/*
    * Copyright 2004-2010 the Seasar Foundation and the Others.
    *
    * Licensed 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.seasar.cubby.internal.controller.impl;
  
  import java.util.Collection;
  import java.util.Map;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpSession;
  
  import org.seasar.cubby.action.FlashMap;
  import org.seasar.cubby.internal.controller.ThreadContext;
  
  /**
   * {@link FlashMap} の実装です。
   * 
   * @author baba
   */
  class FlashMapImpl implements FlashMap {
  
  	/** セッションの属性に格納する {@link Map} のキー。 */
  	private static final String ATTRIBUTE_NAME = FlashMapImpl.class.getName()
  			+ ".MAP";
  
  	/** 要求。 */
  	private final HttpServletRequest request;
  
  	/** 実際に値を格納する {@link Map}。 */
  	private final Map<String, Object> map;
  
  	/**
  	 * インスタンス化します。
  	 * <p>
  	 * 内部で使用する要求は {@link ThreadContext} から取得します。
  	 * </p>
  	 */
  	public FlashMapImpl() {
  		this(ThreadContext.getCurrentContext().getRequest());
  	}
  
  	/**
  	 * インスタンス化します。
  	 * 
  	 * @param request
  	 *            要求
  	 */
  	public FlashMapImpl(final HttpServletRequest request) {
  		this.request = request;
  		this.map = buildMap(request);
  	}
  
  	private Map<String, Object> buildMap(final HttpServletRequest request) {
  		final HttpSession session = request.getSession(false);
  		if (session != null) {
  			final Map<String, Object> map = getAttribute(session,
  					ATTRIBUTE_NAME);
  			if (map != null) {
  				return map;
  			}
  		}
  		return createMap();
  	}
  
  	protected Map<String, Object> createMap() {
  		return new ConcurrentHashMap<String, Object>();
  	}
  
  	private void export(final HttpSession session) {
  		session.setAttribute(ATTRIBUTE_NAME, this.map);
  	}
  
  	/**
  	 * {@inheritDoc}
  	 */
  	public int size() {
  		return map.size();
  	}
  
  	/**
  	 * {@inheritDoc}
  	 */
  	public boolean isEmpty() {
  		return map.isEmpty();
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public boolean containsKey(final Object key) {
 		return map.containsKey(key);
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public boolean containsValue(final Object value) {
 		return map.containsValue(value);
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public Object get(final Object key) {
 		return map.get(key);
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public Object put(final String key, final Object value) {
 		final Object previousValue = map.put(key, value);
 		export(request.getSession());
 		return previousValue;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public Object remove(final Object key) {
 		final Object removedValue = map.remove(key);
 		final HttpSession session = request.getSession(false);
 		if (session != null) {
 			export(session);
 		}
 		return removedValue;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public void putAll(final Map<? extends String, ? extends Object> t) {
 		map.putAll(t);
 		export(request.getSession());
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public void clear() {
 		map.clear();
 		final HttpSession session = request.getSession(false);
 		if (session != null) {
 			export(session);
 		}
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public Set<String> keySet() {
 		return map.keySet();
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public Collection<Object> values() {
 		return map.values();
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public Set<Entry<String, Object>> entrySet() {
 		return map.entrySet();
 	}
 
 	@SuppressWarnings("unchecked")
 	private static <T> T getAttribute(final HttpSession session,
 			final String name) {
 		return (T) session.getAttribute(name);
 	}
 
 }