package org.apache.commons.jcs.access;
   
   /*
    * 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.
   */
  
  import org.apache.commons.jcs.access.behavior.IGroupCacheAccess;
  import org.apache.commons.jcs.access.exception.CacheException;
  import org.apache.commons.jcs.access.exception.InvalidArgumentException;
  import org.apache.commons.jcs.engine.CacheElement;
  import org.apache.commons.jcs.engine.behavior.ICacheElement;
  import org.apache.commons.jcs.engine.behavior.IElementAttributes;
  import org.apache.commons.jcs.engine.control.CompositeCache;
  import org.apache.commons.jcs.engine.control.group.GroupAttrName;
  import org.apache.commons.jcs.engine.control.group.GroupId;
  
  import java.io.IOException;
  import java.util.HashSet;
  import java.util.Set;
  
  /**
   * Access for groups.
   */
  public class GroupCacheAccess<K, V>
      extends AbstractCacheAccess<GroupAttrName<K>, V>
      implements IGroupCacheAccess<K, V>
  {
      /**
       * Constructor for the GroupCacheAccess object
       * <p>
       * @param cacheControl
       */
      public GroupCacheAccess( CompositeCache<GroupAttrName<K>, V> cacheControl )
      {
          super(cacheControl);
      }
  
      /**
       * Gets an item out of the cache that is in a specified group.
       * <p>
       * @param name
       *            The key name.
       * @param group
       *            The group name.
       * @return The cached value, null if not found.
       */
      @Override
      public V getFromGroup( K name, String group )
      {
          ICacheElement<GroupAttrName<K>, V> element = this.getCacheControl().get( getGroupAttrName( group, name ) );
          return ( element != null ) ? element.getVal() : null;
      }
  
      /**
       * Internal method used for group functionality.
       * <p>
       * @param group
       * @param name
       * @return GroupAttrName
       */
      private GroupAttrName<K> getGroupAttrName( String group, K name )
      {
          GroupId gid = new GroupId( this.getCacheControl().getCacheName(), group );
          return new GroupAttrName<K>( gid, name );
      }
  
      /**
       * Allows the user to put an object into a group within a particular cache
       * region. This method sets the object's attributes to the default for the
       * region.
       * <p>
       * @param name
       *            The key name.
       * @param groupName
       *            The group name.
       * @param value
       *            The object to cache
       * @throws CacheException
       */
      @Override
      public void putInGroup( K name, String groupName, V value )
          throws CacheException
      {
          putInGroup( name, groupName, value, null );
     }
 
     /**
      * Allows the user to put an object into a group within a particular cache
      * region. This method allows the object's attributes to be individually
      * specified.
      * <p>
      * @param name
      *            The key name.
      * @param groupName
      *            The group name.
      * @param value
      *            The object to cache
      * @param attr
      *            The objects attributes.
      * @throws CacheException
      */
     @Override
     public void putInGroup( K name, String groupName, V value, IElementAttributes attr )
         throws CacheException
     {
         if ( name == null )
         {
             throw new InvalidArgumentException( "Key must not be null" );
         }
 
         if ( value == null )
         {
             throw new InvalidArgumentException( "Value must not be null" );
         }
 
         // Create the element and update. This may throw an IOException which
         // should be wrapped by cache access.
         try
         {
             GroupAttrName<K> key = getGroupAttrName( groupName, name );
             CacheElement<GroupAttrName<K>, V> ce =
                 new CacheElement<GroupAttrName<K>, V>( this.getCacheControl().getCacheName(), key, value );
 
             IElementAttributes attributes = (attr == null) ? this.getCacheControl().getElementAttributes() : attr;
             ce.setElementAttributes( attributes );
 
             this.getCacheControl().update( ce );
         }
         catch ( IOException e )
         {
             throw new CacheException( e );
         }
 
     }
 
     /**
      * @param name
      * @param group
      */
     @Override
     public void removeFromGroup( K name, String group )
     {
         GroupAttrName<K> key = getGroupAttrName( group, name );
         this.getCacheControl().remove( key );
     }
 
     /**
      * Gets the set of keys of objects currently in the group.
      * <p>
      * @param group
      * @return A Set of keys.
      */
     @Override
     public Set<K> getGroupKeys( String group )
     {
         Set<K> groupKeys = new HashSet<K>();
         GroupId groupId = new GroupId( this.getCacheControl().getCacheName(), group );
 
         for (GroupAttrName<K> gan : this.getCacheControl().getKeySet())
         {
             if (gan.groupId.equals( groupId ))
             {
                 groupKeys.add( gan.attrName );
             }
         }
 
         return groupKeys;
     }
 
     /**
      * Gets the set of group names in the cache
      * <p>
      * @return A Set of group names.
      */
     public Set<String> getGroupNames()
     {
         HashSet<String> names = new HashSet<String>();
         for (GroupAttrName<K> gan : this.getCacheControl().getKeySet())
         {
             names.add(gan.groupId.groupName);
         }
         return names;
     }
 
     /**
      * Invalidates a group: remove all the group members
      * <p>
      * @param group
      *            The name of the group to invalidate
      */
     @Override
     public void invalidateGroup( String group )
     {
         this.getCacheControl().remove(getGroupAttrName(group, null));
     }
 }