/*
 * Copyright 2001-2010 Terracotta, Inc.
 *
 * 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.
 *
 */

package org.quartz.ee.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.quartz.Scheduler;
import org.quartz.impl.StdSchedulerFactory;

/**
 * <p>
 * A ServletContextListner that can be used to initialize Quartz.
 * </p>
 *
 * <p>
 * You'll want to add something like this to your WEB-INF/web.xml file:
 *
 * <pre>
 *     &lt;context-param&gt;
 *         &lt;param-name&gt;quartz:config-file&lt;/param-name&gt;
 *         &lt;param-value&gt;/some/path/my_quartz.properties&lt;/param-value&gt;
 *     &lt;/context-param&gt;
 *     &lt;context-param&gt;
 *         &lt;param-name&gt;quartz:shutdown-on-unload&lt;/param-name&gt;
 *         &lt;param-value&gt;true&lt;/param-value&gt;
 *     &lt;/context-param&gt;
 *     &lt;context-param&gt;
 *         &lt;param-name&gt;quartz:start-on-load&lt;/param-name&gt;
 *         &lt;param-value&gt;true&lt;/param-value&gt;
 *     &lt;/context-param&gt;
 *     
 *     &lt;listener&gt;
 *         &lt;listener-class&gt;
 *             org.quartz.ee.servlet.QuartzInitializerListener
 *         &lt;/listener-class&gt;
 *     &lt;/listener&gt;
 * </pre>
 *
 * </p>
 * <p>
 * The init parameter 'quartz:config-file' can be used to specify the path (and
 * filename) of your Quartz properties file. If you leave out this parameter,
 * the default ("quartz.properties") will be used.
 * </p>
 *
 * <p>
 * The init parameter 'quartz:shutdown-on-unload' can be used to specify whether you
 * want scheduler.shutdown() called when the listener is unloaded (usually when
 * the application server is being shutdown). Possible values are "true" or
 * "false". The default is "true".
 * </p>
 *
 * <p>
 * The init parameter 'quartz:start-on-load' can be used to specify whether
 * you want the scheduler.start() method called when the listener is first loaded.
 * If set to false, your application will need to call the start() method before
 * the scheduler begins to run and process jobs. Possible values are "true" or
 * "false". The default is "true", which means the scheduler is started.
 * </p>
 *
 * A StdSchedulerFactory instance is stored into the ServletContext. You can gain access
 * to the factory from a ServletContext instance like this:
 * <br>
 * <pre>
 * StdSchedulerFactory factory = (StdSchedulerFactory) ctx
 *                .getAttribute(QuartzInitializerListener.QUARTZ_FACTORY_KEY);</pre>
 * <p>
 * The init parameter 'quartz:servlet-context-factory-key' can be used to override the
 * name under which the StdSchedulerFactory is stored into the ServletContext, in 
 * which case you will want to use this name rather than 
 * <code>QuartzInitializerListener.QUARTZ_FACTORY_KEY</code> in the above example.
 * </p>
 *
 * <p>
 * The init parameter 'quartz:start-delay-seconds' can be used to specify the amount
 * of time to wait after initializing the scheduler before scheduler.start()
 * is called.
 * </p>
 *
 * Once you have the factory instance, you can retrieve the Scheduler instance by calling
 * <code>getScheduler()</code> on the factory.
 *
 * @author James House
 * @author Chuck Cavaness
 * @author John Petrocik
 */
public class QuartzInitializerListener implements ServletContextListener {

    public static final String QUARTZ_FACTORY_KEY = "org.quartz.impl.StdSchedulerFactory.KEY";

    private boolean performShutdown = true;

    private Scheduler scheduler = null;

    private final Logger log = LoggerFactory.getLogger(getClass());
    
    /*
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     *
     * Interface.
     *
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     */

    public void contextInitialized(ServletContextEvent sce) {

        log.info("Quartz Initializer Servlet loaded, initializing Scheduler...");

        ServletContext servletContext = sce.getServletContext();
        StdSchedulerFactory factory;
        try {

            String configFile = servletContext.getInitParameter("quartz:config-file");
            if(configFile == null)
                configFile = servletContext.getInitParameter("config-file"); // older name, for backward compatibility
            String shutdownPref = servletContext.getInitParameter("quartz:shutdown-on-unload");
            if(shutdownPref == null)
                shutdownPref = servletContext.getInitParameter("shutdown-on-unload");

            if (shutdownPref != null) {
                performShutdown = Boolean.valueOf(shutdownPref).booleanValue();
            }

            // get Properties
            if (configFile != null) {
                factory = new StdSchedulerFactory(configFile);
            } else {
                factory = new StdSchedulerFactory();
            }

            // Always want to get the scheduler, even if it isn't starting, 
            // to make sure it is both initialized and registered.
            scheduler = factory.getScheduler();

            // Should the Scheduler being started now or later
            String startOnLoad = servletContext.getInitParameter("quartz:start-on-load");
            if(startOnLoad == null)
                startOnLoad = servletContext.getInitParameter("start-scheduler-on-load");

            int startDelay = 0;
            String startDelayS = servletContext.getInitParameter("quartz:start-delay-seconds");
            if(startDelayS == null)
                startDelayS = servletContext.getInitParameter("start-delay-seconds");
            try {
                if(startDelayS != null && startDelayS.trim().length() > 0)
                    startDelay = Integer.parseInt(startDelayS);
            } catch(Exception e) {
                log.error("Cannot parse value of 'start-delay-seconds' to an integer: " + startDelayS + ", defaulting to 5 seconds.");
                startDelay = 5;
            }

            /*
             * If the "quartz:start-on-load" init-parameter is not specified,
             * the scheduler will be started. This is to maintain backwards
             * compatability.
             */
            if (startOnLoad == null || (Boolean.valueOf(startOnLoad).booleanValue())) {
                if(startDelay <= 0) {
                    // Start now
                    scheduler.start();
                    log.info("Scheduler has been started...");
                }
                else {
                    // Start delayed
                    scheduler.startDelayed(startDelay);
                    log.info("Scheduler will start in " + startDelay + " seconds.");
                }
            } else {
                log.info("Scheduler has not been started. Use scheduler.start()");
            }

            String factoryKey = servletContext.getInitParameter("quartz:servlet-context-factory-key");
            if(factoryKey != null)
                factoryKey = servletContext.getInitParameter("servlet-context-factory-key");
            if (factoryKey == null) {
                factoryKey = QUARTZ_FACTORY_KEY;
            }

            log.info("Storing the Quartz Scheduler Factory in the servlet context at key: "
                    + factoryKey);
            servletContext.setAttribute(factoryKey, factory);

        } catch (Exception e) {
            log.error("Quartz Scheduler failed to initialize: " + e.toString());
            e.printStackTrace();
        }
    }

    public void contextDestroyed(ServletContextEvent sce) {

        if (!performShutdown) {
            return;
        }

        try {
            if (scheduler != null) {
                scheduler.shutdown();
            }
        } catch (Exception e) {
            log.error("Quartz Scheduler failed to shutdown cleanly: " + e.toString());
            e.printStackTrace();
        }

        log.info("Quartz Scheduler successful shutdown.");
    }


}
