/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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.opencastproject.job.api;
  
  import static org.opencastproject.util.OsgiUtil.getOptContextProperty;
  
  import org.opencastproject.job.api.Incident.Severity;
  import org.opencastproject.job.api.Job.Status;
  import org.opencastproject.security.api.Organization;
  import org.opencastproject.security.api.OrganizationDirectoryService;
  import org.opencastproject.security.api.SecurityService;
  import org.opencastproject.security.api.User;
  import org.opencastproject.security.api.UserDirectoryService;
  import org.opencastproject.serviceregistry.api.Incidents;
  import org.opencastproject.serviceregistry.api.ServiceRegistry;
  import org.opencastproject.serviceregistry.api.ServiceRegistryException;
  import org.opencastproject.serviceregistry.api.SystemLoad.NodeLoad;
  import org.opencastproject.serviceregistry.api.UndispatchableJobException;
  import org.opencastproject.util.JobCanceledException;
  import org.opencastproject.util.NotFoundException;
  
  import org.osgi.service.component.ComponentContext;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.text.DecimalFormat;
  import java.util.Optional;
  import java.util.concurrent.Callable;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  
  /**
   * This class serves as a convenience for services that implement the {@link JobProducer} api to deal with handling long
   * running, asynchronous operations.
   */
  public abstract class AbstractJobProducer implements JobProducer {
  
    /** The logger */
    static final Logger logger = LoggerFactory.getLogger(AbstractJobProducer.class);
  
    /** The default value whether to accept a job whose load exceeds the host’s max load */
    public static final boolean DEFAULT_ACCEPT_JOB_LOADS_EXCEEDING = true;
  
    /**
     * The key to look for in the service configuration file to override the
     * {@link AbstractJobProducer#DEFAULT_ACCEPT_JOB_LOADS_EXCEEDING}
     */
    public static final String ACCEPT_JOB_LOADS_EXCEEDING_PROPERTY = "org.opencastproject.job.load.acceptexceeding";
  
    /** The formatter for load values */
    private static final DecimalFormat df = new DecimalFormat("#.#");
  
    /** Whether to accept a job whose load exceeds the host’s max load */
    protected boolean acceptJobLoadsExeedingMaxLoad = DEFAULT_ACCEPT_JOB_LOADS_EXCEEDING;
  
    /** The types of job that this producer can handle */
    protected String jobType = null;
  
    /** To enable threading when dispatching jobs */
    protected ExecutorService executor = Executors.newCachedThreadPool();
  
    /**
     * OSGI activate method.
     *
     * @param cc
     *          OSGI component context
     **/
    public void activate(ComponentContext cc) {
      acceptJobLoadsExeedingMaxLoad = getOptContextProperty(cc, ACCEPT_JOB_LOADS_EXCEEDING_PROPERTY)
              .map(Boolean::valueOf)
              .orElse(DEFAULT_ACCEPT_JOB_LOADS_EXCEEDING);
      logger.debug("Job producer {} accepting excessively large jobs: {}", getJobType(), acceptJobLoadsExeedingMaxLoad);
    }
  
    /**
     * Creates a new abstract job producer for jobs of the given type.
     *
     * @param jobType
     *          the job type
     */
   public AbstractJobProducer(String jobType) {
     this.jobType = jobType;
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.job.api.JobProducer#getJobType()
    */
   @Override
   public String getJobType() {
     return jobType;
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.job.api.JobProducer#countJobs(org.opencastproject.job.api.Job.Status)
    */
   @Override
   public long countJobs(Status status) throws ServiceRegistryException {
     if (status == null)
       throw new IllegalArgumentException("Status must not be null");
     return getServiceRegistry().count(getJobType(), status);
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.job.api.JobProducer#acceptJob(org.opencastproject.job.api.Job)
    */
   @Override
   public void acceptJob(final Job job) throws ServiceRegistryException {
     final Job runningJob;
     try {
       job.setStatus(Job.Status.RUNNING);
       runningJob = getServiceRegistry().updateJob(job);
     } catch (NotFoundException e) {
       throw new IllegalStateException(e);
     }
     executor.submit(new JobRunner(runningJob, getServiceRegistry().getCurrentJob()));
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.job.api.JobProducer#isReadyToAcceptJobs(String)
    */
   @Override
   public boolean isReadyToAcceptJobs(String operation) throws ServiceRegistryException {
     return true;
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.job.api.JobProducer#isReadyToAccept(org.opencastproject.job.api.Job)
    */
   @Override
   public boolean isReadyToAccept(Job job) throws ServiceRegistryException, UndispatchableJobException {
     if (!jobType.equals(job.getJobType())) {
       logger.debug("Invalid job type submitted: {}", job.getJobType());
       return false;
     }
     NodeLoad maxload;
     try {
       maxload = getServiceRegistry().getMaxLoadOnNode(getServiceRegistry().getRegistryHostname());
     } catch (NotFoundException e) {
       throw new ServiceRegistryException(e);
     }
 
     // Note: We are not adding the job load in the next line because it is already accounted for in the load values we
     // get back from the service registry.
     float currentLoad = getServiceRegistry().getOwnLoad();
     logger.debug("{} Current load on this host: {}, job's load: {}, job's status: {}, max load: {}",
             Thread.currentThread().getId(), currentLoad, job.getJobLoad(), job.getStatus().name(),
             maxload.getMaxLoad());
     // Add the current job load to compare below
     currentLoad += job.getJobLoad();
 
     /* Note that this first clause looks at the *job's*, the other two look at the *node's* load
      * We're assuming that if this case is true, then we're also the most powerful node in the system for this service,
      * per the current job dispatching code in ServiceRegistryJpaImpl */
     if (job.getJobLoad() > maxload.getMaxLoad() && acceptJobLoadsExeedingMaxLoad) {
       logger.warn(
               "{} Accepting job {} of type {} with load {} even though load of {} is above this node's limit of {}.",
               Thread.currentThread().getId(), job.getId(), job.getJobType(), df.format(job.getJobLoad()),
               df.format(currentLoad), df.format(maxload.getMaxLoad()));
       logger.warn("This is a configuration issue that you should resolve in a production system!");
       return true;
     } else if (currentLoad > maxload.getMaxLoad()) {
       logger.debug(
               "{} Declining job {} of type {} with load {} because load of {} would exceed this node's limit of {}.",
               Thread.currentThread().getId(), job.getId(), job.getJobType(), df.format(job.getJobLoad()),
               df.format(currentLoad), df.format(maxload.getMaxLoad()));
       return false;
     } else  {
       logger.debug("{} Accepting job {} of type {} with load {} because load of {} is within this node's limit of {}.",
               Thread.currentThread().getId(), job.getId(), job.getJobType(), df.format(job.getJobLoad()),
               df.format(currentLoad), df.format(maxload.getMaxLoad()));
       return true;
     }
   }
 
 
   /**
    * Private utility to update and optionally fail job, called from a finally block.
    *
    * @param job
    *          to be updated, may be null
    */
   protected void finallyUpdateJob(Job job)  {
     if (job == null) {
       return;
     }
 
     if (!Job.Status.FINISHED.equals(job.getStatus())) {
       job.setStatus(Job.Status.FAILED);
     }
     try {
       getServiceRegistry().updateJob(job);
     } catch (Exception e) {
       throw new RuntimeException(e);
     }
   }
 
   /** Shorthand for {@link #getServiceRegistry()}.incident() */
   public Incidents incident() {
     return getServiceRegistry().incident();
   }
 
   /**
    * Returns a reference to the service registry.
    *
    * @return the service registry
    */
   protected abstract ServiceRegistry getServiceRegistry();
 
   /**
    * Returns a reference to the security service
    *
    * @return the security service
    */
   protected abstract SecurityService getSecurityService();
 
   /**
    * Returns a reference to the user directory service
    *
    * @return the user directory service
    */
   protected abstract UserDirectoryService getUserDirectoryService();
 
   /**
    * Returns a reference to the organization directory service.
    *
    * @return the organization directory service
    */
   protected abstract OrganizationDirectoryService getOrganizationDirectoryService();
 
   /**
    * Asks the overriding class to process the arguments using the given operation. The result will be added to the
    * associated job as the payload.
    *
    * @param job
    *          the job to process
    * @return the operation result
    * @throws Exception
    */
   protected abstract String process(Job job) throws Exception;
 
   /** A utility class to run jobs */
   class JobRunner implements Callable<Void> {
 
     /** The job to dispatch */
     private final long jobId;
 
     /** The current job */
     private final Optional<Long> currentJobId;
 
     /**
      * Constructs a new job runner
      *
      * @param job
      *          the job to run
      * @param currentJob
      *          the current running job
      */
     JobRunner(Job job, Job currentJob) {
       jobId = job.getId();
       if (currentJob != null) {
         currentJobId = Optional.of(currentJob.getId());
       } else {
         currentJobId = Optional.empty();
       }
     }
 
     @Override
     public Void call() throws Exception {
       final SecurityService securityService = getSecurityService();
       final ServiceRegistry serviceRegistry = getServiceRegistry();
       final Job jobBeforeProcessing = serviceRegistry.getJob(jobId);
 
       if (currentJobId.isPresent())
         serviceRegistry.setCurrentJob(serviceRegistry.getJob(currentJobId.get()));
 
       final Organization organization = getOrganizationDirectoryService()
               .getOrganization(jobBeforeProcessing.getOrganization());
       securityService.setOrganization(organization);
       final User user = getUserDirectoryService().loadUser(jobBeforeProcessing.getCreator());
       securityService.setUser(user);
 
       try {
         final String payload = process(jobBeforeProcessing);
         handleSuccessfulProcessing(payload);
       } catch (Throwable t) {
         handleFailedProcessing(t);
       } finally {
         serviceRegistry.setCurrentJob(null);
         securityService.setUser(null);
         securityService.setOrganization(null);
       }
 
       return null;
     }
 
     private void handleSuccessfulProcessing(final String payload) throws Exception {
       // The job may gets updated internally during processing. It therefore needs to be reload from the service
       // registry in order to prevent inconsistencies.
       final Job jobAfterProcessing = getServiceRegistry().getJob(jobId);
       jobAfterProcessing.setPayload(payload);
       jobAfterProcessing.setStatus(Status.FINISHED);
       getServiceRegistry().updateJob(jobAfterProcessing);
     }
 
     private void handleFailedProcessing(final Throwable t) throws Exception {
       if (t instanceof JobCanceledException) {
         logger.info(t.getMessage());
       } else {
         Job jobAfterProcessing = getServiceRegistry().getJob(jobId);
         jobAfterProcessing.setStatus(Status.FAILED);
         jobAfterProcessing = getServiceRegistry().updateJob(jobAfterProcessing);
         getServiceRegistry().incident().unhandledException(jobAfterProcessing, Severity.FAILURE, t);
         logger.error("Error handling operation '{}':", jobAfterProcessing.getOperation(), t);
         if (t instanceof ServiceRegistryException)
           throw (ServiceRegistryException) t;
       }
     }
 
   }
 }