/***
    * Licensed under the Artistic License; you may not use this file
    * except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *      http://displaytag.sourceforge.net/license.html
    *
    * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR
    * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
   * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
   */
  package org.displaytag.localization;
  
  import java.util.Locale;
  import java.util.MissingResourceException;
  import java.util.ResourceBundle;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.jsp.PageContext;
  import javax.servlet.jsp.jstl.core.Config;
  import javax.servlet.jsp.jstl.fmt.LocalizationContext;
  import javax.servlet.jsp.tagext.Tag;
  import javax.servlet.jsp.tagext.TagSupport;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.taglibs.standard.tag.common.fmt.BundleSupport;
  import org.displaytag.Messages;
  
  
  /***
   * JSTL implementation of a resource provider and locale resolver. It will make the <code>titleKey</code> attribute of
   * column tag works the same as fmt:message's <code>key property</code>. This tag must be the descendant of a
   * <code>fmt:bundle</code> tag in order to use the titleKey. This is just a shortcut, which makes
   * 
   * <pre>
   * &lt;display:column titleKey="bar"/>
   * </pre>
   * 
   * behave the same as
   * 
   * <pre>
   * &lt;c:set var="foo">
   *   &lt;fmt:message key="bar"/>
   * &lt;/c:set>
   * &lt;display:column title="${foo}"/>
   * </pre>
   * 
   * If you don't define either <code>titleKey</code> or <code>titleKey</code> property on your column, first the tag
   * will attempt to look up the <code>property</code> property in your ResourceBundle. Failing that, it will fall back
   * to the parent class's behavior of just using the property name.
   * @author Fabrizio Giustina
   * @version $Revision: 1.5 $ ($Author: fgiust $)
   */
  public class I18nJstlAdapter implements I18nResourceProvider, LocaleResolver
  {
  
      /***
       * prefix/suffix for missing entries.
       */
      public static final String UNDEFINED_KEY = "???"; //$NON-NLS-1$
  
      /***
       * logger.
       */
      private static Log log = LogFactory.getLog(I18nJstlAdapter.class);
  
      /***
       * Instantiates a new I18nJstlAdapter. Throw a NoClassDefFound error if BundleSupport is not available.
       */
      public I18nJstlAdapter()
      {
          // this will check if BundleSupport is available
          // if a NoClassDefFound error is thrown, the I18nJstlAdapter will not be used
          BundleSupport.class.hashCode();
      }
  
      /***
       * @see LocaleResolver#resolveLocale(HttpServletRequest)
       */
      public Locale resolveLocale(HttpServletRequest request)
      {
          Locale locale = (Locale) Config.get(request.getSession(), Config.FMT_LOCALE);
          if (locale == null)
          {
              locale = request.getLocale();
          }
          return locale;
      }
  
      /***
       * @see I18nResourceProvider#getResource(String, String, Tag, PageContext)
       */
      public String getResource(String resourceKey, String defaultValue, Tag tag, PageContext pageContext)
      {
  
          // if titleKey isn't defined either, use property
          String key = (resourceKey != null) ? resourceKey : defaultValue;
          String title = null;
         ResourceBundle bundle = null;
 
         // jakarta jstl implementation, there is no other way to get the bundle from the parent fmt:bundle tag
         Tag bundleTag = TagSupport.findAncestorWithClass(tag, BundleSupport.class);
         if (bundleTag != null)
         {
             BundleSupport parent = (BundleSupport) bundleTag;
             if (key != null)
             {
                 String prefix = parent.getPrefix();
                 if (prefix != null)
                 {
                     key = prefix + key;
                 }
             }
             bundle = parent.getLocalizationContext().getResourceBundle();
         }
 
         // resin jstl implementation, more versatile (we don't need to look up resin classes)
         if (bundle == null)
         {
             Object cauchoBundle = pageContext.getAttribute("caucho.bundle"); //$NON-NLS-1$
             if (cauchoBundle != null && cauchoBundle instanceof LocalizationContext)
             {
                 bundle = ((LocalizationContext) cauchoBundle).getResourceBundle();
 
                 // handle prefix just like resin does
                 String prefix = (String) pageContext.getAttribute("caucho.bundle.prefix"); //$NON-NLS-1$
                 if (prefix != null)
                 {
                     key = prefix + key;
                 }
             }
         }
 
         // standard jstl localizationContest
         if (bundle == null)
         {
             // check for the localizationContext in applicationScope, set in web.xml
             LocalizationContext localization = BundleSupport.getLocalizationContext(pageContext);
 
             if (localization != null)
             {
                 bundle = localization.getResourceBundle();
             }
         }
 
         if (bundle != null)
         {
             try
             {
                 title = bundle.getString(key);
             }
             catch (MissingResourceException e)
             {
                 log.debug(Messages.getString("Localization.missingkey", key)); //$NON-NLS-1$
 
                 // if user explicitely added a titleKey we guess this is an error
                 if (resourceKey != null)
                 {
                     title = UNDEFINED_KEY + resourceKey + UNDEFINED_KEY;
                 }
             }
         }
 
         return title;
     }
 }