/*
 * Copyright 2003-2011 JetBrains s.r.o.
 *
 * 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 jetbrains.mps.util.containers;

import gnu.trove.THashMap;
import org.jetbrains.annotations.Nullable;

import java.util.*;

public class BidirectionalMap<K, V> implements Map<K, V> {
  private final Map<K, V> myKeyToValueMap = new THashMap<K, V>();
  private final Map<V, List<K>> myValueToKeysMap = new THashMap<V, List<K>>();

  @Override
  public V put(K key, V value) {
    V oldValue = myKeyToValueMap.put(key, value);
    if (oldValue != null) {
      if (oldValue.equals(value)) return oldValue;
      List<K> array = myValueToKeysMap.get(oldValue);
      array.remove(key);
    }

    List<K> array = myValueToKeysMap.get(value);
    if (array == null) {
      array = new ArrayList<K>();
      myValueToKeysMap.put(value, array);
    }
    array.add(key);
    return oldValue;
  }

  @Override
  public void clear() {
    myKeyToValueMap.clear();
    myValueToKeysMap.clear();
  }

  @Nullable
  public List<K> getKeysByValue(V value) {
    return myValueToKeysMap.get(value);
  }

  @Override
  public Set<K> keySet() {
    return myKeyToValueMap.keySet();
  }

  @Override
  public int size() {
    return myKeyToValueMap.size();
  }

  @Override
  public boolean isEmpty() {
    return myKeyToValueMap.isEmpty();
  }

  @Override
  public boolean containsKey(Object key) {
    return myKeyToValueMap.containsKey(key);
  }

  @Override
  @SuppressWarnings({"SuspiciousMethodCalls"})
  public boolean containsValue(Object value) {
    return myValueToKeysMap.containsKey(value);
  }

  @Override
  public V get(Object key) {
    return myKeyToValueMap.get(key);
  }

  public void removeValue(V v) {
    List<K> ks = myValueToKeysMap.remove(v);
    if (ks != null) {
      for (K k : ks) {
        myKeyToValueMap.remove(k);
      }
    }
  }

  @Override
  @SuppressWarnings({"SuspiciousMethodCalls"})
  public V remove(Object key) {
    final V value = myKeyToValueMap.remove(key);
    final List<K> ks = myValueToKeysMap.get(value);
    if (ks != null) {
      if (ks.size() > 1) ks.remove(key);
      else myValueToKeysMap.remove(value);
    }
    return value;
  }

  @Override
  public void putAll(Map<? extends K, ? extends V> t) {
    for (final K k1 : t.keySet()) {
      put(k1, t.get(k1));
    }
  }

  @Override
  public Collection<V> values() {
    return myValueToKeysMap.keySet();
  }

  @Override
  public Set<Entry<K, V>> entrySet() {
    return myKeyToValueMap.entrySet();
  }

  @Override
  public String toString() {
    return new HashMap<K, V>(myKeyToValueMap).toString();
  }
}
