// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Read.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Reads Parallels 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 © 2011-2020 Natalia Portillo
// ****************************************************************************/

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Aaru.CommonTypes;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.Console;
using Aaru.Helpers;

namespace Aaru.DiscImages
{
    public sealed partial class Parallels
    {
        public bool Open(IFilter imageFilter)
        {
            Stream stream = imageFilter.GetDataForkStream();
            stream.Seek(0, SeekOrigin.Begin);

            if(stream.Length < 512)
                return false;

            byte[] pHdrB = new byte[Marshal.SizeOf<Header>()];
            stream.Read(pHdrB, 0, Marshal.SizeOf<Header>());
            _pHdr = Marshal.ByteArrayToStructureLittleEndian<Header>(pHdrB);

            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.magic = {0}", StringHandlers.CToString(_pHdr.magic));
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.version = {0}", _pHdr.version);
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.heads = {0}", _pHdr.heads);
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.cylinders = {0}", _pHdr.cylinders);
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.cluster_size = {0}", _pHdr.cluster_size);
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.bat_entries = {0}", _pHdr.bat_entries);
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.sectors = {0}", _pHdr.sectors);
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.in_use = 0x{0:X8}", _pHdr.in_use);
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.data_off = {0}", _pHdr.data_off);
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.flags = {0}", _pHdr.flags);
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.ext_off = {0}", _pHdr.ext_off);

            _extended = _extMagic.SequenceEqual(_pHdr.magic);
            AaruConsole.DebugWriteLine("Parallels plugin", "pHdr.extended = {0}", _extended);

            AaruConsole.DebugWriteLine("Parallels plugin", "Reading BAT");
            _bat = new uint[_pHdr.bat_entries];
            byte[] batB = new byte[_pHdr.bat_entries * 4];
            stream.Read(batB, 0, batB.Length);

            for(int i = 0; i < _bat.Length; i++)
                _bat[i] = BitConverter.ToUInt32(batB, i * 4);

            _clusterBytes = _pHdr.cluster_size * 512;

            if(_pHdr.data_off > 0)
                _dataOffset = _pHdr.data_off * 512;
            else
                _dataOffset = ((stream.Position / _clusterBytes) + (stream.Position % _clusterBytes)) * _clusterBytes;

            _sectorCache = new Dictionary<ulong, byte[]>();

            _empty = (_pHdr.flags & PARALLELS_EMPTY) == PARALLELS_EMPTY;

            _imageInfo.CreationTime         = imageFilter.GetCreationTime();
            _imageInfo.LastModificationTime = imageFilter.GetLastWriteTime();
            _imageInfo.MediaTitle           = Path.GetFileNameWithoutExtension(imageFilter.GetFilename());
            _imageInfo.Sectors              = _pHdr.sectors;
            _imageInfo.SectorSize           = 512;
            _imageInfo.XmlMediaType         = XmlMediaType.BlockMedia;
            _imageInfo.MediaType            = MediaType.GENERIC_HDD;
            _imageInfo.ImageSize            = _pHdr.sectors * 512;
            _imageInfo.Cylinders            = _pHdr.cylinders;
            _imageInfo.Heads                = _pHdr.heads;
            _imageInfo.SectorsPerTrack      = (uint)(_imageInfo.Sectors / _imageInfo.Cylinders / _imageInfo.Heads);
            _imageStream                    = stream;

            return true;
        }

        public byte[] ReadSector(ulong sectorAddress)
        {
            if(sectorAddress > _imageInfo.Sectors - 1)
                throw new ArgumentOutOfRangeException(nameof(sectorAddress),
                                                      $"Sector address {sectorAddress} not found");

            if(_empty)
                return new byte[512];

            if(_sectorCache.TryGetValue(sectorAddress, out byte[] sector))
                return sector;

            ulong index  = sectorAddress / _pHdr.cluster_size;
            ulong secOff = sectorAddress % _pHdr.cluster_size;

            uint  batOff = _bat[index];
            ulong imageOff;

            if(batOff == 0)
                return new byte[512];

            if(_extended)
                imageOff = batOff * _clusterBytes;
            else
                imageOff = batOff * 512;

            byte[] cluster = new byte[_clusterBytes];
            _imageStream.Seek((long)imageOff, SeekOrigin.Begin);
            _imageStream.Read(cluster, 0, (int)_clusterBytes);
            sector = new byte[512];
            Array.Copy(cluster, (int)(secOff * 512), sector, 0, 512);

            if(_sectorCache.Count > MAX_CACHED_SECTORS)
                _sectorCache.Clear();

            _sectorCache.Add(sectorAddress, sector);

            return sector;
        }

        public byte[] ReadSectors(ulong sectorAddress, uint length)
        {
            if(sectorAddress > _imageInfo.Sectors - 1)
                throw new ArgumentOutOfRangeException(nameof(sectorAddress),
                                                      $"Sector address {sectorAddress} not found");

            if(sectorAddress + length > _imageInfo.Sectors)
                throw new ArgumentOutOfRangeException(nameof(length), "Requested more sectors than available");

            if(_empty)
                return new byte[512 * length];

            var ms = new MemoryStream();

            for(uint i = 0; i < length; i++)
            {
                byte[] sector = ReadSector(sectorAddress + i);
                ms.Write(sector, 0, sector.Length);
            }

            return ms.ToArray();
        }
    }
}