/*

  * $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();

             }

         }

     }

 }