// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Identify.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Identifies Sydex TeleDisk 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.Interfaces;
using Aaru.Console;

namespace Aaru.DiscImages
{
    public sealed partial class TeleDisk
    {
        /// <inheritdoc />
        public bool Identify(IFilter imageFilter)
        {
            _header = new Header();
            byte[] headerBytes = new byte[12];
            Stream stream      = imageFilter.GetDataForkStream();
            stream.Seek(0, SeekOrigin.Begin);

            stream.Read(headerBytes, 0, 12);

            _header.Signature = BitConverter.ToUInt16(headerBytes, 0);

            if(_header.Signature != TD_MAGIC &&
               _header.Signature != TD_ADV_COMP_MAGIC)
                return false;

            _header.Sequence      = headerBytes[2];
            _header.DiskSet       = headerBytes[3];
            _header.Version       = headerBytes[4];
            _header.DataRate      = headerBytes[5];
            _header.DriveType     = headerBytes[6];
            _header.Stepping      = headerBytes[7];
            _header.DosAllocation = headerBytes[8];
            _header.Sides         = headerBytes[9];
            _header.Crc           = BitConverter.ToUInt16(headerBytes, 10);

            byte[] headerBytesForCrc = new byte[10];
            Array.Copy(headerBytes, headerBytesForCrc, 10);
            ushort calculatedHeaderCrc = TeleDiskCrc(0x0000, headerBytesForCrc);

            AaruConsole.DebugWriteLine("TeleDisk plugin", "header.signature = 0x{0:X4}", _header.Signature);
            AaruConsole.DebugWriteLine("TeleDisk plugin", "header.sequence = 0x{0:X2}", _header.Sequence);
            AaruConsole.DebugWriteLine("TeleDisk plugin", "header.diskSet = 0x{0:X2}", _header.DiskSet);
            AaruConsole.DebugWriteLine("TeleDisk plugin", "header.version = 0x{0:X2}", _header.Version);
            AaruConsole.DebugWriteLine("TeleDisk plugin", "header.dataRate = 0x{0:X2}", _header.DataRate);
            AaruConsole.DebugWriteLine("TeleDisk plugin", "header.driveType = 0x{0:X2}", _header.DriveType);
            AaruConsole.DebugWriteLine("TeleDisk plugin", "header.stepping = 0x{0:X2}", _header.Stepping);
            AaruConsole.DebugWriteLine("TeleDisk plugin", "header.dosAllocation = 0x{0:X2}", _header.DosAllocation);
            AaruConsole.DebugWriteLine("TeleDisk plugin", "header.sides = 0x{0:X2}", _header.Sides);
            AaruConsole.DebugWriteLine("TeleDisk plugin", "header.crc = 0x{0:X4}", _header.Crc);
            AaruConsole.DebugWriteLine("TeleDisk plugin", "calculated header crc = 0x{0:X4}", calculatedHeaderCrc);

            // We need more checks as the magic is too simply.
            // This may deny legal images

            // That would be much of a coincidence
            if(_header.Crc == calculatedHeaderCrc)
                return true;

            if(_header.Sequence != 0x00)
                return false;

            if(_header.DataRate != DATA_RATE_250_KBPS &&
               _header.DataRate != DATA_RATE_300_KBPS &&
               _header.DataRate != DATA_RATE_500_KBPS)
                return false;

            return _header.DriveType == DRIVE_TYPE_35_DD  || _header.DriveType == DRIVE_TYPE_35_ED          ||
                   _header.DriveType == DRIVE_TYPE_35_HD  || _header.DriveType == DRIVE_TYPE_525_DD         ||
                   _header.DriveType == DRIVE_TYPE_525_HD || _header.DriveType == DRIVE_TYPE_525_HD_DD_DISK ||
                   _header.DriveType == DRIVE_TYPE_8_INCH;
        }
    }
}