/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.apache.shiro.session.mgt.quartz;
  
  import org.quartz.JobBuilder;
  import org.quartz.JobDetail;
  import org.quartz.Scheduler;
  import org.quartz.SchedulerException;
  import org.quartz.SimpleTrigger;
  import org.quartz.TriggerBuilder;
  import org.quartz.TriggerKey;
  import org.quartz.impl.StdSchedulerFactory;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.shiro.session.mgt.DefaultSessionManager;
  import org.apache.shiro.session.mgt.SessionValidationScheduler;
  import org.apache.shiro.session.mgt.ValidatingSessionManager;
  
  import static org.quartz.SimpleScheduleBuilder.simpleSchedule;
  
  
  /**
   * An implementation of the {@link org.apache.shiro.session.mgt.SessionValidationScheduler SessionValidationScheduler} that uses Quartz to schedule a
   * job to call {@link org.apache.shiro.session.mgt.ValidatingSessionManager#validateSessions()} on
   * a regular basis.
   *
   * @since 0.1
   */
  public class QuartzSessionValidationScheduler implements SessionValidationScheduler {
  
      //TODO - complete JavaDoc
  
      /*--------------------------------------------
      |             C O N S T A N T S             |
      ============================================*/
      /**
       * The default interval at which sessions will be validated (1 hour);
       * This can be overridden by calling {@link #setSessionValidationInterval(long)}
       */
      public static final long DEFAULT_SESSION_VALIDATION_INTERVAL = DefaultSessionManager.DEFAULT_SESSION_VALIDATION_INTERVAL;
  
      /**
       * The name assigned to the quartz job.
       */
      private static final String JOB_NAME = "SessionValidationJob";
  
      /*--------------------------------------------
      |    I N S T A N C E   V A R I A B L E S    |
      ============================================*/
      private static final Logger log = LoggerFactory.getLogger(QuartzSessionValidationScheduler.class);
  
      /**
       * The configured Quartz scheduler to use to schedule the Quartz job.  If no scheduler is
       * configured, the scheduler will be retrieved by calling {@link StdSchedulerFactory#getDefaultScheduler()}
       */
      private Scheduler scheduler;
  
      private boolean schedulerImplicitlyCreated = false;
  
      private boolean enabled = false;
  
      /**
       * The session manager used to validate sessions.
       */
      private ValidatingSessionManager sessionManager;
  
      /**
       * The session validation interval in milliseconds.
       */
      private long sessionValidationInterval = DEFAULT_SESSION_VALIDATION_INTERVAL;
  
      /*--------------------------------------------
      |         C O N S T R U C T O R S           |
      ============================================*/
  
      /**
       * Default constructor.
       */
      public QuartzSessionValidationScheduler() {
      }
  
     /**
      * Constructor that specifies the session manager that should be used for validating sessions.
      *
      * @param sessionManager the <tt>SessionManager</tt> that should be used to validate sessions.
      */
     public QuartzSessionValidationScheduler(ValidatingSessionManager sessionManager) {
         this.sessionManager = sessionManager;
     }
 
     /*--------------------------------------------
     |  A C C E S S O R S / M O D I F I E R S    |
     ============================================*/
 
     protected Scheduler getScheduler() throws SchedulerException {
         if (scheduler == null) {
             scheduler = StdSchedulerFactory.getDefaultScheduler();
             schedulerImplicitlyCreated = true;
         }
         return scheduler;
     }
 
     public void setScheduler(Scheduler scheduler) {
         this.scheduler = scheduler;
     }
 
     public void setSessionManager(ValidatingSessionManager sessionManager) {
         this.sessionManager = sessionManager;
     }
 
     public boolean isEnabled() {
         return this.enabled;
     }
 
     /**
      * Specifies how frequently (in milliseconds) this Scheduler will call the
      * {@link org.apache.shiro.session.mgt.ValidatingSessionManager#validateSessions() ValidatingSessionManager#validateSessions()} method.
      *
      * <p>Unless this method is called, the default value is {@link #DEFAULT_SESSION_VALIDATION_INTERVAL}.
      *
      * @param sessionValidationInterval
      */
     public void setSessionValidationInterval(long sessionValidationInterval) {
         this.sessionValidationInterval = sessionValidationInterval;
     }
 
     /*--------------------------------------------
     |               M E T H O D S               |
     ============================================*/
 
     /**
      * Starts session validation by creating a Quartz simple trigger, linking it to
      * the {@link QuartzSessionValidationJob}, and scheduling it with the Quartz scheduler.
      */
     public void enableSessionValidation() {
 
         if (log.isDebugEnabled()) {
             log.debug("Scheduling session validation job using Quartz with " +
                     "session validation interval of [" + sessionValidationInterval + "]ms...");
         }
 
         try {
             TriggerBuilder<SimpleTrigger> triggerBuilder =
                 TriggerBuilder.newTrigger()
                     .withIdentity(getClass().getName(), Scheduler.DEFAULT_GROUP)
                     .withSchedule(simpleSchedule()
                         .withIntervalInMilliseconds(sessionValidationInterval)
                         .withRepeatCount(SimpleTrigger.REPEAT_INDEFINITELY));
             SimpleTrigger trigger = triggerBuilder.build();
 
             JobDetail detail = JobBuilder.newJob(QuartzSessionValidationJob.class)
             		.withIdentity(JOB_NAME, Scheduler.DEFAULT_GROUP).build();
             detail.getJobDataMap().put(QuartzSessionValidationJob.SESSION_MANAGER_KEY, sessionManager);
 
             Scheduler scheduler = getScheduler();
 
             scheduler.scheduleJob(detail, trigger);
             if (schedulerImplicitlyCreated) {
                 scheduler.start();
                 if (log.isDebugEnabled()) {
                     log.debug("Successfully started implicitly created Quartz Scheduler instance.");
                 }
             }
             this.enabled = true;
 
             if (log.isDebugEnabled()) {
                 log.debug("Session validation job successfully scheduled with Quartz.");
             }
 
         } catch (SchedulerException e) {
             if (log.isErrorEnabled()) {
                 log.error("Error starting the Quartz session validation job.  Session validation may not occur.", e);
             }
         }
     }
 
     public void disableSessionValidation() {
         if (log.isDebugEnabled()) {
             log.debug("Stopping Quartz session validation job...");
         }
 
         Scheduler scheduler;
         try {
             scheduler = getScheduler();
             if (scheduler == null) {
                 if (log.isWarnEnabled()) {
                     log.warn("getScheduler() method returned a null Quartz scheduler, which is unexpected.  Please " +
                             "check your configuration and/or implementation.  Returning quietly since there is no " +
                             "validation job to remove (scheduler does not exist).");
                 }
                 return;
             }
         } catch (SchedulerException e) {
             if (log.isWarnEnabled()) {
                 log.warn("Unable to acquire Quartz Scheduler.  Ignoring and returning (already stopped?)", e);
             }
             return;
         }
 
         try {
             scheduler.unscheduleJob(TriggerKey.triggerKey(JOB_NAME, Scheduler.DEFAULT_GROUP));
             if (log.isDebugEnabled()) {
                 log.debug("Quartz session validation job stopped successfully.");
             }
         } catch (SchedulerException e) {
             if (log.isDebugEnabled()) {
                 log.debug("Could not cleanly remove SessionValidationJob from Quartz scheduler.  " +
                         "Ignoring and stopping.", e);
             }
         }
 
         this.enabled = false;
 
         if (schedulerImplicitlyCreated) {
             try {
                 scheduler.shutdown();
             } catch (SchedulerException e) {
                 if (log.isWarnEnabled()) {
                     log.warn("Unable to cleanly shutdown implicitly created Quartz Scheduler instance.", e);
                 }
             } finally {
                 setScheduler(null);
                 schedulerImplicitlyCreated = false;
             }
         }
 
 
     }
 }