//! \file       ArcNPA.cs
//! \date       Fri Jul 18 04:07:42 2014
//! \brief      NPA archive format implementation.
//
// Copyright (C) 2014 by morkt
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//

using System;
using System.IO;
using System.Linq;
using System.Text;
using System.ComponentModel.Composition;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using ZLibNet;
using GameRes.Formats.Strings;
using GameRes.Formats.Properties;

namespace GameRes.Formats.NitroPlus
{
    internal class NpaEntry : PackedEntry
    {
        public byte[] RawName;
        public int    FolderId;
    }

    internal class NpaArchive : ArcFile
    {
        public NpaTitleId   GameId   { get; private set; }
        public int          Key      { get; private set; }
        public byte[]       KeyTable { get { return m_key_table.Value; } }

        private Lazy<byte[]> m_key_table;

        public NpaArchive (ArcView arc, ArchiveFormat impl, ICollection<Entry> dir,
                           NpaTitleId game_id, int key)
            : base (arc, impl, dir)
        {
            GameId   = game_id;
            Key      = key;
            m_key_table = new Lazy<byte[]> (() => NpaOpener.GenerateKeyTable (game_id));
        }
    }

    public enum NpaTitleId
    {
        NotEncrypted,
        CHAOSHEAD, CHAOSHEADTR1, CHAOSHEADTR2, MURAMASATR, MURAMASA, SUMAGA, DJANGO, DJANGOTR,
        LAMENTO, LAMENTOTR, SWEETPOOL, SUMAGASP, DEMONBANE, MURAMASAAD, AXANAEL, KIKOKUGAI, SONICOMITR2,
        SUMAGA3P, SONICOMI, LOSTX, LOSTXTRAILER, DRAMATICALMURDER, TOTONO, PHENOMENO, NEKODA,
    }

    public class NpaOptions : ResourceOptions
    {
        public NpaTitleId    TitleId { get; set; }
        public bool CompressContents { get; set; }
        public int              Key1 { get; set; }
        public int              Key2 { get; set; }
    }

    [Export(typeof(ArchiveFormat))]
    public class NpaOpener : ArchiveFormat
    {
        public override string         Tag { get { return "NPA"; } }
        public override string Description { get { return arcStrings.NPADescription; } }
        public override uint     Signature { get { return 0x0141504e; } } // NPA\x01
        public override bool  IsHierarchic { get { return true; } }
        public override bool     CanCreate { get { return true; } }

        /// <summary>
        /// Known encryption schemes.
        /// Order should match NpaTitleId enumeration.
        /// </summary>
        public static readonly string[] KnownSchemes = new string[] {
            arcStrings.ArcNoEncryption,
            "Chaos;Head", "Chaos;Head Trial 1", "Chaos;Head Trial 2", "Muramasa Trial", "Muramasa",
            "Sumaga", "Zoku Satsuriku no Django", "Zoku Satsuriku no Django Trial", "Lamento",
            "Lamento Trial", "Sweet Pool", "Sumaga Special", "Demonbane", "MuramasaAD", "Axanael",
            "Kikokugai", "Sonicomi Trial 2", "Sumaga 3% Trial", "Sonicomi Version 1.0",
            "Guilty Crown Lost Xmas", "Guilty Crown Lost Xmas Trailer", "DRAMAtical Murder",
            "Kimi to Kanojo to Kanojo no Koi", "Phenomeno", "Nekoda -Nyanda-",
        };

        public const int DefaultKey1 = 0x4147414e;
        public const int DefaultKey2 = 0x21214f54;

        public override ArcFile TryOpen (ArcView file)
        {
            int key1 = file.View.ReadInt32 (7);
            int key2 = file.View.ReadInt32 (11);
            bool compressed = 0 != file.View.ReadByte (15);
            bool encrypted  = 0 != file.View.ReadByte (16);
    		int total_count = file.View.ReadInt32 (17);
		    int folder_count = file.View.ReadInt32 (21);
		    int file_count = file.View.ReadInt32 (25);
            if (total_count < folder_count + file_count)
                return null;
		    uint dir_size = file.View.ReadUInt32 (37);
            if (dir_size >= file.MaxOffset)
                return null;

            var game_id = NpaTitleId.NotEncrypted;
            if (encrypted)
                game_id = QueryGameEncryption();

            int key;
            if (encrypted && (game_id == NpaTitleId.LAMENTO || game_id == NpaTitleId.LAMENTOTR))
                key = key1 + key2;
            else
                key = key1 * key2;

            long cur_offset = 41;
            var dir = new List<Entry> (file_count);
            for (int i = 0; i < total_count; ++i)
            {
                int name_size = file.View.ReadInt32 (cur_offset);
                if ((uint)name_size >= dir_size)
                    return null;
                int type = file.View.ReadByte (cur_offset+4+name_size);
                if (1 != type) // ignore directory entries
                {
                    var raw_name = new byte[name_size];
                    file.View.Read (cur_offset+4, raw_name, 0, (uint)name_size);
                    for (int x = 0; x < name_size; ++x)
                        raw_name[x] += DecryptName (x, i, key);
                    var info_offset = cur_offset + 5 + name_size;

                    int  id = file.View.ReadInt32 (info_offset);
                    uint offset = file.View.ReadUInt32 (info_offset+4);
                    uint size = file.View.ReadUInt32 (info_offset+8);
                    uint unpacked_size = file.View.ReadUInt32 (info_offset+12);

                    var entry = new NpaEntry {
                        Name        = Encodings.cp932.GetString (raw_name),
                        Offset      = dir_size+offset+41,
                        Size        = size,
                        UnpackedSize = unpacked_size,
                        RawName     = raw_name,
                        FolderId    = id,
                    };
                    if (!entry.CheckPlacement (file.MaxOffset))
                        return null;
                    entry.Type = FormatCatalog.Instance.GetTypeFromName (entry.Name);
                    entry.IsPacked = compressed && entry.Type != "image";
                    dir.Add (entry);
                }
                cur_offset += 4 + name_size + 17;
            }
            if (game_id != NpaTitleId.NotEncrypted)
                return new NpaArchive (file, this, dir, game_id, key);
            else
                return new ArcFile (file, this, dir);
        }

        public override void Create (Stream output, IEnumerable<Entry> list, ResourceOptions options,
                                     EntryCallback callback)
        {
            var npa_options = GetOptions<NpaOptions> (options);
            int callback_count = 0;

            // build file index
            var index = new Indexer (list, npa_options);

            output.Position = 41 + index.Size;
            long data_offset = 0;

            // write files
            foreach (var entry in index.Entries.Where (e => e.Type != "directory"))
            {
                if (data_offset > uint.MaxValue)
                    throw new FileSizeException();
                if (null != callback)
                    callback (callback_count++, entry, arcStrings.MsgAddingFile);
                using (var file = File.OpenRead (entry.Name))
                {
                    var size = file.Length;
                    if (size > uint.MaxValue)
                        throw new FileSizeException();
                    entry.Offset = data_offset;
                    entry.UnpackedSize = (uint)size;
                    if (entry.IsPacked)
                    {
                        using (var zstream = new ZLibStream (output, CompressionMode.Compress,
                                                             CompressionLevel.Level9, true))
                        {
                            file.CopyTo (zstream);
                            zstream.Flush();
                            entry.Size = (uint)zstream.TotalOut;
                        }
                    }
                    else
                    {
                        file.CopyTo (output);
                        entry.Size = entry.UnpackedSize;
                    }
                    data_offset += entry.Size;
                }
            }
            if (null != callback)
                callback (callback_count++, null, arcStrings.MsgWritingIndex);

            output.Position = 0;
            using (var header = new BinaryWriter (output, Encoding.ASCII, true))
            {
                header.Write (Signature);
                header.Write ((short)0);
                header.Write ((byte)0);
                header.Write (npa_options.Key1);
                header.Write (npa_options.Key2);
                header.Write (npa_options.CompressContents);
                header.Write (npa_options.TitleId != NpaTitleId.NotEncrypted);
                header.Write (index.TotalCount);
                header.Write (index.FolderCount);
                header.Write (index.FileCount);
                header.Write ((long)0);
                header.Write (index.Size);
                foreach (var entry in index.Entries)
                {
                    header.Write (entry.RawName.Length);
                    header.Write (entry.RawName);
                    header.Write ((byte)("directory" == entry.Type ? 1 : 2));
                    header.Write (entry.FolderId);
                    header.Write ((uint)entry.Offset);
                    header.Write (entry.Size);
                    header.Write (entry.UnpackedSize);
                }
            }
        }

        public override Stream OpenEntry (ArcFile arc, Entry entry)
        {
            if (arc is NpaArchive && entry is NpaEntry)
                return OpenEncryptedEntry (arc as NpaArchive, entry as NpaEntry);

            var input = arc.File.CreateStream (entry.Offset, entry.Size);
            return UnpackEntry (input, entry as PackedEntry);
        }

        private Stream UnpackEntry (Stream input, PackedEntry entry)
        {
            if (null != entry && entry.IsPacked)
                return new ZLibStream (input, CompressionMode.Decompress);
            return input;
        }

        private Stream OpenEncryptedEntry (NpaArchive arc, NpaEntry entry)
        {
            int key = GetKeyFromEntry (entry, arc.GameId, arc.Key);
            int encrypted_length = 0x1000;

            if (arc.GameId != NpaTitleId.LAMENTO && arc.GameId != NpaTitleId.LAMENTOTR)
                encrypted_length += entry.RawName.Length;
            if (encrypted_length > entry.Size)
                encrypted_length = (int)entry.Size;

            using (var view = arc.File.CreateViewAccessor (entry.Offset, entry.Size))
            {
                byte[] buffer = new byte[entry.Size];
                unsafe
                {
                    byte* src = view.GetPointer (entry.Offset);
                    try
                    {
                        int x;
                        for (x = 0; x < encrypted_length; x++)
                        {
                            if (arc.GameId == NpaTitleId.LAMENTO || arc.GameId == NpaTitleId.LAMENTOTR)
                            {
                                buffer[x] = (byte)(arc.KeyTable[src[x]] - key);
                            }
                            else if (arc.GameId == NpaTitleId.TOTONO)
                            {
                                byte r = src[x];
                                r = arc.KeyTable[r];
                                r = arc.KeyTable[r];
                                r = arc.KeyTable[r];
                                r = (byte)~r;
                                buffer[x] = (byte)((sbyte)r - key - x);
                            }
                            else
                            {
                                buffer[x] = (byte)(arc.KeyTable[src[x]] - key - x);
                            }
                        }
                        if (x != entry.Size)
                            Marshal.Copy ((IntPtr)(src+x), buffer, x, (int)(entry.Size-x));
                    } finally {
                        view.SafeMemoryMappedViewHandle.ReleasePointer();
                    }
                }
                return UnpackEntry (new MemoryStream (buffer, false), entry);
            }
        }

        public static byte DecryptName (int index, int curfile, int arc_key)
        {
            int key = 0xFC*index;

            key -= arc_key >> 0x18;
            key -= arc_key >> 0x10;
            key -= arc_key >> 0x08;
            key -= arc_key  & 0xff;

            key -= curfile >> 0x18;
            key -= curfile >> 0x10;
            key -= curfile >> 0x08;
            key -= curfile;

            return (byte)(key & 0xff);
        }

        internal static byte GetKeyFromEntry (NpaEntry entry, NpaTitleId game_id, int key2)
        {
            int key1;
            switch (game_id)
            {
                case NpaTitleId.AXANAEL:
                case NpaTitleId.KIKOKUGAI:
                case NpaTitleId.SONICOMITR2:
                case NpaTitleId.SONICOMI:
                case NpaTitleId.LOSTX:
                case NpaTitleId.DRAMATICALMURDER:
                case NpaTitleId.PHENOMENO:
                    key1 = 0x20101118;
                    break;
                case NpaTitleId.TOTONO:
                    key1 = 0x12345678;
                    break;
                default:
                    key1 = unchecked((int)0x87654321);
                    break;
            }
            var name = entry.RawName;
            int i;
            for (i = 0; i < name.Length; ++i)
                key1 -= name[i];

            int key = key1 * i;

            if (game_id != NpaTitleId.LAMENTO && game_id != NpaTitleId.LAMENTOTR) // if the game is not Lamento
            {
                key += key2;
                key *= (int)entry.UnpackedSize;
            }
            return (byte)(key & 0xff);
        }

        public static byte[] GenerateKeyTable (NpaTitleId title_id)
        {
            int index = (int)title_id;
            if (index < 0 || index >= OrderTable.Length)
                throw new ArgumentOutOfRangeException ("title_id", "Invalid title id specified");

            byte[] order = OrderTable[index];
            if (null == order)
                throw new ArgumentException ("Encryption key table not defined", "title_id");

            var table = new byte[256];
            for (int i = 0; i < 256; ++i)
            {
                int edx = i << 4;
                int dl = (edx + order[i & 0x0f]) & 0xff;
                int dh = (edx + (order[i>>4] << 8)) & 0xff00;
                edx = (dh | dl) >> 4;
                var eax = BaseTable[i];
                table[eax] = (byte)(edx & 0xff);
            }
            for (int i = 16; i+1 < order.Length; i+=2)
            {
                int ecx = order[i];
                int edx = order[i+1];
                byte tmp = table[ecx];
                table[ecx] = table[edx];
                table[edx] = tmp;
            }
            return table;
        }

        public override ResourceOptions GetDefaultOptions ()
        {
            return new NpaOptions {
                TitleId          = GetTitleId (Settings.Default.NPAScheme),
                CompressContents = Settings.Default.NPACompressContents,
                Key1             = (int)Settings.Default.NPAKey1,
                Key2             = (int)Settings.Default.NPAKey2,
            };
        }

        public override object GetAccessWidget ()
        {
            return new GUI.WidgetNPA();
        }

        public override object GetCreationWidget ()
        {
            return new GUI.CreateNPAWidget();
        }

        NpaTitleId QueryGameEncryption ()
        {
            var options = Query<NpaOptions> (arcStrings.ArcEncryptedNotice);
            return options.TitleId;
        }

        public static NpaTitleId GetTitleId (string title)
        {
            var index = Array.IndexOf (KnownSchemes, title);
            if (index != -1)
                return (NpaTitleId)index;
            else
                return NpaTitleId.NotEncrypted;
        }

        static readonly byte[] BaseTable = {
            0x6F,0x05,0x6A,0xBF,0xA1,0xC7,0x8E,0xFB,0xD4,0x2F,0x80,0x58,0x4A,0x17,0x3B,0xB1,
            0x89,0xEC,0xA0,0x9F,0xD3,0xFC,0xC2,0x04,0x68,0x03,0xF3,0x25,0xBE,0x24,0xF1,0xBD,
            0xB8,0x41,0xC9,0x27,0x0E,0xA3,0xD8,0x7F,0x5B,0x8F,0x16,0x49,0xAA,0xB2,0x18,0xA7,
            0x33,0xE4,0xDB,0x48,0xCA,0xDE,0xAE,0xCD,0x13,0x1F,0x15,0x2E,0x39,0xF5,0x1E,0xDD,
            0x0F,0x88,0x4C,0x98,0x36,0xB4,0x3F,0x09,0x83,0xFD,0x32,0xBA,0x14,0x30,0x7A,0x63,
            0xB9,0x56,0x95,0x61,0xCC,0x8B,0xEF,0xDA,0xE5,0x2C,0xDC,0x12,0x1A,0x67,0x23,0x50,
            0xD1,0xC3,0x7E,0x6D,0xB6,0x90,0x3C,0xB3,0x0B,0xE2,0x91,0x70,0xA8,0xDF,0x44,0xC4,
            0xF4,0x01,0x5C,0x10,0x06,0xE7,0x54,0x40,0x43,0x72,0x38,0xBC,0xE3,0x07,0xFA,0x34,
            0x02,0xA4,0xF7,0x74,0xA9,0x4D,0x42,0xA5,0x85,0x35,0x79,0xD2,0x76,0x97,0x45,0x4F,
            0x08,0x5A,0xB0,0xEE,0x51,0x73,0x69,0x9E,0x94,0x47,0x77,0x29,0xD9,0x64,0x11,0xEB,
            0x37,0xAC,0x20,0x62,0x9A,0x6B,0x9C,0x75,0x22,0x87,0xAB,0x78,0x53,0xC8,0x5D,0xAD,
            0x2A,0xF2,0xCB,0xB7,0x0D,0xED,0x86,0x55,0xFF,0x19,0x57,0xD7,0xD5,0x60,0xC6,0x3D,
            0xEA,0xC1,0x6C,0xE1,0xC0,0x65,0x84,0xC5,0xE0,0x3E,0x7D,0x28,0x66,0xAF,0x1C,0x9B,
            0xCF,0x81,0x4E,0x26,0x59,0x2B,0x5F,0x7B,0xE8,0x8D,0x52,0x7C,0xF8,0x82,0x0C,0xF9,
            0x8C,0xE9,0xB5,0xE6,0x31,0x93,0x46,0x5E,0x1D,0x1B,0x4B,0x71,0xD6,0x92,0x3A,0xA6,
            0x2D,0x00,0x9D,0xBB,0x6E,0xF0,0x99,0xCE,0x21,0x0A,0xD0,0xF6,0xFE,0xA2,0x8A,0x96,
        };

        static readonly byte[][] OrderTable = {
            null, // NotEncrypted
            // CHAOSHEAD
            new byte[] { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 },
            // CHAOSHEADTR1
            new byte[] { 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x1e,0x4e,0x66,0xb6 },
            // CHAOSHEADTR2
            new byte[] { 0x05,0x05,0x05,0x05,0x05,0x0b,0x0b,0x0b,0x0b,0x0b,0x00,0x00,0x00,0x00,0x00,0x00 },
            // MURAMASATR
            new byte[] { 0x3c,0xe0,0x2e,0x2f,0x20,0x2e,0x2f,0x20,0x8e,0x80,0x80,0xf2,0xf2,0xf2,0xfa,0xfc },
            // MURAMASA
            new byte[] { 0x35,0x70,0x2e,0x66,0x67,0x65,0x66,0x67,0x85,0x89,0x89,0x3b,0x3b,0x8b,0x81,0x85 },
            // SUMAGA
            new byte[] { 0x3c,0xe0,0x2e,0x2f,0x2f,0x2f,0x2f,0x20,0x8e,0x8f,0x8f,0xf2,0xf2,0xf2,0xfc,0xfc },
            // DJANGO
            new byte[] { 0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0x1e,0x4e,0x66,0xb6 },
            // DJANGOTR
            new byte[] { 0xed,0xee,0xee,0xef,0xed,0xee,0xee,0xee,0xfe,0xde,0xee,0xef,0xed,0xee,0xfe,0xdf,0x1e,0x4e,0x66,0xb6 },
            // LAMENTO
            new byte[] { 0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0x1e,0x4e,0x66,0xb6 },
            // LAMENTOTR
            new byte[] { 0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0xee,0x1e,0x4e,0x66,0xb6 },
            // SWEETPOOL
            new byte[] { 0x38,0x9c,0x2a,0x8b,0x8b,0x8b,0x8b,0x8c,0x8a,0x8b,0x8b,0xae,0xae,0xae,0xa8,0xa8 },
            // SUMAGASP
            new byte[] { 0xab,0x6f,0x9d,0x9e,0x9f,0x9d,0x9e,0xaf,0x8d,0xff,0xff,0x71,0x71,0x71,0x79,0x7b },
            // DEMONBANE
            new byte[] { 0x96,0xb9,0x47,0x48,0x99,0x97,0x9c,0xaa,0x88,0xca,0xea,0x73,0x73,0x7b,0xc9,0xc6 },
            // MURAMASAAD
            new byte[] { 0x00,0x04,0x04,0x68,0x68,0x68,0x68,0x68,0x6f,0x6f,0x9f,0x96,0x96,0x96,0x96,0x9b },
            // AXANAEL
            new byte[] { 0x08,0x0c,0x0c,0xc0,0xf0,0xf0,0xf0,0xf0,0xf7,0xf7,0xf7,0xfe,0xfe,0xfe,0xfe,0xf3 },
            // KIKOKUGAI
            new byte[] { 0x0f,0x07,0x07,0x90,0xf7,0xf7,0xf7,0xf7,0xf2,0x47,0x47,0x49,0xc9,0xc9,0xc9,0xc3 },
            // SONICOMITR2
            new byte[] { 0x08,0x0a,0x0a,0x40,0xfa,0xfa,0x50,0x50,0x55,0xf7,0xf7,0xf9,0x29,0x2c,0x7c,0x73 },
            // SUMAGA3P
            new byte[] { 0x0f,0xef,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff },
            // SONICOMI
            new byte[] { 0x0e,0x0b,0x0e,0x77,0x2e,0x2e,0x80,0x86,0xb9,0x2e,0x2e,0x29,0x89,0x82,0xad,0xaa },
            // LOSTX
            new byte[] { 0x38,0xba,0x4b,0x5b,0x55,0xae,0xee,0xe0,0x67,0x48,0x08,0x0a,0x6a,0x3d,0x32,0x8d },
            // LOSTXTRAILER
            new byte[] { 0x34,0x7a,0xbb,0xcb,0x11,0x65,0xea,0x5c,0x27,0x0f,0xcf,0xc6,0x66,0x39,0x39,0xfd },
            // DRAMATICALMURDER
            new byte[] { 0x05,0x0d,0x0d,0x13,0xb5,0x3d,0x8d,0x2d,0x20,0xc7,0xc7,0xcf,0x1f,0xef,0xef,0x48 },
            // TOTONO
            new byte[] { 0x6e,0x60,0x90,0xac,0xb3,0xe3,0x83,0xd6,0xde,0x7a,0x7a,0x7f,0xef,0xbf,0xb2,0xd6 },
            // PHENOMENO
            new byte[] { 0x30,0x96,0xdb,0x2b,0x3d,0x81,0x02,0x74,0x47,0x2b,0xeb,0xee,0x6e,0x35,0x35,0x5d },
            // NEKODA
            new byte[] { 0xdc,0xdc,0xec,0xcd,0xdb,0xdc,0xdc,0xdc,0xdc,0xdc,0xdc,0xdc,0xdc,0xdc,0xdc,0xdc,0x1e,0x4e,0x66,0xb6 },
        };
    }

    /// <summary>
    /// Archive creation helper.
    /// </summary>
    internal class Indexer
    {
        List<NpaEntry>  m_entries;
        Encoding        m_encoding = Encodings.cp932.WithFatalFallback();
        int             m_key;
        int             m_size = 0;
        int             m_directory_count = 0;
        int             m_file_count = 0;

        public IEnumerable<NpaEntry> Entries { get { return m_entries; } }

        public int         Key { get { return m_key; } }
        public int        Size { get { return m_size; } }
        public int  TotalCount { get { return m_entries.Count; } }
        public int FolderCount { get { return m_directory_count; } }
        public int   FileCount { get { return m_file_count; } }

        public Indexer (IEnumerable<Entry> source_list, NpaOptions options)
        {
            m_entries = new List<NpaEntry> (source_list.Count());
            var game_id = options.TitleId;
            if (game_id == NpaTitleId.LAMENTO || game_id == NpaTitleId.LAMENTOTR)
                m_key = options.Key1 + options.Key2;
            else
                m_key = options.Key1 * options.Key2;

            foreach (var entry in source_list)
            {
                string name = entry.Name;
                var dir = Path.GetDirectoryName (name);
                int folder_id = 0;
                if (!string.IsNullOrEmpty (dir))
                    folder_id = AddDirectory (dir);

                bool compress = options.CompressContents;
                if (compress) // don't compress images
                    compress = !FormatCatalog.Instance.LookupFileName (name).OfType<ImageFormat>().Any();
                var npa_entry = new NpaEntry
                {
                    Name        = name,
                    IsPacked    = compress,
                    RawName     = EncodeName (name, m_entries.Count),
                    FolderId    = folder_id,
                };
                ++m_file_count;
                AddEntry (npa_entry);
            }
        }

        byte[] EncodeName (string name, int entry_number)
        {
            try
            {
                byte[] raw_name = m_encoding.GetBytes (name);
                for (int i = 0; i < name.Length; ++i)
                    raw_name[i] -= NpaOpener.DecryptName (i, entry_number, m_key);
                return raw_name;
            }
            catch (EncoderFallbackException X)
            {
                throw new InvalidFileName (name, arcStrings.MsgIllegalCharacters, X);
            }
        }

        void AddEntry (NpaEntry entry)
        {
            m_entries.Add (entry);
            m_size += 4 + entry.RawName.Length + 17;
        }

        Dictionary<string, int> m_directory_map = new Dictionary<string, int>();

        int AddDirectory (string dir)
        {
            int folder_id = 0;
            if (m_directory_map.TryGetValue (dir, out folder_id))
                return folder_id;
            string path = "";
            foreach (var component in dir.Split (Path.DirectorySeparatorChar))
            {
                path = Path.Combine (path, component);
                if (m_directory_map.TryGetValue (path, out folder_id))
                    continue;
                folder_id = ++m_directory_count;
                m_directory_map[path] = folder_id;

                var npa_entry = new NpaEntry
                {
                    Name        = path,
                    Type        = "directory",
                    Offset      = 0,
                    Size        = 0,
                    UnpackedSize = 0,
                    IsPacked    = false,
                    RawName     = EncodeName (path, m_entries.Count),
                    FolderId    = folder_id,
                };
                m_entries.Add (npa_entry);
            }
            return folder_id;
        }
    }
}