/*
    * Copyright (C) 2011 The Guava Authors
    *
    * 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 com.google.common.collect;
  
  import com.google.common.annotations.GwtCompatible;
  
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * Workaround for
   * <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6312706">
   * EnumMap bug</a>. If you want to pass an {@code EnumMap}, with the
   * intention of using its {@code entrySet()} method, you should
   * wrap the {@code EnumMap} in this class instead.
   *
   * <p>This class is not thread-safe even if the underlying map is.
   *
   * @author Dimitris Andreou
   */
  @GwtCompatible
  final class WellBehavedMap<K, V> extends ForwardingMap<K, V> {
    private final Map<K, V> delegate;
    private Set<Entry<K, V>> entrySet;
  
    private WellBehavedMap(Map<K, V> delegate) {
      this.delegate = delegate;
    }
  
    /**
     * Wraps the given map into a {@code WellBehavedEntriesMap}, which
     * intercepts its {@code entrySet()} method by taking the
     * {@code Set<K> keySet()} and transforming it to
     * {@code Set<Entry<K, V>>}. All other invocations are delegated as-is.
     */
    static <K, V> WellBehavedMap<K, V> wrap(Map<K, V> delegate) {
      return new WellBehavedMap<K, V>(delegate);
    }
  
    @Override protected Map<K, V> delegate() {
      return delegate;
    }
  
    @Override public Set<Entry<K, V>> entrySet() {
      Set<Entry<K, V>> es = entrySet;
      if (es != null) {
        return es;
      }
      return entrySet = new EntrySet();
    }
  
    private final class EntrySet extends Maps.EntrySet<K, V> {
      @Override
      Map<K, V> map() {
        return WellBehavedMap.this;
      }
  
      @Override
      public Iterator<Entry<K, V>> iterator() {
        return new TransformedIterator<K, Entry<K, V>>(keySet().iterator()) {
          @Override
          Entry<K, V> transform(final K key) {
            return new AbstractMapEntry<K, V>() {
              @Override
              public K getKey() {
                return key;
              }
  
              @Override
              public V getValue() {
                return get(key);
              }
  
              @Override
              public V setValue(V value) {
                return put(key, value);
              }
            };
          }
        };
      }
    }
  }