// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Read.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Reads Spectrum FDI 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 © 2011-2026 Natalia Portillo
// ****************************************************************************/

using System;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using Aaru.CommonTypes;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.Helpers;
using Aaru.Logging;

namespace Aaru.Images;

[SuppressMessage("ReSharper", "UnusedType.Global")]
public sealed partial class UkvFdi
{
#region IMediaImage Members

    /// <inheritdoc />
    public ErrorNumber Open(IFilter imageFilter)
    {
        Stream stream = imageFilter.GetDataForkStream();
        stream.Seek(0, SeekOrigin.Begin);

        if(stream.Length < Marshal.SizeOf<Header>()) return ErrorNumber.InvalidArgument;

        var hdrB = new byte[Marshal.SizeOf<Header>()];
        stream.EnsureRead(hdrB, 0, hdrB.Length);

        Header hdr = Marshal.ByteArrayToStructureLittleEndian<Header>(hdrB);

        AaruLogging.Debug(MODULE_NAME, "hdr.addInfoLen = {0}", hdr.addInfoLen);
        AaruLogging.Debug(MODULE_NAME, "hdr.cylinders = {0}",  hdr.cylinders);
        AaruLogging.Debug(MODULE_NAME, "hdr.dataOff = {0}",    hdr.dataOff);
        AaruLogging.Debug(MODULE_NAME, "hdr.descOff = {0}",    hdr.descOff);
        AaruLogging.Debug(MODULE_NAME, "hdr.flags = {0}",      hdr.flags);
        AaruLogging.Debug(MODULE_NAME, "hdr.heads = {0}",      hdr.heads);

        stream.Seek(hdr.descOff, SeekOrigin.Begin);
        var description = new byte[hdr.dataOff - hdr.descOff];
        stream.EnsureRead(description, 0, description.Length);
        _imageInfo.Comments = StringHandlers.CToString(description);

        AaruLogging.Debug(MODULE_NAME, "hdr.description = \"{0}\"", _imageInfo.Comments);

        stream.Seek(0xE + hdr.addInfoLen, SeekOrigin.Begin);

        long spt        = long.MaxValue;
        var  sectorsOff = new uint[hdr.cylinders][][];
        _sectorsData = new byte[hdr.cylinders][][][];

        _imageInfo.Cylinders = hdr.cylinders;
        _imageInfo.Heads     = hdr.heads;

        // Read track descriptors
        for(ushort cyl = 0; cyl < hdr.cylinders; cyl++)
        {
            sectorsOff[cyl]   = new uint[hdr.heads][];
            _sectorsData[cyl] = new byte[hdr.heads][][];

            for(ushort head = 0; head < hdr.heads; head++)
            {
                var sctB = new byte[4];
                stream.EnsureRead(sctB, 0, 4);
                stream.Seek(2, SeekOrigin.Current);
                var sectors = (byte)stream.ReadByte();
                var trkOff  = BitConverter.ToUInt32(sctB, 0);

                AaruLogging.Debug(MODULE_NAME, "trkhdr.c = {0}",       cyl);
                AaruLogging.Debug(MODULE_NAME, "trkhdr.h = {0}",       head);
                AaruLogging.Debug(MODULE_NAME, "trkhdr.sectors = {0}", sectors);
                AaruLogging.Debug(MODULE_NAME, "trkhdr.off = {0}",     trkOff);

                sectorsOff[cyl][head]   = new uint[sectors];
                _sectorsData[cyl][head] = new byte[sectors][];

                if(sectors < spt && sectors > 0) spt = sectors;

                for(ushort sec = 0; sec < sectors; sec++)
                {
                    var c    = (byte)stream.ReadByte();
                    var h    = (byte)stream.ReadByte();
                    var r    = (byte)stream.ReadByte();
                    var n    = (byte)stream.ReadByte();
                    var f    = (SectorFlags)stream.ReadByte();
                    var offB = new byte[2];
                    stream.EnsureRead(offB, 0, 2);
                    var secOff = BitConverter.ToUInt16(offB, 0);

                    AaruLogging.Debug(MODULE_NAME, "sechdr.c = {0}",       c);
                    AaruLogging.Debug(MODULE_NAME, "sechdr.h = {0}",       h);
                    AaruLogging.Debug(MODULE_NAME, "sechdr.r = {0}",       r);
                    AaruLogging.Debug(MODULE_NAME, "sechdr.n = {0} ({1})", n, 128 << n);
                    AaruLogging.Debug(MODULE_NAME, "sechdr.f = {0}",       f);

                    AaruLogging.Debug(MODULE_NAME, "sechdr.off = {0} ({1})", secOff, secOff + trkOff + hdr.dataOff);

                    // TODO: This assumes sequential sectors.
                    sectorsOff[cyl][head][sec]   = secOff + trkOff + hdr.dataOff;
                    _sectorsData[cyl][head][sec] = new byte[128 << n];

                    if(128 << n > _imageInfo.SectorSize) _imageInfo.SectorSize = (uint)(128 << n);
                }
            }
        }

        // Read sectors
        for(ushort cyl = 0; cyl < hdr.cylinders; cyl++)
        {
            var emptyCyl = false;

            for(ushort head = 0; head < hdr.heads; head++)
            {
                for(ushort sec = 0; sec < sectorsOff[cyl][head].Length; sec++)
                {
                    stream.Seek(sectorsOff[cyl][head][sec], SeekOrigin.Begin);
                    stream.EnsureRead(_sectorsData[cyl][head][sec], 0, _sectorsData[cyl][head][sec].Length);
                }

                // For empty cylinders
                if(sectorsOff[cyl][head].Length != 0) continue;

                if(cyl + 1 == hdr.cylinders ||

                   // Next cylinder is also empty
                   sectorsOff[cyl + 1][head].Length == 0)
                    emptyCyl = true;

                // Create empty sectors
                else
                {
                    _sectorsData[cyl][head] = new byte[spt][];

                    for(var i = 0; i < spt; i++) _sectorsData[cyl][head][i] = new byte[_imageInfo.SectorSize];
                }
            }

            if(emptyCyl) _imageInfo.Cylinders--;
        }

        // TODO: What about double sided, half track pitch compact floppies?
        _imageInfo.MediaType            = MediaType.CompactFloppy;
        _imageInfo.ImageSize            = (ulong)stream.Length - hdr.dataOff;
        _imageInfo.CreationTime         = imageFilter.CreationTime;
        _imageInfo.LastModificationTime = imageFilter.LastWriteTime;
        _imageInfo.MediaTitle           = Path.GetFileNameWithoutExtension(imageFilter.Filename);
        _imageInfo.SectorsPerTrack      = (uint)spt;
        _imageInfo.Sectors              = _imageInfo.Cylinders * _imageInfo.Heads * _imageInfo.SectorsPerTrack;
        _imageInfo.MetadataMediaType    = MetadataMediaType.BlockMedia;

        return ErrorNumber.NoError;
    }

    /// <inheritdoc />
    public ErrorNumber ReadSector(ulong sectorAddress, bool negative, out byte[] buffer, out SectorStatus sectorStatus)
    {
        buffer                                    = null;
        sectorStatus                              = SectorStatus.NotDumped;
        (ushort cylinder, byte head, byte sector) = LbaToChs(sectorAddress);

        if(negative) return ErrorNumber.NotSupported;

        if(cylinder >= _sectorsData.Length) return ErrorNumber.SectorNotFound;

        if(head >= _sectorsData[cylinder].Length) return ErrorNumber.SectorNotFound;

        if(sector > _sectorsData[cylinder][head].Length) return ErrorNumber.SectorNotFound;

        buffer       = _sectorsData[cylinder][head][sector - 1];
        sectorStatus = SectorStatus.Dumped;

        return ErrorNumber.NoError;
    }

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

        if(negative) return ErrorNumber.NotSupported;

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

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

        var ms = new MemoryStream();
        sectorStatus = new SectorStatus[length];

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

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

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

        buffer = ms.ToArray();

        return ErrorNumber.NoError;
    }

#endregion
}