// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : NDIF.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Manages Apple New Disk Image Format.
//
// --[ License ] --------------------------------------------------------------
//
//     This library is free software; you can redistribute it and/or modify
//     it under the terms of the GNU Lesser General Public License as
//     published by the Free Software Foundation; either version 2.1 of the
//     License, or (at your option) any later version.
//
//     This library 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
//     Lesser General Public License for more details.
//
//     You should have received a copy of the GNU Lesser General Public
//     License along with this library; if not, see <http://www.gnu.org/licenses/>.
//
// ----------------------------------------------------------------------------
// Copyright © 2011-2018 Natalia Portillo
// ****************************************************************************/

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using Claunia.RsrcFork;
using DiscImageChef.CommonTypes;
using DiscImageChef.Console;
using DiscImageChef.Filters;
using SharpCompress.Compressors.ADC;
using Version = Resources.Version;

namespace DiscImageChef.DiscImages
{
    // TODO: Detect OS X encrypted images
    // TODO: Check checksum
    // TODO: Implement segments
    // TODO: Implement compression
    public class Ndif : IMediaImage
    {
        /// <summary>
        ///     Resource OSType for NDIF is "bcem"
        /// </summary>
        const uint NDIF_RESOURCE = 0x6263656D;
        /// <summary>
        ///     Resource ID is always 128? Never found another
        /// </summary>
        const short NDIF_RESOURCEID = 128;

        const byte CHUNK_TYPE_NOCOPY = 0;
        const byte CHUNK_TYPE_COPY = 2;
        const byte CHUNK_TYPE_KENCODE = 0x80;
        const byte CHUNK_TYPE_RLE = 0x81;
        const byte CHUNK_TYPE_LZH = 0x82;
        const byte CHUNK_TYPE_ADC = 0x83;
        /// <summary>
        ///     Created by ShrinkWrap 3.5, dunno which version of the StuffIt algorithm it is using
        /// </summary>
        const byte CHUNK_TYPE_STUFFIT = 0xF0;
        const byte CHUNK_TYPE_END = 0xFF;

        const byte CHUNK_TYPE_COMPRESSED_MASK = 0x80;

        const short DRIVER_OSX = -1;
        const short DRIVER_HFS = 0;
        const short DRIVER_PRODOS = 256;
        const short DRIVER_DOS = 18771;
        const uint MAX_CACHE_SIZE = 16777216;
        const uint SECTOR_SIZE = 512;
        const uint MAX_CACHED_SECTORS = MAX_CACHE_SIZE / SECTOR_SIZE;
        uint buffersize;
        Dictionary<ulong, byte[]> chunkCache;
        Dictionary<ulong, BlockChunk> chunks;
        uint currentChunkCacheSize;

        ChunkHeader header;
        ImageInfo imageInfo;

        Stream imageStream;

        Dictionary<ulong, byte[]> sectorCache;

        public Ndif()
        {
            imageInfo = new ImageInfo
            {
                ReadableSectorTags = new List<SectorTagType>(),
                ReadableMediaTags = new List<MediaTagType>(),
                HasPartitions = false,
                HasSessions = false,
                Version = null,
                Application = null,
                ApplicationVersion = null,
                Creator = null,
                Comments = null,
                MediaManufacturer = null,
                MediaModel = null,
                MediaSerialNumber = null,
                MediaBarcode = null,
                MediaPartNumber = null,
                MediaSequence = 0,
                LastMediaSequence = 0,
                DriveManufacturer = null,
                DriveModel = null,
                DriveSerialNumber = null,
                DriveFirmwareRevision = null
            };
        }

        public ImageInfo Info => imageInfo;

        public string Name => "Apple New Disk Image Format";
        public Guid Id => new Guid("5A7FF7D8-491E-458D-8674-5B5EADBECC24");

        public string Format => "Apple New Disk Image Format";

        public List<Partition> Partitions =>
            throw new FeatureUnsupportedImageException("Feature not supported by image format");

        public List<Track> Tracks =>
            throw new FeatureUnsupportedImageException("Feature not supported by image format");

        public List<Session> Sessions =>
            throw new FeatureUnsupportedImageException("Feature not supported by image format");

        public bool Identify(IFilter imageFilter)
        {
            if(!imageFilter.HasResourceFork() || imageFilter.GetResourceForkLength() == 0) return false;

            try
            {
                ResourceFork rsrcFork = new ResourceFork(imageFilter.GetResourceForkStream());
                if(!rsrcFork.ContainsKey(NDIF_RESOURCE)) return false;

                Resource rsrc = rsrcFork.GetResource(NDIF_RESOURCE);

                if(rsrc.ContainsId(NDIF_RESOURCEID)) return true;
            }
            catch(InvalidCastException) { return false; }

            return false;
        }

        public bool Open(IFilter imageFilter)
        {
            if(!imageFilter.HasResourceFork() || imageFilter.GetResourceForkLength() == 0) return false;

            ResourceFork rsrcFork;
            Resource rsrc;
            short[] bcems;

            try
            {
                rsrcFork = new ResourceFork(imageFilter.GetResourceForkStream());
                if(!rsrcFork.ContainsKey(NDIF_RESOURCE)) return false;

                rsrc = rsrcFork.GetResource(NDIF_RESOURCE);

                bcems = rsrc.GetIds();

                if(bcems == null || bcems.Length == 0) return false;
            }
            catch(InvalidCastException) { return false; }

            imageInfo.Sectors = 0;
            foreach(byte[] bcem in bcems.Select(id => rsrc.GetResource(NDIF_RESOURCEID)))
            {
                if(bcem.Length < 128) return false;

                header = BigEndianMarshal.ByteArrayToStructureBigEndian<ChunkHeader>(bcem);

                DicConsole.DebugWriteLine("NDIF plugin", "footer.type = {0}", header.version);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.driver = {0}", header.driver);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.name = {0}",
                                          StringHandlers.PascalToString(header.name,
                                                                        Encoding.GetEncoding("macintosh")));
                DicConsole.DebugWriteLine("NDIF plugin", "footer.sectors = {0}", header.sectors);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.maxSectorsPerChunk = {0}", header.maxSectorsPerChunk);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.dataOffset = {0}", header.dataOffset);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.crc = 0x{0:X7}", header.crc);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.segmented = {0}", header.segmented);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.p1 = 0x{0:X8}", header.p1);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.p2 = 0x{0:X8}", header.p2);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.unknown[0] = 0x{0:X8}", header.unknown[0]);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.unknown[1] = 0x{0:X8}", header.unknown[1]);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.unknown[2] = 0x{0:X8}", header.unknown[2]);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.unknown[3] = 0x{0:X8}", header.unknown[3]);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.unknown[4] = 0x{0:X8}", header.unknown[4]);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.encrypted = {0}", header.encrypted);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.hash = 0x{0:X8}", header.hash);
                DicConsole.DebugWriteLine("NDIF plugin", "footer.chunks = {0}", header.chunks);

                // Block chunks and headers
                chunks = new Dictionary<ulong, BlockChunk>();

                BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;

                for(int i = 0; i < header.chunks; i++)
                {
                    // Obsolete read-only NDIF only prepended the header and then put the image without any kind of block references.
                    // So let's falsify a block chunk
                    BlockChunk bChnk = new BlockChunk();
                    byte[] sector = new byte[4];
                    Array.Copy(bcem, 128 + 0 + i * 12, sector, 1, 3);
                    bChnk.sector = BigEndianBitConverter.ToUInt32(sector, 0);
                    bChnk.type = bcem[128 + 3 + i * 12];
                    bChnk.offset = BigEndianBitConverter.ToUInt32(bcem, 128 + 4 + i * 12);
                    bChnk.length = BigEndianBitConverter.ToUInt32(bcem, 128 + 8 + i * 12);

                    DicConsole.DebugWriteLine("NDIF plugin", "bHdr.chunk[{0}].type = 0x{1:X2}", i, bChnk.type);
                    DicConsole.DebugWriteLine("NDIF plugin", "bHdr.chunk[{0}].sector = {1}", i, bChnk.sector);
                    DicConsole.DebugWriteLine("NDIF plugin", "bHdr.chunk[{0}].offset = {1}", i, bChnk.offset);
                    DicConsole.DebugWriteLine("NDIF plugin", "bHdr.chunk[{0}].length = {1}", i, bChnk.length);

                    if(bChnk.type == CHUNK_TYPE_END) break;

                    bChnk.offset += header.dataOffset;
                    bChnk.sector += (uint)imageInfo.Sectors;

                    // TODO: Handle compressed chunks
                    switch(bChnk.type)
                    {
                        case CHUNK_TYPE_KENCODE:
                            throw new
                                ImageNotSupportedException("Chunks compressed with KenCode are not yet supported.");
                        case CHUNK_TYPE_RLE:
                            throw new ImageNotSupportedException("Chunks compressed with RLE are not yet supported.");
                        case CHUNK_TYPE_LZH:
                            throw new ImageNotSupportedException("Chunks compressed with LZH are not yet supported.");
                        case CHUNK_TYPE_STUFFIT:
                            throw new
                                ImageNotSupportedException("Chunks compressed with StuffIt! are not yet supported.");
                    }

                    // TODO: Handle compressed chunks
                    if(bChnk.type > CHUNK_TYPE_COPY && bChnk.type < CHUNK_TYPE_KENCODE ||
                       bChnk.type > CHUNK_TYPE_ADC && bChnk.type < CHUNK_TYPE_STUFFIT ||
                       bChnk.type > CHUNK_TYPE_STUFFIT && bChnk.type < CHUNK_TYPE_END ||
                       bChnk.type == 1)
                        throw new ImageNotSupportedException($"Unsupported chunk type 0x{bChnk.type:X8} found");

                    chunks.Add(bChnk.sector, bChnk);
                }

                imageInfo.Sectors += header.sectors;
            }

            if(header.segmented > 0) throw new ImageNotSupportedException("Segmented images are not yet supported.");

            if(header.encrypted > 0) throw new ImageNotSupportedException("Encrypted images are not yet supported.");

            switch(imageInfo.Sectors)
            {
                case 1440:
                    imageInfo.MediaType = MediaType.DOS_35_DS_DD_9;
                    break;
                case 1600:
                    imageInfo.MediaType = MediaType.AppleSonyDS;
                    break;
                case 2880:
                    imageInfo.MediaType = MediaType.DOS_35_HD;
                    break;
                case 3360:
                    imageInfo.MediaType = MediaType.DMF;
                    break;
                default:
                    imageInfo.MediaType = MediaType.GENERIC_HDD;
                    break;
            }

            if(rsrcFork.ContainsKey(0x76657273))
            {
                Resource versRsrc = rsrcFork.GetResource(0x76657273);
                if(versRsrc != null)
                {
                    byte[] vers = versRsrc.GetResource(versRsrc.GetIds()[0]);

                    Version version = new Version(vers);

                    string release = null;
                    string dev = null;
                    string pre = null;

                    string major = $"{version.MajorVersion}";
                    string minor = $".{version.MinorVersion / 10}";
                    if(version.MinorVersion % 10 > 0) release = $".{version.MinorVersion % 10}";
                    switch(version.DevStage)
                    {
                        case Version.DevelopmentStage.Alpha:
                            dev = "a";
                            break;
                        case Version.DevelopmentStage.Beta:
                            dev = "b";
                            break;
                        case Version.DevelopmentStage.PreAlpha:
                            dev = "d";
                            break;
                    }

                    if(dev == null && version.PreReleaseVersion > 0) dev = "f";

                    if(dev != null) pre = $"{version.PreReleaseVersion}";

                    imageInfo.ApplicationVersion = $"{major}{minor}{release}{dev}{pre}";
                    imageInfo.Application = version.VersionString;
                    imageInfo.Comments = version.VersionMessage;

                    if(version.MajorVersion == 3) imageInfo.Application = "ShrinkWrap™";
                    else if(version.MajorVersion == 6) imageInfo.Application = "DiskCopy";
                }
            }

            DicConsole.DebugWriteLine("NDIF plugin", "Image application = {0} version {1}", imageInfo.Application,
                                      imageInfo.ApplicationVersion);

            sectorCache = new Dictionary<ulong, byte[]>();
            chunkCache = new Dictionary<ulong, byte[]>();
            currentChunkCacheSize = 0;
            imageStream = imageFilter.GetDataForkStream();
            buffersize = header.maxSectorsPerChunk * SECTOR_SIZE;

            imageInfo.CreationTime = imageFilter.GetCreationTime();
            imageInfo.LastModificationTime = imageFilter.GetLastWriteTime();
            imageInfo.MediaTitle = StringHandlers.PascalToString(header.name, Encoding.GetEncoding("macintosh"));
            imageInfo.SectorSize = SECTOR_SIZE;
            imageInfo.XmlMediaType = XmlMediaType.BlockMedia;
            imageInfo.ImageSize = imageInfo.Sectors * SECTOR_SIZE;
            imageInfo.ApplicationVersion = "6";
            imageInfo.Application = "Apple DiskCopy";

            switch(imageInfo.MediaType)
            {
                case MediaType.AppleSonyDS:
                    imageInfo.Cylinders = 80;
                    imageInfo.Heads = 2;
                    imageInfo.SectorsPerTrack = 10;
                    break;
                case MediaType.DOS_35_DS_DD_9:
                    imageInfo.Cylinders = 80;
                    imageInfo.Heads = 2;
                    imageInfo.SectorsPerTrack = 9;
                    break;
                case MediaType.DOS_35_HD:
                    imageInfo.Cylinders = 80;
                    imageInfo.Heads = 2;
                    imageInfo.SectorsPerTrack = 18;
                    break;
                case MediaType.DMF:
                    imageInfo.Cylinders = 80;
                    imageInfo.Heads = 2;
                    imageInfo.SectorsPerTrack = 21;
                    break;
                default:
                    imageInfo.MediaType = MediaType.GENERIC_HDD;
                    imageInfo.Cylinders = (uint)(imageInfo.Sectors / 16 / 63);
                    imageInfo.Heads = 16;
                    imageInfo.SectorsPerTrack = 63;
                    break;
            }

            return true;
        }

        public byte[] ReadSector(ulong sectorAddress)
        {
            if(sectorAddress > imageInfo.Sectors - 1)
                throw new ArgumentOutOfRangeException(nameof(sectorAddress),
                                                      $"Sector address {sectorAddress} not found");

            if(sectorCache.TryGetValue(sectorAddress, out byte[] sector)) return sector;

            BlockChunk currentChunk = new BlockChunk();
            bool chunkFound = false;
            ulong chunkStartSector = 0;

            foreach(KeyValuePair<ulong, BlockChunk> kvp in chunks.Where(kvp => sectorAddress >= kvp.Key))
            {
                currentChunk = kvp.Value;
                chunkFound = true;
                chunkStartSector = kvp.Key;
            }

            long relOff = ((long)sectorAddress - (long)chunkStartSector) * SECTOR_SIZE;

            if(relOff < 0)
                throw new ArgumentOutOfRangeException(nameof(relOff),
                                                      $"Got a negative offset for sector {sectorAddress}. This should not happen.");

            if(!chunkFound)
                throw new ArgumentOutOfRangeException(nameof(sectorAddress),
                                                      $"Sector address {sectorAddress} not found");

            if((currentChunk.type & CHUNK_TYPE_COMPRESSED_MASK) == CHUNK_TYPE_COMPRESSED_MASK)
            {
                if(!chunkCache.TryGetValue(chunkStartSector, out byte[] buffer))
                {
                    byte[] cmpBuffer = new byte[currentChunk.length];
                    imageStream.Seek(currentChunk.offset, SeekOrigin.Begin);
                    imageStream.Read(cmpBuffer, 0, cmpBuffer.Length);
                    MemoryStream cmpMs = new MemoryStream(cmpBuffer);
                    Stream decStream;

                    if(currentChunk.type == CHUNK_TYPE_ADC) decStream = new ADCStream(cmpMs);
                    else throw new ImageNotSupportedException($"Unsupported chunk type 0x{currentChunk.type:X8} found");

                    byte[] tmpBuffer = new byte[buffersize];
                    int realSize = decStream.Read(tmpBuffer, 0, (int)buffersize);
                    buffer = new byte[realSize];
                    Array.Copy(tmpBuffer, 0, buffer, 0, realSize);

                    if(currentChunkCacheSize + realSize > MAX_CACHE_SIZE)
                    {
                        chunkCache.Clear();
                        currentChunkCacheSize = 0;
                    }

                    chunkCache.Add(chunkStartSector, buffer);
                    currentChunkCacheSize += (uint)realSize;
                }

                sector = new byte[SECTOR_SIZE];
                Array.Copy(buffer, relOff, sector, 0, SECTOR_SIZE);

                if(sectorCache.Count >= MAX_CACHED_SECTORS) sectorCache.Clear();

                sectorCache.Add(sectorAddress, sector);

                return sector;
            }

            switch(currentChunk.type)
            {
                case CHUNK_TYPE_NOCOPY:
                    sector = new byte[SECTOR_SIZE];

                    if(sectorCache.Count >= MAX_CACHED_SECTORS) sectorCache.Clear();

                    sectorCache.Add(sectorAddress, sector);
                    return sector;
                case CHUNK_TYPE_COPY:
                    imageStream.Seek(currentChunk.offset + relOff, SeekOrigin.Begin);
                    sector = new byte[SECTOR_SIZE];
                    imageStream.Read(sector, 0, sector.Length);

                    if(sectorCache.Count >= MAX_CACHED_SECTORS) sectorCache.Clear();

                    sectorCache.Add(sectorAddress, sector);
                    return sector;
            }

            throw new ImageNotSupportedException($"Unsupported chunk type 0x{currentChunk.type:X8} found");
        }

        public byte[] ReadSectors(ulong sectorAddress, uint length)
        {
            if(sectorAddress > imageInfo.Sectors - 1)
                throw new ArgumentOutOfRangeException(nameof(sectorAddress),
                                                      $"Sector address {sectorAddress} not found");

            if(sectorAddress + length > imageInfo.Sectors)
                throw new ArgumentOutOfRangeException(nameof(length), "Requested more sectors than available");

            MemoryStream ms = new MemoryStream();

            for(uint i = 0; i < length; i++)
            {
                byte[] sector = ReadSector(sectorAddress + i);
                ms.Write(sector, 0, sector.Length);
            }

            return ms.ToArray();
        }

        public byte[] ReadSectorTag(ulong sectorAddress, SectorTagType tag)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public byte[] ReadSectorsTag(ulong sectorAddress, uint length, SectorTagType tag)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public byte[] ReadDiskTag(MediaTagType tag)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public byte[] ReadSector(ulong sectorAddress, uint track)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public byte[] ReadSectorTag(ulong sectorAddress, uint track, SectorTagType tag)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public byte[] ReadSectors(ulong sectorAddress, uint length, uint track)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public byte[] ReadSectorsTag(ulong sectorAddress, uint length, uint track, SectorTagType tag)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public byte[] ReadSectorLong(ulong sectorAddress)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public byte[] ReadSectorLong(ulong sectorAddress, uint track)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public byte[] ReadSectorsLong(ulong sectorAddress, uint length)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public byte[] ReadSectorsLong(ulong sectorAddress, uint length, uint track)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public List<Track> GetSessionTracks(Session session)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public List<Track> GetSessionTracks(ushort session)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public bool? VerifySector(ulong sectorAddress)
        {
            return null;
        }

        public bool? VerifySector(ulong sectorAddress, uint track)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public bool? VerifySectors(ulong sectorAddress, uint length, out List<ulong> failingLbas,
                                            out List<ulong> unknownLbas)
        {
            failingLbas = new List<ulong>();
            unknownLbas = new List<ulong>();
            for(ulong i = 0; i < imageInfo.Sectors; i++) unknownLbas.Add(i);

            return null;
        }

        public bool? VerifySectors(ulong sectorAddress, uint length, uint track, out List<ulong> failingLbas,
                                            out List<ulong> unknownLbas)
        {
            throw new FeatureUnsupportedImageException("Feature not supported by image format");
        }

        public bool? VerifyMediaImage()
        {
            return null;
        }

        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        struct ChunkHeader
        {
            /// <summary>
            ///     Version
            /// </summary>
            public short version;
            /// <summary>
            ///     Filesystem ID
            /// </summary>
            public short driver;
            /// <summary>
            ///     Disk image name, Str63 (Pascal string)
            /// </summary>
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 64)] public byte[] name;
            /// <summary>
            ///     Sectors in image
            /// </summary>
            public uint sectors;
            /// <summary>
            ///     Maximum number of sectors per chunk
            /// </summary>
            public uint maxSectorsPerChunk;
            /// <summary>
            ///     Offset to add to every chunk offset
            /// </summary>
            public uint dataOffset;
            /// <summary>
            ///     CRC28 of whole image
            /// </summary>
            public uint crc;
            /// <summary>
            ///     Set to 1 if segmented
            /// </summary>
            public uint segmented;
            /// <summary>
            ///     Unknown
            /// </summary>
            public uint p1;
            /// <summary>
            ///     Unknown
            /// </summary>
            public uint p2;
            /// <summary>
            ///     Unknown, spare?
            /// </summary>
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 5)] public uint[] unknown;
            /// <summary>
            ///     Set to 1 by ShrinkWrap if image is encrypted
            /// </summary>
            public uint encrypted;
            /// <summary>
            ///     Set by ShrinkWrap if image is encrypted, value is the same for same password
            /// </summary>
            public uint hash;
            /// <summary>
            ///     How many chunks follow the header
            /// </summary>
            public uint chunks;
        }

        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        struct BlockChunk
        {
            /// <summary>
            ///     Starting sector, 3 bytes
            /// </summary>
            public uint sector;
            /// <summary>
            ///     Chunk type
            /// </summary>
            public byte type;
            /// <summary>
            ///     Offset in start of chunk
            /// </summary>
            public uint offset;
            /// <summary>
            ///     Length in bytes of chunk
            /// </summary>
            public uint length;
        }

        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        struct SegmentHeader
        {
            /// <summary>
            ///     Segment #
            /// </summary>
            public ushort segment;
            /// <summary>
            ///     How many segments
            /// </summary>
            public ushort segments;
            /// <summary>
            ///     Seems to be a Guid, changes with different images, same for all segments of same image
            /// </summary>
            public Guid segmentId;
            /// <summary>
            ///     Seems to be a CRC28 of this segment, unchecked
            /// </summary>
            public uint crc;
        }
    }
}