// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : Write.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Writes QEMU Copy-On-Write 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 © 2011-2019 Natalia Portillo
// ****************************************************************************/

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using DiscImageChef.CommonTypes;
using DiscImageChef.CommonTypes.Enums;
using DiscImageChef.CommonTypes.Structs;
using Schemas;
using Marshal = DiscImageChef.Helpers.Marshal;

namespace DiscImageChef.DiscImages
{
    public partial class Qcow
    {
        public bool Create(string path, MediaType mediaType, Dictionary<string, string> options, ulong sectors,
                           uint   sectorSize)
        {
            if(sectorSize != 512)
            {
                ErrorMessage = "Unsupported sector size";
                return false;
            }

            if(!SupportedMediaTypes.Contains(mediaType))
            {
                ErrorMessage = $"Unsupport media format {mediaType}";
                return false;
            }

            // TODO: Correct this calculation
            if(sectors * sectorSize / 65536 > uint.MaxValue)
            {
                ErrorMessage = "Too many sectors for selected cluster size";
                return false;
            }

            imageInfo = new ImageInfo {MediaType = mediaType, SectorSize = sectorSize, Sectors = sectors};

            try { writingStream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None); }
            catch(IOException e)
            {
                ErrorMessage = $"Could not create new image file, exception {e.Message}";
                return false;
            }

            qHdr = new QCowHeader
            {
                magic           = QCOW_MAGIC,
                version         = QCOW_VERSION,
                size            = sectors * sectorSize,
                cluster_bits    = 12,
                l2_bits         = 9,
                l1_table_offset = (ulong)Marshal.SizeOf<QCowHeader>()
            };

            int shift = qHdr.cluster_bits + qHdr.l2_bits;
            clusterSize    = 1 << qHdr.cluster_bits;
            clusterSectors = 1 << (qHdr.cluster_bits - 9);
            l1Size         = (uint)((qHdr.size + (ulong)(1 << shift) - 1) >> shift);
            l2Size         = 1 << qHdr.l2_bits;

            l1Table = new ulong[l1Size];

            l1Mask = 0;
            int c = 0;
            l1Shift = qHdr.l2_bits + qHdr.cluster_bits;

            for(int i = 0; i < 64; i++)
            {
                l1Mask <<= 1;

                if(c >= 64 - l1Shift) continue;

                l1Mask += 1;
                c++;
            }

            l2Mask = 0;
            for(int i = 0; i < qHdr.l2_bits; i++) l2Mask = (l2Mask << 1) + 1;

            l2Mask <<= qHdr.cluster_bits;

            sectorMask = 0;
            for(int i = 0; i < qHdr.cluster_bits; i++) sectorMask = (sectorMask << 1) + 1;

            byte[] empty = new byte[qHdr.l1_table_offset + l1Size * 8];
            writingStream.Write(empty, 0, empty.Length);

            IsWriting    = true;
            ErrorMessage = null;
            return true;
        }

        public bool WriteMediaTag(byte[] data, MediaTagType tag)
        {
            ErrorMessage = "Writing media tags is not supported.";
            return false;
        }

        public bool WriteSector(byte[] data, ulong sectorAddress)
        {
            if(!IsWriting)
            {
                ErrorMessage = "Tried to write on a non-writable image";
                return false;
            }

            if(data.Length != imageInfo.SectorSize)
            {
                ErrorMessage = "Incorrect data size";
                return false;
            }

            if(sectorAddress >= imageInfo.Sectors)
            {
                ErrorMessage = "Tried to write past image size";
                return false;
            }

            // Ignore empty sectors
            if(ArrayHelpers.ArrayIsNullOrEmpty(data)) return true;

            ulong byteAddress = sectorAddress * 512;

            ulong l1Off = (byteAddress & l1Mask) >> l1Shift;

            if((long)l1Off >= l1Table.LongLength)
                throw new ArgumentOutOfRangeException(nameof(l1Off),
                                                      $"Trying to write past L1 table, position {l1Off} of a max {l1Table.LongLength}");

            if(l1Table[l1Off] == 0)
            {
                writingStream.Seek(0, SeekOrigin.End);
                l1Table[l1Off] = (ulong)writingStream.Position;
                byte[] l2TableB = new byte[l2Size * 8];
                writingStream.Seek(0, SeekOrigin.End);
                writingStream.Write(l2TableB, 0, l2TableB.Length);
            }

            writingStream.Position = (long)l1Table[l1Off];

            ulong l2Off = (byteAddress & l2Mask) >> qHdr.cluster_bits;

            writingStream.Seek((long)(l1Table[l1Off] + l2Off * 8), SeekOrigin.Begin);

            BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;

            byte[] entry = new byte[8];
            writingStream.Read(entry, 0, 8);
            ulong offset = BigEndianBitConverter.ToUInt64(entry, 0);

            if(offset == 0)
            {
                offset = (ulong)writingStream.Length;
                byte[] cluster = new byte[clusterSize];
                entry = BigEndianBitConverter.GetBytes(offset);
                writingStream.Seek((long)(l1Table[l1Off] + l2Off * 8), SeekOrigin.Begin);
                writingStream.Write(entry, 0, 8);
                writingStream.Seek(0, SeekOrigin.End);
                writingStream.Write(cluster, 0, cluster.Length);
            }

            writingStream.Seek((long)(offset + (byteAddress & sectorMask)), SeekOrigin.Begin);
            writingStream.Write(data, 0, data.Length);

            ErrorMessage = "";
            return true;
        }

        // TODO: This can be optimized
        public bool WriteSectors(byte[] data, ulong sectorAddress, uint length)
        {
            if(!IsWriting)
            {
                ErrorMessage = "Tried to write on a non-writable image";
                return false;
            }

            if(data.Length % imageInfo.SectorSize != 0)
            {
                ErrorMessage = "Incorrect data size";
                return false;
            }

            if(sectorAddress + length > imageInfo.Sectors)
            {
                ErrorMessage = "Tried to write past image size";
                return false;
            }

            // Ignore empty sectors
            if(ArrayHelpers.ArrayIsNullOrEmpty(data)) return true;

            for(uint i = 0; i < length; i++)
            {
                byte[] tmp = new byte[imageInfo.SectorSize];
                Array.Copy(data, i * imageInfo.SectorSize, tmp, 0, imageInfo.SectorSize);
                if(!WriteSector(tmp, sectorAddress + i)) return false;
            }

            ErrorMessage = "";
            return true;
        }

        public bool WriteSectorLong(byte[] data, ulong sectorAddress)
        {
            ErrorMessage = "Writing sectors with tags is not supported.";
            return false;
        }

        public bool WriteSectorsLong(byte[] data, ulong sectorAddress, uint length)
        {
            ErrorMessage = "Writing sectors with tags is not supported.";
            return false;
        }

        public bool Close()
        {
            if(!IsWriting)
            {
                ErrorMessage = "Image is not opened for writing";
                return false;
            }

            qHdr.mtime = (uint)(DateTime.Now - new DateTime(1970, 1, 1, 0, 0, 0)).TotalSeconds;

            BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
            writingStream.Seek(0, SeekOrigin.Begin);
            writingStream.Write(BigEndianBitConverter.GetBytes(qHdr.magic),               0, 4);
            writingStream.Write(BigEndianBitConverter.GetBytes(qHdr.version),             0, 4);
            writingStream.Write(BigEndianBitConverter.GetBytes(qHdr.backing_file_offset), 0, 8);
            writingStream.Write(BigEndianBitConverter.GetBytes(qHdr.backing_file_size),   0, 4);
            writingStream.Write(BigEndianBitConverter.GetBytes(qHdr.mtime),               0, 4);
            writingStream.Write(BigEndianBitConverter.GetBytes(qHdr.size),                0, 8);
            writingStream.WriteByte(qHdr.cluster_bits);
            writingStream.WriteByte(qHdr.l2_bits);
            writingStream.Write(BigEndianBitConverter.GetBytes(qHdr.padding),         0, 2);
            writingStream.Write(BigEndianBitConverter.GetBytes(qHdr.crypt_method),    0, 4);
            writingStream.Write(BigEndianBitConverter.GetBytes(qHdr.l1_table_offset), 0, 8);

            writingStream.Seek((long)qHdr.l1_table_offset, SeekOrigin.Begin);
            for(long i = 0; i < l1Table.LongLength; i++) l1Table[i] = Swapping.Swap(l1Table[i]);
            byte[] l1TableB =
                MemoryMarshal.Cast<ulong, byte>(l1Table).ToArray();
            writingStream.Write(l1TableB, 0, l1TableB.Length);

            writingStream.Flush();
            writingStream.Close();

            IsWriting    = false;
            ErrorMessage = "";
            return true;
        }

        public bool SetMetadata(ImageInfo metadata) => true;

        public bool SetGeometry(uint cylinders, uint heads, uint sectorsPerTrack) => true;

        public bool WriteSectorTag(byte[] data, ulong sectorAddress, SectorTagType tag)
        {
            ErrorMessage = "Writing sectors with tags is not supported.";
            return false;
        }

        public bool WriteSectorsTag(byte[] data, ulong sectorAddress, uint length, SectorTagType tag)
        {
            ErrorMessage = "Writing sectors with tags is not supported.";
            return false;
        }

        public bool SetDumpHardware(List<DumpHardwareType> dumpHardware) => false;

        public bool SetCicmMetadata(CICMMetadataType metadata) => false;
    }
}