// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : AmigaDOS.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Amiga Fast File System plugin.
//
// --[ Description ] ----------------------------------------------------------
//
//     Identifies the Amiga Fast 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 © 2011-2017 Natalia Portillo
// ****************************************************************************/

using System;
using System.Text;
using System.Collections.Generic;
using DiscImageChef.Console;

namespace DiscImageChef.Filesystems
{
    class AmigaDOSPlugin : Filesystem
    {
        public AmigaDOSPlugin()
        {
            Name = "Amiga DOS filesystem";
            PluginUUID = new Guid("3c882400-208c-427d-a086-9119852a1bc7");
        }

        public AmigaDOSPlugin(ImagePlugins.ImagePlugin imagePlugin, ulong partitionStart, ulong partitionEnd)
        {
            Name = "Amiga DOS filesystem";
            PluginUUID = new Guid("3c882400-208c-427d-a086-9119852a1bc7");
        }

        /// <summary>
        /// Boot block, first 2 sectors
        /// </summary>
        struct BootBlock
        {
            /// <summary>
            /// Offset 0x00, "DOSx" disk type
            /// </summary>
            public uint diskType;
            /// <summary>
            /// Offset 0x04, Checksum
            /// </summary>
            public uint checksum;
            /// <summary>
            /// Offset 0x08, Pointer to root block, mostly invalid
            /// </summary>
            public uint root_ptr;
            /// <summary>
            /// Offset 0x0C, Boot code, til completion
            /// </summary>
            public byte[] bootCode;
        }

        struct RootBlock
        {
            /// <summary>
            /// Offset 0x00, block type, value = T_HEADER (2)
            /// </summary>
            public uint type;
            /// <summary>
            /// Offset 0x04, unused
            /// </summary>
            public uint headerKey;
            /// <summary>
            /// Offset 0x08, unused
            /// </summary>
            public uint highSeq;
            /// <summary>
            /// Offset 0x0C, longs used by hash table
            /// </summary>
            public uint hashTableSize;
            /// <summary>
            /// Offset 0x10, unused
            /// </summary>
            public uint firstData;
            /// <summary>
            /// Offset 0x14, Rootblock checksum
            /// </summary>
            public uint checksum;
            /// <summary>
            /// Offset 0x18, Hashtable, size = (block size / 4) - 56 or size = hashTableSize
            /// </summary>
            public uint[] hashTable;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+0, bitmap flag, 0xFFFFFFFF if valid
            /// </summary>
            public uint bitmapFlag;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+4, bitmap pages, 25 entries
            /// </summary>
            public uint[] bitmapPages;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+104, pointer to bitmap extension block
            /// </summary>
            public uint bitmapExtensionBlock;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+108, last root alteration days since 1978/01/01
            /// </summary>
            public uint rDays;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+112, last root alteration minutes past midnight
            /// </summary>
            public uint rMins;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+116, last root alteration ticks (1/50 secs)
            /// </summary>
            public uint rTicks;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+120, disk name, pascal string, 32 bytes
            /// </summary>
            public string diskName;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+152, unused
            /// </summary>
            public uint reserved1;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+156, unused
            /// </summary>
            public uint reserved2;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+160, last disk alteration days since 1978/01/01
            /// </summary>
            public uint vDays;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+164, last disk alteration minutes past midnight
            /// </summary>
            public uint vMins;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+168, last disk alteration ticks (1/50 secs)
            /// </summary>
            public uint vTicks;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+172, filesystem creation days since 1978/01/01
            /// </summary>
            public uint cDays;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+176, filesystem creation minutes since 1978/01/01
            /// </summary>
            public uint cMins;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+180, filesystem creation ticks since 1978/01/01
            /// </summary>
            public uint cTicks;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+184, unused
            /// </summary>
            public uint nextHash;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+188, unused
            /// </summary>
            public uint parentDir;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+192, first directory cache block
            /// </summary>
            public uint extension;
            /// <summary>
            /// Offset 0x18+hashTableSize*4+196, block secondary type = ST_ROOT (1)
            /// </summary>
            public uint sec_type;
        }

        public override bool Identify(ImagePlugins.ImagePlugin imagePlugin, ulong partitionStart, ulong partitionEnd)
        {
            if(partitionStart >= partitionEnd)
                return false;

            BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;

            byte[] sector = imagePlugin.ReadSector(0 + partitionStart);

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

            if((magic & 0x6D754600) != 0x6D754600 &&
                (magic & 0x444F5300) != 0x444F5300)
                return false;

            ulong root_ptr = BigEndianBitConverter.ToUInt32(sector, 0x08);
            DicConsole.DebugWriteLine("AmigaDOS plugin", "Bootblock points to {0} as Rootblock", root_ptr);

            if(root_ptr == 0)
            {
                root_ptr = (partitionEnd - partitionStart) / 2 + partitionStart;

                DicConsole.DebugWriteLine("AmigaDOS plugin", "Nonetheless, going to block {0} for Rootblock", root_ptr);
            }
            else
                root_ptr += partitionStart;

            if(root_ptr >= partitionEnd)
                return false;

            sector = imagePlugin.ReadSector(root_ptr);

            uint type = BigEndianBitConverter.ToUInt32(sector, 0x00);
            uint hashTableSize = BigEndianBitConverter.ToUInt32(sector, 0x0C);

            uint blockSize = 0x18 + hashTableSize * 4 + 196;
            uint sectorsPerBlock = (uint)(blockSize / sector.Length);
            if(blockSize % sector.Length > 0)
                sectorsPerBlock++;

            sector = imagePlugin.ReadSectors(root_ptr, sectorsPerBlock);

            //if((0x18 + hashTableSize * 4 + 196) > sector.Length)
            //    return false;

            uint sec_type = BigEndianBitConverter.ToUInt32(sector, (int)(0x18 + hashTableSize * 4 + 196));

            return type == 2 && sec_type == 1;
        }

        public override void GetInformation(ImagePlugins.ImagePlugin imagePlugin, ulong partitionStart, ulong partitionEnd, out string information)
        {
            StringBuilder sbInformation = new StringBuilder();

            byte[] BootBlockSectors = imagePlugin.ReadSectors(0 + partitionStart, 2);

            ulong root_ptr = BigEndianBitConverter.ToUInt32(BootBlockSectors, 0x08);
            DicConsole.DebugWriteLine("AmigaDOS plugin", "Bootblock points to {0} as Rootblock", root_ptr);

            if(root_ptr == 0)
            {
                root_ptr = (partitionEnd - partitionStart) / 2 + partitionStart;

                DicConsole.DebugWriteLine("AmigaDOS plugin", "Nonetheless, going to block {0} for Rootblock", root_ptr);
            }
            else
                root_ptr += partitionStart;

            byte[] RootBlockSector = imagePlugin.ReadSector(root_ptr);

            uint hashTableSize = BigEndianBitConverter.ToUInt32(RootBlockSector, 0x0C);

            uint blockSize = 0x18 + hashTableSize * 4 + 196;
            uint sectorsPerBlock = (uint)(blockSize / RootBlockSector.Length);
            if(blockSize % RootBlockSector.Length > 0)
                sectorsPerBlock++;

            RootBlockSector = imagePlugin.ReadSectors(root_ptr, sectorsPerBlock);

            byte[] diskName = new byte[32];

            BootBlock bootBlk = new BootBlock();
            RootBlock rootBlk = new RootBlock();
            xmlFSType = new Schemas.FileSystemType();

            BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;

            bootBlk.diskType = BigEndianBitConverter.ToUInt32(BootBlockSectors, 0x00);
            bootBlk.checksum = BigEndianBitConverter.ToUInt32(BootBlockSectors, 0x04);
            bootBlk.root_ptr = BigEndianBitConverter.ToUInt32(BootBlockSectors, 0x08);
            bootBlk.bootCode = new byte[BootBlockSectors.Length - 0x0C];
            Array.Copy(BootBlockSectors, 0x0C, bootBlk.bootCode, 0, BootBlockSectors.Length - 0x0C);

            DicConsole.DebugWriteLine("AmigaDOS plugin", "Stored boot blocks checksum is 0x{0:X8}", bootBlk.checksum);
            DicConsole.DebugWriteLine("AmigaDOS plugin", "Probably incorrect calculated boot blocks checksum is 0x{0:X8}", AmigaChecksum(RootBlockSector));
            Checksums.SHA1Context sha1Ctx = new Checksums.SHA1Context();
            sha1Ctx.Init();
            sha1Ctx.Update(bootBlk.bootCode);
            DicConsole.DebugWriteLine("AmigaDOS plugin", "Boot code SHA1 is {0}", sha1Ctx.End());

            rootBlk.type = BigEndianBitConverter.ToUInt32(RootBlockSector, 0x00);
            rootBlk.headerKey = BigEndianBitConverter.ToUInt32(RootBlockSector, 0x04);
            rootBlk.highSeq = BigEndianBitConverter.ToUInt32(RootBlockSector, 0x08);
            rootBlk.hashTableSize = BigEndianBitConverter.ToUInt32(RootBlockSector, 0x0C);
            rootBlk.firstData = BigEndianBitConverter.ToUInt32(RootBlockSector, 0x10);
            rootBlk.checksum = BigEndianBitConverter.ToUInt32(RootBlockSector, 0x14);
            rootBlk.hashTable = new uint[rootBlk.hashTableSize];

            for(int i = 0; i < rootBlk.hashTableSize; i++)
                rootBlk.hashTable[i] = BigEndianBitConverter.ToUInt32(RootBlockSector, 0x18 + i * 4);

            rootBlk.bitmapFlag = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 0));
            rootBlk.bitmapPages = new uint[25];

            for(int i = 0; i < 25; i++)
                rootBlk.bitmapPages[i] = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 4 + i * 4));

            rootBlk.bitmapExtensionBlock = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 104));
            rootBlk.rDays = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 108));
            rootBlk.rMins = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 112));
            rootBlk.rTicks = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 116));

            Array.Copy(RootBlockSector, 0x18 + rootBlk.hashTableSize * 4 + 120, diskName, 0, 32);
            rootBlk.diskName = StringHandlers.PascalToString(diskName);

            rootBlk.reserved1 = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 152));
            rootBlk.reserved2 = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 156));
            rootBlk.vDays = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 160));
            rootBlk.vMins = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 164));
            rootBlk.vTicks = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 168));
            rootBlk.cDays = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 172));
            rootBlk.cMins = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 176));
            rootBlk.cTicks = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 180));
            rootBlk.nextHash = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 184));
            rootBlk.parentDir = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 188));
            rootBlk.extension = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 192));
            rootBlk.sec_type = BigEndianBitConverter.ToUInt32(RootBlockSector, (int)(0x18 + rootBlk.hashTableSize * 4 + 196));

            DicConsole.DebugWriteLine("AmigaDOS plugin", "Stored root block checksum is 0x{0:X8}", rootBlk.checksum);
            DicConsole.DebugWriteLine("AmigaDOS plugin", "Probably incorrect calculated root block checksum is 0x{0:X8}", AmigaChecksum(RootBlockSector));

            switch(bootBlk.diskType & 0xFF)
            {
                case 0:
                    sbInformation.Append("Amiga Original File System");
                    xmlFSType.Type = "Amiga OFS";
                    break;
                case 1:
                    sbInformation.Append("Amiga Fast File System");
                    xmlFSType.Type = "Amiga FFS";
                    break;
                case 2:
                    sbInformation.Append("Amiga Original File System with international characters");
                    xmlFSType.Type = "Amiga OFS";
                    break;
                case 3:
                    sbInformation.Append("Amiga Fast File System with international characters");
                    xmlFSType.Type = "Amiga FFS";
                    break;
                case 4:
                    sbInformation.Append("Amiga Original File System with directory cache");
                    xmlFSType.Type = "Amiga OFS";
                    break;
                case 5:
                    sbInformation.Append("Amiga Fast File System with directory cache");
                    xmlFSType.Type = "Amiga FFS";
                    break;
                case 6:
                    sbInformation.Append("Amiga Original File System with long filenames");
                    xmlFSType.Type = "Amiga OFS";
                    break;
                case 7:
                    sbInformation.Append("Amiga Fast File System with long filenames");
                    xmlFSType.Type = "Amiga FFS";
                    break;
            }

            if((bootBlk.diskType & 0x6D754600) == 0x6D754600)
                sbInformation.Append(", with multi-user patches");

            sbInformation.AppendLine();

            if((bootBlk.diskType & 0xFF) == 6 || (bootBlk.diskType & 0xFF) == 7)
            {
                sbInformation.AppendLine("AFFS v2, following information may be completely incorrect or garbage.");
                xmlFSType.Type = "Amiga FFS2";
            }

            sbInformation.AppendFormat("Volume name: {0}", rootBlk.diskName).AppendLine();

            if(rootBlk.bitmapFlag == 0xFFFFFFFF)
                sbInformation.AppendLine("Volume bitmap is valid");

            if(rootBlk.bitmapExtensionBlock != 0x00000000 && rootBlk.bitmapExtensionBlock != 0xFFFFFFFF)
                sbInformation.AppendFormat("Bitmap extension at block {0}", rootBlk.bitmapExtensionBlock).AppendLine();

            if((bootBlk.diskType & 0xFF) == 4 || (bootBlk.diskType & 0xFF) == 5)
                sbInformation.AppendFormat("Directory cache starts at block {0}", rootBlk.extension).AppendLine();

            sbInformation.AppendFormat("Volume created on {0}", DateHandlers.AmigaToDateTime(rootBlk.cDays, rootBlk.cMins, rootBlk.cTicks)).AppendLine();
            sbInformation.AppendFormat("Volume last modified on {0}", DateHandlers.AmigaToDateTime(rootBlk.vDays, rootBlk.vMins, rootBlk.vTicks)).AppendLine();
            sbInformation.AppendFormat("Volume root directory last modified on on {0}", DateHandlers.AmigaToDateTime(rootBlk.rDays, rootBlk.rMins, rootBlk.rTicks)).AppendLine();

            information = sbInformation.ToString();

            xmlFSType.CreationDate = DateHandlers.AmigaToDateTime(rootBlk.cDays, rootBlk.cMins, rootBlk.cTicks);
            xmlFSType.CreationDateSpecified = true;
            xmlFSType.ModificationDate = DateHandlers.AmigaToDateTime(rootBlk.vDays, rootBlk.vMins, rootBlk.vTicks);
            xmlFSType.ModificationDateSpecified = true;
            xmlFSType.Dirty = rootBlk.bitmapFlag != 0xFFFFFFFF;
            xmlFSType.Clusters = (long)((partitionEnd - partitionStart) + 1);
            xmlFSType.ClusterSize = (int)imagePlugin.GetSectorSize();
        }

        static uint AmigaChecksum(byte[] data)
        {
            BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
            uint sum = 0;

            for(int i = 0; i < data.Length; i += 4)
                sum += BigEndianBitConverter.ToUInt32(data, i);

            return sum;
        }

        public override Errno Mount()
        {
            return Errno.NotImplemented;
        }

        public override Errno Mount(bool debug)
        {
            return Errno.NotImplemented;
        }

        public override Errno Unmount()
        {
            return Errno.NotImplemented;
        }

        public override Errno MapBlock(string path, long fileBlock, ref long deviceBlock)
        {
            return Errno.NotImplemented;
        }

        public override Errno GetAttributes(string path, ref FileAttributes attributes)
        {
            return Errno.NotImplemented;
        }

        public override Errno ListXAttr(string path, ref List<string> xattrs)
        {
            return Errno.NotImplemented;
        }

        public override Errno GetXattr(string path, string xattr, ref byte[] buf)
        {
            return Errno.NotImplemented;
        }

        public override Errno Read(string path, long offset, long size, ref byte[] buf)
        {
            return Errno.NotImplemented;
        }

        public override Errno ReadDir(string path, ref List<string> contents)
        {
            return Errno.NotImplemented;
        }

        public override Errno StatFs(ref FileSystemInfo stat)
        {
            return Errno.NotImplemented;
        }

        public override Errno Stat(string path, ref FileEntryInfo stat)
        {
            return Errno.NotImplemented;
        }

        public override Errno ReadLink(string path, ref string dest)
        {
            return Errno.NotImplemented;
        }
    }
}