// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Read.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Reads Apple Universal 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 © 2011-2021 Natalia Portillo
// ****************************************************************************/

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Aaru.CommonTypes;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.Compression;
using Aaru.Console;
using Aaru.Helpers;
using Claunia.PropertyList;
using Claunia.RsrcFork;
using Ionic.BZip2;
using Ionic.Zlib;
using SharpCompress.Compressors.ADC;
using Version = Resources.Version;

#pragma warning disable 612

namespace Aaru.DiscImages
{
    public sealed partial class Udif
    {
        /// <inheritdoc />
        public ErrorNumber Open(IFilter imageFilter)
        {
            Stream stream = imageFilter.GetDataForkStream();

            if(stream.Length < 512)
                return ErrorNumber.InvalidArgument;

            stream.Seek(-Marshal.SizeOf<Footer>(), SeekOrigin.End);
            byte[] footerB = new byte[Marshal.SizeOf<Footer>()];

            stream.Read(footerB, 0, Marshal.SizeOf<Footer>());
            _footer = Marshal.ByteArrayToStructureBigEndian<Footer>(footerB);

            if(_footer.signature != UDIF_SIGNATURE)
            {
                stream.Seek(0, SeekOrigin.Begin);
                footerB = new byte[Marshal.SizeOf<Footer>()];

                stream.Read(footerB, 0, Marshal.SizeOf<Footer>());
                _footer = Marshal.ByteArrayToStructureBigEndian<Footer>(footerB);

                if(_footer.signature != UDIF_SIGNATURE)
                {
                    AaruConsole.ErrorWriteLine("Unable to find UDIF signature.");

                    return ErrorNumber.InvalidArgument;
                }

                AaruConsole.VerboseWriteLine("Found obsolete UDIF format.");
            }

            AaruConsole.DebugWriteLine("UDIF plugin", "footer.signature = 0x{0:X8}", _footer.signature);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.version = {0}", _footer.version);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.headerSize = {0}", _footer.headerSize);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.flags = {0}", _footer.flags);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.runningDataForkOff = {0}", _footer.runningDataForkOff);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.dataForkOff = {0}", _footer.dataForkOff);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.dataForkLen = {0}", _footer.dataForkLen);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.rsrcForkOff = {0}", _footer.rsrcForkOff);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.rsrcForkLen = {0}", _footer.rsrcForkLen);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.segmentNumber = {0}", _footer.segmentNumber);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.segmentCount = {0}", _footer.segmentCount);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.segmentId = {0}", _footer.segmentId);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.dataForkChkType = {0}", _footer.dataForkChkType);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.dataForkLen = {0}", _footer.dataForkLen);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.dataForkChk = 0x{0:X8}", _footer.dataForkChk);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.plistOff = {0}", _footer.plistOff);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.plistLen = {0}", _footer.plistLen);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.masterChkType = {0}", _footer.masterChkType);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.masterChkLen = {0}", _footer.masterChkLen);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.masterChk = 0x{0:X8}", _footer.masterChk);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.imageVariant = {0}", _footer.imageVariant);
            AaruConsole.DebugWriteLine("UDIF plugin", "footer.sectorCount = {0}", _footer.sectorCount);

            AaruConsole.DebugWriteLine("UDIF plugin", "footer.reserved1 is empty? = {0}",
                                       ArrayHelpers.ArrayIsNullOrEmpty(_footer.reserved1));

            AaruConsole.DebugWriteLine("UDIF plugin", "footer.reserved2 is empty? = {0}",
                                       ArrayHelpers.ArrayIsNullOrEmpty(_footer.reserved2));

            AaruConsole.DebugWriteLine("UDIF plugin", "footer.reserved3 is empty? = {0}",
                                       ArrayHelpers.ArrayIsNullOrEmpty(_footer.reserved3));

            AaruConsole.DebugWriteLine("UDIF plugin", "footer.reserved4 is empty? = {0}",
                                       ArrayHelpers.ArrayIsNullOrEmpty(_footer.reserved4));

            // Block chunks and headers
            List<byte[]> blkxList = new();
            _chunks = new Dictionary<ulong, BlockChunk>();

            byte[] vers = null;

            if(_footer.plistLen    == 0 &&
               _footer.rsrcForkLen != 0)
            {
                AaruConsole.DebugWriteLine("UDIF plugin", "Reading resource fork.");
                byte[] rsrcB = new byte[_footer.rsrcForkLen];
                stream.Seek((long)_footer.rsrcForkOff, SeekOrigin.Begin);
                stream.Read(rsrcB, 0, rsrcB.Length);

                var rsrc = new ResourceFork(rsrcB);

                if(!rsrc.ContainsKey(BLOCK_OS_TYPE))
                {
                    AaruConsole.
                        ErrorWriteLine("Image resource fork doesn't contain UDIF block chunks. Please fill an issue and send it to us.");

                    return ErrorNumber.InvalidArgument;
                }

                Resource blkxRez = rsrc.GetResource(BLOCK_OS_TYPE);

                if(blkxRez == null)
                {
                    AaruConsole.
                        ErrorWriteLine("Image resource fork doesn't contain UDIF block chunks. Please fill an issue and send it to us.");

                    return ErrorNumber.InvalidArgument;
                }

                if(blkxRez.GetIds().Length == 0)
                {
                    AaruConsole.
                        ErrorWriteLine("Image resource fork doesn't contain UDIF block chunks. Please fill an issue and send it to us.");

                    return ErrorNumber.InvalidArgument;
                }

                blkxList.AddRange(blkxRez.GetIds().Select(blkxId => blkxRez.GetResource(blkxId)));

                Resource versRez = rsrc.GetResource(0x76657273);

                if(versRez != null)
                    vers = versRez.GetResource(versRez.GetIds()[0]);
            }
            else if(_footer.plistLen != 0)
            {
                AaruConsole.DebugWriteLine("UDIF plugin", "Reading property list.");
                byte[] plistB = new byte[_footer.plistLen];
                stream.Seek((long)_footer.plistOff, SeekOrigin.Begin);
                stream.Read(plistB, 0, plistB.Length);

                AaruConsole.DebugWriteLine("UDIF plugin", "Parsing property list.");
                var plist = (NSDictionary)XmlPropertyListParser.Parse(plistB);

                if(plist == null)
                {
                    AaruConsole.ErrorWriteLine("Could not parse property list.");

                    return ErrorNumber.InOutError;
                }

                if(!plist.TryGetValue(RESOURCE_FORK_KEY, out NSObject rsrcObj))
                {
                    AaruConsole.ErrorWriteLine("Could not retrieve resource fork.");

                    return ErrorNumber.InOutError;
                }

                var rsrc = (NSDictionary)rsrcObj;

                if(!rsrc.TryGetValue(BLOCK_KEY, out NSObject blkxObj))
                {
                    AaruConsole.ErrorWriteLine("Could not retrieve block chunks array.");

                    return ErrorNumber.InOutError;
                }

                NSObject[] blkx = ((NSArray)blkxObj).GetArray();

                foreach(NSDictionary part in blkx.Cast<NSDictionary>())
                {
                    if(!part.TryGetValue("Name", out _))
                    {
                        AaruConsole.ErrorWriteLine("Could not retrieve Name");

                        return ErrorNumber.InOutError;
                    }

                    if(!part.TryGetValue("Data", out NSObject dataObj))
                    {
                        AaruConsole.ErrorWriteLine("Could not retrieve Data");

                        return ErrorNumber.InOutError;
                    }

                    blkxList.Add(((NSData)dataObj).Bytes);
                }

                if(rsrc.TryGetValue("vers", out NSObject versObj))
                {
                    NSObject[] versArray = ((NSArray)versObj).GetArray();

                    if(versArray.Length >= 1)
                        vers = ((NSData)versArray[0]).Bytes;
                }
            }
            else
            {
                if(imageFilter.ResourceForkLength == 0)
                {
                    AaruConsole.ErrorWriteLine("This image needs the resource fork to work.");

                    return ErrorNumber.InvalidArgument;
                }

                AaruConsole.DebugWriteLine("UDIF plugin", "Reading resource fork.");
                Stream rsrcStream = imageFilter.GetResourceForkStream();

                byte[] rsrcB = new byte[rsrcStream.Length];
                rsrcStream.Position = 0;
                rsrcStream.Read(rsrcB, 0, rsrcB.Length);

                var rsrc = new ResourceFork(rsrcB);

                if(!rsrc.ContainsKey(BLOCK_OS_TYPE))
                {
                    AaruConsole.
                        ErrorWriteLine("Image resource fork doesn't contain UDIF block chunks. Please fill an issue and send it to us.");

                    return ErrorNumber.InvalidArgument;
                }

                Resource blkxRez = rsrc.GetResource(BLOCK_OS_TYPE);

                if(blkxRez == null)
                {
                    AaruConsole.
                        ErrorWriteLine("Image resource fork doesn't contain UDIF block chunks. Please fill an issue and send it to us.");

                    return ErrorNumber.InvalidArgument;
                }

                if(blkxRez.GetIds().Length == 0)
                {
                    AaruConsole.
                        ErrorWriteLine("Image resource fork doesn't contain UDIF block chunks. Please fill an issue and send it to us.");

                    return ErrorNumber.InvalidArgument;
                }

                blkxList.AddRange(blkxRez.GetIds().Select(blkxId => blkxRez.GetResource(blkxId)));

                Resource versRez = rsrc.GetResource(0x76657273);

                if(versRez != null)
                    vers = versRez.GetResource(versRez.GetIds()[0]);
            }

            if(vers != null)
            {
                var 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";
            }
            else
                _imageInfo.Application = "DiskCopy";

            AaruConsole.DebugWriteLine("UDIF plugin", "Image application = {0} version {1}", _imageInfo.Application,
                                       _imageInfo.ApplicationVersion);

            _imageInfo.Sectors = 0;

            if(blkxList.Count == 0)
            {
                AaruConsole.ErrorWriteLine("Could not retrieve block chunks. Please fill an issue and send it to us.");

                return ErrorNumber.InvalidArgument;
            }

            _buffersize = 0;

            foreach(byte[] blkxBytes in blkxList)
            {
                byte[] bHdrB = new byte[Marshal.SizeOf<BlockHeader>()];
                Array.Copy(blkxBytes, 0, bHdrB, 0, Marshal.SizeOf<BlockHeader>());
                BlockHeader bHdr = Marshal.ByteArrayToStructureBigEndian<BlockHeader>(bHdrB);

                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.signature = 0x{0:X8}", bHdr.signature);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.version = {0}", bHdr.version);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.sectorStart = {0}", bHdr.sectorStart);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.sectorCount = {0}", bHdr.sectorCount);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.dataOffset = {0}", bHdr.dataOffset);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.buffers = {0}", bHdr.buffers);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.descriptor = 0x{0:X8}", bHdr.descriptor);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.reserved1 = {0}", bHdr.reserved1);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.reserved2 = {0}", bHdr.reserved2);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.reserved3 = {0}", bHdr.reserved3);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.reserved4 = {0}", bHdr.reserved4);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.reserved5 = {0}", bHdr.reserved5);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.reserved6 = {0}", bHdr.reserved6);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.checksumType = {0}", bHdr.checksumType);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.checksumLen = {0}", bHdr.checksumLen);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.checksum = 0x{0:X8}", bHdr.checksum);
                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.chunks = {0}", bHdr.chunks);

                AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.reservedChk is empty? = {0}",
                                           ArrayHelpers.ArrayIsNullOrEmpty(bHdr.reservedChk));

                if(bHdr.buffers > _buffersize)
                    _buffersize = bHdr.buffers * SECTOR_SIZE;

                for(int i = 0; i < bHdr.chunks; i++)
                {
                    byte[] bChnkB = new byte[Marshal.SizeOf<BlockChunk>()];

                    Array.Copy(blkxBytes, Marshal.SizeOf<BlockHeader>() + (Marshal.SizeOf<BlockChunk>() * i), bChnkB, 0,
                               Marshal.SizeOf<BlockChunk>());

                    BlockChunk bChnk = Marshal.ByteArrayToStructureBigEndian<BlockChunk>(bChnkB);

                    AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.chunk[{0}].type = 0x{1:X8}", i, bChnk.type);
                    AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.chunk[{0}].comment = {1}", i, bChnk.comment);
                    AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.chunk[{0}].sector = {1}", i, bChnk.sector);
                    AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.chunk[{0}].sectors = {1}", i, bChnk.sectors);
                    AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.chunk[{0}].offset = {1}", i, bChnk.offset);
                    AaruConsole.DebugWriteLine("UDIF plugin", "bHdr.chunk[{0}].length = {1}", i, bChnk.length);

                    if(bChnk.type == CHUNK_TYPE_END)
                        break;

                    _imageInfo.Sectors += bChnk.sectors;

                    // Chunk offset is relative
                    bChnk.sector += bHdr.sectorStart;
                    bChnk.offset += bHdr.dataOffset;

                    switch(bChnk.type)
                    {
                        // TODO: Handle comments
                        case CHUNK_TYPE_COMMNT: continue;

                        // TODO: Handle compressed chunks
                        case CHUNK_TYPE_KENCODE:
                            AaruConsole.ErrorWriteLine("Chunks compressed with KenCode are not yet supported.");

                            return ErrorNumber.NotImplemented;
                        case CHUNK_TYPE_LZH:
                            AaruConsole.ErrorWriteLine("Chunks compressed with LZH are not yet supported.");

                            return ErrorNumber.NotImplemented;
                        case CHUNK_TYPE_LZFSE:
                            AaruConsole.ErrorWriteLine("Chunks compressed with lzfse are not yet supported.");

                            return ErrorNumber.NotImplemented;
                        case CHUNK_TYPE_LZMA:
                            AaruConsole.ErrorWriteLine("Chunks compressed with lzma are not yet supported.");

                            return ErrorNumber.NotImplemented;
                    }

                    if((bChnk.type > CHUNK_TYPE_NOCOPY && bChnk.type < CHUNK_TYPE_COMMNT) ||
                       (bChnk.type > CHUNK_TYPE_LZMA   && bChnk.type < CHUNK_TYPE_END))
                    {
                        AaruConsole.ErrorWriteLine($"Unsupported chunk type 0x{bChnk.type:X8} found");

                        return ErrorNumber.InvalidArgument;
                    }

                    if(bChnk.sectors > 0)
                        _chunks.Add(bChnk.sector, bChnk);
                }
            }

            _sectorCache           = new Dictionary<ulong, byte[]>();
            _chunkCache            = new Dictionary<ulong, byte[]>();
            _currentChunkCacheSize = 0;
            _imageStream           = stream;

            _imageInfo.CreationTime         = imageFilter.CreationTime;
            _imageInfo.LastModificationTime = imageFilter.LastWriteTime;
            _imageInfo.MediaTitle           = Path.GetFileNameWithoutExtension(imageFilter.Filename);
            _imageInfo.SectorSize           = SECTOR_SIZE;
            _imageInfo.XmlMediaType         = XmlMediaType.BlockMedia;
            _imageInfo.MediaType            = MediaType.GENERIC_HDD;
            _imageInfo.ImageSize            = _imageInfo.Sectors * SECTOR_SIZE;
            _imageInfo.Version              = $"{_footer.version}";

            _imageInfo.Cylinders       = (uint)(_imageInfo.Sectors / 16 / 63);
            _imageInfo.Heads           = 16;
            _imageInfo.SectorsPerTrack = 63;

            return ErrorNumber.NoError;
        }

        /// <inheritdoc />
        public ErrorNumber ReadSector(ulong sectorAddress, out byte[] buffer)
        {
            buffer = null;

            if(sectorAddress > _imageInfo.Sectors - 1)
                return ErrorNumber.OutOfRange;

            if(_sectorCache.TryGetValue(sectorAddress, out buffer))
                return ErrorNumber.NoError;

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

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

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

            if(relOff < 0)
                return ErrorNumber.InvalidArgument;

            if(!chunkFound)
                return ErrorNumber.SectorNotFound;

            if((readChunk.type & CHUNK_TYPE_COMPRESSED_MASK) == CHUNK_TYPE_COMPRESSED_MASK)
            {
                if(!_chunkCache.TryGetValue(chunkStartSector, out byte[] data))
                {
                    byte[] cmpBuffer = new byte[readChunk.length];
                    _imageStream.Seek((long)(readChunk.offset + _footer.dataForkOff), SeekOrigin.Begin);
                    _imageStream.Read(cmpBuffer, 0, cmpBuffer.Length);
                    var    cmpMs     = new MemoryStream(cmpBuffer);
                    Stream decStream = null;

                    switch(readChunk.type)
                    {
                        case CHUNK_TYPE_ADC:
                            decStream = new ADCStream(cmpMs);

                            break;
                        case CHUNK_TYPE_ZLIB:
                            decStream = new ZlibStream(cmpMs, CompressionMode.Decompress);

                            break;
                        case CHUNK_TYPE_BZIP:
                            decStream = new BZip2InputStream(cmpMs, false);

                            break;
                        case CHUNK_TYPE_RLE: break;
                        default:             return ErrorNumber.NotImplemented;
                    }

                #if DEBUG
                    try
                    {
                    #endif
                        byte[] tmpBuffer;
                        int    realSize;

                        switch(readChunk.type)
                        {
                            case CHUNK_TYPE_ADC:
                            case CHUNK_TYPE_ZLIB:
                            case CHUNK_TYPE_BZIP:
                                tmpBuffer = new byte[_buffersize];
                                realSize  = decStream?.Read(tmpBuffer, 0, (int)_buffersize) ?? 0;
                                data      = new byte[realSize];
                                Array.Copy(tmpBuffer, 0, data, 0, realSize);

                                if(_currentChunkCacheSize + realSize > MAX_CACHE_SIZE)
                                {
                                    _chunkCache.Clear();
                                    _currentChunkCacheSize = 0;
                                }

                                _chunkCache.Add(chunkStartSector, data);
                                _currentChunkCacheSize += (uint)realSize;

                                break;
                            case CHUNK_TYPE_RLE:
                                tmpBuffer = new byte[_buffersize];
                                realSize  = 0;
                                var rle = new AppleRle(cmpMs);

                                for(int i = 0; i < _buffersize; i++)
                                {
                                    int b = rle.ProduceByte();

                                    if(b == -1)
                                        break;

                                    tmpBuffer[i] = (byte)b;
                                    realSize++;
                                }

                                data = new byte[realSize];
                                Array.Copy(tmpBuffer, 0, data, 0, realSize);

                                break;
                        }
                    #if DEBUG
                    }
                    catch(ZlibException)
                    {
                        AaruConsole.WriteLine("zlib exception on chunk starting at sector {0}", readChunk.sector);

                        throw;
                    }
                #endif
                }

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

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

                _sectorCache.Add(sectorAddress, buffer);

                return ErrorNumber.NoError;
            }

            switch(readChunk.type)
            {
                case CHUNK_TYPE_NOCOPY:
                case CHUNK_TYPE_ZERO:
                    buffer = new byte[SECTOR_SIZE];

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

                    _sectorCache.Add(sectorAddress, buffer);

                    return ErrorNumber.NoError;
                case CHUNK_TYPE_COPY:
                    _imageStream.Seek((long)(readChunk.offset + (ulong)relOff + _footer.dataForkOff), SeekOrigin.Begin);
                    buffer = new byte[SECTOR_SIZE];
                    _imageStream.Read(buffer, 0, buffer.Length);

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

                    _sectorCache.Add(sectorAddress, buffer);

                    return ErrorNumber.NoError;
            }

            return ErrorNumber.NotImplemented;
        }

        /// <inheritdoc />
        public ErrorNumber ReadSectors(ulong sectorAddress, uint length, out byte[] buffer)
        {
            buffer = null;

            if(sectorAddress > _imageInfo.Sectors - 1)
                return ErrorNumber.OutOfRange;

            if(sectorAddress + length > _imageInfo.Sectors)
                return ErrorNumber.OutOfRange;

            var ms = new MemoryStream();

            for(uint i = 0; i < length; i++)
            {
                ErrorNumber errno = ReadSector(sectorAddress + i, out byte[] sector);

                if(errno != ErrorNumber.NoError)
                    return errno;

                ms.Write(sector, 0, sector.Length);
            }

            buffer = ms.ToArray();

            return ErrorNumber.NoError;
        }
    }
}