/*
 * Copyright (C) 2007 Google Inc.
 *
 * 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.base.Nullable;

import java.util.EnumMap;
import java.util.HashMap;
import java.util.Map;

/**
 * A {@code BiMap} backed by an {@code EnumMap} instance for keys-to-values, and
 * a {@code HashMap} instance for values-to-keys. Null keys are not permitted,
 * but null values are.
 *
 * @see EnumMap
 * @see HashMap
 * @author Mike Bostock
 */
public final class EnumHashBiMap<K extends Enum<K>, V>
    extends StandardBiMap<K, V> {
  final Class<K> keyType;

  /**
   * Constructs a new empty bimap using the specified key type, sized to contain
   * an entry for every possible key.
   *
   * @param keyType the key type
   * @throws NullPointerException if any argument is null
   */
  public EnumHashBiMap(Class<K> keyType) {
    super(new EnumMap<K, V>(keyType),
        new HashMap<V, K>(keyType.getEnumConstants().length * 3 / 2));
    this.keyType = keyType;
  }

  /**
   * Constructs a new bimap with the same mappings as the specified map. If the
   * specified map is an {@code EnumHashBiMap} or an {@code EnumBiMap} instance,
   * this constructor behaves identically to {@link
   * #EnumHashBiMap(EnumHashBiMap)} or {@link #EnumHashBiMap(EnumHashBiMap)},
   * respectively. Otherwise, the specified map must contain at least one
   * mapping (in order to determine the new enum bimap's key type).
   *
   * @param map the map whose mappings are to be placed in this map
   * @throws IllegalArgumentException if map is not an {@code EnumBiMap} or an
   *     {@code EnumHashBiMap} instance and contains no mappings
   */
  public EnumHashBiMap(Map<K, ? extends V> map) {
    this(EnumBiMap.inferKeyType(map));
    putAll(map); // careful if we make this class non-final
  }

  /**
   * Constructs a new bimap with the same key type as the specified map,
   * initially containing the same mappings (if any).
   *
   * @param map the map whose mappings are to be placed in this map
   */
  public EnumHashBiMap(EnumHashBiMap<K, ? extends V> map) {
    this(map.keyType);
    putAll(map); // careful if we make this class non-final
  }

  /*
   * Constructs a new bimap with the same key type as the specified map,
   * initially containing the same mappings (if any).
   *
   * <p>Note: This constructor has been commented out to work around Eclipse bug
   * 179902. It should be restored when the bug has been fixed. In the meantime,
   * the "(Map<K, ? extends V> map)" overload will suffice. See:
   * <a href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=179902">bug
   * report</a>.
   */
//  @SuppressWarnings("unchecked")
//  public EnumHashBiMap(EnumBiMap<K, ? extends V> map) {
//    this(map.keyType);
//    putAll((Map) map); // careful if we make this class non-final
//  }

  // Overriding these two methods to show that values may be null (but not keys)

  @Override public V put(K key, @Nullable V value) {
    return super.put(key, value);
  }

  @Override public V forcePut(K key, @Nullable V value) {
    return super.forcePut(key, value);
  }

  /** Returns the associated key type. */
  public Class<K> keyType() {
    return keyType;
  }
}