// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Super.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : U.C.S.D. Pascal filesystem plugin.
//
// --[ Description ] ----------------------------------------------------------
//
//     Handles mounting and umounting the U.C.S.D. Pascal filesystem.
//
// --[ 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 © 2011-2025 Natalia Portillo
// ****************************************************************************/

using System;
using System.Collections.Generic;
using Aaru.CommonTypes.AaruMetadata;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.Helpers;
using Claunia.Encoding;
using Encoding = System.Text.Encoding;
using FileSystemInfo = Aaru.CommonTypes.Structs.FileSystemInfo;
using Partition = Aaru.CommonTypes.Partition;

namespace Aaru.Filesystems;

// Information from Call-A.P.P.L.E. Pascal Disk Directory Structure
public sealed partial class PascalPlugin
{
#region IReadOnlyFilesystem Members

    /// <inheritdoc />
    public ErrorNumber Mount(IMediaImage                imagePlugin, Partition partition, Encoding encoding,
                             Dictionary<string, string> options,     string    @namespace)
    {
        _device   = imagePlugin;
        _encoding = encoding ?? new Apple2();

        options ??= GetDefaultOptions();

        if(options.TryGetValue("debug", out string debugString)) bool.TryParse(debugString, out _debug);

        if(_device.Info.Sectors < 3) return ErrorNumber.InvalidArgument;

        _multiplier = (uint)(imagePlugin.Info.SectorSize == 256 ? 2 : 1);

        // Blocks 0 and 1 are boot code
        ErrorNumber errno = _device.ReadSectors(_multiplier * 2, _multiplier, out _catalogBlocks);

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

        // On Apple //, it's little endian
        // TODO: Fix
        //BigEndianBitConverter.IsLittleEndian =
        //    multiplier == 2 ? !BitConverter.IsLittleEndian : BitConverter.IsLittleEndian;

        _mountedVolEntry.FirstBlock = BigEndianBitConverter.ToInt16(_catalogBlocks, 0x00);
        _mountedVolEntry.LastBlock  = BigEndianBitConverter.ToInt16(_catalogBlocks, 0x02);
        _mountedVolEntry.EntryType  = (PascalFileKind)BigEndianBitConverter.ToInt16(_catalogBlocks, 0x04);
        _mountedVolEntry.VolumeName = new byte[8];
        Array.Copy(_catalogBlocks, 0x06, _mountedVolEntry.VolumeName, 0, 8);
        _mountedVolEntry.Blocks   = BigEndianBitConverter.ToInt16(_catalogBlocks, 0x0E);
        _mountedVolEntry.Files    = BigEndianBitConverter.ToInt16(_catalogBlocks, 0x10);
        _mountedVolEntry.Dummy    = BigEndianBitConverter.ToInt16(_catalogBlocks, 0x12);
        _mountedVolEntry.LastBoot = BigEndianBitConverter.ToInt16(_catalogBlocks, 0x14);
        _mountedVolEntry.Tail     = BigEndianBitConverter.ToInt32(_catalogBlocks, 0x16);

        if(_mountedVolEntry.FirstBlock       != 0                                                                     ||
           _mountedVolEntry.LastBlock        <= _mountedVolEntry.FirstBlock                                           ||
           (ulong)_mountedVolEntry.LastBlock > _device.Info.Sectors / _multiplier - 2                                 ||
           _mountedVolEntry.EntryType != PascalFileKind.Volume && _mountedVolEntry.EntryType != PascalFileKind.Secure ||
           _mountedVolEntry.VolumeName[0] > 7                                                                         ||
           _mountedVolEntry.Blocks        < 0                                                                         ||
           (ulong)_mountedVolEntry.Blocks != _device.Info.Sectors / _multiplier                                       ||
           _mountedVolEntry.Files         < 0)
            return ErrorNumber.InvalidArgument;

        errno = _device.ReadSectors(_multiplier                                                          * 2,
                                    (uint)(_mountedVolEntry.LastBlock - _mountedVolEntry.FirstBlock - 2) * _multiplier,
                                    out _catalogBlocks);

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

        int offset = 26;

        _fileEntries = [];

        while(offset + 26 < _catalogBlocks.Length)
        {
            var entry = new PascalFileEntry
            {
                Filename         = new byte[16],
                FirstBlock       = BigEndianBitConverter.ToInt16(_catalogBlocks, offset + 0x00),
                LastBlock        = BigEndianBitConverter.ToInt16(_catalogBlocks, offset + 0x02),
                EntryType        = (PascalFileKind)BigEndianBitConverter.ToInt16(_catalogBlocks, offset + 0x04),
                LastBytes        = BigEndianBitConverter.ToInt16(_catalogBlocks, offset + 0x16),
                ModificationTime = BigEndianBitConverter.ToInt16(_catalogBlocks, offset + 0x18)
            };

            Array.Copy(_catalogBlocks, offset + 0x06, entry.Filename, 0, 16);

            if(entry.Filename[0] <= 15 && entry.Filename[0] > 0) _fileEntries.Add(entry);

            offset += 26;
        }

        errno = _device.ReadSectors(0, 2 * _multiplier, out _bootBlocks);

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

        Metadata = new FileSystem
        {
            Bootable    = !ArrayHelpers.ArrayIsNullOrEmpty(_bootBlocks),
            Clusters    = (ulong)_mountedVolEntry.Blocks,
            ClusterSize = _device.Info.SectorSize,
            Files       = (ulong)_mountedVolEntry.Files,
            Type        = FS_TYPE,
            VolumeName  = StringHandlers.PascalToString(_mountedVolEntry.VolumeName, _encoding)
        };

        _mounted = true;

        return ErrorNumber.NoError;
    }

    /// <inheritdoc />
    public ErrorNumber Unmount()
    {
        _mounted     = false;
        _fileEntries = null;

        return ErrorNumber.NoError;
    }

    /// <inheritdoc />
    public ErrorNumber StatFs(out FileSystemInfo stat)
    {
        stat = new FileSystemInfo
        {
            Blocks         = (ulong)_mountedVolEntry.Blocks,
            FilenameLength = 16,
            Files          = (ulong)_mountedVolEntry.Files,
            FreeBlocks     = 0,
            PluginId       = Id,
            Type           = FS_TYPE
        };

        stat.FreeBlocks = (ulong)(_mountedVolEntry.Blocks - (_mountedVolEntry.LastBlock - _mountedVolEntry.FirstBlock));

        foreach(PascalFileEntry entry in _fileEntries) stat.FreeBlocks -= (ulong)(entry.LastBlock - entry.FirstBlock);

        return ErrorNumber.NotImplemented;
    }

#endregion
}