// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : SaveDskF.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disc image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Manages IBM SaveDskF 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 © 2011-2017 Natalia Portillo
// ****************************************************************************/

using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
using DiscImageChef.CommonTypes;
using DiscImageChef.Console;
using DiscImageChef.Filters;

namespace DiscImageChef.ImagePlugins
{
	public class SaveDskF : ImagePlugin
	{
		#region Internal Structures
		[StructLayout(LayoutKind.Sequential, Pack = 1)]
		struct SaveDskFHeader
		{
			/// <summary>0x00 magic number</summary>
			public ushort magic;
			/// <summary>0x02 media type from FAT</summary>
			public ushort mediaType;
			/// <summary>0x04 bytes per sector</summary>
			public ushort sectorSize;
			/// <summary>0x06 sectors per cluster - 1</summary>
			public byte clusterMask;
			/// <summary>0x07 log2(cluster / sector)</summary>
			public byte clusterShift;
			/// <summary>0x08 reserved sectors</summary>
			public ushort reservedSectors;
			/// <summary>0x0A copies of FAT</summary>
			public byte fatCopies;
			/// <summary>0x0B entries in root directory</summary>
			public ushort rootEntries;
			/// <summary>0x0D first cluster</summary>
			public ushort firstCluster;
			/// <summary>0x0F clusters present in image</summary>
			public ushort clustersCopied;
			/// <summary>0x11 sectors per FAT</summary>
			public byte sectorsPerFat;
			/// <summary>0x12 sector number of root directory</summary>
			public ushort rootDirectorySector;
			/// <summary>0x14 sum of all image bytes</summary>
			public uint checksum;
			/// <summary>0x18 cylinders</summary>
			public ushort cylinders;
			/// <summary>0x1A heads</summary>
			public ushort heads;
			/// <summary>0x1C sectors per track</summary>
			public ushort sectorsPerTrack;
			/// <summary>0x1E always zero</summary>
			public uint padding;
			/// <summary>0x22 sectors present in image</summary>
			public ushort sectorsCopied;
			/// <summary>0x24 offset to comment</summary>
			public ushort commentOffset;
			/// <summary>0x26 offset to data</summary>
			public ushort dataOffset;
		}
		#endregion Internal Structures

		#region Internal Constants
		const ushort SDF_MAGIC_OLD = 0x58AA;
		const ushort SDF_MAGIC = 0x59AA;
		const ushort SDF_MAGIC_COMPRESSED = 0x5AAA;
		#endregion Internal Constants

		#region Internal variables
		SaveDskFHeader header;
		long sectors;
		uint calculatedChk;
		byte[] decodedDisk;
		#endregion Internal variables

		public SaveDskF()
		{
			Name = "IBM SaveDskF";
			PluginUUID = new Guid("288CE058-1A51-4034-8C45-5A256CAE1461");
			ImageInfo = new ImageInfo()
			{
				readableSectorTags = new List<SectorTagType>(),
				readableMediaTags = new List<MediaTagType>(),
				imageHasPartitions = false,
				imageHasSessions = false,
				imageVersion = null,
				imageApplication = null,
				imageApplicationVersion = null,
				imageCreator = null,
				imageComments = null,
				mediaManufacturer = null,
				mediaModel = null,
				mediaSerialNumber = null,
				mediaBarcode = null,
				mediaPartNumber = null,
				mediaSequence = 0,
				lastMediaSequence = 0,
				driveManufacturer = null,
				driveModel = null,
				driveSerialNumber = null,
				driveFirmwareRevision = null
			};
		}

		#region Public methods
		public override bool IdentifyImage(Filter imageFilter)
		{
			Stream stream = imageFilter.GetDataForkStream();
			stream.Seek(0, SeekOrigin.Begin);
			if(stream.Length < 41)
				return false;

			byte[] hdr = new byte[40];
			stream.Read(hdr, 0, 40);

			header = new SaveDskFHeader();
			IntPtr hdrPtr = Marshal.AllocHGlobal(40);
			Marshal.Copy(hdr, 0, hdrPtr, 40);
			header = (SaveDskFHeader)Marshal.PtrToStructure(hdrPtr, typeof(SaveDskFHeader));
			Marshal.FreeHGlobal(hdrPtr);

			return (header.magic == SDF_MAGIC || header.magic == SDF_MAGIC_COMPRESSED || header.magic == SDF_MAGIC_OLD) &&
				header.fatCopies <= 2 && header.padding == 0 && header.commentOffset < stream.Length && header.dataOffset < stream.Length;
		}

		public override bool OpenImage(Filter imageFilter)
		{
			Stream stream = imageFilter.GetDataForkStream();
			stream.Seek(0, SeekOrigin.Begin);

			byte[] hdr = new byte[40];
			byte[] cmt;

			stream.Read(hdr, 0, 40);
			header = new SaveDskFHeader();
			IntPtr hdrPtr = Marshal.AllocHGlobal(40);
			Marshal.Copy(hdr, 0, hdrPtr, 40);
			header = (SaveDskFHeader)Marshal.PtrToStructure(hdrPtr, typeof(SaveDskFHeader));
			Marshal.FreeHGlobal(hdrPtr);

			DicConsole.DebugWriteLine("SaveDskF plugin", "header.magic = 0x{0:X4}", header.magic);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.mediaType = 0x{0:X2}", header.mediaType);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.sectorSize = {0}", header.sectorSize);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.clusterMask = {0}", header.clusterMask);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.clusterShift = {0}", header.clusterShift);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.reservedSectors = {0}", header.reservedSectors);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.fatCopies = {0}", header.fatCopies);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.rootEntries = {0}", header.rootEntries);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.firstCluster = {0}", header.firstCluster);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.clustersCopied = {0}", header.clustersCopied);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.sectorsPerFat = {0}", header.sectorsPerFat);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.checksum = 0x{0:X8}", header.checksum);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.cylinders = {0}", header.cylinders);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.heads = {0}", header.heads);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.sectorsPerTrack = {0}", header.sectorsPerTrack);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.padding = {0}", header.padding);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.sectorsCopied = {0}", header.sectorsCopied);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.commentOffset = {0}", header.commentOffset);
			DicConsole.DebugWriteLine("SaveDskF plugin", "header.dataOffset = {0}", header.dataOffset);

			if(header.dataOffset == 0 && header.magic == SDF_MAGIC_OLD)
				header.dataOffset = 512;

			cmt = new byte[header.dataOffset - header.commentOffset];
			stream.Seek(header.commentOffset, SeekOrigin.Begin);
			stream.Read(cmt, 0, cmt.Length);
			if(cmt.Length > 1)
				ImageInfo.imageComments = StringHandlers.CToString(cmt, Encoding.GetEncoding("ibm437"));

			calculatedChk = 0;
			stream.Seek(0, SeekOrigin.Begin);

			int b = 0;
			do
			{
				b = stream.ReadByte();
				if(b >= 0)
					calculatedChk += (uint)b;
			}
			while(b >= 0);

			// In case there is omitted data
			sectors = (header.sectorsPerTrack) * header.heads * header.cylinders;

			DicConsole.DebugWriteLine("SaveDskF plugin", "Calculated checksum = 0x{0:X8}, {1}", calculatedChk, calculatedChk == header.checksum);

			ImageInfo.imageApplication = "SaveDskF";
			ImageInfo.imageCreationTime = imageFilter.GetCreationTime();
			ImageInfo.imageLastModificationTime = imageFilter.GetLastWriteTime();
			ImageInfo.imageName = imageFilter.GetFilename();
			ImageInfo.imageSize = (ulong)(stream.Length - header.dataOffset);
			ImageInfo.sectors = (ulong)(header.sectorsPerTrack * header.heads * header.cylinders);
			ImageInfo.sectorSize = header.sectorSize;

			ImageInfo.mediaType = MediaType.Unknown;
			switch(header.cylinders)
			{
				case 40:
					switch(header.heads)
					{
						case 1:
							switch(header.sectorsPerTrack)
							{
								case 8:
									ImageInfo.mediaType = MediaType.DOS_525_SS_DD_8;
									break;
									case 9:
									ImageInfo.mediaType = MediaType.DOS_525_SS_DD_9;
									break;
							}
							break;
						case 2:
							switch(header.sectorsPerTrack)
							{
								case 8:
									ImageInfo.mediaType = MediaType.DOS_525_DS_DD_8;
									break;
								case 9:
									ImageInfo.mediaType = MediaType.DOS_525_DS_DD_9;
									break;
							}
							break;
					}
					break;
				case 80:
					switch(header.heads)
					{
						case 1:
							switch(header.sectorsPerTrack)
							{
								case 8:
									ImageInfo.mediaType = MediaType.DOS_35_SS_DD_8;
									break;
								case 9:
									ImageInfo.mediaType = MediaType.DOS_35_SS_DD_9;
									break;
							}
							break;
						case 2:
							switch(header.sectorsPerTrack)
							{
								case 8:
									ImageInfo.mediaType = MediaType.DOS_35_DS_DD_8;
									break;
								case 9:
									ImageInfo.mediaType = MediaType.DOS_35_DS_DD_9;
									break;
								case 15:
									ImageInfo.mediaType = MediaType.DOS_525_HD;
									break;
								case 18:
									ImageInfo.mediaType = MediaType.DOS_35_HD;
									break;
								case 23:
									ImageInfo.mediaType = MediaType.XDF_35;
									break;
								case 36:
									ImageInfo.mediaType = MediaType.DOS_35_ED;
									break;
							}
							break;
					}
					break;
				default:
					ImageInfo.mediaType = MediaType.Unknown;
					break;
			}

			ImageInfo.xmlMediaType = XmlMediaType.BlockMedia;

			DicConsole.VerboseWriteLine("SaveDskF image contains a disk of type {0}", ImageInfo.mediaType);
			if(!string.IsNullOrEmpty(ImageInfo.imageComments))
				DicConsole.VerboseWriteLine("SaveDskF comments: {0}", ImageInfo.imageComments);

			// TODO: Support compressed images
			if(header.magic == SDF_MAGIC_COMPRESSED)
				throw new FeatureSupportedButNotImplementedImageException("Compressed SaveDskF images are not supported.");

			// SaveDskF only ommits ending clusters, leaving no gaps behind, so reading all data we have...
			stream.Seek(header.dataOffset, SeekOrigin.Begin);
			decodedDisk = new byte[ImageInfo.sectors * ImageInfo.sectorSize];
			stream.Read(decodedDisk, 0, (int)(stream.Length - header.dataOffset));

			ImageInfo.cylinders = header.cylinders;
			ImageInfo.heads = header.heads;
			ImageInfo.sectorsPerTrack = header.sectorsPerTrack;

			return true;
		}

		public override bool? VerifySector(ulong sectorAddress)
		{
			return null;
		}

		public override bool? VerifySector(ulong sectorAddress, uint track)
		{
			return null;
		}

		public override bool? VerifySectors(ulong sectorAddress, uint length, out List<ulong> FailingLBAs, out List<ulong> UnknownLBAs)
		{
			FailingLBAs = new List<ulong>();
			UnknownLBAs = new List<ulong>();

			for(ulong i = sectorAddress; i < sectorAddress + length; i++)
				UnknownLBAs.Add(i);

			return null;
		}

		public override bool? VerifySectors(ulong sectorAddress, uint length, uint track, out List<ulong> FailingLBAs, out List<ulong> UnknownLBAs)
		{
			FailingLBAs = new List<ulong>();
			UnknownLBAs = new List<ulong>();

			for(ulong i = sectorAddress; i < sectorAddress + length; i++)
				UnknownLBAs.Add(i);

			return null;
		}

		public override bool? VerifyMediaImage()
		{
			return calculatedChk == header.checksum;
		}

		public override bool ImageHasPartitions()
		{
			return ImageInfo.imageHasPartitions;
		}

		public override ulong GetImageSize()
		{
			return ImageInfo.imageSize;
		}

		public override ulong GetSectors()
		{
			return ImageInfo.sectors;
		}

		public override uint GetSectorSize()
		{
			return ImageInfo.sectorSize;
		}

		public override byte[] ReadSector(ulong sectorAddress)
		{
			return ReadSectors(sectorAddress, 1);
		}

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

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

			byte[] buffer = new byte[length * ImageInfo.sectorSize];

			Array.Copy(decodedDisk, (int)sectorAddress * ImageInfo.sectorSize, buffer, 0, length * ImageInfo.sectorSize);

			return buffer;
		}

		public override string GetImageFormat()
		{
			return "IBM SaveDskF";
		}

		public override string GetImageVersion()
		{
			return ImageInfo.imageVersion;
		}

		public override string GetImageApplication()
		{
			return ImageInfo.imageApplication;
		}

		public override string GetImageApplicationVersion()
		{
			return ImageInfo.imageApplicationVersion;
		}

		public override DateTime GetImageCreationTime()
		{
			return ImageInfo.imageCreationTime;
		}

		public override DateTime GetImageLastModificationTime()
		{
			return ImageInfo.imageLastModificationTime;
		}

		public override string GetImageName()
		{
			return ImageInfo.imageName;
		}

		public override MediaType GetMediaType()
		{
			return ImageInfo.mediaType;
		}
		public override string GetImageCreator()
		{
			return ImageInfo.imageCreator;
		}

		public override string GetImageComments()
		{
			return ImageInfo.imageComments;
		}

		public override string GetMediaManufacturer()
		{
			return ImageInfo.mediaManufacturer;
		}

		public override string GetMediaModel()
		{
			return ImageInfo.mediaModel;
		}

		public override string GetMediaSerialNumber()
		{
			return ImageInfo.mediaSerialNumber;
		}

		public override string GetMediaBarcode()
		{
			return ImageInfo.mediaBarcode;
		}

		public override string GetMediaPartNumber()
		{
			return ImageInfo.mediaPartNumber;
		}

		public override int GetMediaSequence()
		{
			return ImageInfo.mediaSequence;
		}

		public override int GetLastDiskSequence()
		{
			return ImageInfo.lastMediaSequence;
		}

		public override string GetDriveManufacturer()
		{
			return ImageInfo.driveManufacturer;
		}

		public override string GetDriveModel()
		{
			return ImageInfo.driveModel;
		}

		public override string GetDriveSerialNumber()
		{
			return ImageInfo.driveSerialNumber;
		}
		#endregion Public methods

		#region Unsupported features

		public override byte[] ReadSectorTag(ulong sectorAddress, SectorTagType tag)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorsTag(ulong sectorAddress, uint length, SectorTagType tag)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorLong(ulong sectorAddress)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorsLong(ulong sectorAddress, uint length)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadDiskTag(MediaTagType tag)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override List<Partition> GetPartitions()
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override List<Track> GetTracks()
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override List<Track> GetSessionTracks(Session session)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override List<Track> GetSessionTracks(ushort session)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override List<Session> GetSessions()
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSector(ulong sectorAddress, uint track)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorTag(ulong sectorAddress, uint track, SectorTagType tag)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectors(ulong sectorAddress, uint length, uint track)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorsTag(ulong sectorAddress, uint length, uint track, SectorTagType tag)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorLong(ulong sectorAddress, uint track)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorsLong(ulong sectorAddress, uint length, uint track)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}
		#endregion Unsupported features
	}
}