/**********************************************************************************
 * $URL: https://source.sakaiproject.org/svn/msgcntr/trunk/messageforums-app/src/java/org/sakaiproject/tool/messageforums/jsf/MessageForumsNavigationHandler.java $
 * $Id: MessageForumsNavigationHandler.java 9227 2006-05-15 15:02:42Z cwen@iupui.edu $
 ***********************************************************************************
 *
 * Copyright (c) 2003, 2004, 2005, 2006, 2008 The Sakai 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/ECL-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.sakaiproject.tool.messageforums.jsf;

import javax.faces.application.NavigationHandler;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.servlet.http.HttpSession;

/**
 * <p>
 * SakaiNavigationHandler catches the response that is being redirected to preserve the faces messages for the return request.
 * </p>
 * 
 */
public class MessageForumsNavigationHandler extends NavigationHandler
{
	/** The other navigation handler. */
	protected NavigationHandler m_chain = null;

	/**
	 * Construct.
	 */
	public MessageForumsNavigationHandler()
	{
	}

	/**
	 * Construct.
	 */
	public MessageForumsNavigationHandler(NavigationHandler chain)
	{
		m_chain = chain;
	}

	/**
	 * Handle the navigation
	 * 
	 * @param context
	 *        The Faces context.
	 * @param fromAction
	 *        The action string that triggered the action.
	 * @param outcome
	 *        The logical outcome string, which is the new tool mode, or if null, the mode does not change.
	 */
	public void handleNavigation(FacesContext context, String fromAction, String outcome)
	{
		m_chain.handleNavigation(context, fromAction, outcome);		
		
		ExternalContext exContext = context.getExternalContext();
    HttpSession session = (HttpSession) exContext.getSession(false);

    if (session == null){
      return;
    }
		
		// add previous navigationString (outcome) to session
		session.setAttribute("MC_PREVIOUS_NAV", outcome);
	}
}