/*
    * Copyright (C) 2007 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 static com.google.common.base.Preconditions.checkArgument;
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import com.google.common.annotations.GwtCompatible;
  import com.google.common.annotations.GwtIncompatible;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.util.EnumMap;
  import java.util.Map;
  
  /**
   * A {@code BiMap} backed by two {@code EnumMap} instances. Null keys and values
   * are not permitted. An {@code EnumBiMap} and its inverse are both
   * serializable.
   * 
   * <p>See the Guava User Guide article on <a href=
   * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#BiMap">
   * {@code BiMap}</a>.
   *
   * @author Mike Bostock
   * @since 2.0 (imported from Google Collections Library)
   */
  @GwtCompatible(emulated = true)
  public final class EnumBiMap<K extends Enum<K>, V extends Enum<V>>
      extends AbstractBiMap<K, V> {
    private transient Class<K> keyType;
    private transient Class<V> valueType;
  
    /**
     * Returns a new, empty {@code EnumBiMap} using the specified key and value
     * types.
     *
     * @param keyType the key type
     * @param valueType the value type
     */
    public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V>
        create(Class<K> keyType, Class<V> valueType) {
      return new EnumBiMap<K, V>(keyType, valueType);
    }
  
    /**
     * Returns a new bimap with the same mappings as the specified map. If the
     * specified map is an {@code EnumBiMap}, the new bimap has the same types as
     * the provided map. Otherwise, the specified map must contain at least one
     * mapping, in order to determine the key and value types.
     *
     * @param map the map whose mappings are to be placed in this map
     * @throws IllegalArgumentException if map is not an {@code EnumBiMap}
     *     instance and contains no mappings
     */
    public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V>
        create(Map<K, V> map) {
      EnumBiMap<K, V> bimap = create(inferKeyType(map), inferValueType(map));
      bimap.putAll(map);
      return bimap;
    }
  
    private EnumBiMap(Class<K> keyType, Class<V> valueType) {
      super(WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
          WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
      this.keyType = keyType;
      this.valueType = valueType;
    }
  
    static <K extends Enum<K>> Class<K> inferKeyType(Map<K, ?> map) {
      if (map instanceof EnumBiMap) {
        return ((EnumBiMap<K, ?>) map).keyType();
      }
      if (map instanceof EnumHashBiMap) {
        return ((EnumHashBiMap<K, ?>) map).keyType();
      }
      checkArgument(!map.isEmpty());
      return map.keySet().iterator().next().getDeclaringClass();
    }
  
    private static <V extends Enum<V>> Class<V> inferValueType(Map<?, V> map) {
      if (map instanceof EnumBiMap) {
        return ((EnumBiMap<?, V>) map).valueType;
      }
     checkArgument(!map.isEmpty());
     return map.values().iterator().next().getDeclaringClass();
   }
 
   /** Returns the associated key type. */
   public Class<K> keyType() {
     return keyType;
   }
 
   /** Returns the associated value type. */
   public Class<V> valueType() {
     return valueType;
   }
 
   @Override
   K checkKey(K key) {
     return checkNotNull(key);
   }
 
   @Override
   V checkValue(V value) {
     return checkNotNull(value);
   }
 
   /**
    * @serialData the key class, value class, number of entries, first key, first
    *     value, second key, second value, and so on.
    */
   @GwtIncompatible("java.io.ObjectOutputStream")
   private void writeObject(ObjectOutputStream stream) throws IOException {
     stream.defaultWriteObject();
     stream.writeObject(keyType);
     stream.writeObject(valueType);
     Serialization.writeMap(this, stream);
   }
 
   @SuppressWarnings("unchecked") // reading fields populated by writeObject
   @GwtIncompatible("java.io.ObjectInputStream")
   private void readObject(ObjectInputStream stream)
       throws IOException, ClassNotFoundException {
     stream.defaultReadObject();
     keyType = (Class<K>) stream.readObject();
     valueType = (Class<V>) stream.readObject();
     setDelegates(
         WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
         WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
     Serialization.populateMap(this, stream);
   }
 
   @GwtIncompatible("not needed in emulated source.")
   private static final long serialVersionUID = 0;
 }