/*
    * 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.logging.log4j.core.appender.rolling;
  
  import java.text.ParseException;
  import java.util.Date;
  import java.util.Objects;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.logging.log4j.core.Core;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.config.Configuration;
  import org.apache.logging.log4j.core.config.ConfigurationScheduler;
  import org.apache.logging.log4j.core.config.CronScheduledFuture;
  import org.apache.logging.log4j.core.config.Scheduled;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
  import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
  import org.apache.logging.log4j.core.config.plugins.PluginFactory;
  import org.apache.logging.log4j.core.util.CronExpression;
  
  /**
   * Rolls a file over based on a cron schedule.
   */
  @Plugin(name = "CronTriggeringPolicy", category = Core.CATEGORY_NAME, printObject = true)
  @Scheduled
  public final class CronTriggeringPolicy extends AbstractTriggeringPolicy {
  
      private static final String defaultSchedule = "0 0 0 * * ?";
      private RollingFileManager manager;
      private final CronExpression cronExpression;
      private final Configuration configuration;
      private final boolean checkOnStartup;
      private volatile Date lastRollDate;
      private CronScheduledFuture<?> future;
  
      private CronTriggeringPolicy(final CronExpression schedule, final boolean checkOnStartup,
              final Configuration configuration) {
          this.cronExpression = Objects.requireNonNull(schedule, "schedule");
          this.configuration = Objects.requireNonNull(configuration, "configuration");
          this.checkOnStartup = checkOnStartup;
      }
  
      /**
       * Initializes the policy.
       * 
       * @param aManager
       *            The RollingFileManager.
       */
      @Override
      public void initialize(final RollingFileManager aManager) {
          this.manager = aManager;
          final Date now = new Date();
          final Date lastRollForFile = cronExpression.getPrevFireTime(new Date(this.manager.getFileTime()));
          final Date lastRegularRoll = cronExpression.getPrevFireTime(new Date());
          aManager.getPatternProcessor().setCurrentFileTime(lastRegularRoll.getTime());
          LOGGER.debug("LastRollForFile {}, LastRegularRole {}", lastRollForFile, lastRegularRoll);
          aManager.getPatternProcessor().setPrevFileTime(lastRegularRoll.getTime());
          if (checkOnStartup && lastRollForFile != null && lastRegularRoll != null &&
                  lastRollForFile.before(lastRegularRoll)) {
              lastRollDate = lastRollForFile;
              rollover();
          }
  
          final ConfigurationScheduler scheduler = configuration.getScheduler();
          if (!scheduler.isExecutorServiceSet()) {
              // make sure we have a thread pool
              scheduler.incrementScheduledItems();
          }
          if (!scheduler.isStarted()) {
              scheduler.start();
          }
          lastRollDate = lastRegularRoll;
          future = scheduler.scheduleWithCron(cronExpression, now, new CronTrigger());
          LOGGER.debug(scheduler.toString());
      }
  
      /**
       * Determines whether a rollover should occur.
       * 
       * @param event
       *            A reference to the currently event.
       * @return true if a rollover should occur.
       */
      @Override
     public boolean isTriggeringEvent(final LogEvent event) {
         return false;
     }
 
     public CronExpression getCronExpression() {
         return cronExpression;
     }
 
     /**
      * Creates a ScheduledTriggeringPolicy.
      * 
      * @param configuration
      *            the Configuration.
      * @param evaluateOnStartup
      *            check if the file should be rolled over immediately.
      * @param schedule
      *            the cron expression.
      * @return a ScheduledTriggeringPolicy.
      */
     @PluginFactory
     public static CronTriggeringPolicy createPolicy(@PluginConfiguration final Configuration configuration,
             @PluginAttribute("evaluateOnStartup") final String evaluateOnStartup,
             @PluginAttribute("schedule") final String schedule) {
         CronExpression cronExpression;
         final boolean checkOnStartup = Boolean.parseBoolean(evaluateOnStartup);
         if (schedule == null) {
             LOGGER.info("No schedule specified, defaulting to Daily");
             cronExpression = getSchedule(defaultSchedule);
         } else {
             cronExpression = getSchedule(schedule);
             if (cronExpression == null) {
                 LOGGER.error("Invalid expression specified. Defaulting to Daily");
                 cronExpression = getSchedule(defaultSchedule);
             }
         }
         return new CronTriggeringPolicy(cronExpression, checkOnStartup, configuration);
     }
 
     private static CronExpression getSchedule(final String expression) {
         try {
             return new CronExpression(expression);
         } catch (final ParseException pe) {
             LOGGER.error("Invalid cron expression - " + expression, pe);
             return null;
         }
     }
 
     private void rollover() {
         manager.getPatternProcessor().setPrevFileTime(lastRollDate.getTime());
         final Date thisRoll = cronExpression.getPrevFireTime(new Date());
         manager.getPatternProcessor().setCurrentFileTime(thisRoll.getTime());
         manager.rollover();
         if (future != null) {
             lastRollDate = future.getFireTime();
         }
     }
 
     @Override
     public boolean stop(final long timeout, final TimeUnit timeUnit) {
         setStopping();
         final boolean stopped = stop(future);
         setStopped();
         return stopped;
     }
 
     @Override
     public String toString() {
         return "CronTriggeringPolicy(schedule=" + cronExpression.getCronExpression() + ")";
     }
 
     private class CronTrigger implements Runnable {
 
         @Override
         public void run() {
             rollover();
         }
     }
 }