/**
 * <copyright> Copyright 2006 by Know-Center, Graz, Austria </copyright>
 * PDF-AS has been contracted by the E-Government Innovation Center EGIZ, a
 * joint initiative of the Federal Chancellery Austria and Graz University of
 * Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */
package at.gv.egiz.pdfas.web.i18n;

import java.io.File;
import java.util.Locale;
import java.util.Properties;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.apache.log4j.Logger;

import com.opensymphony.module.sitemesh.Config;
import com.opensymphony.module.sitemesh.Decorator;
import com.opensymphony.module.sitemesh.DecoratorMapper;
import com.opensymphony.module.sitemesh.Page;
import com.opensymphony.module.sitemesh.mapper.AbstractDecoratorMapper;
import com.opensymphony.module.sitemesh.mapper.DefaultDecorator;

public class LanguageDecoratorMapper extends AbstractDecoratorMapper {
   
   
   private String decoratorParameter = null;
   
   private static final Logger LOG = Logger.getLogger(LanguageDecoratorMapper.class);

   public void init(Config config, Properties properties, DecoratorMapper parent) throws InstantiationException {
      super.init(config, properties, parent);
   }
   
   public static Object getFirstNotNull(Object[] objects) {
      if (objects == null) {
         return null;
      }
      for (int i = 0; i < objects.length; i++) {
         if (objects[i] != null) {
            return objects[i];
         }
      }
      return null;
   }
   
   public static Locale getLocale(HttpServletRequest request, String decoratorParameter) {
      Locale locale = null;
      HttpSession session = request.getSession();
      
      LOG.trace("Looking for locale in session (ID=" + session.getId() + ").");
      locale = (Locale) session.getAttribute(LocaleParamFilter.LOCALE_SESSION_KEY);
      if (locale == null) {
         LOG.debug("Unable to find locale in session. Trying to create new locale based on Accept-Language header entry.");
         String acceptLanguage = request.getHeader("Accept-Language");
         if (acceptLanguage != null) {
            LOG.trace("Accept-Language header entry: " + acceptLanguage);
         } else {
            LOG.trace("No header entry found.");
         }
         if (acceptLanguage != null && acceptLanguage.length() >= 2) {
            locale = new Locale(acceptLanguage.substring(0, 2));
            LOG.debug("New Locale created: " + locale);
            LOG.trace("Setting language to " + locale.getDisplayLanguage() + ".");
            session.setAttribute(LocaleParamFilter.LOCALE_SESSION_KEY, locale);
         }
      } else {
         LOG.trace("Locale found: " + locale);
      }

      return locale;
   }

   public Decorator getDecorator(HttpServletRequest request, Page page) {
      LOG.trace("SiteMesh language resource decorator mapper invoked.");
      
      try {
         Decorator result = null;
         final Decorator d = super.getDecorator(request, page);
         Locale locale = getLocale(request, this.decoratorParameter);
         
         String path;
         if (locale != null) {
            path = modifyPath(d.getPage(), locale.getLanguage());
         } else {
            path = d.getPage();
         }

         File decFile = new File(config.getServletContext().getRealPath(path));
         
         LOG.trace("Looking for decorator \"" + path + "\".");
         if (decFile.isFile()) {
            result = new DefaultDecorator(d.getName(), path, null) {
               public String getInitParameter(String paramName) {
                  return d.getInitParameter(paramName);
               }
            };
         }

         if (result != null) {
            LOG.trace("Decorator found (\"" + result.getName() + "\", \"" + getFirstNotNull(new Object[] { result.getURIPath(), result.getPage(), "<n/a>"}) + "\").");
            return result;
         } else {
            LOG.trace("No decorator found. Delegating to super class.");
            result = super.getDecorator(request, page);
            if (result != null) {
               LOG.trace("Super class returned decorator (\"" + result.getName() + "\", \"" + getFirstNotNull(new Object[] { result.getURIPath(), result.getPage(), "<n/a>"}) + "\").");
            } else {
               LOG.trace("Super class did not return a decorator.");
            }
            return result;
         }
      } catch (NullPointerException e) {
         return super.getDecorator(request, page);
      }
   }

   private static String modifyPath(String path, String ext) {
      if (ext == null || ext.length() == 0) {
         return path;
      }
      int dot = path.lastIndexOf('.');
      if (dot > -1) {
         return path.substring(0, dot) + '-' + ext + path.substring(dot);
      } else {
         return path + '-' + ext;
      }
   }

}