/*
    * 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.set;
  
  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.SortedSet;
  
  import org.apache.commons.collections.Unmodifiable;
  import org.apache.commons.collections.iterators.UnmodifiableIterator;
  
  /**
   * Decorates another <code>SortedSet</code> 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: UnmodifiableSortedSet.java 1429905 2013-01-07 17:15:14Z ggregory $
   */
  public final class UnmodifiableSortedSet<E>
          extends AbstractSortedSetDecorator<E>
          implements Unmodifiable, Serializable {
  
      /** Serialization version */
      private static final long serialVersionUID = -725356885467962424L;
  
      /**
       * Factory method to create an unmodifiable set.
       * 
       * @param <E> the element type
       * @param set  the set to decorate, must not be null
       * @return a new unmodifiable {@link SortedSet}
       * @throws IllegalArgumentException if set is null
       */
      public static <E> SortedSet<E> unmodifiableSortedSet(final SortedSet<E> set) {
          if (set instanceof Unmodifiable) {
              return set;
          }
          return new UnmodifiableSortedSet<E>(set);
      }
  
      //-----------------------------------------------------------------------
      /**
       * 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") // (1) should only fail if input stream is incorrect 
      private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
          in.defaultReadObject();
          collection = (Collection<E>) in.readObject(); // (1)
      }
  
      //-----------------------------------------------------------------------
      /**
       * Constructor that wraps (not copies).
       * 
       * @param set  the set to decorate, must not be null
       * @throws IllegalArgumentException if set is null
       */
      private UnmodifiableSortedSet(final SortedSet<E> set) {
          super(set);
      }
  
      //-----------------------------------------------------------------------
      @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 SortedSet<E> subSet(final E fromElement, final E toElement) {
         final SortedSet<E> sub = decorated().subSet(fromElement, toElement);
         return new UnmodifiableSortedSet<E>(sub);
     }
 
     @Override
     public SortedSet<E> headSet(final E toElement) {
         final SortedSet<E> sub = decorated().headSet(toElement);
         return new UnmodifiableSortedSet<E>(sub);
     }
 
     @Override
     public SortedSet<E> tailSet(final E fromElement) {
         final SortedSet<E> sub = decorated().tailSet(fromElement);
         return new UnmodifiableSortedSet<E>(sub);
     }
 
 }