/**
    * Copyright 2010-2014 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.common.util.xml.jaxb.adapter;
  
  import java.util.Collections;
  import java.util.Map;
  
  import javax.xml.bind.annotation.adapters.XmlAdapter;
  
  import org.kuali.common.util.xml.jaxb.wrapper.MapWrapper;
  
  public class ImmutableMapAdapter<K, V> extends XmlAdapter<MapWrapper<K, V>, Map<K, V>> {
  
  	private final Map<K, V> EMPTY_MAP = Collections.emptyMap();
  	private final MapWrapper<K, V> EMPTY_WRAPPER = new MapWrapper<K, V>(EMPTY_MAP);
  
  	@Override
  	public MapWrapper<K, V> marshal(Map<K, V> map) {
  		if (isEmpty(map)) {
  			return EMPTY_WRAPPER;
  		} else {
  			return new MapWrapper<K, V>(map);
  		}
  	}
  
  	@Override
  	public Map<K, V> unmarshal(MapWrapper<K, V> wrapper) {
  		if (isEmpty(wrapper.getMap())) {
  			return EMPTY_MAP;
  		} else {
  			return Collections.unmodifiableMap(wrapper.getMap());
  		}
  	}
  
  	protected static boolean isEmpty(Map<?, ?> map) {
  		return map == null || map.size() == 0;
  	}
  
  }