/*
    * 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.datamodel.ifs2;
  
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.StandardCopyOption;
  import java.nio.file.attribute.BasicFileAttributes;
  
  import org.apache.commons.io.IOUtils;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.jdom2.Element;
  import org.mycore.common.content.MCRContent;
  import org.mycore.common.content.streams.MCRDevNull;
  import org.mycore.datamodel.ifs.MCRContentInputStream;
  import org.mycore.datamodel.niofs.MCRFileAttributes;
  
  /**
   * Represents a file stored in a file collection. This is a file that is
   * imported from outside the system, and may be updated and modified afterwards.
   * 
   * @author Frank Lützenkirchen
   * 
   */
  public class MCRFile extends MCRStoredNode {
  
      private static final MCRDevNull DEV_NULL = new MCRDevNull();
  
      private static final Logger LOGGER = LogManager.getLogger(MCRFile.class);
  
      /**
       * The md5 checksum of the empty file
       */
      public static final String MD5_OF_EMPTY_FILE = "d41d8cd98f00b204e9800998ecf8427e";
  
      /**
       * Returns a MCRFile object representing an existing file already stored in
       * the store.
       * 
       * @param parent
       *            the parent directory containing this file
       * @param fo
       *            the file in the local underlying filesystem storing this file
       */
      protected MCRFile(MCRDirectory parent, Path fo, Element data) {
          super(parent, fo, data);
      }
  
      /**
       * Creates a new MCRFile that does not exist yet
       * 
       * @param parent
       *            the parent directory
       * @param name
       *            the file name
       */
      protected MCRFile(MCRDirectory parent, String name) throws IOException {
          super(parent, name, "file");
          Files.createFile(path);
          writeData(e -> e.setAttribute("md5", MCRFile.MD5_OF_EMPTY_FILE));
          getRoot().saveAdditionalData();
      }
  
      /**
       * Returns a MCRVirtualNode contained in this file as a child. A file that
       * is a container, like zip or tar, may contain other files as children.
       */
      @Override
      protected MCRVirtualNode buildChildNode(Path fo) {
          return null; //not implemented
      }
  
      /**
       * Returns the md5 checksum of the file's content.
       * 
       * @return the md5 checksum of the file's content.
       */
      public String getMD5() {
          return readData(e -> e.getAttributeValue("md5"));
      }
  
     /**
      * Returns the file name extension, which is the part after the last dot in
      * the filename.
      * 
      * @return the file extension, or the empty string if the file name does not
      *         have an extension
      */
     public String getExtension() {
         String name = getName();
         int pos = name.lastIndexOf(".");
         return pos == -1 ? "" : name.substring(pos + 1);
     }
 
     /**
      * Sets the content of this file.
      * 
      * @param source
      *            the content to be read
      * @return the MD5 checksum of the stored content
      */
     public String setContent(MCRContent source) throws IOException {
         try (MCRContentInputStream cis = source.getContentInputStream()) {
             source.sendTo(path, StandardCopyOption.REPLACE_EXISTING);
             String md5 = cis.getMD5String();
             writeData(e -> e.setAttribute("md5", md5));
             getRoot().saveAdditionalData();
             return md5;
         }
     }
 
     /**
      * updates the MD5 sum of this file to the given value.
      *
      * Use only if you modified the content outside of {@link #setContent(MCRContent)}.
      * @param md5
      * @throws IOException
      */
     public void setMD5(String md5) throws IOException {
         writeData(e -> e.setAttribute("md5", md5));
         getRoot().saveAdditionalData();
     }
 
     /**
      * Repairs additional metadata of this file and all its children
      */
     @Override
     void repairMetadata() throws IOException {
         MCRContentInputStream cis = getContent().getContentInputStream();
         IOUtils.copy(cis, DEV_NULL);
         cis.close();
         String path = getPath();
         writeData(e -> {
             e.setName("file");
             e.setAttribute("name", getName());
             e.removeChildren("file");
             e.removeChildren("directory");
             String md5 = cis.getMD5String();
             if (!md5.equals(e.getAttributeValue("md5"))) {
                 LOGGER.warn("Fixed MD5 of {} to {}", path, md5);
                 e.setAttribute("md5", md5);
             }
         });
     }
 
     @Override
     public MCRFileAttributes<String> getBasicFileAttributes() throws IOException {
         BasicFileAttributes attrs = Files.readAttributes(path, BasicFileAttributes.class);
         return MCRFileAttributes.fromAttributes(attrs, getMD5());
     }
 }