// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Read.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Reads Sydex CopyQM disk images.
//
// --[ 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.IO;
using Aaru.CommonTypes;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.Console;
using Aaru.Helpers;

namespace Aaru.DiscImages
{
    public sealed partial class CopyQm
    {
        /// <inheritdoc />
        public ErrorNumber Open(IFilter imageFilter)
        {
            Stream stream = imageFilter.GetDataForkStream();
            stream.Seek(0, SeekOrigin.Begin);

            byte[] hdr = new byte[133];

            stream.Read(hdr, 0, 133);
            _header = Marshal.ByteArrayToStructureLittleEndian<Header>(hdr);

            AaruConsole.DebugWriteLine("CopyQM plugin", "header.magic = 0x{0:X4}", _header.magic);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.mark = 0x{0:X2}", _header.mark);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.sectorSize = {0}", _header.sectorSize);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.sectorPerCluster = {0}", _header.sectorPerCluster);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.reservedSectors = {0}", _header.reservedSectors);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.fatCopy = {0}", _header.fatCopy);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.rootEntries = {0}", _header.rootEntries);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.sectors = {0}", _header.sectors);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.mediaType = 0x{0:X2}", _header.mediaType);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.sectorsPerFat = {0}", _header.sectorsPerFat);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.sectorsPerTrack = {0}", _header.sectorsPerTrack);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.heads = {0}", _header.heads);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.hidden = {0}", _header.hidden);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.sectorsBig = {0}", _header.sectorsBig);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.description = {0}", _header.description);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.blind = {0}", _header.blind);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.density = {0}", _header.density);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.imageCylinders = {0}", _header.imageCylinders);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.totalCylinders = {0}", _header.totalCylinders);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.crc = 0x{0:X8}", _header.crc);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.volumeLabel = {0}", _header.volumeLabel);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.time = 0x{0:X4}", _header.time);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.date = 0x{0:X4}", _header.date);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.commentLength = {0}", _header.commentLength);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.secbs = {0}", _header.secbs);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.unknown = 0x{0:X4}", _header.unknown);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.interleave = {0}", _header.interleave);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.skew = {0}", _header.skew);
            AaruConsole.DebugWriteLine("CopyQM plugin", "header.drive = {0}", _header.drive);

            byte[] cmt = new byte[_header.commentLength];
            stream.Read(cmt, 0, _header.commentLength);
            _imageInfo.Comments = StringHandlers.CToString(cmt);
            _decodedImage       = new MemoryStream();

            _calculatedDataCrc = 0;

            while(stream.Position + 2 < stream.Length)
            {
                byte[] runLengthBytes = new byte[2];

                if(stream.Read(runLengthBytes, 0, 2) != 2)
                    break;

                short runLength = BitConverter.ToInt16(runLengthBytes, 0);

                if(runLength < 0)
                {
                    byte   repeatedByte  = (byte)stream.ReadByte();
                    byte[] repeatedArray = new byte[runLength * -1];
                    ArrayHelpers.ArrayFill(repeatedArray, repeatedByte);

                    for(int i = 0; i < runLength * -1; i++)
                    {
                        _decodedImage.WriteByte(repeatedByte);

                        _calculatedDataCrc = _copyQmCrcTable[(repeatedByte ^ _calculatedDataCrc) & 0x3F] ^
                                             (_calculatedDataCrc >> 8);
                    }
                }
                else if(runLength > 0)
                {
                    byte[] nonRepeated = new byte[runLength];
                    stream.Read(nonRepeated, 0, runLength);
                    _decodedImage.Write(nonRepeated, 0, runLength);

                    foreach(byte c in nonRepeated)
                        _calculatedDataCrc =
                            _copyQmCrcTable[(c ^ _calculatedDataCrc) & 0x3F] ^ (_calculatedDataCrc >> 8);
                }
            }

            // In case there is omitted data
            long sectors = _header.sectorsPerTrack * _header.heads * _header.totalCylinders;

            long fillingLen = (sectors * _header.sectorSize) - _decodedImage.Length;

            if(fillingLen > 0)
            {
                byte[] filling = new byte[fillingLen];
                ArrayHelpers.ArrayFill(filling, (byte)0xF6);
                _decodedImage.Write(filling, 0, filling.Length);
            }

            int sum = 0;

            for(int i = 0; i < hdr.Length - 1; i++)
                sum += hdr[i];

            _headerChecksumOk = ((-1 * sum) & 0xFF) == _header.headerChecksum;

            AaruConsole.DebugWriteLine("CopyQM plugin", "Calculated header checksum = 0x{0:X2}, {1}", (-1 * sum) & 0xFF,
                                       _headerChecksumOk);

            AaruConsole.DebugWriteLine("CopyQM plugin", "Calculated data CRC = 0x{0:X8}, {1}", _calculatedDataCrc,
                                       _calculatedDataCrc == _header.crc);

            _imageInfo.Application          = "CopyQM";
            _imageInfo.CreationTime         = DateHandlers.DosToDateTime(_header.date, _header.time);
            _imageInfo.LastModificationTime = _imageInfo.CreationTime;
            _imageInfo.MediaTitle           = _header.volumeLabel;
            _imageInfo.ImageSize            = (ulong)(stream.Length - 133 - _header.commentLength);
            _imageInfo.Sectors              = (ulong)sectors;
            _imageInfo.SectorSize           = _header.sectorSize;

            _imageInfo.MediaType = Geometry.GetMediaType((_header.totalCylinders, (byte)_header.heads,
                                                          _header.sectorsPerTrack, _header.sectorSize,
                                                          MediaEncoding.MFM, false));

            switch(_imageInfo.MediaType)
            {
                case MediaType.NEC_525_HD when _header.drive == COPYQM_35_HD || _header.drive == COPYQM_35_ED:
                    _imageInfo.MediaType = MediaType.NEC_35_HD_8;

                    break;
                case MediaType.DOS_525_HD when _header.drive == COPYQM_35_HD || _header.drive == COPYQM_35_ED:
                    _imageInfo.MediaType = MediaType.NEC_35_HD_15;

                    break;
                case MediaType.RX50 when _header.drive == COPYQM_525_DD || _header.drive == COPYQM_525_HD:
                    _imageInfo.MediaType = MediaType.ATARI_35_SS_DD;

                    break;
            }

            _imageInfo.XmlMediaType = XmlMediaType.BlockMedia;
            _decodedDisk            = _decodedImage.ToArray();

            _decodedImage.Close();

            AaruConsole.VerboseWriteLine("CopyQM image contains a disk of type {0}", _imageInfo.MediaType);

            if(!string.IsNullOrEmpty(_imageInfo.Comments))
                AaruConsole.VerboseWriteLine("CopyQM comments: {0}", _imageInfo.Comments);

            _imageInfo.Heads           = _header.heads;
            _imageInfo.Cylinders       = _header.totalCylinders;
            _imageInfo.SectorsPerTrack = _header.sectorsPerTrack;

            return ErrorNumber.NoError;
        }

        /// <inheritdoc />
        public ErrorNumber ReadSector(ulong sectorAddress, out byte[] buffer) =>
            ReadSectors(sectorAddress, 1, out buffer);

        /// <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;

            buffer = new byte[length * _imageInfo.SectorSize];

            Array.Copy(_decodedDisk, (int)sectorAddress * _imageInfo.SectorSize, buffer, 0,
                       length                           * _imageInfo.SectorSize);

            return ErrorNumber.NoError;
        }

        /// <inheritdoc />
        public bool? VerifyMediaImage() => _calculatedDataCrc == _header.crc && _headerChecksumOk;
    }
}