/*
 * $Id$
 *
 * 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.struts2.util;

import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.util.ValueStack;


/**
 * InvocationSessionStore
 *
 */
public class InvocationSessionStore {

    private static final String INVOCATION_MAP_KEY = "org.apache.struts2.util.InvocationSessionStore.invocationMap";


    private InvocationSessionStore() {
    }


    /**
     * Checks the Map in the Session for the key and the token. If the
     * ActionInvocation is saved in the Session, the ValueStack from the
     * ActionProxy associated with the ActionInvocation is set into the
     * ActionContext and the ActionInvocation is returned.
     *
     * @param key the name the DefaultActionInvocation and ActionContext were saved as
     * @return the DefaultActionInvocation saved using the key, or null if none was found
     */
    public static ActionInvocation loadInvocation(String key, String token) {
        InvocationContext invocationContext = (InvocationContext) getInvocationMap().get(key);

        if ((invocationContext == null) || !invocationContext.token.equals(token)) {
            return null;
        }

        ValueStack stack = invocationContext.invocation.getStack();
        ActionContext.getContext().setValueStack(stack);

        return invocationContext.invocation;
    }

    /**
     * Stores the DefaultActionInvocation and ActionContext into the Session using the provided key for loading later using
     * {@link #loadInvocation}
     *
     * @param key
     * @param invocation
     */
    public static void storeInvocation(String key, String token, ActionInvocation invocation) {
        InvocationContext invocationContext = new InvocationContext(invocation, token);
        Map invocationMap = getInvocationMap();
        invocationMap.put(key, invocationContext);
        setInvocationMap(invocationMap);
    }

    static void setInvocationMap(Map invocationMap) {
        Map session = ActionContext.getContext().getSession();

        if (session == null) {
            throw new IllegalStateException("Unable to access the session.");
        }

        session.put(INVOCATION_MAP_KEY, invocationMap);
    }

    static Map getInvocationMap() {
        Map session = ActionContext.getContext().getSession();

        if (session == null) {
            throw new IllegalStateException("Unable to access the session.");
        }

        Map invocationMap = (Map) session.get(INVOCATION_MAP_KEY);

        if (invocationMap == null) {
            invocationMap = new HashMap();
            setInvocationMap(invocationMap);
        }

        return invocationMap;
    }


    private static class InvocationContext implements Serializable {

        private static final long serialVersionUID = -286697666275777888L;

        ActionInvocation invocation;
        String token;

        public InvocationContext(ActionInvocation invocation, String token) {
            this.invocation = invocation;
            this.token = token;
        }
    }
}
