/*
    * 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.bag;
  
  import java.util.Set;
  
  import org.apache.commons.collections4.Bag;
  import org.apache.commons.collections4.Transformer;
  import org.apache.commons.collections4.collection.TransformedCollection;
  import org.apache.commons.collections4.set.TransformedSet;
  
  /**
   * Decorates another {@link Bag} to transform objects that are added.
   * <p>
   * The add methods are affected by this class.
   * Thus objects must be removed or searched for using their transformed form.
   * For example, if the transformation converts Strings to Integers, you must
   * use the Integer form to remove objects.
   * </p>
   * <p>
   * This class is Serializable from Commons Collections 3.1.
   * </p>
   *
   * @param <E> the type of elements in this bag
   * @since 3.0
   */
  public class TransformedBag<E> extends TransformedCollection<E> implements Bag<E> {
  
      /** Serialization version */
      private static final long serialVersionUID = 5421170911299074185L;
  
      /**
       * Factory method to create a transforming bag that will transform
       * existing contents of the specified bag.
       * <p>
       * If there are any elements already in the bag being decorated, they
       * will be transformed by this method.
       * Contrast this with {@link #transformingBag(Bag, Transformer)}.
       *
       * @param <E> the type of the elements in the bag
       * @param bag  the bag to decorate, must not be null
       * @param transformer  the transformer to use for conversion, must not be null
       * @return a new transformed Bag
       * @throws NullPointerException if bag or transformer is null
       * @since 4.0
       */
      public static <E> Bag<E> transformedBag(final Bag<E> bag, final Transformer<? super E, ? extends E> transformer) {
          final TransformedBag<E> decorated = new TransformedBag<>(bag, transformer);
          if (!bag.isEmpty()) {
              @SuppressWarnings("unchecked") // Bag is of type E
              final E[] values = (E[]) bag.toArray(); // NOPMD - false positive for generics
              bag.clear();
              for (final E value : values) {
                  decorated.decorated().add(transformer.apply(value));
              }
          }
          return decorated;
      }
  
      /**
       * Factory method to create a transforming bag.
       * <p>
       * If there are any elements already in the bag being decorated, they
       * are NOT transformed. Contrast this with {@link #transformedBag(Bag, Transformer)}.
       *
       * @param <E> the type of the elements in the bag
       * @param bag  the bag to decorate, must not be null
       * @param transformer  the transformer to use for conversion, must not be null
       * @return a new transformed Bag
       * @throws NullPointerException if bag or transformer is null
       * @since 4.0
       */
      public static <E> Bag<E> transformingBag(final Bag<E> bag, final Transformer<? super E, ? extends E> transformer) {
          return new TransformedBag<>(bag, transformer);
      }
  
      /**
       * Constructor that wraps (not copies).
       * <p>
       * If there are any elements already in the bag being decorated, they
       * are NOT transformed.
       *
       * @param bag  the bag to decorate, must not be null
       * @param transformer  the transformer to use for conversion, must not be null
       * @throws NullPointerException if bag or transformer is null
      */
     protected TransformedBag(final Bag<E> bag, final Transformer<? super E, ? extends E> transformer) {
         super(bag, transformer);
     }
 
     @Override
     public boolean add(final E object, final int nCopies) {
         return getBag().add(transform(object), nCopies);
     }
 
     @Override
     public boolean equals(final Object object) {
         return object == this || decorated().equals(object);
     }
 
     /**
      * Gets the decorated bag.
      *
      * @return the decorated bag
      */
     protected Bag<E> getBag() {
         return (Bag<E>) decorated();
     }
 
     @Override
     public int getCount(final Object object) {
         return getBag().getCount(object);
     }
 
     @Override
     public int hashCode() {
         return decorated().hashCode();
     }
 
     @Override
     public boolean remove(final Object object, final int nCopies) {
         return getBag().remove(object, nCopies);
     }
 
     @Override
     public Set<E> uniqueSet() {
         final Set<E> set = getBag().uniqueSet();
         return TransformedSet.<E>transformingSet(set, transformer);
     }
 
 }