/*-
 * ============LICENSE_START=======================================================
 * sdc-distribution-client
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.sdc.utils;

import java.beans.IntrospectionException;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.HashMap;

import org.onap.sdc.utils.heat.HeatConfiguration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.yaml.snakeyaml.TypeDescription;
import org.yaml.snakeyaml.Yaml;
import org.yaml.snakeyaml.introspector.BeanAccess;
import org.yaml.snakeyaml.introspector.Property;
import org.yaml.snakeyaml.introspector.PropertyUtils;

public class YamlToObjectConverter {

	private static Logger log = LoggerFactory
			.getLogger(YamlToObjectConverter.class.getName());

	private static HashMap<String, Yaml> yamls = new HashMap<String, Yaml>();

	private static Yaml defaultYaml = new Yaml();

	static {

		org.yaml.snakeyaml.constructor.Constructor heatConstructor = new org.yaml.snakeyaml.constructor.Constructor(HeatConfiguration.class);
		TypeDescription heatDescription = new TypeDescription(HeatConfiguration.class);
		//heatDescription.putListPropertyType("parameters", HeatParameterConfiguration.class);
		heatConstructor.addTypeDescription(heatDescription);
		PropertyUtils propertyUtils = new PropertyUtils() {
			@Override
			//This is in order to workaround "default" field in HeatParameterEntry, since default is Java keyword
			public Property getProperty(Class<? extends Object> type, String name, BeanAccess bAccess)
					throws IntrospectionException {
				name = name.substring(0, 1).toLowerCase() + name.substring(1);
				return super.getProperty(type, name, bAccess);
			}

		};
		//Skip properties which are not found - we only are interested in "parameters"
		propertyUtils.setSkipMissingProperties(true);
		heatConstructor.setPropertyUtils(propertyUtils);

		Yaml yaml = new Yaml(heatConstructor);

		yamls.put(HeatConfiguration.class.getName(), yaml);

	}

	private static <T> Yaml getYamlByClassName(Class<T> className) {

		Yaml yaml = yamls.get(className.getName());
		if (yaml == null) {
			yaml = defaultYaml;
		}

		return yaml;
	}

	public <T> T convert(String dirPath, Class<T> className,
			String configFileName) {

		T config = null;

		try {

			String fullFileName = dirPath + File.separator + configFileName;

			config = convert(fullFileName, className);

		} catch (Exception e) {
			log.error("Failed to convert yaml file " + configFileName
					+ " to object.", e);
		} 

		return config;
	}

	public <T> T convert(String fullFileName, Class<T> className) {

		T config = null;

		Yaml yaml = getYamlByClassName(className);

		InputStream in = null;
		try {

			File f = new File(fullFileName);
			if (false == f.exists()) {
				log.warn("The file " + fullFileName
						+ " cannot be found. Ignore reading configuration.");
				return null;
			}
			in = Files.newInputStream(Paths.get(fullFileName));

			config = yaml.loadAs(in, className);

			// System.out.println(config.toString());
		} catch (Exception e) {
			log.error("Failed to convert yaml file " + fullFileName
					+ " to object.", e);
		} finally {
			if (in != null) {
				try {
					in.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}

		return config;
	}

	public <T> T convertFromString(String yamlContents, Class<T> className) {

		T config = null;

		Yaml yaml = getYamlByClassName(className);

		try {
			config = yaml.loadAs(yamlContents, className);
		} catch (Exception e){
			log.error("Failed to convert YAML {} to object." , yamlContents, e);
		}

		return config;
	}
}