/*
 * 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.queue;

import java.util.Queue;

import org.apache.commons.collections4.Transformer;
import org.apache.commons.collections4.collection.TransformedCollection;

Decorates another Queue to transform objects that are added. 

The add/offer 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.

Type parameters:
<E> – the type of elements held in this queue
Since:
4.0/**
 * Decorates another {@link Queue} to transform objects that are added.
 * <p>
 * The add/offer 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>
 *
 * @param <E> the type of elements held in this queue
 * @since 4.0
 */
public class TransformedQueue<E> extends TransformedCollection<E> implements Queue<E> {

    
Serialization version /** Serialization version */
    private static final long serialVersionUID = -7901091318986132033L;

    
Factory method to create a transforming queue.
 If there are any elements already in the queue being decorated, they are NOT transformed. Contrast this with transformedQueue(Queue<Object>, Transformer<? super Object,? extends Object>). 
Params:
queue –  the queue to decorate, must not be null
transformer –  the transformer to use for conversion, must not be null
Type parameters:
<E> – the type of the elements in the queue
Throws:
NullPointerException – if queue or transformer is null
Returns:
a new transformed Queue/**
     * Factory method to create a transforming queue.
     * <p>
     * If there are any elements already in the queue being decorated, they
     * are NOT transformed.
     * Contrast this with {@link #transformedQueue(Queue, Transformer)}.
     *
     * @param <E> the type of the elements in the queue
     * @param queue  the queue to decorate, must not be null
     * @param transformer  the transformer to use for conversion, must not be null
     * @return a new transformed Queue
     * @throws NullPointerException if queue or transformer is null
     */
    public static <E> TransformedQueue<E> transformingQueue(final Queue<E> queue,
                                                            final Transformer<? super E, ? extends E> transformer) {
        return new TransformedQueue<>(queue, transformer);
    }

    
Factory method to create a transforming queue that will transform
existing contents of the specified queue.
 If there are any elements already in the queue being decorated, they will be transformed by this method. Contrast this with transformingQueue(Queue<Object>, Transformer<? super Object,? extends Object>). 
Params:
queue –  the queue to decorate, must not be null
transformer –  the transformer to use for conversion, must not be null
Type parameters:
<E> – the type of the elements in the queue
Throws:
NullPointerException – if queue or transformer is null
Returns:
a new transformed Queue
Since:
4.0/**
     * Factory method to create a transforming queue that will transform
     * existing contents of the specified queue.
     * <p>
     * If there are any elements already in the queue being decorated, they
     * will be transformed by this method.
     * Contrast this with {@link #transformingQueue(Queue, Transformer)}.
     *
     * @param <E> the type of the elements in the queue
     * @param queue  the queue to decorate, must not be null
     * @param transformer  the transformer to use for conversion, must not be null
     * @return a new transformed Queue
     * @throws NullPointerException if queue or transformer is null
     * @since 4.0
     */
    public static <E> TransformedQueue<E> transformedQueue(final Queue<E> queue,
                                                           final Transformer<? super E, ? extends E> transformer) {
        // throws IAE if queue or transformer is null
        final TransformedQueue<E> decorated = new TransformedQueue<>(queue, transformer);
        if (queue.size() > 0) {
            @SuppressWarnings("unchecked") // queue is type <E>
            final E[] values = (E[]) queue.toArray(); // NOPMD - false positive for generics
            queue.clear();
            for (final E value : values) {
                decorated.decorated().add(transformer.transform(value));
            }
        }
        return decorated;
    }

    //-----------------------------------------------------------------------
    
Constructor that wraps (not copies).

If there are any elements already in the queue being decorated, they
are NOT transformed.
Params:
queue –  the queue to decorate, must not be null
transformer –  the transformer to use for conversion, must not be null
Throws:
NullPointerException – if queue or transformer is null/**
     * Constructor that wraps (not copies).
     * <p>
     * If there are any elements already in the queue being decorated, they
     * are NOT transformed.
     *
     * @param queue  the queue to decorate, must not be null
     * @param transformer  the transformer to use for conversion, must not be null
     * @throws NullPointerException if queue or transformer is null
     */
    protected TransformedQueue(final Queue<E> queue, final Transformer<? super E, ? extends E> transformer) {
        super(queue, transformer);
    }

    
Gets the decorated queue.
Returns:
the decorated queue/**
     * Gets the decorated queue.
     *
     * @return the decorated queue
     */
    protected Queue<E> getQueue() {
        return (Queue<E>) decorated();
    }

    //-----------------------------------------------------------------------

    @Override
    public boolean offer(final E obj) {
        return getQueue().offer(transform(obj));
    }

    @Override
    public E poll() {
        return getQueue().poll();
    }

    @Override
    public E peek() {
        return getQueue().peek();
    }

    @Override
    public E element() {
        return getQueue().element();
    }

    @Override
    public E remove() {
        return getQueue().remove();
    }

}