using System;
using System.Collections.Generic;
using System.Text;

namespace MakeMasterKeyForCtr3rd
{
    class Program
    {
        const int TABLE_SIZE = 0x100;
        const uint BYTE_BITS = 8;
        const uint POLY_MASK = 0xedba6320;
        static readonly uint[] CRC_TABLE = CreateCrc32Table();

        static uint[] CreateCrc32Table()
        {
            uint[] table = new uint[TABLE_SIZE];
            uint crc;

            for ( uint ui = 0; ui < TABLE_SIZE; ui++ )
            {
                crc = ui;
                for ( uint uj = BYTE_BITS; uj > 0; uj-- )
                {
                    if ( (crc & 1) == 1 )
                    {
                        crc = (crc >> 1) ^ POLY_MASK;
                    }
                    else
                    {
                        crc = crc >> 1;
                    }
                }

                table[ui] = crc;
            }

            return table;
        }

        static uint CalculateCrc32(byte[] src, int len)
        {
            uint crc = 0xffffffff;
            int index = 0;

            while ( len != 0 )
            {
                crc = ((crc >> 8) & 0xffffffff) ^ CRC_TABLE[(crc ^ src[index]) & 0xff];
                index++;
                len--;
            }

            return crc;
        }

        static uint MakeMasterKeyOld(byte[] src)
        {
            uint masterKey;

            masterKey = ((CalculateCrc32(src, src.Length) ^ 0xaaaa) + 5719) % 100000;

            return masterKey;
        }

        /// <summary>
        /// Main 関数
        /// </summary>
        static int Main(string[] args)
        {
            uint masterKey;

            // 引数の数チェック
            if ( args.Length != 2 )
            {
                Console.Write("Invalid Argument!\n\n");
                ShowUsage();
                return -1;
            }

            // 引数の文字数チェック
            if ( (args[0].Length != 4) || ((args[1].Length != 8) && (args[1].Length != 10)) )
            {
                Console.Write("Invalid Argument!\n\n");
                ShowUsage();
                return -1;
            }

            // 引数の数値チェック
            {
                long tmp;
                if ( !long.TryParse(args[0], out tmp) || !long.TryParse(args[1], out tmp) )
                {
                    Console.Write("Invalid Argument!\n\n");
                    ShowUsage();
                    return -1;
                }
            }

            // フォーマットの分岐
            if ( args[1].Length == 8 )
            {
                // 入力データの作成（旧フォーマット）
                byte[] inputData = System.Text.Encoding.ASCII.GetBytes(args[0] + args[1].Substring(4, 4));

                masterKey = MakeMasterKeyOld(inputData);
            }
            else
            {
                // 入力データの作成（新フォーマット）
                byte[] inputData = System.Text.Encoding.ASCII.GetBytes(args[0] + args[1]);
                byte[] keyData;
                String region = args[1].Substring(0, 1);

                // リージョンチェック
                if ( (region != REGION.JPN) && (region != REGION.USZ) && (region != REGION.EUR)
                    && (region != REGION.KOR) && (region != REGION.EX_JPN) )
                {
                    Console.Write("Unsupported Region!\n\n");
                    return -1;
                }

                // バージョンチェック
                if ( args[1].Substring(1, 1) == HMAC_OLD_KEY.VERSION )
                {
                    // 旧仕様
                    if ( (region == REGION.KOR) || (region == REGION.EX_JPN) )
                    {
                        Console.Write("Unsupported Version!\n\n");
                        return -1;
                    }
                    switch ( region )
                    {
                        case REGION.JPN: keyData = HMAC_OLD_KEY.JPN; break;
                        case REGION.USZ: keyData = HMAC_OLD_KEY.USZ; break;
                        case REGION.EUR: keyData = HMAC_OLD_KEY.EUR; break;
                        default:
                            // 到達することはないけどビルドエラー対策
                            Console.Write("Unsupported Region!\n\n");
                            return -1;
                    }
                }
                else
                {
                    // 新仕様
                    int keyVersion = int.Parse(args[1].Substring(1, 2));

                    if ( (HMAC_NEW_KEY.VERSION_MIN <= keyVersion) && (keyVersion <= HMAC_NEW_KEY.VERSION_MAX) )
                    {
                        switch ( region )
                        {
                            case REGION.JPN: keyData = HMAC_NEW_KEY.JPN[keyVersion - HMAC_NEW_KEY.VERSION_MIN]; break;
                            case REGION.USZ: keyData = HMAC_NEW_KEY.USZ[keyVersion - HMAC_NEW_KEY.VERSION_MIN]; break;
                            case REGION.EUR: keyData = HMAC_NEW_KEY.EUR[keyVersion - HMAC_NEW_KEY.VERSION_MIN]; break;
                            case REGION.KOR: keyData = HMAC_NEW_KEY.KOR[keyVersion - HMAC_NEW_KEY.VERSION_MIN]; break;
                            case REGION.EX_JPN: keyData = HMAC_NEW_KEY.JPN[keyVersion - HMAC_NEW_KEY.VERSION_MIN]; break;
                            default:
                                // 到達することはないけどビルドエラー対策
                                Console.Write("Unsupported Region!\n\n");
                                return -1;
                        }
                    }
                    else
                    {
                        Console.Write("Unsupported Version!\n\n");
                        return -1;
                    }
                }

                {
                    // HAMC-SHA256 の計算
                    System.Security.Cryptography.HMACSHA256 hmac = new System.Security.Cryptography.HMACSHA256(keyData);
                    byte[] result = hmac.ComputeHash(inputData);

                    // 先頭 4 バイトをリトルエンディアンで数値化
                    masterKey = (result[3] & (uint)0xff) << 24 | (result[2] & (uint)0xff) << 16 | (result[1] & (uint)0xff) << 8 | result[0] & (uint)0xff;

                    // 10進 5 桁にまるめる
                    masterKey = masterKey % 100000;
                }
            }

            // 結果出力
            Console.Write("Master Key = {0:D5}\n", masterKey);

            // 正常終了
            return 0;
        }

        static void ShowUsage()
        {
            Console.Write("---- MakeMasterKeyForCtr - Feb. 10, 2015 ----\n");
            Console.Write("\n");
            Console.Write("Usage:   MakeMasterKeyForCtr [date] [code]\n");
            Console.Write("\n");
            Console.Write("Example: date = Sep. 8   code = 12345678\n");
            Console.Write("         > MakeMasterKeyForCtr 0908 12345678\n");
            Console.Write("\n");
            Console.Write("Example: date = Nov. 12  code = 10123 45678\n");
            Console.Write("         > MakeMasterKeyForCtr 1112 1012345678\n");
        }
    }
}