/*
 * 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 BiMap backed by two EnumMap instances. Null keys and values are not permitted. An EnumBiMap and its inverse are both serializable. 
See the Guava User Guide article on  BiMap.
Author:
Mike Bostock
Since:
2.0/**
 * 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=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap}</a>.
 *
 * @author Mike Bostock
 * @since 2.0
 */
@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 EnumBiMap using the specified key and value types. 
Params:
keyType – the key type
valueType – the value type/**
   * 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<>(keyType, valueType);
  }

  
Returns a new bimap with the same mappings as the specified map. If the specified map is an 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. 
Params:
map – the map whose mappings are to be placed in this map
Throws:
IllegalArgumentException – if map is not an EnumBiMap instance and contains no mappings/**
   * 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(new EnumMap<K, V>(keyType), 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. /** Returns the associated key type. */
  public Class<K> keyType() {
    return keyType;
  }

  
Returns the associated value type. /** 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./**
   * @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(new EnumMap<K, V>(keyType), new EnumMap<V, K>(valueType));
    Serialization.populateMap(this, stream);
  }

  @GwtIncompatible // not needed in emulated source.
  private static final long serialVersionUID = 0;
}