/*
    * 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.workflow.api;
  
  import static java.lang.String.format;
  
  import org.opencastproject.job.api.Job;
  import org.opencastproject.job.api.JobBarrier;
  import org.opencastproject.job.api.JobContext;
  import org.opencastproject.mediapackage.MediaPackage;
  import org.opencastproject.mediapackage.MediaPackageElement;
  import org.opencastproject.mediapackage.MediaPackageElementFlavor;
  import org.opencastproject.serviceregistry.api.ServiceRegistry;
  import org.opencastproject.workflow.api.WorkflowOperationResult.Action;
  
  import org.apache.commons.io.FilenameUtils;
  import org.apache.commons.lang3.StringUtils;
  import org.osgi.framework.Constants;
  import org.osgi.service.component.ComponentContext;
  import org.osgi.service.component.annotations.Activate;
  import org.osgi.service.component.annotations.Reference;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  
  /**
   * Abstract base implementation for an operation handler, which implements a simple start operation that returns a
   * {@link WorkflowOperationResult} with the current mediapackage and {@link Action#CONTINUE}.
   */
  public abstract class AbstractWorkflowOperationHandler implements WorkflowOperationHandler {
  
    /** The logging facility */
    private static final Logger logger = LoggerFactory.getLogger(AbstractWorkflowOperationHandler.class);
  
    /** The ID of this operation handler */
    protected String id = null;
  
    /** The description of what this handler actually does */
    protected String description = null;
  
    /** Optional service registry */
    protected ServiceRegistry serviceRegistry = null;
  
    /** The JobBarrier polling interval */
    private long jobBarrierPollingInterval = JobBarrier.DEFAULT_POLLING_INTERVAL;
  
    /** Config for Tag Parsing operation */
    protected enum Configuration { none, one, many };
  
    public static final String TARGET_FLAVORS = "target-flavors";
    public static final String TARGET_FLAVOR = "target-flavor";
    public static final String TARGET_TAGS = "target-tags";
    public static final String TARGET_TAG = "target-tag";
    public static final String SOURCE_FLAVORS = "source-flavors";
    public static final String SOURCE_FLAVOR = "source-flavor";
    public static final String SOURCE_TAG = "source-tag";
    public static final String SOURCE_TAGS = "source-tags";
  
    /**
     * Activates this component with its properties once all of the collaborating services have been set
     *
     * @param cc
     *          The component's context, containing the properties used for configuration
     */
    @Activate
    protected void activate(ComponentContext cc) {
      this.id = (String) cc.getProperties().get(WorkflowService.WORKFLOW_OPERATION_PROPERTY);
      this.description = (String) cc.getProperties().get(Constants.SERVICE_DESCRIPTION);
    }
  
    /**
     * {@inheritDoc}
     *
     * @see org.opencastproject.workflow.api.WorkflowOperationHandler#start(org.opencastproject.workflow.api.WorkflowInstance,
     *      JobContext)
     */
   @Override
   public abstract WorkflowOperationResult start(WorkflowInstance workflowInstance, JobContext context)
           throws WorkflowOperationException;
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.workflow.api.WorkflowOperationHandler#skip(org.opencastproject.workflow.api.WorkflowInstance,
    *      JobContext)
    */
   @Override
   public WorkflowOperationResult skip(WorkflowInstance workflowInstance, JobContext context)
           throws WorkflowOperationException {
     return createResult(Action.SKIP);
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.workflow.api.WorkflowOperationHandler#destroy(org.opencastproject.workflow.api.WorkflowInstance,
    *      JobContext)
    */
   @Override
   public void destroy(WorkflowInstance workflowInstance, JobContext context) throws WorkflowOperationException {
   }
 
   /**
    * Converts a comma separated string into a set of values. Useful for converting operation configuration strings into
    * multi-valued sets.
    *
    * @param elements
    *          The comma space separated string
    * @return the set of values
    */
   protected List<String> asList(String elements) {
     elements = StringUtils.trimToEmpty(elements);
     List<String> list = new ArrayList<>();
     for (String s : StringUtils.split(elements, ",")) {
       if (StringUtils.trimToNull(s) != null) {
         list.add(s.trim());
       }
     }
     return list;
   }
 
   /**
    * Generates a filename using the base name of a source element and the extension of a derived element.
    *
    * @param source
    *          the source media package element
    * @param derived
    *          the derived media package element
    * @return the filename
    */
   protected String getFileNameFromElements(MediaPackageElement source, MediaPackageElement derived) {
     String fileName = FilenameUtils.getBaseName(source.getURI().getPath());
     String fileExtension = FilenameUtils.getExtension(derived.getURI().getPath());
     return fileName + "." + fileExtension;
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.workflow.api.WorkflowOperationHandler#getId()
    */
   @Override
   public String getId() {
     return id;
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.workflow.api.WorkflowOperationHandler#getDescription()
    */
   @Override
   public String getDescription() {
     return description;
   }
 
   /**
    * Creates a result for the execution of this workflow operation handler.
    *
    * @param action
    *          the action to take
    * @return the result
    */
   protected WorkflowOperationResult createResult(Action action) {
     return createResult(null, null, action, 0);
   }
 
   /**
    * Creates a result for the execution of this workflow operation handler.
    *
    * @param mediaPackage
    *          the modified mediapackage
    * @param action
    *          the action to take
    * @return the result
    */
   protected WorkflowOperationResult createResult(MediaPackage mediaPackage, Action action) {
     return createResult(mediaPackage, null, action, 0);
   }
 
   /**
    * Creates a result for the execution of this workflow operation handler.
    * <p>
    * Since there is no way for the workflow service to determine the queuing time (e. g. waiting on services), it needs
    * to be provided by the handler.
    *
    * @param mediaPackage
    *          the modified mediapackage
    * @param action
    *          the action to take
    * @param timeInQueue
    *          the amount of time this handle spent waiting for services
    * @return the result
    */
   protected WorkflowOperationResult createResult(MediaPackage mediaPackage, Action action, long timeInQueue) {
     return createResult(mediaPackage, null, action, timeInQueue);
   }
 
   /**
    * Creates a result for the execution of this workflow operation handler.
    * <p>
    * Since there is no way for the workflow service to determine the queuing time (e. g. waiting on services), it needs
    * to be provided by the handler.
    *
    * @param mediaPackage
    *          the modified mediapackage
    * @param properties
    *          the properties to add to the workflow instance
    * @param action
    *          the action to take
    * @param timeInQueue
    *          the amount of time this handle spent waiting for services
    * @return the result
    */
   protected WorkflowOperationResult createResult(MediaPackage mediaPackage, Map<String, String> properties,
           Action action, long timeInQueue) {
     return new WorkflowOperationResultImpl(mediaPackage, properties, action, timeInQueue);
   }
 
   /**
    * Sets the service registry. This method is here as a convenience for developers that need the registry to do job
    * waiting.
    *
    * @param serviceRegistry
    *          the service registry
    */
   @Reference
   public void setServiceRegistry(ServiceRegistry serviceRegistry) {
     this.serviceRegistry = serviceRegistry;
   }
 
   /**
    * Waits until all of the jobs have reached either one of these statuses:
    * <ul>
    * <li>{@link Job.Status#FINISHED}</li>
    * <li>{@link Job.Status#FAILED}</li>
    * <li>{@link Job.Status#DELETED}</li>
    * </ul>
    * After that, the method returns with the actual outcomes of the jobs.
    *
    * @param jobs
    *          the jobs
    * @return the jobs and their outcomes
    * @throws IllegalStateException
    *           if the service registry has not been set
    * @throws IllegalArgumentException
    *           if the jobs collecion is either <code>null</code> or empty
    */
   protected JobBarrier.Result waitForStatus(Job... jobs) throws IllegalStateException, IllegalArgumentException {
     return waitForStatus(0, jobs);
   }
 
   /**
    * Waits until all of the jobs have reached either one of these statuses:
    * <ul>
    * <li>{@link Job.Status#FINISHED}</li>
    * <li>{@link Job.Status#FAILED}</li>
    * <li>{@link Job.Status#DELETED}</li>
    * </ul>
    * After that, the method returns with the actual outcomes of the jobs.
    *
    * @param timeout
    *          the maximum amount of time in milliseconds to wait
    * @param jobs
    *          the jobs
    * @return the jobs and their outcomes
    * @throws IllegalStateException
    *           if the service registry has not been set
    * @throws IllegalArgumentException
    *           if the jobs collection is either <code>null</code> or empty
    */
   protected JobBarrier.Result waitForStatus(long timeout, Job... jobs) throws IllegalStateException,
           IllegalArgumentException {
     if (serviceRegistry == null) {
       throw new IllegalStateException("Can't wait for job status without providing a service registry first");
     }
     JobBarrier barrier = new JobBarrier(null, serviceRegistry, jobBarrierPollingInterval, jobs);
     return barrier.waitForJobs(timeout);
   }
 
   /**
    * Get a configuration option.
    *
    * @deprecated use {@link #getConfig(WorkflowInstance, String)} or {@link #getOptConfig(org.opencastproject.workflow.api.WorkflowInstance, String)}
    */
   protected Optional<String> getCfg(WorkflowInstance wi, String key) {
     return Optional.ofNullable(wi.getCurrentOperation().getConfiguration(key));
   }
 
   /**
    * Get a mandatory configuration key. Values are returned trimmed.
    *
    * @throws WorkflowOperationException
    *         if the configuration key is either missing or empty
    */
   protected String getConfig(WorkflowInstance wi, String key) throws WorkflowOperationException {
     return getConfig(wi.getCurrentOperation(), key);
   }
 
   /**
    * Get a configuration key. Values are returned trimmed.
    *
    * @param w
    *        WorkflowInstance with current operation
    * @param key
    *        Configuration key to check for
    * @param defaultValue
    *        Value to return if key does not exists
    */
   protected String getConfig(WorkflowInstance w, String key, String defaultValue) {
     Optional<String> cfgOpt = getOptConfig(w.getCurrentOperation(), key);
     if (cfgOpt.isPresent()) {
       return cfgOpt.get();
     }
     return defaultValue;
   }
 
   /**
    * Get a mandatory configuration key. Values are returned trimmed.
    *
    * @throws WorkflowOperationException
    *         if the configuration key is either missing or empty
    */
   protected String getConfig(WorkflowOperationInstance woi, String key) throws WorkflowOperationException {
     Optional<String> cfgOpt = getOptConfig(woi, key);
     if (cfgOpt.isPresent()) {
       return cfgOpt.get();
     }
     throw new WorkflowOperationException(format("Configuration key '%s' is either missing or empty", key));
   }
 
   /**
    * Get an optional configuration key. Values are returned trimmed.
    */
   protected Optional<String> getOptConfig(WorkflowInstance wi, String key) {
     return getOptConfig(wi.getCurrentOperation(), key);
   }
 
   /**
    * Get an optional configuration key. Values are returned trimmed.
    */
   protected Optional<String> getOptConfig(WorkflowOperationInstance woi, String key) {
     return Optional.ofNullable(woi.getConfiguration(key))
         .map(String::trim)
         .filter(s -> !s.isEmpty());
   }
 
   /**
    * Returns a ConfiguredTagsAndFlavors instance, which includes all specified source/target tags and flavors if they are valid
    * Lists can be empty, if no values were specified! This is to enable WOHs to individually check if a given tag/flavor was set.
    * This also means that you should use Configuration.many as parameter, if a tag/flavor is optional.
    * @param srcTags none, one or many
    * @param srcFlavors none, one or many
    * @param targetFlavors none, one or many
    * @param targetTags none, one or many
    * @return ConfiguredTagsAndFlavors object including lists for the configured tags/flavors
    */
   protected ConfiguredTagsAndFlavors getTagsAndFlavors(WorkflowInstance workflow, Configuration srcTags, Configuration srcFlavors, Configuration targetTags, Configuration targetFlavors) throws WorkflowOperationException {
     WorkflowOperationInstance operation = workflow.getCurrentOperation();
     ConfiguredTagsAndFlavors tagsAndFlavors = new ConfiguredTagsAndFlavors();
     MediaPackageElementFlavor flavor;
 
     List<String> srcTagList = new ArrayList<>();
     String srcTag;
     switch(srcTags) {
       case none:
         break;
       case one:
         srcTag = StringUtils.trimToNull(operation.getConfiguration(SOURCE_TAG));
         if (srcTag == null) {
           throw new WorkflowOperationException("Configuration key '" + SOURCE_TAG + "' must be set");
         }
         srcTagList.add(srcTag);
         break;
       case many:
         srcTagList = asList(StringUtils.trimToNull(operation.getConfiguration(SOURCE_TAGS)));
         srcTag = StringUtils.trimToNull(operation.getConfiguration(SOURCE_TAG));
         if (srcTagList.isEmpty() && srcTag != null) {
           srcTagList.add(srcTag);
         }
         break;
       default:
         throw new WorkflowOperationException("Couldn't process srcTags configuration option!");
     }
     tagsAndFlavors.setSrcTags(srcTagList);
 
     List<MediaPackageElementFlavor> srcFlavorList = new ArrayList<>();
     String singleSourceFlavor;
     switch(srcFlavors) {
       case none:
         break;
       case one:
         singleSourceFlavor = StringUtils.trimToNull(operation.getConfiguration(SOURCE_FLAVOR));
         if (singleSourceFlavor == null) {
           throw new WorkflowOperationException("Configuration key '" + SOURCE_FLAVOR + "' must be set");
         }
         try {
           flavor = MediaPackageElementFlavor.parseFlavor(singleSourceFlavor);
         } catch (IllegalArgumentException e) {
           throw new WorkflowOperationException(singleSourceFlavor + " is not a valid flavor!");
         }
         srcFlavorList.add(flavor);
         break;
       case many:
         List<String> srcFlavorString = asList(StringUtils.trimToNull(operation.getConfiguration(SOURCE_FLAVORS)));
         singleSourceFlavor = StringUtils.trimToNull(operation.getConfiguration(SOURCE_FLAVOR));
         if (srcFlavorString.isEmpty() && singleSourceFlavor != null) {
           srcFlavorString.add(singleSourceFlavor);
         }
         for (String elem : srcFlavorString) {
           try {
             flavor = MediaPackageElementFlavor.parseFlavor(elem);
             srcFlavorList.add(flavor);
           } catch (IllegalArgumentException e) {
             throw new WorkflowOperationException(elem + " is not a valid flavor!");
           }
         }
         break;
       default:
         throw new WorkflowOperationException("Couldn't process srcFlavors configuration option!");
     }
     tagsAndFlavors.setSrcFlavors(srcFlavorList);
 
     ConfiguredTagsAndFlavors.TargetTags targetTagMap = new ConfiguredTagsAndFlavors.TargetTags();
     String targetTag;
     switch(targetTags) {
       case none:
         break;
       case one:
         targetTag = StringUtils.trimToNull(operation.getConfiguration(TARGET_TAG));
         if (targetTag == null) {
           throw new WorkflowOperationException("Configuration key '" + TARGET_TAG + "' must be set");
         }
         targetTagMap = parseTargetTagsByType(List.of(targetTag));
         break;
       case many:
         List<String> targetTagList = asList(StringUtils.trimToNull(operation.getConfiguration(TARGET_TAGS)));
         targetTagMap = parseTargetTagsByType(targetTagList);
         targetTag = StringUtils.trimToNull(operation.getConfiguration(TARGET_TAG));
         if (targetTagList.isEmpty() && targetTag != null) {
           targetTagMap = parseTargetTagsByType(List.of(targetTag));
         }
         break;
       default:
         throw new WorkflowOperationException("Couldn't process target-tag configuration option!");
     }
     tagsAndFlavors.setTargetTags(targetTagMap);
 
     List<MediaPackageElementFlavor> targetFlavorList = new ArrayList<>();
     String singleTargetFlavor;
     switch(targetFlavors) {
       case none:
         break;
       case one:
         singleTargetFlavor = StringUtils.trimToNull(operation.getConfiguration(TARGET_FLAVOR));
         if (singleTargetFlavor == null) {
           throw new WorkflowOperationException("Configuration key '" + TARGET_FLAVOR + "' must be set");
         }
         try {
           flavor = MediaPackageElementFlavor.parseFlavor(singleTargetFlavor);
         } catch (IllegalArgumentException e) {
           throw new WorkflowOperationException(singleTargetFlavor + " is not a valid flavor!");
         }
         targetFlavorList.add(flavor);
         break;
       case many:
         List<String> targetFlavorString = asList(StringUtils.trimToNull(operation.getConfiguration(TARGET_FLAVORS)));
         singleTargetFlavor = StringUtils.trimToNull(operation.getConfiguration(TARGET_FLAVOR));
         if (targetFlavorString.isEmpty() && singleTargetFlavor != null) {
           targetFlavorString.add(singleTargetFlavor);
         }
         for (String elem : targetFlavorString) {
           try {
             flavor = MediaPackageElementFlavor.parseFlavor(elem);
           } catch (IllegalArgumentException e) {
             throw new WorkflowOperationException(elem + " is not a valid flavor!");
           }
           targetFlavorList.add(flavor);
         }
         break;
       default:
         throw new WorkflowOperationException("Couldn't process targetFlavors configuration option!");
     }
     tagsAndFlavors.setTargetFlavors(targetFlavorList);
     return tagsAndFlavors;
   }
 
   private ConfiguredTagsAndFlavors.TargetTags parseTargetTagsByType(List<String> tags) {
     final String plus = "+";
     final String minus = "-";
     List<String> overrideTags = new ArrayList();
     List<String> addTags = new ArrayList();
     List<String> removeTags = new ArrayList();
 
     for (String targetTag : tags) {
       if (!StringUtils.startsWithAny(targetTag, plus, minus)) {
         if (addTags.size() > 0
             || removeTags.size() > 0) {
           logger.warn("You may not mix override tags and tag changes. "
               + "The list of override tags so far is {}. "
               + "The tag {} is not prefixed with '{}' or '{}'.", overrideTags, targetTag, plus, minus);
         }
         overrideTags.add(targetTag);
       } else if (StringUtils.startsWith(targetTag, plus)) {
         addTags.add(StringUtils.substring(targetTag, 1));
       } else if (StringUtils.startsWith(targetTag, minus)) {
         removeTags.add(StringUtils.substring(targetTag, 1));
       }
     }
 
     return new ConfiguredTagsAndFlavors.TargetTags(overrideTags, addTags, removeTags);
   }
 
   /**
    * Helper function that applies target tags to the given element, based on the type(s) of the tag(s)
    * @param targetTags The target tags to apply to the element
    * @param element The element the target tags are applied to
    * @return The element with the applied target tags
    */
   protected <T extends MediaPackageElement> T applyTargetTagsToElement(
       ConfiguredTagsAndFlavors.TargetTags targetTags,
       T element
   ) {
     // set tags on target element
     List<String> overrideTags = targetTags.getOverrideTags();
     List<String> addTags = targetTags.getAddTags();
     List<String> removeTags = targetTags.getRemoveTags();
     if (overrideTags.size() > 0) {
       element.clearTags();
       for (String tag : overrideTags) {
         element.addTag(tag);
       }
     } else {
       for (String tag : removeTags) {
         element.removeTag(tag);
       }
       for (String tag : addTags) {
         element.addTag(tag);
       }
     }
 
     return element;
   }
 
   /**
    * Set the @link org.opencastproject.job.api.JobBarrier polling interval.
    * <p>
    * While waiting for other jobs to finish, the barrier will poll the status of these jobs until they are finished. To
    * reduce load on the system, the polling is done only every x milliseconds. This interval defines the sleep time
    * between these polls.
    * <p>
    * If most cases you want to leave this at its default value. It will make sense, though, to adjust this time if you
    * know that your job will be exceptionally short. An example of this might be the unit tests where other jobs are
    * usually mocked. But this setting is not limited to tests and may be a sensible options for other jobs as well.
    *
    * @param interval the time in miliseconds between two polling operations
    *
    * @see org.opencastproject.job.api.JobBarrier#DEFAULT_POLLING_INTERVAL
    */
   public void setJobBarrierPollingInterval(long interval) {
     this.jobBarrierPollingInterval = interval;
   }
 
   /**
    * {@inheritDoc}
    *
    * @see java.lang.Object#hashCode()
    */
   @Override
   public int hashCode() {
     return id != null ? id.hashCode() : super.hashCode();
   }
 
   /**
    * {@inheritDoc}
    *
    * @see java.lang.Object#equals(java.lang.Object)
    */
   @Override
   public boolean equals(Object obj) {
     if (obj instanceof WorkflowOperationHandler) {
       if (id != null)
         return id.equals(((WorkflowOperationHandler) obj).getId());
       else
         return this == obj;
     }
     return false;
   }
 
   /**
    * {@inheritDoc}
    *
    * @see java.lang.Object#toString()
    */
   @Override
   public String toString() {
     return getId();
   }
 }