/*
    * 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.collections.bag;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.Set;
  
  import org.apache.commons.collections.SortedBag;
  import org.apache.commons.collections.Unmodifiable;
  import org.apache.commons.collections.iterators.UnmodifiableIterator;
  import org.apache.commons.collections.set.UnmodifiableSet;
  
  /**
   * Decorates another {@link SortedBag} to ensure it can't be altered.
   * <p>
   * This class is Serializable from Commons Collections 3.1.
   * <p>
   * Attempts to modify it will result in an UnsupportedOperationException. 
   *
   * @since 3.0
   * @version $Id: UnmodifiableSortedBag.java 1429905 2013-01-07 17:15:14Z ggregory $
   */
  public final class UnmodifiableSortedBag<E>
          extends AbstractSortedBagDecorator<E> implements Unmodifiable, Serializable {
  
      /** Serialization version */
      private static final long serialVersionUID = -3190437252665717841L;
  
      /**
       * Factory method to create an unmodifiable bag.
       * <p>
       * If the bag passed in is already unmodifiable, it is returned.
       * 
       * @param <E> the type of the elements in the bag
       * @param bag  the bag to decorate, must not be null
       * @return an unmodifiable SortedBag
       * @throws IllegalArgumentException if bag is null
       */
      public static <E> SortedBag<E> unmodifiableSortedBag(final SortedBag<E> bag) {
          if (bag instanceof Unmodifiable) {
              return bag;
          }
          return new UnmodifiableSortedBag<E>(bag);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Constructor that wraps (not copies).
       * 
       * @param bag  the bag to decorate, must not be null
       * @throws IllegalArgumentException if bag is null
       */
      private UnmodifiableSortedBag(final SortedBag<E> bag) {
          super(bag);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Write the collection out using a custom routine.
       * 
       * @param out  the output stream
       * @throws IOException
       */
      private void writeObject(final ObjectOutputStream out) throws IOException {
          out.defaultWriteObject();
          out.writeObject(collection);
      }
  
      /**
       * Read the collection in using a custom routine.
       * 
       * @param in  the input stream
       * @throws IOException
       * @throws ClassNotFoundException
       */
      @SuppressWarnings("unchecked")
      private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
          in.defaultReadObject();
          collection = (Collection<E>) in.readObject();
      }
 
     //-----------------------------------------------------------------------
     @Override
     public Iterator<E> iterator() {
         return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
     }
 
     @Override
     public boolean add(final E object) {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public boolean addAll(final Collection<? extends E> coll) {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public void clear() {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public boolean remove(final Object object) {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public boolean removeAll(final Collection<?> coll) {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public boolean retainAll(final Collection<?> coll) {
         throw new UnsupportedOperationException();
     }
 
     //-----------------------------------------------------------------------
     @Override
     public boolean add(final E object, final int count) {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public boolean remove(final Object object, final int count) {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public Set<E> uniqueSet() {
         final Set<E> set = decorated().uniqueSet();
         return UnmodifiableSet.unmodifiableSet(set);
     }
 
 }