// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : VMfs.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : VMware file system plugin.
//
// --[ Description ] ----------------------------------------------------------
//
//     Identifies the VMware 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.Diagnostics.CodeAnalysis;
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 VMware filesystem</summary>
    [SuppressMessage("ReSharper", "UnusedType.Local"), SuppressMessage("ReSharper", "IdentifierTypo"),
     SuppressMessage("ReSharper", "UnusedMember.Local")]
    public sealed class VMfs : IFilesystem
    {
        /// <summary>Identifier for VMfs</summary>
        const uint VMFS_MAGIC = 0xC001D00D;
        const uint VMFS_BASE = 0x00100000;

        /// <inheritdoc />
        public FileSystemType XmlFsType { get; private set; }
        /// <inheritdoc />
        public Encoding Encoding { get; private set; }
        /// <inheritdoc />
        public string Name => "VMware filesystem";
        /// <inheritdoc />
        public Guid Id => new("EE52BDB8-B49C-4122-A3DA-AD21CBE79843");
        /// <inheritdoc />
        public string Author => "Natalia Portillo";

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

            ulong vmfsSuperOff = VMFS_BASE / imagePlugin.Info.SectorSize;

            if(partition.Start + vmfsSuperOff > partition.End)
                return false;

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

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

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

            return magic == VMFS_MAGIC;
        }

        /// <inheritdoc />
        public void GetInformation(IMediaImage imagePlugin, Partition partition, out string information,
                                   Encoding encoding)
        {
            Encoding    = encoding ?? Encoding.UTF8;
            information = "";
            ulong       vmfsSuperOff = VMFS_BASE / imagePlugin.Info.SectorSize;
            ErrorNumber errno        = imagePlugin.ReadSector(partition.Start + vmfsSuperOff, out byte[] sector);

            if(errno != ErrorNumber.NoError)
                return;

            VolumeInfo volInfo = Marshal.ByteArrayToStructureLittleEndian<VolumeInfo>(sector);

            var sbInformation = new StringBuilder();

            sbInformation.AppendLine("VMware file system");

            uint ctimeSecs     = (uint)(volInfo.ctime / 1000000);
            uint ctimeNanoSecs = (uint)(volInfo.ctime % 1000000);
            uint mtimeSecs     = (uint)(volInfo.mtime / 1000000);
            uint mtimeNanoSecs = (uint)(volInfo.mtime % 1000000);

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

            sbInformation.AppendFormat("Volume name {0}", StringHandlers.CToString(volInfo.name, Encoding)).
                          AppendLine();

            sbInformation.AppendFormat("Volume size {0} bytes", volInfo.size * 256).AppendLine();
            sbInformation.AppendFormat("Volume UUID {0}", volInfo.uuid).AppendLine();

            sbInformation.
                AppendFormat("Volume created on {0}", DateHandlers.UnixUnsignedToDateTime(ctimeSecs, ctimeNanoSecs)).
                AppendLine();

            sbInformation.AppendFormat("Volume last modified on {0}",
                                       DateHandlers.UnixUnsignedToDateTime(mtimeSecs, mtimeNanoSecs)).AppendLine();

            information = sbInformation.ToString();

            XmlFsType = new FileSystemType
            {
                Type                      = "VMware file system",
                CreationDate              = DateHandlers.UnixUnsignedToDateTime(ctimeSecs, ctimeNanoSecs),
                CreationDateSpecified     = true,
                ModificationDate          = DateHandlers.UnixUnsignedToDateTime(mtimeSecs, mtimeNanoSecs),
                ModificationDateSpecified = true,
                Clusters                  = volInfo.size * 256 / imagePlugin.Info.SectorSize,
                ClusterSize               = imagePlugin.Info.SectorSize,
                VolumeSerial              = volInfo.uuid.ToString()
            };
        }

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

        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        readonly struct VolumeInfo
        {
            public readonly uint magic;
            public readonly uint version;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 6)]
            public readonly byte[] unknown1;
            public readonly byte lun;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
            public readonly byte[] unknown2;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 28)]
            public readonly byte[] name;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 49)]
            public readonly byte[] unknown3;
            public readonly uint size;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 31)]
            public readonly byte[] unknown4;
            public readonly Guid  uuid;
            public readonly ulong ctime;
            public readonly ulong mtime;
        }
    }
}