/*
    * This file is part of ***  M y C o R e  ***
    * See http://www.mycore.de/ for details.
    *
    * MyCoRe is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    *
   * MyCoRe 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 Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with MyCoRe.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  package org.mycore.services.queuedjob;
  
  import java.util.Date;
  import java.util.HashMap;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.mycore.backend.jpa.MCREntityManagerProvider;
  import org.mycore.common.config.MCRConfiguration2;
  
  import jakarta.persistence.EntityManager;
  import jakarta.persistence.EntityTransaction;
  import jakarta.persistence.RollbackException;
  import jakarta.persistence.TypedQuery;
  
  /**
   * Resets jobs that took to long to perform action.
   * Set property <code>MCR.QueuedJob.TimeTillReset</code> to alter grace period.
   * 
   * @author Ren\u00E9 Adler
   */
  public class MCRStalledJobResetter implements Runnable {
  
      private static HashMap<String, MCRStalledJobResetter> INSTANCES = new HashMap<>();
  
      private static Logger LOGGER = LogManager.getLogger(MCRStalledJobResetter.class);
  
      private int maxTimeDiff = MCRConfiguration2.getInt(MCRJobQueue.CONFIG_PREFIX + "TimeTillReset").orElse(10);
  
      private Class<? extends MCRJobAction> action = null;
  
      private MCRStalledJobResetter(Class<? extends MCRJobAction> action) {
          if (action != null) {
              this.action = action;
              maxTimeDiff = MCRConfiguration2
                  .getInt(MCRJobQueue.CONFIG_PREFIX + action.getSimpleName() + ".TimeTillReset").orElse(maxTimeDiff);
          }
      }
  
      public static MCRStalledJobResetter getInstance(Class<? extends MCRJobAction> action) {
          String key = action != null && !MCRJobQueue.singleQueue ? action.getName() : "single";
  
          return INSTANCES.computeIfAbsent(key,
              k -> new MCRStalledJobResetter(MCRJobQueue.singleQueue ? null : action));
      }
  
      /**
       * Resets jobs to {@link MCRJobStatus#NEW} that where in status {@link MCRJobStatus#PROCESSING} for to long time.
       */
      public void run() {
          EntityManager em = MCREntityManagerProvider.getEntityManagerFactory().createEntityManager();
          EntityTransaction transaction = em.getTransaction();
  
          LOGGER.info("MCRJob is Checked for dead Entries");
          transaction.begin();
  
          StringBuilder sb = new StringBuilder("FROM MCRJob WHERE ");
          if (action != null) {
              sb.append("action='").append(action.getName()).append("' AND ");
          }
          sb.append(" status='" + MCRJobStatus.PROCESSING + "' ORDER BY id ASC");
  
          TypedQuery<MCRJob> query = em.createQuery(sb.toString(), MCRJob.class);
  
          long current = new Date(System.currentTimeMillis()).getTime() / 60000;
  
          boolean reset = query
              .getResultList()
              .stream()
              .map(job -> {
                  boolean ret = false;
                  long start = job.getStart().getTime() / 60000;
                  if (current - start >= maxTimeDiff) {
                      LOGGER.debug("->Resetting too long in queue");
  
                      job.setStatus(MCRJobStatus.NEW);
                      job.setStart(null);
                      ret = true;
                  } else {
                      LOGGER.debug("->ok");
                  }
                 return ret;
             })
             .reduce(Boolean::logicalOr)
             .orElse(false);
         try {
             transaction.commit();
         } catch (RollbackException e) {
             e.printStackTrace();
             if (transaction != null) {
                 transaction.rollback();
                 reset = false;//No changes are applied, so no notification is needed as well
             }
         }
         //Only notify Listeners on Queue if really something is set back
         if (reset) {
             synchronized (MCRJobQueue.getInstance(action)) {
                 MCRJobQueue.getInstance(action).notifyListener();
             }
         }
         em.close();
         LOGGER.info("MCRJob checking is done");
     }
 }