/*
    * Copyright 2006-2016 The JGUIraffe Team.
    *
    * 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 net.sf.jguiraffe.resources.impl.bundle;
  
  import java.util.Enumeration;
  import java.util.HashSet;
  import java.util.Locale;
  import java.util.MissingResourceException;
  import java.util.ResourceBundle;
  import java.util.Set;
  
  import net.sf.jguiraffe.resources.ResourceGroup;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  /**
   * <p>
   * A specialized implementation of the {@code ResourceGroup} interface that
   * is backed by a {@code java.util.ResourceBundle}.
   * </p>
   * <p>
   * The methods required by the {@code ResourceGroup} interface are
   * delegated to the internally managed resource bundle. During construction this
   * bundle is loaded for the specified base name and locale.
   * </p>
   *
   * @author Oliver Heger
   * @version $Id: BundleResourceGroup.java 211 2012-07-10 19:49:13Z oheger $
   */
  class BundleResourceGroup implements ResourceGroup
  {
      /** The logger. */
      private final Log log = LogFactory.getLog(getClass());
  
      /** Stores the bundle this implementation is based on. */
      private final ResourceBundle bundle;
  
      /** Stores the name of this group. */
      private final String name;
  
      /** Stores the locale of this group. */
      private final Locale locale;
  
      /**
       * Creates a new instance of {@code BundleResourceGroup} and
       * initializes it.
       *
       * @param name the group's name
       * @param locale the locale
       * @param cl the class loader for resolving the bundle
       * @throws java.util.MissingResourceException if the bundle cannot be found
       */
      public BundleResourceGroup(String name, Locale locale, ClassLoader cl)
      {
          this.name = name;
          this.locale = locale;
          bundle = initBundle(name, locale, cl);
      }
  
      /**
       * Returns the bundle that is wrapped by this resource group.
       *
       * @return the underlying bundle
       */
      public ResourceBundle getBundle()
      {
          return bundle;
      }
  
      /**
       * Returns the name of this resource group.
       *
       * @return the name of this group
       */
      public Object getName()
      {
          return name;
      }
  
      /**
       * Returns a set with all keys contained in this resource group.
       *
       * @return a set with the defined keys
       */
      public Set<Object> getKeys()
     {
         Set<Object> result = new HashSet<Object>();
         for (Enumeration<String> en = getBundle().getKeys(); en
                 .hasMoreElements();)
         {
             result.add(en.nextElement());
         }
 
         return result;
     }
 
     /**
      * Returns the locale of this group.
      *
      * @return the locale
      */
     public Locale getLocale()
     {
         return locale;
     }
 
     /**
      * Returns the resource for the specified key.
      *
      * @param key the key
      * @return the resource for this key
      * @throws java.util.MissingResourceException if this key is unknown
      * @throws IllegalArgumentException for a <b>null</b> key
      */
     public Object getResource(Object key)
     {
         if (key == null)
         {
             throw new IllegalArgumentException("Resource key must not be null!");
         }
 
         return getBundle().getObject(key.toString());
     }
 
     /**
      * Initializes the specified resource bundle. This method tries to load the
      * underlying resource bundle. First the provided class loader is used. If
      * this fails, a 2nd attempt is made with the class loader which loaded this
      * class.
      *
      * @param name the bundle's base name
      * @param locale the locale
      * @param cl the class loader for resolving the bundle
      * @return the bundle instance
      * @throws java.util.MissingResourceException if the bundle cannot be found
      */
     private ResourceBundle initBundle(String name, Locale locale, ClassLoader cl)
     {
         try
         {
             return ResourceBundle.getBundle(name, locale, cl);
         }
         catch (MissingResourceException mrex)
         {
             if (log.isInfoEnabled())
             {
                 log.info("Could not load resource bundle '" + name
                         + "' using default class loader.");
             }
             return ResourceBundle.getBundle(name, locale);
         }
     }
 }