/*
    * 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.handler.comments;
  
  import org.opencastproject.event.comment.EventComment;
  import org.opencastproject.event.comment.EventCommentException;
  import org.opencastproject.event.comment.EventCommentService;
  import org.opencastproject.job.api.JobContext;
  import org.opencastproject.security.api.SecurityService;
  import org.opencastproject.security.api.User;
  import org.opencastproject.security.api.UserDirectoryService;
  import org.opencastproject.serviceregistry.api.ServiceRegistry;
  import org.opencastproject.util.NotFoundException;
  import org.opencastproject.workflow.api.AbstractWorkflowOperationHandler;
  import org.opencastproject.workflow.api.WorkflowInstance;
  import org.opencastproject.workflow.api.WorkflowOperationException;
  import org.opencastproject.workflow.api.WorkflowOperationHandler;
  import org.opencastproject.workflow.api.WorkflowOperationInstance;
  import org.opencastproject.workflow.api.WorkflowOperationResult;
  import org.opencastproject.workflow.api.WorkflowOperationResult.Action;
  
  import org.apache.commons.lang3.StringUtils;
  import org.osgi.service.component.annotations.Component;
  import org.osgi.service.component.annotations.Reference;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.Date;
  import java.util.List;
  import java.util.Optional;
  
  /**
   * A workflow operation handler for creating, resolving and deleting comments
   * automatically during the workflow process.
   */
  @Component(
      immediate = true,
      service = WorkflowOperationHandler.class,
      property = {
          "service.description=Comment Workflow Operation Handler",
          "workflow.operation=comment"
      }
  )
  public class CommentWorkflowOperationHandler extends AbstractWorkflowOperationHandler {
    protected static final String ACTION = "action";
    protected static final String DESCRIPTION = "description";
    protected static final String REASON = "reason";
  
    /** The logging facility */
    private static final Logger logger = LoggerFactory.getLogger(CommentWorkflowOperationHandler.class);
  
    /* service references */
    private EventCommentService eventCommentService;
    private SecurityService securityService;
    private UserDirectoryService userDirectoryService;
  
    public enum Operation {
      create, resolve, delete
    };
  
    /**
     * {@inheritDoc}
     */
    @Override
    public WorkflowOperationResult start(WorkflowInstance workflowInstance, JobContext context)
            throws WorkflowOperationException {
      logger.debug("Running comment workflow operation on workflow {}", workflowInstance.getId());
      try {
        return handleCommentOperation(workflowInstance);
      } catch (Exception e) {
        throw new WorkflowOperationException(e);
      }
    }
  
    /**
     * Determine the type of operation to do on a comment and execute it.
     *
     * @param workflowInstance
     *          The {@link WorkflowInstance} to be handled.
     * @return The result of handling the {@link WorkflowInstance}
    * @throws EventCommentException
    *           Thrown if there is an issue creating, resolving or deleting a comment
    * @throws NotFoundException
    *           Thrown if the comment cannot be found to delete.
    */
   private WorkflowOperationResult handleCommentOperation(WorkflowInstance workflowInstance)
           throws EventCommentException, NotFoundException {
     Date date = new Date();
     WorkflowOperationInstance operation = workflowInstance.getCurrentOperation();
     Operation action;
     String inputAction = StringUtils.trimToNull(operation.getConfiguration(ACTION));
     if (inputAction == null) {
       action = Operation.create;
     } else {
       action = Operation.valueOf(inputAction.toLowerCase());
     }
     String reason = StringUtils.trimToNull(operation.getConfiguration(REASON));
     String description = StringUtils.trimToNull(operation.getConfiguration(DESCRIPTION));
     switch (action) {
       case create:
         createComment(workflowInstance, reason, description);
         break;
       case resolve:
         resolveComment(workflowInstance, reason, description);
         break;
       case delete:
         deleteComment(workflowInstance, reason, description);
         break;
       default:
         logger.warn(
             "Unknown action '{}' for comment with description '{}' and reason '{}'. It should be "
                 + "one of the following: {}",
             inputAction, description, reason, StringUtils.join(Operation.values(), ","));
     }
     WorkflowOperationResult result = createResult(workflowInstance.getMediaPackage(), Action.CONTINUE,
             (new Date().getTime()) - date.getTime());
     return result;
   }
 
   /**
    * Create a new comment if one doesn't already exist with the reason and description.
    *
    * @param workflowInstance
    *          The {@link WorkflowInstance} to handle.
    * @param reason
    *          The reason for the comment.
    * @param description
    *          The descriptive text of the comment.
    * @throws EventCommentException
    *           Thrown if unable to create the comment.
    */
   private void createComment(WorkflowInstance workflowInstance, String reason, String description)
           throws EventCommentException {
     String mpId = workflowInstance.getMediaPackage().getIdentifier().toString();
     Optional<EventComment> optComment = findComment(mpId, reason, description);
     if (optComment.isEmpty()) {
       final User user = userDirectoryService.loadUser(workflowInstance.getCreatorName());
       EventComment comment = EventComment.create(
           Optional.empty(), mpId,
           securityService.getOrganization().getId(), description, user, reason, false);
       eventCommentService.updateComment(comment);
     } else {
       logger.debug("Not creating comment with '{}' text and '{}' reason as it already exists for this event.",
               description, reason);
     }
   }
 
   /**
    * Resolve a comment with matching reason and description.
    *
    * @param workflowInstance
    *          The {@link WorkflowInstance} to handle.
    * @param reason
    *          The reason for the comment.
    * @param description
    *          The comment's descriptive text.
    * @throws EventCommentException
    *           Thrown if unable to update the comment.
    */
   private void resolveComment(WorkflowInstance workflowInstance, String reason, String description)
           throws EventCommentException {
     String mpId = workflowInstance.getMediaPackage().getIdentifier().toString();
     Optional<EventComment> optComment = findComment(mpId, reason, description);
     if (optComment.isPresent()) {
       EventComment comment = EventComment.create(
           optComment.get().getId(),
           mpId,
           securityService.getOrganization().getId(), optComment.get().getText(),
           optComment.get().getAuthor(), optComment.get().getReason(), true, optComment.get().getCreationDate(),
           optComment.get().getModificationDate(), optComment.get().getReplies());
       eventCommentService.updateComment(comment);
     } else {
       logger.debug("Not resolving comment with '{}' text and/or '{}' reason as it doesn't exist.", description, reason);
     }
   }
 
   /**
    * Delete a comment with matching reason and description.
    *
    * @param workflowInstance
    *          The {@link WorkflowInstance} to handle.
    * @param reason
    *          The reason for the comment.
    * @param description
    *          The comment's descriptive text.
    * @throws EventCommentException
    *           Thrown if unable to delete the comment.
    * @throws NotFoundException
    *           Thrown if unable to find the comment.
    */
   private void deleteComment(WorkflowInstance workflowInstance, String reason, String description)
           throws EventCommentException, NotFoundException {
     String mpId = workflowInstance.getMediaPackage().getIdentifier().toString();
     Optional<EventComment> optComment = findComment(mpId, reason, description);
     if (optComment.isPresent()) {
       try {
         eventCommentService.deleteComment(optComment.get().getId().get());
       } catch (NotFoundException e) {
         logger.debug("Not deleting comment with '{}' text and '{}' reason and id '{}' as it doesn't exist.",
                 description, reason, optComment.get().getId());
       }
     } else {
       logger.debug("Not deleting comment with '{}' text and/or '{}' reason as it doesn't exist.", description, reason);
     }
   }
 
   /**
    * Find a comment by its reason, description or both
    *
    * @param eventId
    *          The event id to search the comments for.
    * @param reason
    *          The reason for the comment (optional)
    * @param description
    *          The description for the comment (optional)
    * @return The comment if one is found matching the reason and description.
    * @throws EventCommentException
    *           Thrown if there was a problem finding the comment.
    */
   private Optional<EventComment> findComment(String eventId, String reason, String description)
           throws EventCommentException {
     Optional<EventComment> comment = Optional.empty();
     List<EventComment> eventComments = eventCommentService.getComments(eventId);
 
     for (EventComment existingComment : eventComments) {
       // Match on reason and description
       if (reason != null && description != null
           && reason.equals(existingComment.getReason()) && description.equals(existingComment.getText())) {
         comment = Optional.of(existingComment);
         break;
       }
       // Match on reason only
       if (reason != null && description == null && reason.equals(existingComment.getReason())) {
         comment = Optional.of(existingComment);
         break;
       }
       // Match on description only
       if (reason == null && description != null && description.equals(existingComment.getText())) {
         comment = Optional.of(existingComment);
         break;
       }
     }
     return comment;
   }
 
   /**
    * Callback from the OSGi environment that will pass a reference to the workflow service upon component activation.
    *
    * @param eventCommentService
    *          the workflow service
    */
   @Reference
   public void setEventCommentService(EventCommentService eventCommentService) {
     this.eventCommentService = eventCommentService;
   }
 
   /** OSGi DI */
   @Reference
   void setSecurityService(SecurityService service) {
     this.securityService = service;
   }
 
   @Reference
   public void setUserDirectoryService(UserDirectoryService userDirectoryService) {
     this.userDirectoryService = userDirectoryService;
   }
 
   @Reference
   @Override
   public void setServiceRegistry(ServiceRegistry serviceRegistry) {
     super.setServiceRegistry(serviceRegistry);
   }
 
 }