/*
    * 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
    *
    *      https://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.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.Queue;
  import java.util.function.Predicate;
  
  import org.apache.commons.collections4.Unmodifiable;
  import org.apache.commons.collections4.iterators.UnmodifiableIterator;
  
  /**
   * Decorates another {@link Queue} to ensure it can't be altered.
   * <p>
   * Attempts to modify it will result in an UnsupportedOperationException.
   * </p>
   *
   * @param <E> The type of elements held in this queue
   * @since 4.0
   */
  public final class UnmodifiableQueue<E>
          extends AbstractQueueDecorator<E>
          implements Unmodifiable {
  
      /** Serialization version */
      private static final long serialVersionUID = 1832948656215393357L;
  
      /**
       * Factory method to create an unmodifiable queue.
       * <p>
       * If the queue passed in is already unmodifiable, it is returned.
       *
       * @param <E> The type of the elements in the queue
       * @param queue  The queue to decorate, must not be null
       * @return An unmodifiable Queue
       * @throws NullPointerException if queue is null
       */
      public static <E> Queue<E> unmodifiableQueue(final Queue<? extends E> queue) {
          if (queue instanceof Unmodifiable) {
              @SuppressWarnings("unchecked") // safe to upcast
              final Queue<E> tmpQueue = (Queue<E>) queue;
              return tmpQueue;
          }
          return new UnmodifiableQueue<>(queue);
      }
  
      /**
       * Constructor that wraps (not copies).
       *
       * @param queue  The queue to decorate, must not be null
       * @throws NullPointerException if queue is null
       */
      @SuppressWarnings("unchecked") // safe to upcast
      private UnmodifiableQueue(final Queue<? extends E> queue) {
          super((Queue<E>) queue);
      }
  
      /**
       * Always throws {@link UnsupportedOperationException}.
       *
       * @param object Ignored.
       * @throws UnsupportedOperationException Always thrown.
       */
      @Override
      public boolean add(final Object object) {
          throw new UnsupportedOperationException();
      }
  
      /**
       * Always throws {@link UnsupportedOperationException}.
       *
       * @param coll Ignored.
       * @throws UnsupportedOperationException Always thrown.
       */
      @Override
      public boolean addAll(final Collection<? extends E> coll) {
          throw new UnsupportedOperationException();
      }
  
      /**
       * Always throws {@link UnsupportedOperationException}.
      *
      * @throws UnsupportedOperationException Always thrown.
      */
     @Override
     public void clear() {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public Iterator<E> iterator() {
         return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
     }
 
     /**
      * Always throws {@link UnsupportedOperationException}.
      *
      * @param obj Ignored.
      * @throws UnsupportedOperationException Always thrown.
      */
     @Override
     public boolean offer(final E obj) {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Always throws {@link UnsupportedOperationException}.
      *
      * @throws UnsupportedOperationException Always thrown.
      */
     @Override
     public E poll() {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Deserializes the collection in using a custom routine.
      *
      * @param in  The input stream
      * @throws IOException Thrown if an I/O error occurs while reading from the input stream
      * @throws ClassNotFoundException if the class of a serialized object cannot be found
      */
     @SuppressWarnings("unchecked")
     private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
         in.defaultReadObject();
         setCollection((Collection<E>) in.readObject());
     }
 
     /**
      * Always throws {@link UnsupportedOperationException}.
      *
      * @throws UnsupportedOperationException Always thrown.
      */
     @Override
     public E remove() {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Always throws {@link UnsupportedOperationException}.
      *
      * @param object Ignored.
      * @throws UnsupportedOperationException Always thrown.
      */
     @Override
     public boolean remove(final Object object) {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Always throws {@link UnsupportedOperationException}.
      *
      * @param coll Ignored.
      * @throws UnsupportedOperationException Always thrown.
      */
     @Override
     public boolean removeAll(final Collection<?> coll) {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Always throws {@link UnsupportedOperationException}.
      *
      * @param filter Ignored.
      * @throws UnsupportedOperationException Always thrown.
      * @since 4.4
      */
     @Override
     public boolean removeIf(final Predicate<? super E> filter) {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Always throws {@link UnsupportedOperationException}.
      *
      * @param coll Ignored.
      * @throws UnsupportedOperationException Always thrown.
      */
     @Override
     public boolean retainAll(final Collection<?> coll) {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Serializes this object to an ObjectOutputStream.
      *
      * @param out The target ObjectOutputStream.
      * @throws IOException thrown when an I/O errors occur writing to the target stream.
      */
     private void writeObject(final ObjectOutputStream out) throws IOException {
         out.defaultWriteObject();
         out.writeObject(decorated());
     }
 
 }