/*
    * 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.niofs;
  
  import java.nio.file.attribute.BasicFileAttributes;
  import java.nio.file.attribute.FileTime;
  import java.util.Objects;
  import java.util.regex.Pattern;
  
  /**
   * @author Thomas Scheffler (yagee)
   *
   */
  public class MCRFileAttributes<T> implements BasicFileAttributes {
      enum FileType {
          file, directory, link, other;
  
          public static FileType fromAttribute(BasicFileAttributes attrs) {
              if (attrs.isRegularFile()) {
                  return file;
              }
              if (attrs.isDirectory()) {
                  return directory;
              }
              if (attrs.isSymbolicLink()) {
                  return link;
              }
              return other;
          }
      }
  
      private static final FileTime EPOCHE_TIME = FileTime.fromMillis(0);
  
      private static final Pattern MD5_HEX_PATTERN = Pattern.compile("[a-fA-F0-9]{32}");
  
      FileTime lastModified, lastAccessTime, creationTime;
  
      long size;
  
      T filekey;
  
      String md5sum;
  
      FileType type;
  
      private MCRFileAttributes(final FileType type, final long size, final T filekey, final String md5sum,
          final FileTime creationTime, final FileTime lastModified, final FileTime lastAccessTime) {
          super();
          this.type = type;
          if (size < 0) {
              throw new IllegalArgumentException("'size' cannot be negative");
          }
          this.size = size;
          this.filekey = filekey;
          setMd5sum(type, md5sum);
          this.creationTime = creationTime == null ? lastModified == null ? EPOCHE_TIME : lastModified : creationTime;
          this.lastModified = lastModified == null ? creationTime == null ? EPOCHE_TIME : creationTime : lastModified;
          this.lastAccessTime = lastAccessTime == null ? EPOCHE_TIME : lastAccessTime;
      }
  
      /**
       *
       */
      public static <T> MCRFileAttributes<T> directory(final T filekey, final long size, final FileTime lastModified) {
          return new MCRFileAttributes<>(FileType.directory, size, filekey, null, null, lastModified, null);
      }
  
      public static <T> MCRFileAttributes<T> file(final T filekey, final long size, final String md5sum,
          final FileTime lastModified) {
          return file(filekey, size, md5sum, null, lastModified, null);
      }
  
      public static <T> MCRFileAttributes<T> file(final T filekey, final long size, final String md5sum,
          final FileTime creationTime, final FileTime lastModified, final FileTime lastAccessTime) {
          return new MCRFileAttributes<>(FileType.file, size, filekey, md5sum, creationTime, lastModified,
              lastAccessTime);
      }
  
      public static <T> MCRFileAttributes<T> fromAttributes(BasicFileAttributes attrs, String md5) {
          return new MCRFileAttributes<>(FileType.fromAttribute(attrs), attrs.size(), (T) attrs.fileKey(), md5,
              attrs.creationTime(), attrs.lastModifiedTime(), attrs.lastAccessTime());
      }
  
     /* (non-Javadoc)
      * @see java.nio.file.attribute.BasicFileAttributes#creationTime()
      */
     @Override
     public FileTime creationTime() {
         return creationTime;
     }
 
     /* (non-Javadoc)
      * @see java.nio.file.attribute.BasicFileAttributes#fileKey()
      */
     @Override
     public T fileKey() {
         return filekey;
     }
 
     /* (non-Javadoc)
      * @see java.nio.file.attribute.BasicFileAttributes#isDirectory()
      */
     @Override
     public boolean isDirectory() {
         return type == FileType.directory;
     }
 
     /* (non-Javadoc)
      * @see java.nio.file.attribute.BasicFileAttributes#isOther()
      */
     @Override
     public boolean isOther() {
         return type == FileType.other;
     }
 
     /* (non-Javadoc)
      * @see java.nio.file.attribute.BasicFileAttributes#isRegularFile()
      */
     @Override
     public boolean isRegularFile() {
         return type == FileType.file;
     }
 
     /* (non-Javadoc)
      * @see java.nio.file.attribute.BasicFileAttributes#isSymbolicLink()
      */
     @Override
     public boolean isSymbolicLink() {
         return type == FileType.link;
     }
 
     /* (non-Javadoc)
      * @see java.nio.file.attribute.BasicFileAttributes#lastAccessTime()
      */
     @Override
     public FileTime lastAccessTime() {
         return lastAccessTime;
     }
 
     /* (non-Javadoc)
      * @see java.nio.file.attribute.BasicFileAttributes#lastModifiedTime()
      */
     @Override
     public FileTime lastModifiedTime() {
         return lastModified;
     }
 
     public String md5sum() {
         return md5sum;
     }
 
     /* (non-Javadoc)
      * @see java.nio.file.attribute.BasicFileAttributes#size()
      */
     @Override
     public long size() {
         return size;
     }
 
     private void setMd5sum(final FileType type, final String md5sum) {
         if (type != FileType.file && md5sum == null) {
             return;
         }
         Objects.requireNonNull(md5sum, "'md5sum' is required for files");
         if (md5sum.length() != 32 || !MD5_HEX_PATTERN.matcher(md5sum).matches()) {
             throw new IllegalArgumentException("Not a valid md5sum: " + md5sum);
         }
         this.md5sum = md5sum;
     }
 
 }