/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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 org.apache.commons.collections4.multiset;
  
  import java.util.Set;
  
  import org.apache.commons.collections4.MultiSet;
  import org.apache.commons.collections4.collection.SynchronizedCollection;
  
  /**
   * Decorates another {@link MultiSet} to synchronize its behavior
   * for a multithreaded environment.
   * <p>
   * Methods are synchronized, then forwarded to the decorated multiset.
   * Iterators must be separately synchronized around the loop.
   * </p>
   *
   * @param <E> the type held in the multiset.
   * @since 4.1
   */
  public class SynchronizedMultiSet<E> extends SynchronizedCollection<E> implements MultiSet<E> {
  
      /**
       * Synchronized Set for the MultiSet class.
       *
       * @param <T> the type held in this Set.
       */
      static class SynchronizedSet<T> extends SynchronizedCollection<T> implements Set<T> {
          /** Serialization version */
          private static final long serialVersionUID = 20150629L;
  
          /**
           * Constructs a new instance.
           * @param set  the set to decorate
           * @param lock  the lock to use, shared with the multiset
           */
          SynchronizedSet(final Set<T> set, final Object lock) {
              super(set, lock);
          }
      }
  
      /** Serialization version */
      private static final long serialVersionUID = 20150629L;
  
      /**
       * Factory method to create a synchronized multiset.
       *
       * @param <E> the type of the elements in the multiset
       * @param multiset  the multiset to decorate, must not be null
       * @return a new synchronized MultiSet
       * @throws NullPointerException if multiset is null
       */
      public static <E> SynchronizedMultiSet<E> synchronizedMultiSet(final MultiSet<E> multiset) {
          return new SynchronizedMultiSet<>(multiset);
      }
  
      /**
       * Constructor that wraps (not copies).
       *
       * @param multiset  the multiset to decorate, must not be null
       * @throws NullPointerException if multiset is null
       */
      protected SynchronizedMultiSet(final MultiSet<E> multiset) {
          super(multiset);
      }
  
      /**
       * Constructor that wraps (not copies).
       *
       * @param multiset  the multiset to decorate, must not be null
       * @param lock  the lock to use, must not be null
       * @throws NullPointerException if multiset or lock is null
       */
      protected SynchronizedMultiSet(final MultiSet<E> multiset, final Object lock) {
          super(multiset, lock);
      }
  
      @Override
      public int add(final E object, final int count) {
          synchronized (lock) {
              return decorated().add(object, count);
          }
      }
  
      /**
      * Gets the multiset being decorated.
      *
      * @return the decorated multiset
      */
     @Override
     protected MultiSet<E> decorated() {
         return (MultiSet<E>) super.decorated();
     }
 
     @Override
     public Set<Entry<E>> entrySet() {
         synchronized (lock) {
             final Set<MultiSet.Entry<E>> set = decorated().entrySet();
             return new SynchronizedSet<>(set, lock);
         }
     }
 
     @Override
     public boolean equals(final Object object) {
         if (object == this) {
             return true;
         }
         synchronized (lock) {
             return decorated().equals(object);
         }
     }
 
     @Override
     public int getCount(final Object object) {
         synchronized (lock) {
             return decorated().getCount(object);
         }
     }
 
     @Override
     public int hashCode() {
         synchronized (lock) {
             return decorated().hashCode();
         }
     }
 
     @Override
     public int remove(final Object object, final int count) {
         synchronized (lock) {
             return decorated().remove(object, count);
         }
     }
 
     @Override
     public int setCount(final E object, final int count) {
         synchronized (lock) {
             return decorated().setCount(object, count);
         }
     }
 
     @Override
     public Set<E> uniqueSet() {
         synchronized (lock) {
             final Set<E> set = decorated().uniqueSet();
             return new SynchronizedSet<>(set, lock);
         }
     }
 
 }