package envoy.util;

import java.io.*;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.logging.*;

import envoy.data.Config;

/**
 * Configures the {@link java.util.logging} API to output the log into the console and a log file.
 *
 * @author Leon Hofmeister
 * @author Kai S. K. Engelbart
 * @since Envoy Common v0.1-beta
 */
public final class EnvoyLog {

	private static FileHandler		fileHandler;
	private static StreamHandler	consoleHandler;
	private static boolean			initialized;

	private EnvoyLog() {}

	/**
	 * Initializes logging.
	 *
	 * @param config the config providing the console and log file barriers
	 * @since Envoy Common v0.1-beta
	 */
	public static void initialize(Config config) {
		if (initialized)
			throw new IllegalStateException("EnvoyLog is already initialized");

		// Remove default console handler
		LogManager.getLogManager().reset();

		// Configure log file
		final File logFile = new File(config.getHomeDirectory(),
			"log/" + DateTimeFormatter.ofPattern("yyyy-MM-dd--hh-mm").format(LocalDateTime.now())
				+ ".log");
		logFile.getParentFile().mkdirs();

		// Configure formatting
		// Sample log entry: [2020-06-13 16:50:26] [INFORMATION]
		// [envoy.client.ui.Startup] Closing connection...
		System.setProperty("java.util.logging.SimpleFormatter.format",
			"[%1$tF %1$tT] [%4$-7s] [%3$s] %5$s %6$s%n");
		final SimpleFormatter formatter = new SimpleFormatter();

		try {
			fileHandler = new FileHandler(logFile.getAbsolutePath());
			fileHandler.setLevel(config.getFileLevelBarrier());
			fileHandler.setFormatter(formatter);
		} catch (SecurityException | IOException e) {
			e.printStackTrace();
		}
		consoleHandler = new StreamHandler(System.out, formatter) {

			@Override
			public synchronized void publish(LogRecord record) {
				super.publish(record);
				flush();
			}
		};
		consoleHandler.setLevel(config.getConsoleLevelBarrier());
		consoleHandler.setFormatter(formatter);

		initialized = true;
		EnvoyLog.attach("envoy");
	}

	/**
	 * Configures all loggers that are contained within the hierarchy of a specific path to use the
	 * console and file handlers.
	 *
	 * @param path the path to the loggers to configure
	 * @since Envoy Common v0.1-beta
	 */
	private static void attach(String path) {
		if (!initialized)
			throw new IllegalStateException("EnvoyLog is not initialized");

		// Get root logger
		final Logger logger = Logger.getLogger(path);

		// Add handlers
		if (fileHandler != null)
			logger.addHandler(fileHandler);
		logger.addHandler(consoleHandler);

		// Delegate logger level filtering to the handlers
		logger.setLevel(Level.ALL);
	}

	/**
	 * Creates a logger for a specified class, which output will be displayed inside the console and
	 * written to the log file.
	 *
	 * @param logClass the class in which the logger is used
	 * @return the created logger
	 * @since Envoy Common v0.1-beta
	 */
	public static Logger getLogger(Class<?> logClass) {
		return Logger.getLogger(logClass.getCanonicalName());
	}
}