/**
    * This file Copyright (c) 2019 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.ui.framework.util;
  
  import info.magnolia.cms.core.FileSystemHelper;
  import info.magnolia.ui.api.ioc.ViewScoped;
  import info.magnolia.ui.framework.ioc.Destructible;
  
  import java.io.File;
  import java.io.IOException;
  import java.util.HashSet;
  import java.util.Set;
  
  import javax.inject.Inject;
  
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.io.FilenameUtils;
  import org.apache.commons.lang3.StringUtils;
  
  
  /**
   * View context holding created temp files.
   */
  @ViewScoped
  public class TempFilesManager implements Destructible {
      private static final String FILENAME_PREFIX = "___";
      private static final String SEPARATOR = ".";
  
      private final Set<File> files = new HashSet<>();
  
      private final FileSystemHelper fileSystemHelper;
  
      @Inject
      public TempFilesManager(FileSystemHelper fileSystemHelper) {
          this.fileSystemHelper = fileSystemHelper;
      }
  
      public File createTempFile(String filename) throws IOException {
          String prefix = expandShortFileNameToLengthThree(filename);
          String suffix = SEPARATOR + FilenameUtils.getExtension(filename);
  
          File tempFile = new TempFile(File.createTempFile(prefix, suffix, fileSystemHelper.getTempDirectory()).getPath());
          tempFile.deleteOnExit();
          register(tempFile);
          return tempFile;
      }
  
      /**
       * Adds a {@link TempFilesManager#FILENAME_PREFIX} prefix to the filename.
       *
       * @param filename The name of the file that needs to be prepended with prefix.
       * @return The expanded filename using the algorithm defined above.
       */
      private String expandShortFileNameToLengthThree(String filename) {
          // A fixed length prefix is added to prevent IllegalArgumentException from
          // the API File.createTempFile
          return  FILENAME_PREFIX + FilenameUtils.removeExtension(filename) + SEPARATOR;
      }
  
      public void register(File tempFile) {
          files.add(tempFile);
      }
  
      public String toStandardFileName(String tempFileName) {
          String extension = FilenameUtils.getExtension(tempFileName);
          String fileName = FilenameUtils.removeExtension(tempFileName);
          fileName = StringUtils.substringBeforeLast(fileName, SEPARATOR);
          fileName = StringUtils.startsWith(fileName, FILENAME_PREFIX) ? StringUtils.substringAfter(fileName, FILENAME_PREFIX) : fileName;
         return  String.join(SEPARATOR, fileName, extension);
     }
 
     @Override
     public void destroy() {
         files.forEach(FileUtils::deleteQuietly);
     }
 
     private class TempFile extends File {
         private String pathname;
 
         private TempFile(String pathname) {
             super(pathname);
             this.pathname = pathname;
         }
 
         @Override
         public String getName() {
             return toStandardFileName(FilenameUtils.getName(pathname));
         }
     }
 
 }