/*
    * 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.event.handler;
  
  import org.opencastproject.message.broker.api.assetmanager.AssetManagerItem;
  import org.opencastproject.message.broker.api.update.AssetManagerUpdateHandler;
  
  import org.osgi.service.component.ComponentContext;
  import org.osgi.service.component.annotations.Activate;
  import org.osgi.service.component.annotations.Component;
  import org.osgi.service.component.annotations.Deactivate;
  import org.osgi.service.component.annotations.Reference;
  import org.osgi.service.component.annotations.ReferenceCardinality;
  import org.osgi.service.component.annotations.ReferencePolicy;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * This handler listens for changes to episodes. Whenever a change is done, this is propagated to OAI-PMH.
   */
  @Component(
      immediate = true,
      service = {
          AssetManagerUpdateHandler.class
      },
      property = {
          "service.description=Conducting event handler for recording events",
      }
  )
  public class ConductingEpisodeUpdatedEventHandler implements AssetManagerUpdateHandler {
  
    private static final Logger logger = LoggerFactory.getLogger(ConductingEpisodeUpdatedEventHandler.class);
  
    private OaiPmhUpdatedEventHandler oaiPmhUpdatedEventHandler;
  
    @Activate
    public void activate(ComponentContext cc) {
      logger.info("Activating {}", ConductingEpisodeUpdatedEventHandler.class.getName());
    }
  
    @Deactivate
    public void deactivate(ComponentContext cc) {
      logger.info("Deactivating {}", ConductingEpisodeUpdatedEventHandler.class.getName());
    }
  
    @Override
    public void execute(AssetManagerItem messageItem) {
      if (! (messageItem instanceof AssetManagerItem.TakeSnapshot)) {
        // We don't want to handle anything but TakeSnapshot messages.
        return;
      }
      AssetManagerItem.TakeSnapshot snapshotItem = (AssetManagerItem.TakeSnapshot) messageItem;
      if (AssetManagerItem.Type.Update.equals(snapshotItem.getType())) {
        // the OAI-PMH handler is a dynamic dependency
        if (oaiPmhUpdatedEventHandler != null) {
          oaiPmhUpdatedEventHandler.handleEvent(snapshotItem);
        }
      }
    }
  
    /**
     * OSGi DI callback.
     */
    @Reference (
        policy = ReferencePolicy.DYNAMIC,
        cardinality = ReferenceCardinality.OPTIONAL,
        unbind = "unsetOaiPmhUpdatedEventHandler"
    )
    public void setOaiPmhUpdatedEventHandler(OaiPmhUpdatedEventHandler h) {
      this.oaiPmhUpdatedEventHandler = h;
    }
  
    public void unsetOaiPmhUpdatedEventHandler(OaiPmhUpdatedEventHandler h) {
      if (this.oaiPmhUpdatedEventHandler == h) {
        this.oaiPmhUpdatedEventHandler = null;
      }
    }
  }