/*
    * Copyright 2002,2004 The Apache Software Foundation.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.jelly.tags.fmt;
  
  import org.apache.commons.jelly.JellyContext;
  import org.apache.commons.jelly.JellyTagException;
  import org.apache.commons.jelly.XMLOutput;
  import org.apache.commons.jelly.TagSupport;
  import org.apache.commons.jelly.expression.Expression;
  import java.util.Enumeration;
  import java.util.Locale;
  import java.util.ResourceBundle;
  import java.util.MissingResourceException;
  
  /***
   * Support for tag handlers for <bundle>, the resource bundle loading
   * tag in JSTL.
   *
   * @author <a href="mailto:willievu@yahoo.com">Willie Vu</a>
   * @version 1.1
   *
   * @todo decide how to implement setResponseLocale
   */
  public class BundleTag extends TagSupport {
  
  
      //**********************************************************************
      // Private constants
  
      private static final Locale EMPTY_LOCALE = new Locale("", "");
  
  
      //*********************************************************************
      // Protected state
  
      private Expression basename;                  // 'basename' attribute
      private Expression prefix;                    // 'prefix' attribute
      /** evaluated basename */
      private String ebasename;
      /*** evaluated prefix */
      private String eprefix;
  
  
      //**********************************************************************
      // Private state
  
      private LocalizationContext locCtxt;
  
  
      //*********************************************************************
      // Constructor and initialization
  
      public BundleTag() {
      }
  
      //*********************************************************************
      // Collaboration with subtags
  
      public LocalizationContext getLocalizationContext() {
          return locCtxt;
      }
  
      public String getPrefixAsString() {
          return eprefix;
      }
  
  
      //*********************************************************************
      // Tag logic
  
      /**
       * Evaluates this tag after all the tags properties have been initialized.
       *
       */
      public void doTag(XMLOutput output) throws JellyTagException {
          Object basenameInput = null;
          if (this.basename != null) {
              basenameInput = this.basename.evaluate(context);
          }
          if (basenameInput != null) {
              ebasename = basenameInput.toString();
          }
  
          Object prefixInput = null;
          if (this.prefix != null) {
              prefixInput = this.prefix.evaluate(context);
         }
         if (prefixInput != null) {
             eprefix = prefixInput.toString();
         }
 
         this.locCtxt = this.getLocalizationContext(context, ebasename);
         invokeBody(output);
     }
 
 
     //**********************************************************************
     // Public utility methods
 
     /**
      * Gets the default I18N localization context.
      *
      * @param jc Page in which to look up the default I18N localization context
      */
     public static LocalizationContext getLocalizationContext(JellyContext jc) {
         LocalizationContext locCtxt = null;
 
         Object obj = jc.getVariable(Config.FMT_LOCALIZATION_CONTEXT);
         if (obj == null) {
             return null;
         }
 
         if (obj instanceof LocalizationContext) {
             locCtxt = (LocalizationContext) obj;
         } else {
             // localization context is a bundle basename
             locCtxt = getLocalizationContext(jc, (String) obj);
         }
 
         return locCtxt;
     }
 
     /***
      * Gets the resource bundle with the given base name, whose locale is
      * determined as follows:
      *
      * Check if a match exists between the ordered set of preferred
      * locales and the available locales, for the given base name.
      * The set of preferred locales consists of a single locale
      * (if the <tt>org.apache.commons.jelly.tags.fmt.locale</tt> configuration
      * setting is present).
      *
      * <p> If no match was found in the previous step, check if a match
      * exists between the fallback locale (given by the
      * <tt>org.apache.commons.jelly.tags.fmt.fallbackLocale</tt> configuration
      * setting) and the available locales, for the given base name.
      *
      * @param pageContext Page in which the resource bundle with the
      * given base name is requested
      * @param basename Resource bundle base name
      *
      * @return Localization context containing the resource bundle with the
      * given base name and the locale that led to the resource bundle match,
      * or the empty localization context if no resource bundle match was found
      */
     public static LocalizationContext getLocalizationContext(JellyContext jc,
     String basename) {
         LocalizationContext locCtxt = null;
         ResourceBundle bundle = null;
 
         if ((basename == null) || basename.equals("")) {
             return new LocalizationContext();
         }
 
 
         // Try preferred locales
         Locale pref = null; {
             Object tmp = jc.getVariable(Config.FMT_LOCALE);
             if (tmp != null && tmp instanceof Locale) {
                 pref = (Locale) tmp;
             }
         }
         if (pref != null) {
             // Preferred locale is application-based
             bundle = findMatch(basename, pref, jc.getClassLoader());
             if (bundle != null) {
                 locCtxt = new LocalizationContext(bundle, pref);
             }
         }
 
         if (locCtxt == null) {
             // No match found with preferred locales, try using fallback locale
             {
                 Object tmp = jc.getVariable(Config.FMT_FALLBACK_LOCALE);
                 if (tmp != null && tmp instanceof Locale) {
                     pref = (Locale) tmp;
                 }
             }
             if (pref != null) {
                 bundle = findMatch(basename, pref, jc.getClassLoader());
                 if (bundle != null) {
                     locCtxt = new LocalizationContext(bundle, pref);
                 }
             }
         }
 
         if (locCtxt == null) {
             // try using the root resource bundle with the given basename
             try {
                 bundle = ResourceBundle.getBundle(basename, EMPTY_LOCALE,
                 jc.getClassLoader());
                 if (bundle != null) {
                     locCtxt = new LocalizationContext(bundle, null);
                 }
             } catch (MissingResourceException mre) {
                 // do nothing
             }
         }
 
         if (locCtxt != null) {
             // set response locale
             if (locCtxt.getLocale() != null) {
                 // TODO
                 // SetLocaleSupport.setResponseLocale(jc, locCtxt.getLocale());
             }
         } else {
             // create empty localization context
             locCtxt = new LocalizationContext();
         }
 
         return locCtxt;
     }
 
 
 
     /*
      * Gets the resource bundle with the given base name and preferred locale.
      *
      * This method calls java.util.ResourceBundle.getBundle(), but ignores
      * its return value unless its locale represents an exact or language match
      * with the given preferred locale.
      *
      * @param basename the resource bundle base name
      * @param pref the preferred locale
      * @param cl   classloader used to find resource bundle
      *
      * @return the requested resource bundle, or <tt>null</tt> if no resource
      * bundle with the given base name exists or if there is no exact- or
      * language-match between the preferred locale and the locale of
      * the bundle returned by java.util.ResourceBundle.getBundle().
      */
     private static ResourceBundle findMatch(String basename, Locale pref, ClassLoader cl) {
         ResourceBundle match = null;
 
         try {
             ResourceBundle bundle =
             ResourceBundle.getBundle(basename, pref, cl);
             Locale avail = bundle.getLocale();
             if (pref.equals(avail)) {
                 // Exact match
                 match = bundle;
             } else {
                 if (pref.getLanguage().equals(avail.getLanguage())
                 && ("".equals(avail.getCountry()))) {
 
                     // Language match.
                     // By making sure the available locale does not have a
                     // country and matches the preferred locale's language, we
                     // rule out "matches" based on the container's default
                     // locale. For example, if the preferred locale is
                     // "en-US", the container's default locale is "en-UK", and
                     // there is a resource bundle (with the requested base
                     // name) available for "en-UK", ResourceBundle.getBundle()
                     // will return it, but even though its language matches
                     // that of the preferred locale, we must ignore it,
                     // because matches based on the container's default locale
                     // are not portable across different containers with
                     // different default locales.
 
                     match = bundle;
                 }
             }
         } catch (MissingResourceException mre) {
         }
 
         return match;
     }
 
     /*** Setter for property basename.
      * @param basename New value of property basename.
      *
      */
     public void setBasename(Expression basename) {
         this.basename = basename;
     }
 
     /*** Setter for property prefix.
      * @param prefix New value of property prefix.
      *
      */
     public void setPrefix(Expression prefix) {
         this.prefix = prefix;
     }
 
 }