/*
 * Copyright 2001-2009 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 java.io.IOException;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.quartz.Scheduler;
import org.quartz.SchedulerException;
import org.quartz.impl.StdSchedulerFactory;

/**
 * <p>
 * A Servlet that can be used to initialize Quartz, if configured as a
 * load-on-startup servlet in a web application.
 * </p>
 *
 * <p>Using this start-up servlet may be preferred to using the {@link QuartzInitializerListener}
 * in some situations - namely when you want to initialize more than one scheduler in the same
 * application.</p>
 *
 * <p>
 * You'll want to add something like this to your WEB-INF/web.xml file:
 *
 * <pre>
 *     &lt;servlet&gt;
 *         &lt;servlet-name&gt;
 *             QuartzInitializer
 *         &lt;/servlet-name&gt;
 *         &lt;display-name&gt;
 *             Quartz Initializer Servlet
 *         &lt;/display-name&gt;
 *         &lt;servlet-class&gt;
 *             org.quartz.ee.servlet.QuartzInitializerServlet
 *         &lt;/servlet-class&gt;
 *         &lt;load-on-startup&gt;
 *             1
 *         &lt;/load-on-startup&gt;
 *         &lt;init-param&gt;
 *             &lt;param-name&gt;config-file&lt;/param-name&gt;
 *             &lt;param-value&gt;/some/path/my_quartz.properties&lt;/param-value&gt;
 *         &lt;/init-param&gt;
 *         &lt;init-param&gt;
 *             &lt;param-name&gt;shutdown-on-unload&lt;/param-name&gt;
 *             &lt;param-value&gt;true&lt;/param-value&gt;
 *         &lt;/init-param&gt;
 *         &lt;init-param&gt;
 *             &lt;param-name&gt;wait-on-shutdown&lt;/param-name&gt;
 *             &lt;param-value&gt;true&lt;/param-value&gt;
 *         &lt;/init-param&gt;
 *         &lt;init-param&gt;
 *             &lt;param-name&gt;start-scheduler-on-load&lt;/param-name&gt;
 *             &lt;param-value&gt;true&lt;/param-value&gt;
 *         &lt;/init-param&gt;
 *     &lt;/servlet&gt;
 * </pre>
 *
 * </p>
 * <p>
 * The init parameter '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 'shutdown-on-unload' can be used to specify whether you
 * want scheduler.shutdown() called when the servlet 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 'wait-on-shutdown' has effect when 
 * 'shutdown-on-unload' is specified "true", and indicates whether you
 * want scheduler.shutdown(true) called when the listener is unloaded (usually when
 * the application server is being shutdown).  Passing "true" to the shutdown() call
 * causes the scheduler to wait for existing jobs to complete. Possible values are 
 * "true" or "false". The default is "false".
 * </p>
 *
 * <p>
 * The init parameter 'start-scheduler-on-load' can be used to specify whether
 * you want the scheduler.start() method called when the servlet 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(QuartzFactoryServlet.QUARTZ_FACTORY_KEY);</pre>
 * <p>
 * The init parameter '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>QuartzFactoryServlet.QUARTZ_FACTORY_KEY</code> in the above example.
 * </p>
 * 
 * <p>
 * The init parameter 'scheduler-context-servlet-context-key' if set, the 
 * ServletContext will be stored in the SchedulerContext under the given key
 * name (and will therefore be available to jobs during execution). 
 * </p>
 * 
 * <p>
 * The init parameter '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
 */
public class QuartzInitializerServlet extends HttpServlet {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

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

    private boolean performShutdown = true;
    private boolean waitOnShutdown = false;

    private transient Scheduler scheduler = null;


    /*
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     *
     * Interface.
     *
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     */

    @Override
    public void init(ServletConfig cfg) throws javax.servlet.ServletException {
        super.init(cfg);

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

        StdSchedulerFactory factory;
        try {

            String configFile = cfg.getInitParameter("config-file");
            String shutdownPref = cfg.getInitParameter("shutdown-on-unload");

            if (shutdownPref != null) {
                performShutdown = Boolean.valueOf(shutdownPref).booleanValue();
            }
            String shutdownWaitPref = cfg.getInitParameter("wait-on-shutdown");
            if (shutdownPref != null) {
                waitOnShutdown  = Boolean.valueOf(shutdownWaitPref).booleanValue();
            }

            factory = getSchedulerFactory(configFile);
            
            // 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 = cfg
                    .getInitParameter("start-scheduler-on-load");

            int startDelay = 0;
            String startDelayS = cfg.getInitParameter("start-delay-seconds");
            try {
                if(startDelayS != null && startDelayS.trim().length() > 0)
                    startDelay = Integer.parseInt(startDelayS);
            } catch(Exception e) {
                log("Cannot parse value of 'start-delay-seconds' to an integer: " + startDelayS + ", defaulting to 5 seconds.", e);
                startDelay = 5;
            }
            
            /*
             * If the "start-scheduler-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("Scheduler has been started...");
                }
                else {
                    // Start delayed
                    scheduler.startDelayed(startDelay);
                    log("Scheduler will start in " + startDelay + " seconds.");
                }
            } else {
                log("Scheduler has not been started. Use scheduler.start()");
            }

            String factoryKey = cfg.getInitParameter("servlet-context-factory-key");
            if (factoryKey == null) {
                factoryKey = QUARTZ_FACTORY_KEY;
            }
            
            log("Storing the Quartz Scheduler Factory in the servlet context at key: "
                    + factoryKey);
            cfg.getServletContext().setAttribute(factoryKey, factory);
            
            
            String servletCtxtKey = cfg.getInitParameter("scheduler-context-servlet-context-key");
            if (servletCtxtKey != null) {
                log("Storing the ServletContext in the scheduler context at key: "
                        + servletCtxtKey);
                scheduler.getContext().put(servletCtxtKey, cfg.getServletContext());
            }

        } catch (Exception e) {
            log("Quartz Scheduler failed to initialize: " + e.toString());
            throw new ServletException(e);
        }
    }

    protected StdSchedulerFactory getSchedulerFactory(String configFile)
            throws SchedulerException {
        StdSchedulerFactory factory;
        // get Properties
        if (configFile != null) {
            factory = new StdSchedulerFactory(configFile);
        } else {
            factory = new StdSchedulerFactory();
        }
        return factory;
    }

    @Override
    public void destroy() {

        if (!performShutdown) {
            return;
        }

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

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

    @Override
    public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        response.sendError(HttpServletResponse.SC_FORBIDDEN);
    }

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        response.sendError(HttpServletResponse.SC_FORBIDDEN);
    }

}
