/*
    * #%L
    * Bitrepository Integrity Client
    * 
    * $Id$
    * $HeadURL$
    * %%
    * Copyright (C) 2010 - 2011 The State and University Library, The Royal Library and The State Archives, Denmark
    * %%
   * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as 
   * published by the Free Software Foundation, either version 2.1 of the 
   * License, or (at your option) any later version.
   * 
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Lesser Public License for more details.
   * 
   * You should have received a copy of the GNU General Lesser Public 
   * License along with this program.  If not, see
   * <http://www.gnu.org/licenses/lgpl-2.1.html>.
   * #L%
   */
  package org.bitrepository.service.scheduler;
  
  import org.bitrepository.common.utils.TimeUtils;
  import org.bitrepository.service.workflow.JobID;
  import org.bitrepository.service.workflow.JobTimerTask;
  import org.bitrepository.service.workflow.SchedulableJob;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.*;
  
  /**
   * Scheduler that uses Timer to run workflows.
   */
  public class TimerbasedScheduler implements JobScheduler {
      private Logger log = LoggerFactory.getLogger(getClass());
  
      /** The timer that schedules events. */
      private final Timer timer;
      /** The map between the running timertasks and their names. */
      private Map<JobID, JobTimerTask> intervalTasks = new HashMap<JobID, JobTimerTask>();
      public static final long SCHEDULE_INTERVAL = 60000;
  
      /** The name of the timer.*/
      private static final String TIMER_NAME = "Service Scheduler";
      /** Whether the timer is a daemon.*/
      private static final boolean TIMER_IS_DEAMON = false;
      /** A timer delay of 0 seconds.*/
      private static final Long NO_DELAY = 0L;
      private List<JobEventListener> jobListeners = new LinkedList<JobEventListener>();
  
      /** Setup a timer task for running the workflows at requested interval.
       */
      public TimerbasedScheduler() {
          timer = new Timer(TIMER_NAME, TIMER_IS_DEAMON);
      }
  
      @Override
      public void schedule(SchedulableJob workflow, Long interval) {
          log.info("Scheduling job : " + workflow.getJobID() + " to run every " + TimeUtils.millisecondsToHuman(interval));
  
          JobTimerTask task = new JobTimerTask(interval, workflow, Collections.unmodifiableList(jobListeners));
          timer.scheduleAtFixedRate(task, NO_DELAY, SCHEDULE_INTERVAL);
          intervalTasks.put(workflow.getJobID(), task);
      }
  
      @Override
      public String startJob(SchedulableJob job) {
          long timeBetweenRuns = -1;
          JobTimerTask oldTask = cancelJob(job.getJobID());
          if (oldTask != null) {
              timeBetweenRuns = oldTask.getIntervalBetweenRuns();
          }
  
          JobTimerTask task = new JobTimerTask(timeBetweenRuns, job, jobListeners);
          timer.scheduleAtFixedRate(task, NO_DELAY, SCHEDULE_INTERVAL);
          intervalTasks.put(job.getJobID(), task);
          return null;
      }
  
      @Override
      public Date getNextRun(JobID jobId) {
          if (intervalTasks.containsKey(jobId)) {
              return intervalTasks.get(jobId).getNextRun();
          } else return null;
      }
  
      @Override
      public long getRunInterval(JobID jobId) {
          if (intervalTasks.containsKey(jobId)) {
              return intervalTasks.get(jobId).getIntervalBetweenRuns();
          } else return -1;
      }
  
      @Override
     public void addJobEventListener(JobEventListener listener) {
         jobListeners.add(listener);
     }
 
     @Override
     public JobTimerTask cancelJob(JobID jobID) {
         JobTimerTask task = intervalTasks.remove(jobID);
         if(task == null) {
             return null;
         }
         task.cancel();
 
         return task;
     }
 }