/*
    * $Id: ReadOnlyEnumerationMap.java 1306435 2012-03-28 15:39:11Z nlebas $
    *
    * 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.ArrayList;
  import java.util.Collection;
  import java.util.Enumeration;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.tiles.request.attribute.HasKeys;
  
  /**
   * Wraps an {@link HasKeys} object into a read-only map.
   *
   * @version $Rev: 1306435 $ $Date: 2012-03-29 02:39:11 +1100 (Thu, 29 Mar 2012) $
   * @param <V> The type of the values.
   */
  public class ReadOnlyEnumerationMap<V> implements Map<String, V> {
  
      /**
       * The request.
       */
      protected HasKeys<V> request;
  
      /**
       * Constructor.
       *
       * @param request The request object to use.
       */
      public ReadOnlyEnumerationMap(HasKeys<V> request) {
          this.request = request;
      }
  
      /** {@inheritDoc} */
      public void clear() {
          throw new UnsupportedOperationException();
      }
  
  
      /** {@inheritDoc} */
      public boolean containsKey(Object key) {
          return (request.getValue(key(key)) != null);
      }
  
  
      /** {@inheritDoc} */
      @SuppressWarnings("unchecked")
      public boolean containsValue(Object value) {
          V realValue = (V) value;
          for (Enumeration<String> keysIt = request.getKeys(); keysIt.hasMoreElements();) {
              if (realValue.equals(request.getValue(keysIt.nextElement()))) {
                  return true;
              }
          }
          return false;
      }
  
  
      /** {@inheritDoc} */
      public Set<Map.Entry<String, V>> entrySet() {
          return new ReadOnlyEnumerationMapEntrySet();
      }
  
  
      /** {@inheritDoc} */
      public V get(Object key) {
          return (request.getValue(key(key)));
      }
  
  
      /** {@inheritDoc} */
      public boolean isEmpty() {
          return !request.getKeys().hasMoreElements();
      }
  
 
     /** {@inheritDoc} */
     public Set<String> keySet() {
         return new KeySet(request);
     }
 
 
     /** {@inheritDoc} */
     public V put(String key, V value) {
         throw new UnsupportedOperationException();
     }
 
 
     /** {@inheritDoc} */
     public void putAll(Map<? extends String, ? extends V> map) {
         throw new UnsupportedOperationException();
     }
 
 
     /** {@inheritDoc} */
     public V remove(Object key) {
         throw new UnsupportedOperationException();
     }
 
 
     /** {@inheritDoc} */
     public int size() {
         return enumerationSize(request.getKeys());
     }
 
 
     /** {@inheritDoc} */
     public Collection<V> values() {
         return new ReadOnlyEnumerationMapValuesCollection();
     }
 
 
     /** {@inheritDoc} */
     @SuppressWarnings("unchecked")
     @Override
     public boolean equals(Object o) {
         HasKeys<V> otherRequest = ((ReadOnlyEnumerationMap<V>) o).request;
         boolean retValue = true;
         Set<String> otherKeys = new HashSet<String>();
         for (Enumeration<String> attribs = otherRequest.getKeys(); attribs
                 .hasMoreElements();) {
             otherKeys.add(attribs.nextElement());
         }
         for (Enumeration<String> attribs = request.getKeys(); attribs
                 .hasMoreElements()
                 && retValue;) {
             String parameterName = attribs.nextElement();
             retValue = request.getValue(parameterName).equals(
                     otherRequest.getValue(parameterName));
             otherKeys.remove(parameterName);
         }
 
         return retValue && otherKeys.isEmpty();
     }
 
     /** {@inheritDoc} */
     @Override
     public int hashCode() {
         int retValue = 0;
         for (Enumeration<String> attribs = request.getKeys(); attribs
                 .hasMoreElements();) {
             String parameterName = attribs.nextElement();
             V value = request.getValue(parameterName);
             retValue += parameterName.hashCode() ^ (value == null ? 0 : value.hashCode());
         }
         return retValue;
     }
 
     /**
      * Entry set implementation for {@link ReadOnlyEnumerationMap}.
      */
     class ReadOnlyEnumerationMapEntrySet implements Set<Map.Entry<String, V>> {
 
         @Override
         public boolean add(java.util.Map.Entry<String, V> e) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean addAll(
                 Collection<? extends java.util.Map.Entry<String, V>> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public void clear() {
             throw new UnsupportedOperationException();
         }
 
         @SuppressWarnings("unchecked")
         @Override
         public boolean contains(Object o) {
             return containsEntry((java.util.Map.Entry<String, V>) o);
         }
 
         @SuppressWarnings("unchecked")
         @Override
         public boolean containsAll(Collection<?> c) {
             Collection<Map.Entry<String, V>> realCollection =
                 (Collection<Map.Entry<String, V>>) c;
             for (Map.Entry<String, V> entry : realCollection) {
                 if (!containsEntry(entry)) {
                     return false;
                 }
             }
             return true;
         }
 
         @Override
         public boolean isEmpty() {
             return ReadOnlyEnumerationMap.this.isEmpty();
         }
 
         @Override
         public Iterator<java.util.Map.Entry<String, V>> iterator() {
             return new ReadOnlyEnumerationMapEntrySetIterator();
         }
 
         @Override
         public boolean remove(Object o) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean removeAll(Collection<?> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean retainAll(Collection<?> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public int size() {
             return ReadOnlyEnumerationMap.this.size();
         }
 
         @Override
         public Object[] toArray() {
             return toList().toArray();
         }
 
         @Override
         public <T> T[] toArray(T[] a) {
             return toList().toArray(a);
         }
 
         /**
          * Checks whether the entry is present.
          *
          * @param entry The entry to check.
          * @return <code>true</code> if the entry is present.
          */
         protected boolean containsEntry(Map.Entry<String, V> entry) {
             V storedValue = request.getValue(key(entry.getKey()));
             return storedValue != null && storedValue.equals(entry.getValue());
         }
 
         /**
          * Turns this set into a list.
          *
          * @return The list.
          */
         private List<Map.Entry<String, V>> toList() {
             List<Map.Entry<String, V>> entries = new ArrayList<Map.Entry<String, V>>();
             Enumeration<String> names = request.getKeys();
             while (names.hasMoreElements()) {
                 entries.add(extractNextEntry(names));
             }
             return entries;
         }
 
         /**
          * Returns the next entry, given the enumeration.
          *
          * @param names The enumeration to get the next key from.
          * @return The next entry.
          */
         private MapEntry<String, V> extractNextEntry(
                 Enumeration<String> names) {
             String name = names.nextElement();
             return new MapEntry<String, V>(name, request.getValue(name),
                     false);
         }
 
         /**
          * Iterates entries of {@link ReadOnlyEnumerationMap}.
          */
         private class ReadOnlyEnumerationMapEntrySetIterator implements Iterator<Map.Entry<String, V>> {
 
             /**
              * Enumerates keys.
              */
             private Enumeration<String> namesEnumeration = request.getKeys();
 
             @Override
             public boolean hasNext() {
                 return namesEnumeration.hasMoreElements();
             }
 
             @Override
             public java.util.Map.Entry<String, V> next() {
                 return extractNextEntry(namesEnumeration);
             }
 
             @Override
             public void remove() {
                 throw new UnsupportedOperationException();
             }
 
         }
     }
 
     /**
      * Values collection for {@link ReadOnlyEnumerationMap}.
      */
     private class ReadOnlyEnumerationMapValuesCollection implements Collection<V> {
 
         @Override
         public boolean add(V e) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean addAll(Collection<? extends V> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public void clear() {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean contains(Object o) {
             return containsValue(o);
         }
 
         @SuppressWarnings("unchecked")
         @Override
         public boolean containsAll(Collection<?> c) {
             Collection<String> realCollection = (Collection<String>) c;
             List<String> valueList = new ArrayList<String>(realCollection);
             for (Enumeration<String> keysEnum = request.getKeys(); keysEnum.hasMoreElements();) {
                 valueList.remove(request.getValue(keysEnum.nextElement()));
                 if (valueList.isEmpty()) {
                     return true;
                 }
             }
             return false;
         }
 
         @Override
         public boolean isEmpty() {
             return ReadOnlyEnumerationMap.this.isEmpty();
         }
 
         @Override
         public Iterator<V> iterator() {
             return new ReadOnlyEnumerationMapValuesCollectionIterator();
         }
 
         @Override
         public boolean remove(Object o) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean removeAll(Collection<?> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean retainAll(Collection<?> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public int size() {
             return ReadOnlyEnumerationMap.this.size();
         }
 
         @Override
         public Object[] toArray() {
             return toList().toArray();
         }
 
         @Override
         public <T> T[] toArray(T[] a) {
             return toList().toArray(a);
         }
 
         /**
          * Turns this collection into a list.
          *
          * @return The list.
          */
         private List<V> toList() {
             List<V> entries = new ArrayList<V>();
             Enumeration<String> names = request.getKeys();
             while (names.hasMoreElements()) {
                 entries.add(request.getValue(names.nextElement()));
             }
             return entries;
         }
 
         /**
          * Iterates values of {@link ReadOnlyEnumerationMap}.
          */
         private class ReadOnlyEnumerationMapValuesCollectionIterator implements Iterator<V> {
 
             /**
              * Enumerates attribute keys.
              */
             private Enumeration<String> namesEnumeration = request.getKeys();
 
             @Override
             public boolean hasNext() {
                 return namesEnumeration.hasMoreElements();
             }
 
             @Override
             public V next() {
                 return request.getValue(namesEnumeration.nextElement());
             }
 
             @Override
             public void remove() {
                 throw new UnsupportedOperationException();
             }
         }
     }
 }