package org.apache.turbine.modules.actions;

/*
 * 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.turbine.modules.screens.TemplateScreen;
import org.apache.turbine.pipeline.PipelineData;
import org.apache.turbine.util.velocity.VelocityActionEvent;
import org.apache.velocity.context.Context;

/**
 * This class provides a convenience methods for Velocity Actions to use. Since
 * this class is abstract, it should only be extended and not used directly.
 *
 * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
 * @author <a href="mailto:jvanzyl@periapt.com">Jason van Zyl</a>
 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
 * @version $Id$
 */
public abstract class VelocityAction extends VelocityActionEvent
{
    /**
     * Initialize the module.
     *
     * @throws Exception a generic exception.
     */
    @Override
    public void initialize() throws Exception
    {
        initialized = true;
    }

    /**
     * You SHOULD override this method and implement it in your action.
     *
     * @param pipelineData Turbine information.
     * @param context Context for web pages.
     * @throws Exception a generic exception.
     */
    public abstract void doPerform(PipelineData pipelineData, Context context)
            throws Exception;

    /**
     * Sets up the context and then calls super.perform(); thus, subclasses
     * don't have to worry about getting a context themselves! If a subclass
     * throws an exception then depending on whether
     * action.event.bubbleexception is true, then it bubbles it farther up, or
     * traps it there.
     *
     * @param pipelineData Turbine information.
     * @throws Exception a generic exception.
     */
    @Override
    public void perform(PipelineData pipelineData) throws Exception
    {
        try
        {
            super.perform(pipelineData);
        }
        catch (Exception e)
        {
            if (bubbleUpException)
            {
                throw e;
            }
        }
    }

    /**
     * This method is used when you want to short circuit an Action and change
     * the template that will be executed next.
     *
     * @param pipelineData Turbine information.
     * @param template The template that will be executed next.
     */
    public void setTemplate(PipelineData pipelineData, String template)
    {
        TemplateScreen.setTemplate(pipelineData, template);
    }
}
