/*
    * 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;
  
  import java.util.Locale;
  import java.util.MissingResourceException;
  
  import net.sf.jguiraffe.resources.ResourceGroup;
  import net.sf.jguiraffe.resources.ResourceLoader;
  import net.sf.jguiraffe.resources.ResourceManager;
  
  /**
   * <p>
   * A default implementation of the <code>ResourceManager</code> interface.
   * </p>
   * <p>
   * This class provides a fully functional <code>ResourceManager</code>
   * implementation that can be used as is. There is usually no need to subclass
   * this class or use a different implementation.
   * </p>
   * <p>
   * The class uses the associated <code>ResourceLoader</code> to retrieve
   * requested resources or resource groups. No caching is performed, this can be
   * done in the <code>ResourceLoader</code>.
   * </p>
   * <p>Implementation note: This class is thread-safe.</p>
   *
   * @author Oliver Heger
   * @version $Id: ResourceManagerImpl.java 205 2012-01-29 18:29:57Z oheger $
   */
  public class ResourceManagerImpl implements ResourceManager
  {
      /** Stores the associated resource loader object. */
      private volatile ResourceLoader resourceLoader;
  
      /** Stores the name of the default resource group. */
      private volatile Object defaultResourceGroup;
  
      /**
       * Creates a new instance of <code>ResourceManagerImpl</code>.
       */
      public ResourceManagerImpl()
      {
          this(null);
      }
  
      /**
       * Creates a new instance of <code>ResourceManagerImpl</code> and
       * initializes the associated resource loader.
       *
       * @param loader the resource loader to use
       */
      public ResourceManagerImpl(ResourceLoader loader)
      {
          setResourceLoader(loader);
      }
  
      /**
       * Returns the specified resource.
       *
       * @param locale the <code>Locale</code>
       * @param group the owning resource group's name
       * @param key the resource key
       * @return the found resource
       * @throws MissingResourceException if the resource cannot be found
       */
      public Object getResource(Locale locale, Object group, Object key)
      {
          return getResourceGroup(locale,
                  (group != null) ? group : getDefaultResourceGroup())
                  .getResource(key);
      }
  
      /**
       * Returns the specified resource group.
       *
       * @param locale the <code>Locale</code> of the group
       * @param group the group's name
       * @return the specified resource group
       * @throws MissingResourceException if the group cannot be found
       */
      public ResourceGroup getResourceGroup(Locale locale, Object group)
      {
          return fetchLoader().loadGroup(locale, group);
      }
  
     /**
      * Returns the text of the specified resource.
      *
      * @param locale the <code>Locale</code>
      * @param group the name of the resource group
      * @param key the resource key
      * @return the text of the specified resource
      * @throws MissingResourceException if the resource cannot be found
      */
     public String getText(Locale locale, Object group, Object key)
             throws MissingResourceException
     {
         return getResource(locale, group, key).toString();
     }
 
     /**
      * Returns the associated <code>ResourceLoader</code> object.
      *
      * @return the <code>ResourceLoader</code>
      */
     public ResourceLoader getResourceLoader()
     {
         return resourceLoader;
     }
 
     /**
      * Sets the <code>ResourceLoader</code> to use. Requests for resource
      * groups are delegated to this object.
      *
      * @param resourceLoader the <code>ResourceLoader</code> to use
      */
     public void setResourceLoader(ResourceLoader resourceLoader)
     {
         this.resourceLoader = resourceLoader;
     }
 
     /**
      * Fetches the resource loader. This method is called whenever access to a
      * resource loader is needed. It checks if a resource loader is defined and
      * if not, throws an exception.
      *
      * @return the resource loader to use
      */
     protected ResourceLoader fetchLoader()
     {
         ResourceLoader loader = getResourceLoader();
         if (loader == null)
         {
             throw new IllegalStateException("No ResourceLoader defined!");
         }
         return getResourceLoader();
     }
 
     /**
      * Returns the name of the default resource group.
      *
      * @return the name of the default resource group
      */
     public Object getDefaultResourceGroup()
     {
         return defaultResourceGroup;
     }
 
     /**
      * Sets the name of the default resource group.
      *
      * @param grp the name of the default resource group
      */
     public void setDefaultResourceGroup(Object grp)
     {
         defaultResourceGroup = grp;
     }
 }