content: /*
   * Copyright 2002-2019 Drew Noakes and contributors
   *
   *    Licensed under the Apache 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
   *
   *        https://www.apache.org/licenses/LICENSE-2.0
   *
   *    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.
   *
   * More information about this project is available at:
   *
   *    https://drewnoakes.com/code/exif/
   *    https://github.com/drewnoakes/metadata-extractor
   */
  package com.drew.imaging;
  
  import com.drew.imaging.mp3.MpegAudioTypeChecker;
  import com.drew.imaging.quicktime.QuickTimeTypeChecker;
  import com.drew.imaging.riff.RiffTypeChecker;
  import com.drew.lang.ByteTrie;
  import com.drew.lang.annotations.NotNull;
  import com.drew.lang.annotations.Nullable;
  
  import java.io.InputStream;
  import java.io.IOException;
  
  /**
   * Examines a file's first bytes and estimates the file's type.
   */
  public class FileTypeDetector
  {
      private final static ByteTrie<FileType> _root;
      private final static TypeChecker[] _fixedCheckers;
      private final static int _bytesNeeded;
  
      static
      {
          _fixedCheckers = new TypeChecker[] {
              new QuickTimeTypeChecker(),
              new RiffTypeChecker(),
              new MpegAudioTypeChecker()
          };
  
          _root = new ByteTrie<FileType>();
          _root.setDefaultValue(FileType.Unknown);
  
          // https://en.wikipedia.org/wiki/List_of_file_signatures
  
          _root.addPath(FileType.Jpeg, new byte[]{(byte)0xff, (byte)0xd8});
          _root.addPath(FileType.Tiff, "II".getBytes(), new byte[]{0x2a, 0x00});
          _root.addPath(FileType.Tiff, "MM".getBytes(), new byte[]{0x00, 0x2a});
          _root.addPath(FileType.Psd, "8BPS".getBytes());
          _root.addPath(FileType.Png, new byte[]{(byte)0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, 0x00, 0x00, 0x00, 0x0D, 0x49, 0x48, 0x44, 0x52});
          _root.addPath(FileType.Bmp, "BM".getBytes()); // Standard Bitmap Windows and OS/2
          _root.addPath(FileType.Bmp, "BA".getBytes()); // OS/2 Bitmap Array
          _root.addPath(FileType.Bmp, "CI".getBytes()); // OS/2 Color Icon
          _root.addPath(FileType.Bmp, "CP".getBytes()); // OS/2 Color Pointer
          _root.addPath(FileType.Bmp, "IC".getBytes()); // OS/2 Icon
          _root.addPath(FileType.Bmp, "PT".getBytes()); // OS/2 Pointer
          _root.addPath(FileType.Gif, "GIF87a".getBytes());
          _root.addPath(FileType.Gif, "GIF89a".getBytes());
          _root.addPath(FileType.Ico, new byte[]{0x00, 0x00, 0x01, 0x00});
          _root.addPath(FileType.Pcx, new byte[]{0x0A, 0x00, 0x01}); // multiple PCX versions, explicitly listed
          _root.addPath(FileType.Pcx, new byte[]{0x0A, 0x02, 0x01});
          _root.addPath(FileType.Pcx, new byte[]{0x0A, 0x03, 0x01});
          _root.addPath(FileType.Pcx, new byte[]{0x0A, 0x05, 0x01});
          // NOTE several file types match this, which we handle in TryDisambiguate: DNG, GPR (GoPro), KDC (Kodak), 3FR (Hasselblad)
          //_root.addPath(FileType.Arw, "II".getBytes(), new byte[]{0x2a, 0x00, 0x08, 0x00});
          _root.addPath(FileType.Crw, "II".getBytes(), new byte[]{0x1a, 0x00, 0x00, 0x00}, "HEAPCCDR".getBytes());
          _root.addPath(FileType.Cr2, "II".getBytes(), new byte[]{0x2a, 0x00, 0x10, 0x00, 0x00, 0x00, 0x43, 0x52});
          // NOTE this doesn't work for NEF as it incorrectly flags many other TIFF files as being NEF
  //        _root.addPath(FileType.Nef, "MM".getBytes(), new byte[]{0x00, 0x2a, 0x00, 0x00, 0x00, (byte)0x08, 0x00});
          _root.addPath(FileType.Orf, "IIRO".getBytes(), new byte[]{(byte)0x08, 0x00});
          _root.addPath(FileType.Orf, "MMOR".getBytes(), new byte[]{(byte)0x00, 0x00});
          _root.addPath(FileType.Orf, "IIRS".getBytes(), new byte[]{(byte)0x08, 0x00});
          _root.addPath(FileType.Raf, "FUJIFILMCCD-RAW".getBytes());
          _root.addPath(FileType.Rw2, "II".getBytes(), new byte[]{0x55, 0x00});
          _root.addPath(FileType.Eps, "%!PS".getBytes());
          _root.addPath(FileType.Eps, new byte[]{(byte)0xC5, (byte)0xD0, (byte)0xD3, (byte)0xC6});
  
          // Only file detection
          _root.addPath(FileType.Aac, new byte[]{(byte)0xFF, (byte)0xF1});
          _root.addPath(FileType.Aac, new byte[]{(byte)0xFF, (byte)0xF9});
          _root.addPath(FileType.Asf, new byte[]{0x30, 0x26, (byte)0xB2, 0x75, (byte)0x8E, 0x66, (byte)0xCF, 0x11, (byte)0xA6, (byte)0xD9, 0x00, (byte)0xAA, 0x00, 0x62, (byte)0xCE, 0x6C});
          _root.addPath(FileType.Cfbf, new byte[]{(byte)0xD0, (byte)0xCF, 0x11, (byte)0xE0, (byte)0xA1, (byte)0xB1, 0x1A, (byte)0xE1, 0x00});
          _root.addPath(FileType.Flv, new byte[]{0x46, 0x4C, 0x56});
          _root.addPath(FileType.Indd, new byte[]{0x06, 0x06, (byte)0xED, (byte)0xF5, (byte)0xD8, 0x1D, 0x46, (byte)0xE5, (byte)0xBD, 0x31, (byte)0xEF, (byte)0xE7, (byte)0xFE, 0x74, (byte)0xB7, 0x1D});
          _root.addPath(FileType.Mxf, new byte[]{0x06, 0x0e, 0x2b, 0x34, 0x02, 0x05, 0x01, 0x01, 0x0d, 0x01, 0x02, 0x01, 0x01, 0x02}); // has offset?
          _root.addPath(FileType.Pdf, new byte[]{0x25, 0x50, 0x44, 0x46});
          _root.addPath(FileType.Qxp, new byte[]{0x00, 0x00, 0x49, 0x49, 0x58, 0x50, 0x52, 0x33}); // "..IIXPR3" (little-endian - intel)
          _root.addPath(FileType.Qxp, new byte[]{0x00, 0x00, 0x4D, 0x4D, 0x58, 0x50, 0x52, 0x33}); // "..MMXPR3" (big-endian - motorola)
          _root.addPath(FileType.Ram, new byte[]{0x72, 0x74, 0x73, 0x70, 0x3A, 0x2F, 0x2F});
          _root.addPath(FileType.Rtf, new byte[]{0x7B, 0x5C, 0x72, 0x74, 0x66, 0x31});
          _root.addPath(FileType.Sit, new byte[]{ 0x53, 0x49, 0x54, 0x21, 0x00 }); // SIT!);
          _root.addPath(FileType.Sit, new byte[]{ 0x53, 0x74, 0x75, 0x66, 0x66, 0x49, 0x74, 0x20, 0x28, 0x63, 0x29, 0x31, 0x39, 0x39, 0x37, 0x2D}); // StuffIt (c)1997-
          _root.addPath(FileType.Sitx, new byte[]{ 0x53, 0x74, 0x75, 0x66, 0x66, 0x49, 0x74, 0x21 });
          _root.addPath(FileType.Swf, "CWS".getBytes());
          _root.addPath(FileType.Swf, "FWS".getBytes());
          _root.addPath(FileType.Swf, "ZWS".getBytes());
          _root.addPath(FileType.Vob, new byte[]{0x00, 0x00, 0x01, (byte)0xBA});
          _root.addPath(FileType.Zip, "PK".getBytes());
  
          int bytesNeeded = _root.getMaxDepth();
          for (TypeChecker fixedChecker : _fixedCheckers) {
              if (fixedChecker.getByteCount() > bytesNeeded)
                  bytesNeeded = fixedChecker.getByteCount();
          }
          _bytesNeeded = bytesNeeded;
      }
  
      private FileTypeDetector() throws Exception
      {
          throw new Exception("Not intended for instantiation");
      }
  
      /**
       * Examines the file's bytes and estimates the file's type.
       * <p>
       * The input stream must support mark and reset, in order to
       * return the stream to the position at which it was provided
       * to this method once completed.
       * <p>
       * Requires the stream to contain at least eight bytes.
       *
       * @throws IOException if the stream does not support mark/reset.
       */
      @NotNull
      public static FileType detectFileType(@NotNull final InputStream inputStream) throws IOException
      {
          return detectFileType(inputStream, null);
      }
  
      /**
       * Examines the file's bytes and estimates the file's type.
       * When ambiguous, use the file name extension (if available).
       * <p>
       * The input stream must support mark and reset, in order to
       * return the stream to the position at which it was provided
       * to this method once completed.
       * <p>
       * Requires the stream to contain at least eight bytes.
       *
       * @param filePath The file path or file name of the file, if available. Only the extension is used.
       * @throws IOException if the stream does not support mark/reset.
       */
      @NotNull
      public static FileType detectFileType(@NotNull final InputStream inputStream, @Nullable String filePath) throws IOException
      {
          if (!inputStream.markSupported())
              throw new IOException("Stream must support mark/reset");
  
          inputStream.mark(_bytesNeeded);
  
          byte[] bytes = new byte[_bytesNeeded];
          int offset = 0;
          int count = _bytesNeeded;
          while (count != 0) {
              int bytesRead = inputStream.read(bytes, offset, count);
              if (bytesRead == -1)
                  break;
              count -= bytesRead;
              offset += bytesRead;
          }
  
          inputStream.reset();
  
          FileType fileType = _root.find(bytes, 0, offset);
  
          assert(fileType != null);
  
          if (fileType != FileType.Unknown) {
              // Found
              return filePath == null ? fileType : tryDisambiguate(fileType, filePath);
          }
  
          for (TypeChecker checker : _fixedCheckers) {
              fileType = checker.checkType(bytes);
              if (fileType != FileType.Unknown)
                  return fileType;
          }
  
          return fileType;
      }
  
      private static FileType tryDisambiguate(@NotNull FileType detectedFileType, @NotNull String fileName)
      {
          if (detectedFileType == FileType.Tiff)
          {
              String extension = getExtension(fileName);
  
              if (extension.equalsIgnoreCase(".arw"))
              {
                  return FileType.Arw;
              }
              else if (extension.equalsIgnoreCase(".dng"))
              {
                  return FileType.Dng;
              }
              else if (extension.equalsIgnoreCase(".gpr"))
              {
                  return FileType.GoPro;
              }
              else if (extension.equalsIgnoreCase(".kdc"))
              {
                  return FileType.Kdc;
              }
              else if (extension.equalsIgnoreCase(".nef"))
              {
                  return FileType.Nef;
              }
              else if (extension.equalsIgnoreCase(".3fr"))
              {
                  return FileType.ThreeFR;
              }
              else if (extension.equalsIgnoreCase(".pef"))
              {
                  return FileType.Pef;
              }
              else if (extension.equalsIgnoreCase(".srw"))
              {
                  return FileType.Srw;
              }
          }
  
          return detectedFileType;
      }
  
      private static String getExtension(@NotNull String fileName)
      {
          int index = fileName.lastIndexOf('.');
  
          if (index == -1)
          {
              return "";
          }
  
          return fileName.substring(index);
      }
  }
  