/*
 * Copyright (C) 2005-2007 Alfresco Software Limited.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 * As a special exception to the terms and conditions of version 2.0 of 
 * the GPL, you may redistribute this Program in connection with Free/Libre 
 * and Open Source Software ("FLOSS") applications as described in Alfresco's 
 * FLOSS exception.  You should have recieved a copy of the text describing 
 * the FLOSS exception, and it is also available here: 
 * http://www.alfresco.com/legal/licensing"
 */
package org.alfresco.web.scripts;

import java.io.FileNotFoundException;
import java.io.IOException;

import org.alfresco.repo.template.FreeMarkerProcessor;
import org.alfresco.repo.template.QNameAwareObjectWrapper;
import org.alfresco.service.cmr.repository.ProcessorExtension;
import org.alfresco.util.AbstractLifecycleBean;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;

import freemarker.cache.MruCacheStorage;
import freemarker.cache.TemplateLoader;
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateExceptionHandler;


/**
 * FreeMarker Processor for use in Web Scripts
 * 
 * Adds the ability to:
 * - specify template loaders
 * - caching of templates
 * 
 * @author davidc
 */
public class TemplateProcessor extends FreeMarkerProcessor implements ApplicationContextAware, ApplicationListener
{
    private ProcessorLifecycle lifecycle = new ProcessorLifecycle();
    private TemplateLoader templateLoader = null;
    private String defaultEncoding;
    private Configuration templateConfig;
    private FreeMarkerProcessor freeMarkerProcessor;


    /* (non-Javadoc)
     * @see org.alfresco.repo.template.FreeMarkerProcessor#setDefaultEncoding(java.lang.String)
     */
    public void setDefaultEncoding(String defaultEncoding)
    {
        this.defaultEncoding = defaultEncoding;
    }
    
    /* (non-Javadoc)
     * @see org.alfresco.repo.template.FreeMarkerProcessor#getConfig()
     */
    @Override
    protected Configuration getConfig()
    {
        return templateConfig;
    }

    /**
     * Sets the Template Loader
     * 
     * @param templateLoader  template loader
     */
    public void setTemplateLoader(TemplateLoader templateLoader)
    {
        this.templateLoader = templateLoader;
    }
    
    /**
     * Set the freemarker processor
     * 
     * @param freeMarkerProcessor   the free marker processor
     */
    public void setFreeMarkerProcessor(FreeMarkerProcessor freeMarkerProcessor)
    {
        this.freeMarkerProcessor = freeMarkerProcessor;
    }

    /**
     * Reset template cache
     */
    public void resetCache()
    {
        if (templateConfig != null)
        {
            templateConfig.clearTemplateCache();
        }
    }
    
    /**
     * Determines if a template exists
     * 
     * @param template
     * @return  true => exists
     */
    public boolean hasTemplate(String templatePath)
    {
        boolean hasTemplate = false;
        try
        {
            Template template = templateConfig.getTemplate(templatePath);
            hasTemplate = (template != null);
        }
        catch(FileNotFoundException e)
        {
            // NOTE: return false as template is not found
        }
        catch(IOException e)
        {
            throw new WebScriptException("Failed to retrieve template " + templatePath, e);
        }
        return hasTemplate;
    }
    
    /**
     * Initialise FreeMarker Configuration
     */
    protected void initConfig()
    {
        Configuration config = new Configuration();
        
        // setup template cache
        config.setCacheStorage(new MruCacheStorage(20, 100));

        // setup template loaders
        config.setTemplateLoader(templateLoader);
        
        // use our custom object wrapper that can deal with QNameMap objects directly
        config.setObjectWrapper(new QNameAwareObjectWrapper());
        
        // rethrow any exception so we can deal with them
        config.setTemplateExceptionHandler(TemplateExceptionHandler.RETHROW_HANDLER);
        
        // set template encoding
        if (defaultEncoding != null)
        {
            config.setDefaultEncoding(defaultEncoding);
        }
        
        // set output encoding
        config.setOutputEncoding("UTF-8");
        
        templateConfig = config;
    }
    
    /**
     * Tempory fix to initialise this template processor with the freeMarker extensions expected by
     * the templates.    
     */
    private void initProcessorExtensions()
    {
        for (ProcessorExtension processorExtension : this.freeMarkerProcessor.getProcessorExtensions())
        {
            this.registerProcessorExtension(processorExtension);
        }
    }
    
    /* (non-Javadoc)
     * @see org.springframework.context.ApplicationContextAware#setApplicationContext(org.springframework.context.ApplicationContext)
     */
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException
    {
        lifecycle.setApplicationContext(applicationContext);
    }

    /* (non-Javadoc)
     * @see org.springframework.context.ApplicationListener#onApplicationEvent(org.springframework.context.ApplicationEvent)
     */
    public void onApplicationEvent(ApplicationEvent event)
    {
        lifecycle.onApplicationEvent(event);
    }
    
    /**
     * Hooks into Spring Application Lifecycle
     */
    private class ProcessorLifecycle extends AbstractLifecycleBean
    {
        @Override
        protected void onBootstrap(ApplicationEvent event)
        {
            initConfig();
            initProcessorExtensions();
        }
    
        @Override
        protected void onShutdown(ApplicationEvent event)
        {
        }
    }

}