// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : SFS.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : SmartFileSystem plugin.
//
// --[ Description ] ----------------------------------------------------------
//
//     Identifies the SmartFileSystem and shows information.
//
// --[ 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.Runtime.InteropServices;
using System.Text;
using Aaru.CommonTypes;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.Helpers;
using Schemas;
using Marshal = Aaru.Helpers.Marshal;

namespace Aaru.Filesystems
{
    /// <inheritdoc />
    /// <summary>Implements detection of the Smart File System</summary>
    public sealed class SFS : IFilesystem
    {
        /// <summary>Identifier for SFS v1</summary>
        const uint SFS_MAGIC = 0x53465300;
        /// <summary>Identifier for SFS v2</summary>
        const uint SFS2_MAGIC = 0x53465302;

        /// <inheritdoc />
        public FileSystemType XmlFsType { get; private set; }
        /// <inheritdoc />
        public Encoding Encoding { get; private set; }
        /// <inheritdoc />
        public string Name => "SmartFileSystem";
        /// <inheritdoc />
        public Guid Id => new("26550C19-3671-4A2D-BC2F-F20CEB7F48DC");
        /// <inheritdoc />
        public string Author => "Natalia Portillo";

        /// <inheritdoc />
        public bool Identify(IMediaImage imagePlugin, Partition partition)
        {
            if(partition.Start >= partition.End)
                return false;

            ErrorNumber errno = imagePlugin.ReadSector(partition.Start, out byte[] sector);

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

            uint magic = BigEndianBitConverter.ToUInt32(sector, 0x00);

            return magic == SFS_MAGIC || magic == SFS2_MAGIC;
        }

        /// <inheritdoc />
        public void GetInformation(IMediaImage imagePlugin, Partition partition, out string information,
                                   Encoding encoding)
        {
            information = "";
            Encoding    = encoding ?? Encoding.GetEncoding("iso-8859-1");
            ErrorNumber errno = imagePlugin.ReadSector(partition.Start, out byte[] rootBlockSector);

            if(errno != ErrorNumber.NoError)
                return;

            RootBlock rootBlock = Marshal.ByteArrayToStructureBigEndian<RootBlock>(rootBlockSector);

            var sbInformation = new StringBuilder();

            sbInformation.AppendLine("SmartFileSystem");

            sbInformation.AppendFormat("Volume version {0}", rootBlock.version).AppendLine();

            sbInformation.AppendFormat("Volume starts on device byte {0} and ends on byte {1}", rootBlock.firstbyte,
                                       rootBlock.lastbyte).AppendLine();

            sbInformation.
                AppendFormat("Volume has {0} blocks of {1} bytes each", rootBlock.totalblocks, rootBlock.blocksize).
                AppendLine();

            sbInformation.AppendFormat("Volume created on {0}",
                                       DateHandlers.UnixUnsignedToDateTime(rootBlock.datecreated).AddYears(8)).
                          AppendLine();

            sbInformation.AppendFormat("Bitmap starts in block {0}", rootBlock.bitmapbase).AppendLine();

            sbInformation.AppendFormat("Admin space container starts in block {0}", rootBlock.adminspacecontainer).
                          AppendLine();

            sbInformation.AppendFormat("Root object container starts in block {0}", rootBlock.rootobjectcontainer).
                          AppendLine();

            sbInformation.
                AppendFormat("Root node of the extent B-tree resides in block {0}", rootBlock.extentbnoderoot).
                AppendLine();

            sbInformation.AppendFormat("Root node of the object B-tree resides in block {0}", rootBlock.objectnoderoot).
                          AppendLine();

            if(rootBlock.bits.HasFlag(Flags.CaseSensitive))
                sbInformation.AppendLine("Volume is case sensitive");

            if(rootBlock.bits.HasFlag(Flags.RecycledFolder))
                sbInformation.AppendLine("Volume moves deleted files to a recycled folder");

            information = sbInformation.ToString();

            XmlFsType = new FileSystemType
            {
                CreationDate          = DateHandlers.UnixUnsignedToDateTime(rootBlock.datecreated).AddYears(8),
                CreationDateSpecified = true,
                Clusters              = rootBlock.totalblocks,
                ClusterSize           = rootBlock.blocksize,
                Type                  = "SmartFileSystem"
            };
        }

        [Flags]
        enum Flags : byte
        {
            RecycledFolder = 64, CaseSensitive = 128
        }

        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        readonly struct RootBlock
        {
            public readonly uint   blockId;
            public readonly uint   blockChecksum;
            public readonly uint   blockSelfPointer;
            public readonly ushort version;
            public readonly ushort sequence;
            public readonly uint   datecreated;
            public readonly Flags  bits;
            public readonly byte   padding1;
            public readonly ushort padding2;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)]
            public readonly uint[] reserved1;
            public readonly ulong firstbyte;
            public readonly ulong lastbyte;
            public readonly uint  totalblocks;
            public readonly uint  blocksize;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)]
            public readonly uint[] reserved2;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
            public readonly uint[] reserved3;
            public readonly uint bitmapbase;
            public readonly uint adminspacecontainer;
            public readonly uint rootobjectcontainer;
            public readonly uint extentbnoderoot;
            public readonly uint objectnoderoot;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
            public readonly uint[] reserved4;
        }
    }
}