/*
    * $Id: RemovableKeySet.java 1229087 2012-01-09 10:35:14Z mck $
    *
    * 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.tiles.request.collection;
  
  import static org.apache.tiles.request.collection.CollectionUtil.*;
  
  import java.util.Collection;
  import java.util.Enumeration;
  import java.util.LinkedHashSet;
  import java.util.Set;
  
  import org.apache.tiles.request.attribute.HasRemovableKeys;
  
  /**
   * Wraps {@link HasRemovableKeys} keys as a set.
   *
   * @version $Rev: 1229087 $ $Date: 2012-01-09 21:35:14 +1100 (Mon, 09 Jan 2012) $
   */
  public class RemovableKeySet extends KeySet {
  
      /**
       * The request.
       */
      private HasRemovableKeys<?> request;
  
      /**
       * Constructor.
       *
       * @param request The request.
       */
      public RemovableKeySet(HasRemovableKeys<?> request) {
          super(request);
          this.request = request;
      }
  
      @Override
      public boolean remove(Object o) {
          String skey = key(o);
          Object previous = request.getValue(skey);
          if (previous != null) {
              request.removeValue(skey);
              return true;
          }
          return false;
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public boolean removeAll(Collection<?> c) {
          Collection<String> realCollection = (Collection<String>) c;
          boolean retValue = false;
          for (String entry : realCollection) {
              retValue |= remove(entry);
          }
          return retValue;
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public boolean retainAll(Collection<?> c) {
          Collection<String> realCollection = (Collection<String>) c;
          boolean retValue = false;
          Set<String> keysToRemove = new LinkedHashSet<String>();
          for (Enumeration<String> keys = request.getKeys(); keys.hasMoreElements();) {
              String key = keys.nextElement();
              if (!realCollection.contains(key)) {
                  retValue = true;
                  keysToRemove.add(key);
              }
          }
          for (String key : keysToRemove) {
              request.removeValue(key);
          }
          return retValue;
      }
  
  }