/*
    * 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.iview2.events;
  
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.List;
  import java.util.Locale;
  import java.util.Optional;
  import java.util.stream.Collectors;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.mycore.common.config.MCRConfiguration2;
  import org.mycore.common.events.MCREvent;
  import org.mycore.common.events.MCREventHandlerBase;
  import org.mycore.datamodel.metadata.MCRDerivate;
  import org.mycore.datamodel.metadata.MCRMetaClassification;
  import org.mycore.iview2.backend.MCRDefaultTileFileProvider;
  import org.mycore.iview2.backend.MCRPDFThumbnailJobAction;
  import org.mycore.iview2.backend.MCRTileInfo;
  import org.mycore.services.queuedjob.MCRJob;
  import org.mycore.services.queuedjob.MCRJobQueue;
  
  /**
   * This event handler creates iview2 files for title pages in PDFs which can be
   * used as thumbnails in IIIF API
   *
   * @author Robert Stephan
   */
  public class MCRThumbnailForPdfEventHandler extends MCREventHandlerBase {
  
      public static final MCRDefaultTileFileProvider TILE_FILE_PROVIDER = new MCRDefaultTileFileProvider();
  
      private static final Logger LOGGER = LogManager.getLogger(MCRThumbnailForPdfEventHandler.class);
  
      private static final MCRJobQueue PDF_THUMBNAIL_JOB_QUEUE = initializeJobQueue();
  
      private static final List<String> DERIVATE_TYPES_FOR_CONTENT = MCRConfiguration2
          .getOrThrow("MCR.IIIFImage.Iview.ThumbnailForPdfEventHandler.Derivate.Types",
              MCRConfiguration2::splitValue)
          .collect(Collectors.toList());
  
      private static MCRJobQueue initializeJobQueue() {
          LOGGER.info("Initializing jobQueue for PDF Thumbnail generation!");
          return MCRJobQueue.getInstance(MCRPDFThumbnailJobAction.class);
      }
  
      @Override
      protected void handleDerivateCreated(MCREvent evt, MCRDerivate der) {
          updateThumbnail(der);
      }
  
      @Override
      protected void handleDerivateRepaired(MCREvent evt, MCRDerivate der) {
          updateThumbnail(der);
      }
  
      @Override
      protected void handleDerivateUpdated(MCREvent evt, MCRDerivate der) {
          updateThumbnail(der);
      }
  
      @Override
      protected void handleDerivateDeleted(MCREvent evt, MCRDerivate der) {
          deleteThumbnail(der);
      }
  
      private void updateThumbnail(MCRDerivate der) {
          deleteThumbnail(der);
          if (isQualifyingDerivate(der)) {
              final MCRJob job = new MCRJob(MCRPDFThumbnailJobAction.class);
              job.setParameter(MCRPDFThumbnailJobAction.DERIVATE_PARAMETER, der.getId().toString());
              PDF_THUMBNAIL_JOB_QUEUE.add(job);
          }
      }
  
      private void deleteThumbnail(MCRDerivate der) {
          String mainDoc = der.getDerivate().getInternals().getMainDoc();
          if (mainDoc != null && mainDoc.toLowerCase(Locale.ROOT).endsWith(".pdf")) {
              MCRTileInfo tileInfo = new MCRTileInfo(der.getId().toString(), mainDoc, null);
              Optional<Path> oPIview2File = TILE_FILE_PROVIDER.getTileFile(tileInfo);
             if (oPIview2File.isPresent()) {
                 try {
                     Files.deleteIfExists(oPIview2File.get());
                 } catch (IOException e) {
                     LOGGER.error(e);
                 }
             }
         }
     }
 
     private boolean isQualifyingDerivate(MCRDerivate der) {
         for (MCRMetaClassification c : der.getDerivate().getClassifications()) {
             String classid = c.getClassId() + ":" + c.getCategId();
             if (DERIVATE_TYPES_FOR_CONTENT.contains(classid)) {
                 String mainDoc = der.getDerivate().getInternals().getMainDoc();
                 return (mainDoc != null && mainDoc.toLowerCase(Locale.ROOT).endsWith(".pdf"));
             }
         }
         return false;
     }
 }