/*
    * Copyright (C) 2009 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.collect.CollectPreconditions.checkEntryNotNull;
  
  import java.util.Map;
  
  /**
   * GWT emulation of {@link ImmutableBiMap}.
   *
   * @author Hayward Chan
   */
  public abstract class ImmutableBiMap<K, V> extends ForwardingImmutableMap<K, V>
      implements BiMap<K, V> {
  
    // Casting to any type is safe because the set will never hold any elements.
    @SuppressWarnings("unchecked")
    public static <K, V> ImmutableBiMap<K, V> of() {
      return (ImmutableBiMap<K, V>) EmptyImmutableBiMap.INSTANCE;
    }
  
    public static <K, V> ImmutableBiMap<K, V> of(K k1, V v1) {
      checkEntryNotNull(k1, v1);
      return new SingletonImmutableBiMap<K, V>(k1, v1);
    }
  
    public static <K, V> ImmutableBiMap<K, V> of(K k1, V v1, K k2, V v2) {
      return new RegularImmutableBiMap<K, V>(ImmutableMap.of(k1, v1, k2, v2));
    }
  
    public static <K, V> ImmutableBiMap<K, V> of(
        K k1, V v1, K k2, V v2, K k3, V v3) {
      return new RegularImmutableBiMap<K, V>(ImmutableMap.of(
          k1, v1, k2, v2, k3, v3));
    }
  
    public static <K, V> ImmutableBiMap<K, V> of(
        K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
      return new RegularImmutableBiMap<K, V>(ImmutableMap.of(
          k1, v1, k2, v2, k3, v3, k4, v4));
    }
  
    public static <K, V> ImmutableBiMap<K, V> of(
        K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
      return new RegularImmutableBiMap<K, V>(ImmutableMap.of(
          k1, v1, k2, v2, k3, v3, k4, v4, k5, v5));
    }
  
    public static <K, V> Builder<K, V> builder() {
      return new Builder<K, V>();
    }
  
    public static final class Builder<K, V> extends ImmutableMap.Builder<K, V> {
  
      public Builder() {}
  
      @Override public Builder<K, V> put(K key, V value) {
        super.put(key, value);
        return this;
      }
  
      @Override public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
        super.putAll(map);
        return this;
      }
  
      @Override public ImmutableBiMap<K, V> build() {
        ImmutableMap<K, V> map = super.build();
        if (map.isEmpty()) {
          return of();
        }
        return new RegularImmutableBiMap<K, V>(super.build());
      }
    }
  
    public static <K, V> ImmutableBiMap<K, V> copyOf(
        Map<? extends K, ? extends V> map) {
      if (map instanceof ImmutableBiMap) {
        @SuppressWarnings("unchecked") // safe since map is not writable
        ImmutableBiMap<K, V> bimap = (ImmutableBiMap<K, V>) map;
        return bimap;
      }
  
      if (map.isEmpty()) {
       return of();
     }
 
     ImmutableMap<K, V> immutableMap = ImmutableMap.copyOf(map);
     return new RegularImmutableBiMap<K, V>(immutableMap);
   }
 
   ImmutableBiMap(Map<K, V> delegate) {
     super(delegate);
   }
 
   public abstract ImmutableBiMap<V, K> inverse();
 
   @Override public ImmutableSet<V> values() {
     return inverse().keySet();
   }
 
   public final V forcePut(K key, V value) {
     throw new UnsupportedOperationException();
   }
 }