/*
    * $Id: MessagesMap.java 471754 2006-11-06 14:55:09Z husted $
    *
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.struts.faces.util;
  
  
  import java.util.Collection;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.struts.util.MessageResources;
  
  
  /**
   * <p>A limited immutable <code>Map</code> implementation that wraps the
   * <code>MessageResources</code> instance for the specified
   * <code>Locale</code>.  Exposing the messages as a <code>Map</code>
   * makes them easily accessible via value binding expressions, as
   * well as JSP 2.0 expression language expressions.
   */
  
  public class MessagesMap implements Map {
  
  
      // ------------------------------------------------------------ Constructors
  
  
      /**
       * <p>Construct a new {@link MessagesMap} instance that wraps the
       * specified <code>MessageResources</code> instance, and returns messages
       * for the specified <code>Locale</code>.</p>
       *
       * @param messages <code>MessageResources</code> instance to wrap
       * @param locale <code>Locale</code> for which to retrieve messages,
       *  or <code>null</code> for the system default <code>Locale</code>
       *
       * @exception NullPointerException if <code>messages</code>
       *  is <code>null</code>
       */
      public MessagesMap(MessageResources messages, Locale locale) {
  
          super();
          if (messages == null) {
              throw new NullPointerException();
          }
          this.messages = messages;
          this.locale = locale;
  
      }
  
  
      // ------------------------------------------------------ Instance Variables
  
  
      /**
       * <p>The <code>Locale</code> for which to return messages, or
       * <code>null</code> for the system default <code>Locale</code>.</p>
       */
      private Locale locale = null;
  
  
      /**
       * <p>The <code>MessageResources</code> being wrapped by this
       * {@link MessagesMap}.</p>
       */
      private MessageResources messages = null;
  
  
      // ---------------------------------------------------------- Public Methods
  
  
      /**
       * <p>The <code>clear()</code> method is not supported.</p>
       */
      public void clear() {
  
          throw new UnsupportedOperationException();
  
      }
  
 
     /**
      * <p>Return <code>true</code> if there is a message for the
      * specified key.</p>
      *
      * @param key Message key to evaluate
      */
     public boolean containsKey(Object key) {
 
         if (key == null) {
             return (false);
         } else {
             return (messages.isPresent(locale, key.toString()));
         }
 
     }
 
 
     /**
      * <p>The <code>containsValue()</code> method is not supported.</p>
      *
      * @param value Value to evaluate
      */
     public boolean containsValue(Object value) {
 
         throw new UnsupportedOperationException();
 
     }
 
 
     /**
      * <p>The <code>entrySet()</code> method is not supported.</p>
      */
     public Set entrySet() {
 
         throw new UnsupportedOperationException();
 
     }
 
 
     /**
      * <p>The <code>equals</code> method checks whether equal
      * <code>MessageResources</code> and <code>Locale</code> are
      * being wrapped.</p>
      *
      * @param o The object to be compared
      */
     public boolean equals(Object o) {
 
         if (!(o instanceof MessagesMap)) {
             return (false);
         }
         MessagesMap other = (MessagesMap) o;
         if (!messages.equals(other.getMessages())) {
             return (false);
         }
         if (locale == null) {
             return (other.getLocale() == null);
         } else {
             return (locale.equals(other.getLocale()));
         }
 
     }
 
 
     /**
      * <p>Return the message string for the specified key.</p>
      *
      * @param key Key for message to return
      */
     public Object get(Object key) {
 
         if (key == null) {
             return ("??????");
         } else {
             return (messages.getMessage(locale, key.toString()));
         }
 
     }
 
 
     /**
      * <p>The <code>hashCode()</code> method returns values that will
      * be identical if the <code>equals</code> method returns <code>true</code>.
      * </p>
      */
     public int hashCode() {
 
         int value = messages.hashCode();
         if (locale != null) {
             value = value ^ locale.hashCode();
         }
         return (value);
 
     }
 
 
     /**
      * <p>The <code>isEmpty()</code> method returns <code>false</code>, on the
      * assumption that there is always at least one message available.</p>
      */
     public boolean isEmpty() {
 
         return (false);
 
     }
 
 
     /**
      * <p>The <code>keySet()</code> method is not supported.</p>
      */
     public Set keySet() {
 
         throw new UnsupportedOperationException();
 
     }
 
 
     /**
      * <p>The <code>put()</code> method is not supported.</p>
      *
      * @param key Key to store
      * @param value Value to store
      */
     public Object put(Object key, Object value) {
 
         throw new UnsupportedOperationException();
 
     }
 
 
     /**
      * <p>The <code>putAll()</code> method is not supported.</p>
      *
      * @param map Keys and values to store
      */
     public void putAll(Map map) {
 
         throw new UnsupportedOperationException();
 
     }
 
 
     /**
      * <p>The <code>remove()</code> method is not supported.</p>
      *
      * @param key Key to remove
      */
     public Object remove(Object key) {
 
         throw new UnsupportedOperationException();
 
     }
 
 
     /**
      * <p>The <code>size()</code> method is not supported.</p>
      */
     public int size() {
 
         throw new UnsupportedOperationException();
 
     }
 
 
     /**
      * <p>The <code>values()</code> method is not supported.</p>
      */
     public Collection values() {
 
         throw new UnsupportedOperationException();
 
     }
 
 
     // --------------------------------------------------------- Package Methods
 
 
     /**
      * <p>Return the <code>Locale</code> we object we are wrapping.</p>
      */
     Locale getLocale() {
 
         return (this.locale);
 
     }
 
 
     /**
      * <p>Return the <code>MessageResources</code> object we are wrapping.</p>
      */
     MessageResources getMessages() {
 
         return (this.messages);
 
     }
 
 
 
 }