/*
    * $Id$
    *
    * 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.Objects;
  import java.util.Set;
  
  import org.apache.struts.util.MessageResources;
  
  
  /**
   * A limited immutable {@code Map} implementation that wraps the
   * {@code MessageResources} instance for the specified {@code Locale}.
   * Exposing the messages as a {@code Map} makes them easily accessible
   * via value binding expressions, as well as JSP 2.0 expression
   * language expressions.
   */
  public class MessagesMap implements Map<String, String> {
  
  
      // ------------------------------------------------------ Instance Variables
  
  
      /**
       * The {@code Locale} for which to return messages, or
       * {@code null} for the system default {@code Locale}.
       */
      private final Locale locale;
  
  
      /**
       * The {@code MessageResources} being wrapped by this
       * {@link MessagesMap}.
       */
      private final MessageResources messages;
  
  
      // ------------------------------------------------------------ Constructors
  
  
      /**
       * Construct a new {@link MessagesMap} instance that wraps the specified
       * {@code MessageResources} instance, and returns messages for the
       * specified {@code Locale}.
       *
       * @param messages {@code MessageResources} instance to wrap
       * @param locale {@code Locale} for which to retrieve messages, or
       *     {@code null} for the system default {@code Locale}
       *
       * @throws NullPointerException if {@code messages} is {@code null}
       */
      public MessagesMap(MessageResources messages, Locale locale) {
          super();
          if (messages == null) {
              throw new NullPointerException();
          }
          this.messages = messages;
          this.locale = locale;
      }
  
  
      // ---------------------------------------------------------- Public Methods
  
  
      /**
       * The {@code clear()} method is not supported.
       */
      public void clear() {
          throw new UnsupportedOperationException();
      }
  
  
      /**
       * Return {@code true} if there is a message for the specified key.
       *
       * @param key Message key to evaluate
      */
     public boolean containsKey(Object key) {
         return key != null && messages.isPresent(locale, key.toString());
     }
 
 
     /**
      * The {@code containsValue()} method is not supported.
      *
      * @param value Value to evaluate
      */
     public boolean containsValue(Object value) {
         throw new UnsupportedOperationException();
     }
 
 
     /**
      * The {@code entrySet()} method is not supported.
      */
     public Set<Map.Entry<String, String>> entrySet() {
         throw new UnsupportedOperationException();
     }
 
 
     /**
      * The {@code equals} method checks whether equal
      * {@code MessageResources} and {@code Locale} are
      * being wrapped.
      *
      * @param o The object to be compared
      */
     public boolean equals(Object o) {
         if (this == o) {
             return true;
         }
 
         if (o == null) {
             return false;
         }
 
         if (getClass() != o.getClass()) {
             return (false);
         }
 
         final MessagesMap other = (MessagesMap) o;
         if (!messages.equals(other.getMessages())) {
             return false;
         }
 
         return Objects.equals(locale, other.locale);
     }
 
 
     /**
      * Return the message string for the specified key.
      *
      * @param key Key for message to return
      */
     public String get(Object key) {
         if (key == null) {
             return "??????";
         } else {
             return messages.getMessage(locale, key.toString());
         }
     }
 
 
     /**
      * The {@code hashCode()} method returns values that will be
      * identical if the {@code equals} method returns {@code true}.
      */
     @Override
     public int hashCode() {
         int value = messages.hashCode();
         if (locale != null) {
             value = value ^ locale.hashCode();
         }
         return value;
     }
 
 
     /**
      * The {@code isEmpty()} method returns {@code false}, on the
      * assumption that there is always at least one message available.
      */
     public boolean isEmpty() {
         return false;
     }
 
 
     /**
      * The {@code keySet()} method is not supported.
      */
     public Set<String> keySet() {
         throw new UnsupportedOperationException();
     }
 
 
     /**
      * The {@code put()} method is not supported.
      *
      * @param key Key to store
      * @param value Value to store
      */
     public String put(String key, String value) {
         throw new UnsupportedOperationException();
     }
 
 
     /**
      * The {@code putAll()} method is not supported.
      *
      * @param map Keys and values to store
      */
     public void putAll(Map<? extends String, ? extends String> map) {
         throw new UnsupportedOperationException();
     }
 
 
     /**
      * The {@code remove()} method is not supported.
      *
      * @param key Key to remove
      */
     public String remove(Object key) {
         throw new UnsupportedOperationException();
     }
 
 
     /**
      * The {@code size()} method is not supported.
      */
     public int size() {
         throw new UnsupportedOperationException();
     }
 
 
     /**
      * The {@code values()} method is not supported.
      */
     public Collection<String> values() {
         throw new UnsupportedOperationException();
     }
 
 
     // --------------------------------------------------------- Package Methods
 
 
     /**
      * Return the {@code Locale} we object we are wrapping.
      */
     Locale getLocale() {
         return this.locale;
     }
 
 
     /**
      * Return the {@code MessageResources} object we are wrapping.
      */
     MessageResources getMessages() {
         return this.messages;
     }
 
 
 }