File file) {

         if (file.exists()) {

             try {

                 FileInputStream fileStream = new FileInputStream(file);

                 return fileStream;

             } catch (FileNotFoundException ignore) {

                 throw new IllegalStateException("File exist but filenotfoundexception thrown: " + ignore);

             }

         } else {

             throw new IllegalArgumentException("File does not exist");

         }

     }

     // -- Write the document to the writer

     private void internalWriteDocument(final Document d, final Writer w) {

         final DOMSource source = new DOMSource(d);

         final StreamResult result = new StreamResult(w);

         final TransformerFactory factory = TransformerFactory.newInstance();

         try {

             final Transformer transformer = factory.newTransformer();

             transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

             transformer.transform(source, result);

         } catch (TransformerConfigurationException e) {

             throw new RuntimeException("Xml Parser: " + e);

         } catch (TransformerException ignore) {

             LOG.debug("Ingoring the following ", ignore);

         }

     }

     // -- Create a DOM document

     private Document createDocument() {

         final DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();

         try {

             return docFactory.newDocumentBuilder().newDocument();

         } catch (ParserConfigurationException e) {

             throw new RuntimeException(e);

         }

     }

     /**

      * Add some debug function to the interpreter.

      */

     static {

         Interpreter.addFunction("velocity-debug", new Interpreter.Function() {

             public String execute(Interpreter.Context ctx) {

                 if (ctx.length() == 1) {

                     System.setProperty(VELOCITY_DEBUG_ON, ctx.getArgument(0));

                     String style = ctx.getKeywordArgument("style");

                     if (style != null) {

                         if (style.toUpperCase().startsWith("ON")) {

                             System.setProperty(VELOCITY_DEBUG_STYLE, "onmouseover");

                         }

                         else if (style.toUpperCase().startsWith("SI")) {

                             System.setProperty(VELOCITY_DEBUG_STYLE, "silent");

                         }

                         else {

                             System.setProperty(VELOCITY_DEBUG_STYLE, "default");

                         }

                     }

                 }

                 String res = VELOCITY_DEBUG + " = " + Boolean.parseBoolean(System.getProperty(VELOCITY_DEBUG)) + " (must be set before starting up)\n";

                 res += VELOCITY_DEBUG_ON + " = " + Boolean.parseBoolean(System.getProperty(VELOCITY_DEBUG_ON)) + "\n";

                 res += VELOCITY_DEBUG_STYLE + " = " + System.getProperty(VELOCITY_DEBUG_STYLE) + "\n";

                 res += VELOCITY_DEVELOP_BASEDIR + " = " + System.getProperty(VELOCITY_DEVELOP_BASEDIR) + "\n";

                 return res;

             }

             @Override

             protected String describe() {

                 return "Change or view velocity debug options. 'velocity-debug [true|false] [style=silent|onmouseover|default]'";

             }

         });

     }

 }