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

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

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

            long diskSize = stream.Length - DATA_OFFSET;

            _comment = new byte[60];
            _hdrId   = new byte[13];
            stream.Seek(0, SeekOrigin.Begin);
            _dskType = (DiskType)stream.ReadByte();
            stream.Seek(0xAB, SeekOrigin.Begin);
            stream.Read(_hdrId, 0, 13);
            stream.Seek(0xC2, SeekOrigin.Begin);
            stream.Read(_comment, 0, 60);

            if(!_headerId.SequenceEqual(_hdrId))
                return ErrorNumber.InvalidArgument;

            _imageInfo.MediaType = MediaType.Unknown;

            switch(_dskType)
            {
                // 8 spt, 1024 bps
                case DiskType.Hd2:
                    if(diskSize % (2 * 8 * 1024) != 0)
                    {
                        AaruConsole.ErrorWriteLine("DIM shows unknown image with {0} tracks",
                                                   diskSize / (2 * 8 * 1024));

                        return ErrorNumber.NotSupported;
                    }

                    if(diskSize / (2 * 8 * 1024) == 77)
                        _imageInfo.MediaType = MediaType.SHARP_525;

                    _imageInfo.SectorSize = 1024;

                    break;

                // 9 spt, 1024 bps
                case DiskType.Hs2:
                    if(diskSize % (2 * 9 * 512) != 0)
                    {
                        AaruConsole.ErrorWriteLine("DIM shows unknown image with {0} tracks", diskSize / (2 * 9 * 512));

                        return ErrorNumber.NotSupported;
                    }

                    if(diskSize / (2 * 9 * 512) == 80)
                        _imageInfo.MediaType = MediaType.SHARP_525_9;

                    _imageInfo.SectorSize = 512;

                    break;

                // 15 spt, 512 bps
                case DiskType.Hc2:
                    if(diskSize % (2 * 15 * 512) != 0)
                    {
                        AaruConsole.ErrorWriteLine("DIM shows unknown image with {0} tracks",
                                                   diskSize / (2 * 15 * 512));

                        return ErrorNumber.NotSupported;
                    }

                    if(diskSize / (2 * 15 * 512) == 80)
                        _imageInfo.MediaType = MediaType.DOS_525_HD;

                    _imageInfo.SectorSize = 512;

                    break;

                // 9 spt, 1024 bps
                case DiskType.Hde2:
                    if(diskSize % (2 * 9 * 512) != 0)
                    {
                        AaruConsole.ErrorWriteLine("DIM shows unknown image with {0} tracks", diskSize / (2 * 9 * 512));

                        return ErrorNumber.NotSupported;
                    }

                    if(diskSize / (2 * 9 * 512) == 80)
                        _imageInfo.MediaType = MediaType.SHARP_35_9;

                    _imageInfo.SectorSize = 512;

                    break;

                // 18 spt, 512 bps
                case DiskType.Hq2:
                    if(diskSize % (2 * 18 * 512) != 0)
                    {
                        AaruConsole.ErrorWriteLine("DIM shows unknown image with {0} tracks",
                                                   diskSize / (2 * 18 * 512));

                        return ErrorNumber.NotSupported;
                    }

                    if(diskSize / (2 * 18 * 512) == 80)
                        _imageInfo.MediaType = MediaType.DOS_35_HD;

                    _imageInfo.SectorSize = 512;

                    break;

                // 26 spt, 256 bps
                case DiskType.N88:
                    if(diskSize % (2 * 26 * 256) == 0)
                    {
                        if(diskSize % (2 * 26 * 256) == 77)
                            _imageInfo.MediaType = MediaType.NEC_8_DD;

                        _imageInfo.SectorSize = 256;
                    }
                    else if(diskSize % (2 * 26 * 128) == 0)
                    {
                        if(diskSize % (2 * 26 * 128) == 77)
                            _imageInfo.MediaType = MediaType.NEC_8_SD;

                        _imageInfo.SectorSize = 256;
                    }
                    else
                    {
                        AaruConsole.ErrorWriteLine("DIM shows unknown image with {0} tracks",
                                                   diskSize / (2 * 26 * 256));

                        return ErrorNumber.NotSupported;
                    }

                    break;
                default: return ErrorNumber.InvalidArgument;
            }

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

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

            _dimImageFilter = imageFilter;

            _imageInfo.ImageSize            = (ulong)diskSize;
            _imageInfo.CreationTime         = imageFilter.CreationTime;
            _imageInfo.LastModificationTime = imageFilter.LastWriteTime;
            _imageInfo.MediaTitle           = Path.GetFileNameWithoutExtension(imageFilter.Filename);
            _imageInfo.Sectors              = _imageInfo.ImageSize / _imageInfo.SectorSize;
            _imageInfo.Comments             = StringHandlers.CToString(_comment, Encoding.GetEncoding(932));
            _imageInfo.XmlMediaType         = XmlMediaType.BlockMedia;

            switch(_imageInfo.MediaType)
            {
                case MediaType.SHARP_525:
                    _imageInfo.Cylinders       = 77;
                    _imageInfo.Heads           = 2;
                    _imageInfo.SectorsPerTrack = 8;

                    break;
                case MediaType.SHARP_525_9:
                    _imageInfo.Cylinders       = 80;
                    _imageInfo.Heads           = 2;
                    _imageInfo.SectorsPerTrack = 9;

                    break;
                case MediaType.DOS_525_HD:
                    _imageInfo.Cylinders       = 80;
                    _imageInfo.Heads           = 2;
                    _imageInfo.SectorsPerTrack = 15;

                    break;
                case MediaType.SHARP_35_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.NEC_8_DD:
                case MediaType.NEC_8_SD:
                    _imageInfo.Cylinders       = 77;
                    _imageInfo.Heads           = 2;
                    _imageInfo.SectorsPerTrack = 26;

                    break;
            }

            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];

            Stream stream = _dimImageFilter.GetDataForkStream();

            stream.Seek((long)(DATA_OFFSET + (sectorAddress * _imageInfo.SectorSize)), SeekOrigin.Begin);

            stream.Read(buffer, 0, (int)(length * _imageInfo.SectorSize));

            return ErrorNumber.NoError;
        }
    }
}