com.epam.gmp.service.yaml.YamlFreemarkerEngine Maven / Gradle / Ivy

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/*
 *  /***************************************************************************
 *  Copyright (c) 2017, EPAM SYSTEMS INC
 *  Licensed 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 com.epam.gmp.service.yaml;

import com.epam.gmp.GmpResourceUtils;
import com.epam.gmp.ScriptInitializationException;
import freemarker.cache.ClassTemplateLoader;
import freemarker.cache.MultiTemplateLoader;
import freemarker.cache.TemplateLoader;
import freemarker.cache.URLTemplateLoader;
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;
import org.springframework.core.io.Resource;

import java.io.IOException;
import java.io.StringWriter;
import java.net.URL;


public class YamlFreemarkerEngine {
    private Configuration config;

    public class GmpURLTemplateLoader extends URLTemplateLoader {
        Resource baseFolder;

        public GmpURLTemplateLoader(Resource baseFolder) {
            this.baseFolder = baseFolder;
        }

        @Override
        protected URL getURL(String name) {
            try {
                return GmpResourceUtils.getRelativeResource(baseFolder, name).getURL();
            } catch (ScriptInitializationException | IOException ex) {
                //TODO
            }
            return null;
        }
    }

    public YamlFreemarkerEngine(ClassLoader classLoader, String path, Resource baseFolder) throws IOException {
        Configuration cfg = new Configuration(Configuration.VERSION_2_3_25);
        TemplateLoader[] loaders = {new ClassTemplateLoader(classLoader, path), new GmpURLTemplateLoader(baseFolder)};
        cfg.setTemplateLoader(new MultiTemplateLoader(loaders));
        cfg.setDefaultEncoding("UTF-8");
        cfg.setTemplateExceptionHandler(freemarker.template.TemplateExceptionHandler.RETHROW_HANDLER);
        config = cfg;
    }

    public String loadYaml(String templateName, YamlLoaderContext context) throws IOException, TemplateException {
        Template template = config.getTemplate(templateName);
        StringWriter out = new StringWriter();
        template.process(context.getParams(), out);
        return out.toString();
    }
}