/*
 * This file is a part of EpnTAPClient.
 * This program aims to provide EPN-TAP support for software clients, like CASSIS spectrum analyzer.
 * See draft specifications: https://voparis-confluence.obspm.fr/pages/viewpage.action?pageId=559861
 * Copyright (C) 2016 Institut de Recherche en Astrophysique et Planétologie.
 * 
 * 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 3 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, see
 * <http://www.gnu.org/licenses/>.
 */

package eu.omp.irap.vespa.epntapclient.utils;

import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

import org.apache.log4j.Logger;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

import eu.omp.irap.vespa.epntapclient.EpnTapMainApp;

/**
 * Simple class to provide logging features
 * 
 * @author N. Jourdane
 */
public class Log {
	/** The logger for this class. */
	private static final Logger logger = Logger.getLogger(EpnTapMainApp.class);

	/** The log file path used by `logInFile` and `clearLogFile`. */
	private static String logPath = Const.TMP_DIR + "/log";

	/** Constructor to hide the implicit public one. */
	private Log() {
	}

	/**
	 * Print the specified object in JSON format in a file on the temp directory. The default file
	 * name is "log.json"
	 * 
	 * @param obj the object to print in a file.
	 * @return The path of the file.
	 */
	public static String printObject(Object obj) {
		return printObject("log", obj);
	}

	/**
	 * Print the specified object in JSON format in a file on the temp directory.
	 * 
	 * @param title The name of the file.
	 * @param obj the object to print in a file.
	 * @return The path of the file.
	 */
	public static String printObject(String title, Object obj) {
		Gson gson = new GsonBuilder().setPrettyPrinting().create();
		String json = gson.toJson(obj);
		String path = Const.TMP_DIR + "/" + title + ".json";
		try (FileWriter writer = new FileWriter(path)) {
			writer.write(json);

		} catch (IOException e) {
			logger.error("Can not print in the file " + path, e);
		}

		return path;
	}

	// TODO: Use log4j FileAppender instead

	/**
	 * Delete the content of the log file.
	 */
	public static void clearLogFile() {
		try (PrintWriter writer = new PrintWriter(logPath)) {
			writer.print("");
		} catch (FileNotFoundException e) {
			logger.error("File " + logPath + " not found, can not clear it.", e);
		}
	}

	// TODO: Use log4j FileAppender instead

	/**
	 * Print a message in a log file (named "log").
	 * 
	 * @param text The text to log in the file
	 */
	public static void logInFile(Object text) {

		try {
			Files.write(Paths.get(logPath), (text.toString() + "\n").getBytes(),
					StandardOpenOption.APPEND);
		} catch (IOException e) {
			logger.error("Can not print in the file " + logPath, e);
		}
	}

}