/*
 * This is eMonocot, a global online biodiversity information resource.
 *
 * Copyright © 2011–2015 The Board of Trustees of the Royal Botanic Gardens, Kew and The University of Oxford
 *
 * eMonocot is free software: you can redistribute it and/or modify it under the terms of the
 * GNU Affero General Public License as published by the Free Software Foundation, either version 3
 * of the License, or (at your option) any later version.
 *
 * eMonocot 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 Affero General Public License for more details.
 *
 * The complete text of the GNU Affero General Public License is in the source repository as the file
 * ‘COPYING’.  It is also available from <http://www.gnu.org/licenses/>.
 */
package org.emonocot.common.logback;

import java.io.File;
import java.io.FileNotFoundException;
import java.net.URL;

import org.slf4j.LoggerFactory;
import org.springframework.util.ResourceUtils;
import org.springframework.util.SystemPropertyUtils;

import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.joran.JoranConfigurator;
import ch.qos.logback.core.joran.spi.JoranException;
import ch.qos.logback.core.util.StatusPrinter;

/**
 * Convenience class that features simple methods for custom Log4J
 * configuration.
 *
 * <p>
 * Only needed for non-default Logback initialization with a custom config
 * location. By default, Logback will simply read its configuration from a
 * "logback.xml" or "logback_test.xml" file in the root of the class path.</p>
 *
 * <p>
 * For web environments, the analogous LogbackWebConfigurer class can be found
 * in the web package, reading in its configuration from context-params in
 * web.xml. In a J2EE web application, Logback is usually set up via
 * LogbackConfigListener or LogbackConfigServlet, delegating to
 * LogbackWebConfigurer underneath.</p>
 *
 * @author Juergen Hoeller
 * @author Davide Baroncelli
 * @since 27-set-2007 11.42.07
 * @see LogbackWebConfigurer
 * @see LogbackConfigListener
 * @see LogbackConfigServlet
 */
public final class LogbackConfigurer {
	/**
	 *
	 */
	private LogbackConfigurer() {
	}

	/**
	 * Initialize logback from the given file.
	 *
	 * @param location
	 *            the location of the config file: either a "classpath:"
	 *            location (e.g. "classpath:logback.xml"), an absolute file URL
	 *            (e.g. "file:C:/logback.xml), or a plain absolute path in the
	 *            file system (e.g. "C:/logback.xml")
	 * @throws java.io.FileNotFoundException
	 *             if the location specifies an invalid file path
	 */
	public static void initLogging(final String location)
			throws FileNotFoundException {
		String resolvedLocation = SystemPropertyUtils.resolvePlaceholders(location);
		URL url = ResourceUtils.getURL(resolvedLocation);
		LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();

		try {
			JoranConfigurator configurator = new JoranConfigurator();
			configurator.setContext(loggerContext);
			// the context was probably already configured by default
			// configuration
			// rules
			loggerContext.reset();
			configurator.doConfigure(url);
		} catch (JoranException je) {
			// StatusPrinter will handle this
		}
		StatusPrinter.printInCaseOfErrorsOrWarnings(loggerContext);
	}

	/**
	 * Shut down logback.
	 * <p>
	 * This isn't strictly necessary, but recommended for shutting down logback
	 * in a scenario where the host VM stays alive (for example, when shutting
	 * down an application in a J2EE environment).
	 */
	public static void shutdownLogging() {
		LoggerContext loggerContext = (LoggerContext) LoggerFactory
				.getILoggerFactory();
		loggerContext.stop();
	}

	/**
	 * Set the specified system property to the current working directory.
	 * <p>
	 * This can be used e.g. for test environments, for applications that
	 * leverage LogbackWebConfigurer's "webAppRootKey" support in a web
	 * environment.
	 *
	 * @param key
	 *            system property key to use, as expected in Logback
	 *            configuration (for example: "demo.root", used as
	 *            "${demo.root}/WEB-INF/demo.log")
	 * @see LogbackWebConfigurer
	 */
	public static void setWorkingDirSystemProperty(final String key) {
		System.setProperty(key, new File("").getAbsolutePath());
	}
}