/**
 * This file Copyright (c) 2003-2012 Magnolia International
 * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
 *
 *
 * This file is dual-licensed under both the Magnolia
 * Network Agreement and the GNU General Public License.
 * You may elect to use one or the other of these licenses.
 *
 * This file is distributed in the hope that it will be
 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
 * implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
 * Redistribution, except as permitted by whichever of the GPL
 * or MNA you select, is prohibited.
 *
 * 1. For the GPL license (GPL), you can redistribute and/or
 * modify this file under the terms of the GNU General
 * Public License, Version 3, as published by the Free Software
 * Foundation.  You should have received a copy of the GNU
 * General Public License, Version 3 along with this program;
 * if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * 2. For the Magnolia Network Agreement (MNA), this file
 * and the accompanying materials are made available under the
 * terms of the MNA which accompanies this distribution, and
 * is available at http://www.magnolia-cms.com/mna.html
 *
 * Any modifications to this file must keep this entire header
 * intact.
 *
 */
package info.magnolia.logging;

import info.magnolia.cms.core.SystemProperty;
import info.magnolia.cms.util.ConfigUtil;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.log4j.LogManager;
import org.apache.log4j.PropertyConfigurator;
import org.apache.log4j.xml.DOMConfigurator;
import org.w3c.dom.Document;

import java.io.IOException;
import java.util.Collections;
import java.util.Map;
import java.util.Properties;

/**
 * <p>
 * Log4j initializer. Loads the file specified using the <code>log4j.config</code> init parameter and optionally set a
 * system property containing the magnolia web application root directory with the name specified by the
 * <code>magnolia.root.sysproperty</code> init parameter.
 * </p>
 * <p>
 * If <code>magnolia.root.sysproperty</code> is empty no system variable will be set; if <code>log4j.config</code>
 * is empty no log4j initialization will be performed.
 * </p>
 * <p>
 * You can easily specify relative paths for log4j configuration files using the magnolia root system property, for
 * example using <code>${magnolia.root}logs/magnolia-debug.log</code>
 * </p>
 * <p>
 * Note: if you drop multiple magnolia wars in a container which doesn't isolate system properties (e.g. tomcat) you
 * could need to change the name of the <code>magnolia.root.sysproperty</code> variable in web.xml and in log4j
 * configuration files.
 * </p>
 * <p>
 * <em>Some ideas and snippets borrowed from the more complex Spring implementation http://www.springframework.org</em>
 * </p>
 * @author Fabrizio Giustina
 * @version $Id$
 */
public class Log4jConfigurer {

    /**
     * Init parameter specifying the location of the Log4J config file.
     */
    public static final String LOG4J_CONFIG = "log4j.config"; //$NON-NLS-1$

    /**
     * Initialize Log4J, including setting the web app root system property.
     */
    public static void initLogging() {

        // can't use log4j yet
        log("Initializing Log4J"); //$NON-NLS-1$

        String log4jFileName = SystemProperty.getProperty(LOG4J_CONFIG);
        if (StringUtils.isNotEmpty(log4jFileName)) {
            boolean isXml = log4jFileName.toLowerCase().endsWith(".xml"); //$NON-NLS-1$

            log("Initializing Log4J from [" + log4jFileName + "]"); //$NON-NLS-1$ //$NON-NLS-2$

            final String config;
            try {
                config = ConfigUtil.getTokenizedConfigFile(log4jFileName);
            }
            catch (IOException e) {
                log("Unable to initialize Log4J from [" + log4jFileName + "], got a IOException " + e.getMessage());
                return;
            }

            // classpath?
            if (isXml) {
                try {
                    final Map dtds = Collections.singletonMap("log4j.dtd", "/org/apache/log4j/xml/log4j.dtd");
                    final Document document = ConfigUtil.string2DOM(config, dtds);
                    DOMConfigurator.configure(document.getDocumentElement());
                } catch (Exception e) {
                    log("Unable to initialize Log4J from [" + log4jFileName + "], got an Exception during reading the xml file : " + e.getMessage());
                }
            } else {
                try {
                    final Properties properties = new Properties();
                    properties.load(IOUtils.toInputStream(config));
                    PropertyConfigurator.configure(properties);
                } catch (IOException e) {
                    log("Unable to initialize Log4J from [" + log4jFileName + "], got an Exception during reading the properties file : " + e.getMessage());
                }
            }

        }
    }

    /**
     * Shuts down Log4J.
     */
    public static void shutdownLogging() {
        log("Shutting down Log4J"); //$NON-NLS-1$
        LogManager.shutdown();
    }

    /**
     * Handy System.out method to use when logging isn't configured yet.
     * @param message log message
     */
    private static void log(String message) {
        System.out.println(message);
    }

}