// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : UCSDPascal.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : U.C.S.D. Pascal filesystem plugin.
//
// --[ Description ] ----------------------------------------------------------
//
//     Identifies the U.C.S.D. Pascal filesystem 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 © 2011-2016 Natalia Portillo
// ****************************************************************************/

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

namespace DiscImageChef.Filesystems
{
    // Information from Call-A.P.P.L.E. Pascal Disk Directory Structure
    public class PascalPlugin : Filesystem
    {
        public PascalPlugin()
        {
            Name = "U.C.S.D. Pascal filesystem";
            PluginUUID = new Guid("B0AC2CB5-72AA-473A-9200-270B5A2C2D53");
        }

        public PascalPlugin(ImagePlugins.ImagePlugin imagePlugin, ulong partitionStart, ulong partitionEnd)
        {
            Name = "U.C.S.D. Pascal filesystem";
            PluginUUID = new Guid("B0AC2CB5-72AA-473A-9200-270B5A2C2D53");
        }

        public override bool Identify(ImagePlugins.ImagePlugin imagePlugin, ulong partitionStart, ulong partitionEnd)
        {
            if(imagePlugin.GetSectors() < 3)
                return false;

            // Blocks 0 and 1 are boot code
            byte[] volBlock = imagePlugin.ReadSector(2 + partitionStart);

            PascalVolumeEntry volEntry = new PascalVolumeEntry();

            BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;

            volEntry.firstBlock = BigEndianBitConverter.ToInt16(volBlock, 0x00);
            volEntry.lastBlock = BigEndianBitConverter.ToInt16(volBlock, 0x02);
            volEntry.entryType = (PascalFileKind)BigEndianBitConverter.ToInt16(volBlock, 0x04);
            volEntry.volumeName = new byte[8];
            Array.Copy(volBlock, 0x06, volEntry.volumeName, 0, 8);
            volEntry.blocks = BigEndianBitConverter.ToInt16(volBlock, 0x0E);
            volEntry.files = BigEndianBitConverter.ToInt16(volBlock, 0x10);
            volEntry.dummy = BigEndianBitConverter.ToInt16(volBlock, 0x12);
            volEntry.lastBoot = BigEndianBitConverter.ToInt16(volBlock, 0x14);
            volEntry.tail = BigEndianBitConverter.ToInt32(volBlock, 0x16);

            // First block is always 0 (even is it's sector 2)
            if(volEntry.firstBlock != 0)
                return false;

            // Last volume record block must be after first block, and before end of device
            if(volEntry.lastBlock <= volEntry.firstBlock || (ulong)volEntry.lastBlock > imagePlugin.GetSectors() - 2)
                return false;

            // Volume record entry type must be volume or secure
            if(volEntry.entryType != PascalFileKind.Volume && volEntry.entryType != PascalFileKind.Secure)
                return false;

            // Volume name is max 7 characters
            if(volEntry.volumeName[0] > 7)
                return false;

            // Volume blocks is equal to volume sectors
            if(volEntry.blocks < 0 || (ulong)volEntry.blocks != imagePlugin.GetSectors())
                return false;

            // There can be not less than zero files
            if(volEntry.files < 0)
                return false;

            return true;
        }

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

            if(imagePlugin.GetSectors() < 3)
                return;

            // Blocks 0 and 1 are boot code
            byte[] volBlock = imagePlugin.ReadSector(2 + partitionStart);

            PascalVolumeEntry volEntry = new PascalVolumeEntry();

            BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;

            volEntry.firstBlock = BigEndianBitConverter.ToInt16(volBlock, 0x00);
            volEntry.lastBlock = BigEndianBitConverter.ToInt16(volBlock, 0x02);
            volEntry.entryType = (PascalFileKind)BigEndianBitConverter.ToInt16(volBlock, 0x04);
            volEntry.volumeName = new byte[8];
            Array.Copy(volBlock, 0x06, volEntry.volumeName, 0, 8);
            volEntry.blocks = BigEndianBitConverter.ToInt16(volBlock, 0x0E);
            volEntry.files = BigEndianBitConverter.ToInt16(volBlock, 0x10);
            volEntry.dummy = BigEndianBitConverter.ToInt16(volBlock, 0x12);
            volEntry.lastBoot = BigEndianBitConverter.ToInt16(volBlock, 0x14);
            volEntry.tail = BigEndianBitConverter.ToInt32(volBlock, 0x16);

            // First block is always 0 (even is it's sector 2)
            if(volEntry.firstBlock != 0)
                return;

            // Last volume record block must be after first block, and before end of device
            if(volEntry.lastBlock <= volEntry.firstBlock || (ulong)volEntry.lastBlock > imagePlugin.GetSectors() - 2)
                return;

            // Volume record entry type must be volume or secure
            if(volEntry.entryType != PascalFileKind.Volume && volEntry.entryType != PascalFileKind.Secure)
                return;

            // Volume name is max 7 characters
            if(volEntry.volumeName[0] > 7)
                return;

            // Volume blocks is equal to volume sectors
            if(volEntry.blocks < 0 || (ulong)volEntry.blocks != imagePlugin.GetSectors())
                return;

            // There can be not less than zero files
            if(volEntry.files < 0)
                return;

            sbInformation.AppendFormat("Volume record spans from block {0} to block {1}", volEntry.firstBlock, volEntry.lastBlock).AppendLine();
            sbInformation.AppendFormat("Volume name: {0}", StringHandlers.PascalToString(volEntry.volumeName)).AppendLine();
            sbInformation.AppendFormat("Volume has {0} blocks", volEntry.blocks).AppendLine();
            sbInformation.AppendFormat("Volume has {0} files", volEntry.files).AppendLine();
            sbInformation.AppendFormat("Volume last booted at {0}", DateHandlers.UCSDPascalToDateTime(volEntry.lastBoot)).AppendLine();

            information = sbInformation.ToString();

            byte[] bootBlocks = imagePlugin.ReadSectors(partitionStart, 2);

            xmlFSType = new Schemas.FileSystemType();
            xmlFSType.Bootable = !ArrayHelpers.ArrayIsNullOrEmpty(bootBlocks);
            xmlFSType.Clusters = volEntry.blocks;
            xmlFSType.ClusterSize = (int)imagePlugin.GetSectorSize();
            xmlFSType.Files = volEntry.files;
            xmlFSType.FilesSpecified = true;
            xmlFSType.Type = "UCSD Pascal";
            xmlFSType.VolumeName = StringHandlers.PascalToString(volEntry.volumeName);

            return;
        }

        enum PascalFileKind : short
        {
            /// <summary>Disk volume entry</summary>
            Volume = 0,
            /// <summary>File containing bad blocks</summary>
            Bad,
            /// <summary>Code file, machine executable</summary>
            Code,
            /// <summary>Text file, human readable</summary>
            Text,
            /// <summary>Information file for debugger</summary>
            Info,
            /// <summary>Data file</summary>
            Data,
            /// <summary>Graphics vectors</summary>
            Graf,
            /// <summary>Graphics screen image</summary>
            Foto,
            /// <summary>Security, not used</summary>
            Secure
        }

        struct PascalVolumeEntry
        {
            /// <summary>0x00, first block of volume entry</summary>
            public short firstBlock;
            /// <summary>0x02, last block of volume entry</summary>
            public short lastBlock;
            /// <summary>0x04, entry type</summary>
            public PascalFileKind entryType;
            /// <summary>0x06, volume name</summary>
            public byte[] volumeName;
            /// <summary>0x0E, block in volume</summary>
            public short blocks;
            /// <summary>0x10, files in volume</summary>
            public short files;
            /// <summary>0x12, dummy</summary>
            public short dummy;
            /// <summary>0x14, last booted</summary>
            public short lastBoot;
            /// <summary>0x16, tail to make record same size as <see cref="PascalFileEntry"/></summary>
            public int tail;
        }

        struct PascalFileEntry
        {
            /// <summary>0x00, first block of file</summary>
            public short firstBlock;
            /// <summary>0x02, last block of file</summary>
            public short lastBlock;
            /// <summary>0x04, entry type</summary>
            public PascalFileKind entryType;
            /// <summary>0x06, file name</summary>
            public byte[] filename;
            /// <summary>0x16, bytes used in last block</summary>
            public short lastBytes;
            /// <summary>0x18, modification time</summary>
            public short mtime;
        }

        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;
        }
    }
}