/*
    * $Id: HeaderValuesMap.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.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.EnumeratedValuesExtractor;
  
  
  /**
   * Exposes an {@link EnumeratedValuesExtractor} object as a read-only map.
   *
   * @version $Rev: 1229087 $ $Date: 2012-01-09 21:35:14 +1100 (Mon, 09 Jan 2012) $
   */
  public class HeaderValuesMap implements Map<String, String[]> {
  
      /**
       * The request.
       */
      private EnumeratedValuesExtractor request;
  
      /**
       * Constructor.
       *
       * @param request The request object to use.
       */
      public HeaderValuesMap(EnumeratedValuesExtractor request) {
          this.request = request;
      }
  
  
      /** {@inheritDoc} */
      public void clear() {
          throw new UnsupportedOperationException();
      }
  
  
      /** {@inheritDoc} */
      public boolean containsKey(Object key) {
          return (request.getValue(key(key)) != null);
      }
  
  
      /** {@inheritDoc} */
      public boolean containsValue(Object value) {
          if (!(value instanceof String[])) {
              return (false);
          }
          String[] test = (String[]) value;
          Enumeration<String> names = request.getKeys();
          while (names.hasMoreElements()) {
              String name = names.nextElement();
              if (compareHeaders(name, array2set(test))) {
                  return true;
              }
          }
          return false;
      }
  
  
      /** {@inheritDoc} */
      public Set<Map.Entry<String, String[]>> entrySet() {
          return new HeadersEntrySet();
      }
  
  
      /** {@inheritDoc} */
      @Override
      public boolean equals(Object o) {
          EnumeratedValuesExtractor otherRequest = ((HeaderValuesMap) o).request;
          boolean retValue = true;
          for (Enumeration<String> attribs = request.getKeys(); attribs
                 .hasMoreElements()
                 && retValue;) {
             String parameterName = attribs.nextElement();
             Set<String> valueSet = enumeration2set(otherRequest.getValues(parameterName));
             retValue = compareHeaders(parameterName, valueSet);
         }
 
         return retValue;
     }
 
 
     /** {@inheritDoc} */
     public String[] get(Object key) {
         return getHeaderValues(key(key));
     }
 
     /** {@inheritDoc} */
     @Override
     public int hashCode() {
         int retValue = 0;
         for (Enumeration<String> attribs = request.getKeys(); attribs
                 .hasMoreElements();) {
             String parameterName = attribs.nextElement();
             Enumeration<String> values = request.getValues(parameterName);
             int valueHash = 0;
             while (values.hasMoreElements()) {
                 valueHash += values.nextElement().hashCode();
             }
             retValue += parameterName.hashCode() ^ valueHash;
         }
         return retValue;
     }
 
 
     /** {@inheritDoc} */
     public boolean isEmpty() {
         return !request.getKeys().hasMoreElements();
     }
 
 
     /** {@inheritDoc} */
     public Set<String> keySet() {
         return new KeySet(request);
     }
 
 
     /** {@inheritDoc} */
     public String[] put(String key, String[] value) {
         throw new UnsupportedOperationException();
     }
 
 
     /** {@inheritDoc} */
     public void putAll(Map<? extends String, ? extends String[]> map) {
         throw new UnsupportedOperationException();
     }
 
 
     /** {@inheritDoc} */
     public String[] remove(Object key) {
         throw new UnsupportedOperationException();
     }
 
 
 
     /** {@inheritDoc} */
     public int size() {
         return enumerationSize(request.getKeys());
     }
 
 
     /** {@inheritDoc} */
     public Collection<String[]> values() {
         return new HeaderValuesCollection();
     }
 
     /**
      * Extracts values enumeration of an attribute and returns the corresponding array of values.
      *
      * @param key The key of the attribute.
      * @return The values of the attribute.
      */
     private String[] getHeaderValues(String key) {
         List<String> list = new ArrayList<String>();
         Enumeration<String> values = request.getValues(key);
         while (values.hasMoreElements()) {
             list.add(values.nextElement());
         }
         String[] retValue = list.toArray(new String[list.size()]);
         return retValue;
     }
 
     /**
      * Converts the content of a string enumeration to an array of strings.
      *
      * @param enumeration The enumeration to convert.
      * @return The corresponding array.
      */
     private Set<String> enumeration2set(Enumeration<String> enumeration) {
         Set<String> retValue = new HashSet<String>();
         while (enumeration.hasMoreElements()) {
             retValue.add(enumeration.nextElement());
         }
         return retValue;
     }
 
     /**
      * Transforms a string array in a string set.
      *
      * @param valueArray The array to convert.
      * @return The corresponding set.
      */
     private Set<String> array2set(String[] valueArray) {
         Set<String> values = new HashSet<String>();
         for (int i = 0; i < valueArray.length; i++) {
             values.add(valueArray[i]);
         }
         return values;
     }
 
     /**
      * Checks if values of a header attribute are the same as the one passed in
      * the set.
      *
      * @param name The name of the header.
      * @param testSet The set of values it must contain.
      * @return <code>true</code> if all the values, and only them, are present
      * in the header values.
      */
     private boolean compareHeaders(String name, Set<String> testSet) {
         Enumeration<String> values = request.getValues(name);
         boolean matched = true;
         while (values.hasMoreElements() && matched) {
             String currentValue = values.nextElement();
             matched = testSet.remove(currentValue);
         }
         matched = matched && testSet.isEmpty();
         return matched;
     }
 
     /**
      * Entry set implementation for {@link HeaderValuesMap}.
      */
     private class HeadersEntrySet implements Set<Map.Entry<String, String[]>> {
 
         @Override
         public boolean add(java.util.Map.Entry<String, String[]> e) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean addAll(
                 Collection<? extends java.util.Map.Entry<String, String[]>> 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, String[]>) o);
         }
 
         @SuppressWarnings("unchecked")
         @Override
         public boolean containsAll(Collection<?> c) {
             Collection<Map.Entry<String, String[]>> realCollection =
                 (Collection<Map.Entry<String, String[]>>) c;
             for (Map.Entry<String, String[]> entry : realCollection) {
                 if (!containsEntry(entry)) {
                     return false;
                 }
             }
             return true;
         }
 
         @Override
         public boolean isEmpty() {
             return HeaderValuesMap.this.isEmpty();
         }
 
         @Override
         public Iterator<java.util.Map.Entry<String, String[]>> iterator() {
             return new HeadersEntrySetIterator();
         }
 
         @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 HeaderValuesMap.this.size();
         }
 
         @Override
         public Object[] toArray() {
             return toList().toArray();
         }
 
         @Override
         public <T> T[] toArray(T[] a) {
             return toList().toArray(a);
         }
 
         /**
          * Checks whether the given entry is present in the headers.
          *
          * @param entry The entry to check.
          * @return <code></code> if the key and the values of the entry are present.
          */
         private boolean containsEntry(Map.Entry<String, String[]> entry) {
             Enumeration<String> entryValues = request.getValues(key(entry.getKey()));
             String[] valueArray = entry.getValue();
             Set<String> values = array2set(valueArray);
             while (entryValues.hasMoreElements()) {
                 if (!values.remove(entryValues.nextElement())) {
                     return false;
                 }
             }
             return values.isEmpty();
         }
 
         /**
          * Turns this entry set into a list.
          *
          * @return The collection, turned into a list.
          */
         private List<Map.Entry<String, String[]>> toList() {
             List<Map.Entry<String, String[]>> entries = new ArrayList<Map.Entry<String, String[]>>();
             Enumeration<String> names = request.getKeys();
             while (names.hasMoreElements()) {
                 entries.add(extractNextEntry(names));
             }
             return entries;
         }
 
         /**
          * Returns the next entry, by getting the next element in the given enumeration.
          *
          * @param names The enumeration to get the next name from..
          * @return The next map entry.
          */
         private MapEntry<String, String[]> extractNextEntry(
                 Enumeration<String> names) {
             String name = names.nextElement();
             return new MapEntryArrayValues<String, String>(name, getHeaderValues(name), false);
         }
 
         /**
          * Iterates {@link HeadersEntrySet} elements.
          */
         private class HeadersEntrySetIterator implements Iterator<Map.Entry<String, String[]>> {
 
             /**
              * The enumeration to use.
              */
             private Enumeration<String> namesEnumeration = request.getKeys();
 
             @Override
             public boolean hasNext() {
                 return namesEnumeration.hasMoreElements();
             }
 
             @Override
             public Map.Entry<String, String[]> next() {
                 return extractNextEntry(namesEnumeration);
             }
 
             @Override
             public void remove() {
                 throw new UnsupportedOperationException();
             }
 
         }
     }
 
     /**
      * It is a collection of all values of the header. Each element is an array
      * of values of a single header.
      */
     private class HeaderValuesCollection implements Collection<String[]> {
 
         @Override
         public boolean add(String[] e) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean addAll(Collection<? extends String[]> 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;
             for (String[] value : realCollection) {
                 if (!containsValue(value)) {
                     return false;
                 }
             }
             return true;
         }
 
         @Override
         public boolean isEmpty() {
             return HeaderValuesMap.this.isEmpty();
         }
 
         @Override
         public Iterator<String[]> iterator() {
             return new HeaderValuesCollectionIterator();
         }
 
         @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 HeaderValuesMap.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<String[]> toList() {
             List<String[]> entries = new ArrayList<String[]>();
             Enumeration<String> names = request.getKeys();
             while (names.hasMoreElements()) {
                 entries.add(enumeration2array(request.getValues(names.nextElement())));
             }
             return entries;
         }
 
         /**
          * Converts the content of a string enumeration to an array of strings.
          *
          * @param enumeration The enumeration to convert.
          * @return The corresponding array.
          */
         private String[] enumeration2array(Enumeration<String> enumeration) {
             List<String> list1 = new ArrayList<String>();
             while (enumeration.hasMoreElements()) {
                 list1.add(enumeration.nextElement());
             }
 
             return list1.toArray(new String[list1.size()]);
         }
 
         /**
          * Iterates elements of {@link HeaderValuesCollection}.
          */
         private class HeaderValuesCollectionIterator implements Iterator<String[]> {
 
             /**
              * The enumeration of the name of header attributes.
              */
             private Enumeration<String> namesEnumeration = request.getKeys();
 
             @Override
             public boolean hasNext() {
                 return namesEnumeration.hasMoreElements();
             }
 
             @Override
             public String[] next() {
                 return enumeration2array(request.getValues(namesEnumeration.nextElement()));
             }
 
             @Override
             public void remove() {
                 throw new UnsupportedOperationException();
             }
         }
     }
 }