VelocityTemplateUtils.java

/*
 * GovWay - A customizable API Gateway 
 * https://govway.org
 * 
 * Copyright (c) 2005-2025 Link.it srl (https://link.it). 
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3, as published by
 * the Free Software Foundation.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 *
 */

package org.openspcoop2.utils.resources;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.RuntimeInstance;
import org.apache.velocity.runtime.parser.ParseException;



/**
 *  TemplateUtils
 *
 * @author Poli Andrea (apoli@link.it)
 * @author $Author$
 * @version $Rev$, $Date$
 */
public class VelocityTemplateUtils {

    
    /** -------- Utility per la creazione delle configurazioni ------------- */
    
    public static VelocityEngine newTemplateEngine() {
        VelocityEngine engine = new VelocityEngine();
        engine.init();
        return engine;
    }
    public static VelocityEngine newTemplateEngine(String propsFileName) {
        VelocityEngine engine = new VelocityEngine();
        engine.init(propsFileName);
        return engine;
    }
    public static VelocityEngine newTemplateEngine(Properties p) {
        VelocityEngine engine = new VelocityEngine();
        engine.init(p);
        return engine;
    }
    
    
    
    /** -------- Utility per la creazione dei template ------------- */
    
    public static Template getTemplate(VelocityEngine engine,String templateName) throws IOException{
        return engine.getTemplate(templateName);
    }
    public static Template getTemplate(VelocityEngine engine,String templateName, String encoding) throws IOException{
        return engine.getTemplate(templateName, encoding);
    }
    
    public static Template buildTemplate(String name,byte[] bytes) throws IOException, ParseException{
        return buildTemplate(name, bytes, Charset.UTF_8.getValue(), null);
    }
    public static Template buildTemplate(String name,byte[] bytes, String encoding) throws IOException, ParseException{
        return buildTemplate(name, bytes, encoding,
                null);
    }
    
    public static Template buildTemplate(String name,byte[] bytes,
            Map<String, byte[]> templateIncludes) throws IOException, ParseException{
        return buildTemplate(name, bytes, Charset.UTF_8.getValue(), 
                templateIncludes);
    }
    public static Template buildTemplate(String name,byte[] bytes, String encoding,
            Map<String, byte[]> templateIncludes) throws IOException, ParseException{
        
        RuntimeInstance instance = new RuntimeInstance();
        
        String defaultTemplate = "_____DEFAULT_TEMPLATE___";
        
        if(templateIncludes==null) {
            templateIncludes= new HashMap<String, byte[]>();
        }
        VelocityTemplateLoader loader = new VelocityTemplateLoader(templateIncludes);
        templateIncludes.put(defaultTemplate, bytes);
        instance.setProperty(RuntimeConstants.RESOURCE_LOADER, "govway_rl" );
        instance.setProperty("govway_rl."+RuntimeConstants.RESOURCE_LOADER+"."+RuntimeConstants.RESOURCE_LOADER_INSTANCE, loader);

        instance.init();

        Template template = instance.getTemplate(defaultTemplate, encoding);
        
        /*
        Metodo che non consentiva la risoluzione dei template interni
        Template template = new Template();
        template.setName(name);
        template.setEncoding(encoding);
        RuntimeServices runtimeServices = RuntimeSingleton.getRuntimeServices();
        StringReader reader = new StringReader(new String(bytes));
        SimpleNode node = runtimeServices.parse(reader, template);
        template.setRuntimeServices(runtimeServices);
        template.setData(node);
        template.initDocument();
        */
        return template;
    }
    
    
    
    /** -------- Trasformazioni dei template ------------- */
        
    public static VelocityContext toVelocityContext(Map<String, Object> map) {
        VelocityContext context = new VelocityContext(map);
        return context;
    }
    
    public static byte[] toByteArray(Template template,Map<String, Object> map) throws IOException {
        ByteArrayOutputStream bout = new ByteArrayOutputStream();
        OutputStreamWriter writer = new OutputStreamWriter(bout);
        template.merge( toVelocityContext(map), writer );
        writer.flush();
        writer.close();
        bout.flush();
        bout.close();
        return bout.toByteArray();
    }
    public static String toString(Template template,Map<String, Object> map) throws IOException{
        ByteArrayOutputStream bout = new ByteArrayOutputStream();
        OutputStreamWriter writer = new OutputStreamWriter(bout);
        template.merge( toVelocityContext(map), writer );
        writer.flush();
        writer.close();
        bout.flush();
        bout.close();
        return bout.toString();
    }
    public static void writeFile(Template template,Map<String, Object> map,File file,boolean overwrite) throws Exception{
        if(!overwrite){
            if(file.exists()){
                System.out.println(": WARNING !! File ["+file.getAbsolutePath()+"] is already exist, it is not overwritten !!");
                return;
            }
        }
        FileSystemUtilities.mkdirParentDirectory(file);
        FileSystemUtilities.writeFile(file, VelocityTemplateUtils.toByteArray(template, map));
    }
    

    
}