// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : NTFS.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Microsoft NT File System plugin.
//
// --[ Description ] ----------------------------------------------------------
//
//     Identifies the Microsoft NT File System 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.Checksums;
using Aaru.CommonTypes;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.Helpers;
using Schemas;
using Marshal = Aaru.Helpers.Marshal;

namespace Aaru.Filesystems
{
    // Information from Inside Windows NT
    /// <inheritdoc />
    /// <summary>Implements detection of the New Technology File System (NTFS)</summary>
    public sealed class NTFS : IFilesystem
    {
        /// <inheritdoc />
        public FileSystemType XmlFsType { get; private set; }
        /// <inheritdoc />
        public Encoding Encoding { get; private set; }
        /// <inheritdoc />
        public string Name => "New Technology File System (NTFS)";
        /// <inheritdoc />
        public Guid Id => new("33513B2C-1e6d-4d21-a660-0bbc789c3871");
        /// <inheritdoc />
        public string Author => "Natalia Portillo";

        /// <inheritdoc />
        public bool Identify(IMediaImage imagePlugin, Partition partition)
        {
            if(2 + partition.Start >= partition.End)
                return false;

            byte[] eigthBytes = new byte[8];

            ErrorNumber errno = imagePlugin.ReadSector(0 + partition.Start, out byte[] ntfsBpb);

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

            Array.Copy(ntfsBpb, 0x003, eigthBytes, 0, 8);
            string oemName = StringHandlers.CToString(eigthBytes);

            if(oemName != "NTFS    ")
                return false;

            byte   fatsNo    = ntfsBpb[0x010];
            ushort spFat     = BitConverter.ToUInt16(ntfsBpb, 0x016);
            ushort signature = BitConverter.ToUInt16(ntfsBpb, 0x1FE);

            if(fatsNo != 0)
                return false;

            if(spFat != 0)
                return false;

            return signature == 0xAA55;
        }

        /// <inheritdoc />
        public void GetInformation(IMediaImage imagePlugin, Partition partition, out string information,
                                   Encoding encoding)
        {
            Encoding    = Encoding.Unicode;
            information = "";

            var sb = new StringBuilder();

            ErrorNumber errno = imagePlugin.ReadSector(0 + partition.Start, out byte[] ntfsBpb);

            if(errno != ErrorNumber.NoError)
                return;

            BiosParameterBlock ntfsBb = Marshal.ByteArrayToStructureLittleEndian<BiosParameterBlock>(ntfsBpb);

            sb.AppendFormat("{0} bytes per sector", ntfsBb.bps).AppendLine();
            sb.AppendFormat("{0} sectors per cluster ({1} bytes)", ntfsBb.spc, ntfsBb.spc * ntfsBb.bps).AppendLine();

            //          sb.AppendFormat("{0} reserved sectors", ntfs_bb.rsectors).AppendLine();
            //          sb.AppendFormat("{0} FATs", ntfs_bb.fats_no).AppendLine();
            //          sb.AppendFormat("{0} entries in the root folder", ntfs_bb.root_ent).AppendLine();
            //          sb.AppendFormat("{0} sectors on volume (small)", ntfs_bb.sml_sectors).AppendLine();
            sb.AppendFormat("Media descriptor: 0x{0:X2}", ntfsBb.media).AppendLine();

            //          sb.AppendFormat("{0} sectors per FAT", ntfs_bb.spfat).AppendLine();
            sb.AppendFormat("{0} sectors per track", ntfsBb.sptrk).AppendLine();
            sb.AppendFormat("{0} heads", ntfsBb.heads).AppendLine();
            sb.AppendFormat("{0} hidden sectors before filesystem", ntfsBb.hsectors).AppendLine();

            //          sb.AppendFormat("{0} sectors on volume (big)", ntfs_bb.big_sectors).AppendLine();
            sb.AppendFormat("BIOS drive number: 0x{0:X2}", ntfsBb.drive_no).AppendLine();

            //          sb.AppendFormat("NT flags: 0x{0:X2}", ntfs_bb.nt_flags).AppendLine();
            //          sb.AppendFormat("Signature 1: 0x{0:X2}", ntfs_bb.signature1).AppendLine();
            sb.AppendFormat("{0} sectors on volume ({1} bytes)", ntfsBb.sectors, ntfsBb.sectors * ntfsBb.bps).
               AppendLine();

            sb.AppendFormat("Cluster where $MFT starts: {0}", ntfsBb.mft_lsn).AppendLine();
            sb.AppendFormat("Cluster where $MFTMirr starts: {0}", ntfsBb.mftmirror_lsn).AppendLine();

            if(ntfsBb.mft_rc_clusters > 0)
                sb.AppendFormat("{0} clusters per MFT record ({1} bytes)", ntfsBb.mft_rc_clusters,
                                ntfsBb.mft_rc_clusters * ntfsBb.bps * ntfsBb.spc).AppendLine();
            else
                sb.AppendFormat("{0} bytes per MFT record", 1 << -ntfsBb.mft_rc_clusters).AppendLine();

            if(ntfsBb.index_blk_cts > 0)
                sb.AppendFormat("{0} clusters per Index block ({1} bytes)", ntfsBb.index_blk_cts,
                                ntfsBb.index_blk_cts * ntfsBb.bps * ntfsBb.spc).AppendLine();
            else
                sb.AppendFormat("{0} bytes per Index block", 1 << -ntfsBb.index_blk_cts).AppendLine();

            sb.AppendFormat("Volume serial number: {0:X16}", ntfsBb.serial_no).AppendLine();

            //          sb.AppendFormat("Signature 2: 0x{0:X4}", ntfs_bb.signature2).AppendLine();

            XmlFsType = new FileSystemType();

            if(ntfsBb.jump[0]    == 0xEB &&
               ntfsBb.jump[1]    > 0x4E  &&
               ntfsBb.jump[1]    < 0x80  &&
               ntfsBb.signature2 == 0xAA55)
            {
                XmlFsType.Bootable = true;
                string bootChk = Sha1Context.Data(ntfsBb.boot_code, out _);
                sb.AppendLine("Volume is bootable");
                sb.AppendFormat("Boot code's SHA1: {0}", bootChk).AppendLine();
            }

            XmlFsType.ClusterSize  = (uint)(ntfsBb.spc      * ntfsBb.bps);
            XmlFsType.Clusters     = (ulong)(ntfsBb.sectors / ntfsBb.spc);
            XmlFsType.VolumeSerial = $"{ntfsBb.serial_no:X16}";
            XmlFsType.Type         = "NTFS";

            information = sb.ToString();
        }

        /// <summary>NTFS $BOOT</summary>
        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        readonly struct BiosParameterBlock
        {
            // Start of BIOS Parameter Block
            /// <summary>0x000, Jump to boot code</summary>
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
            public readonly byte[] jump;
            /// <summary>0x003, OEM Name, 8 bytes, space-padded, must be "NTFS    "</summary>
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
            public readonly byte[] oem_name;
            /// <summary>0x00B, Bytes per sector</summary>
            public readonly ushort bps;
            /// <summary>0x00D, Sectors per cluster</summary>
            public readonly byte spc;
            /// <summary>0x00E, Reserved sectors, seems 0</summary>
            public readonly ushort rsectors;
            /// <summary>0x010, Number of FATs... obviously, 0</summary>
            public readonly byte fats_no;
            /// <summary>0x011, Number of entries on root directory... 0</summary>
            public readonly ushort root_ent;
            /// <summary>0x013, Sectors in volume... 0</summary>
            public readonly ushort sml_sectors;
            /// <summary>0x015, Media descriptor</summary>
            public readonly byte media;
            /// <summary>0x016, Sectors per FAT... 0</summary>
            public readonly ushort spfat;
            /// <summary>0x018, Sectors per track, required to boot</summary>
            public readonly ushort sptrk;
            /// <summary>0x01A, Heads... required to boot</summary>
            public readonly ushort heads;
            /// <summary>0x01C, Hidden sectors before BPB</summary>
            public readonly uint hsectors;
            /// <summary>0x020, Sectors in volume if &gt; 65535... 0</summary>
            public readonly uint big_sectors;
            /// <summary>0x024, Drive number</summary>
            public readonly byte drive_no;
            /// <summary>0x025, 0</summary>
            public readonly byte nt_flags;
            /// <summary>0x026, EPB signature, 0x80</summary>
            public readonly byte signature1;
            /// <summary>0x027, Alignment</summary>
            public readonly byte dummy;

            // End of BIOS Parameter Block

            // Start of NTFS real superblock
            /// <summary>0x028, Sectors on volume</summary>
            public readonly long sectors;
            /// <summary>0x030, LSN of $MFT</summary>
            public readonly long mft_lsn;
            /// <summary>0x038, LSN of $MFTMirror</summary>
            public readonly long mftmirror_lsn;
            /// <summary>0x040, Clusters per MFT record</summary>
            public readonly sbyte mft_rc_clusters;
            /// <summary>0x041, Alignment</summary>
            public readonly byte dummy2;
            /// <summary>0x042, Alignment</summary>
            public readonly ushort dummy3;
            /// <summary>0x044, Clusters per index block</summary>
            public readonly sbyte index_blk_cts;
            /// <summary>0x045, Alignment</summary>
            public readonly byte dummy4;
            /// <summary>0x046, Alignment</summary>
            public readonly ushort dummy5;
            /// <summary>0x048, Volume serial number</summary>
            public readonly ulong serial_no;
            /// <summary>Boot code.</summary>
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 430)]
            public readonly byte[] boot_code;
            /// <summary>0x1FE, 0xAA55</summary>
            public readonly ushort signature2;
        }
    }
}