// Copyright 2008 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

// Most of the code in this file is from:
// GCNcrypt - GameCube AR Crypto Program
// Copyright (C) 2003-2004 Parasyte

#include "Core/ARDecrypt.h"

#include <algorithm>
#include <cstring>
#include <string>
#include <vector>

#ifdef _WIN32
#include <windows.h>
#endif

#include "Common/BitUtils.h"
#include "Common/CommonTypes.h"
#include "Common/MsgHandler.h"
#include "Common/Swap.h"

namespace ActionReplay
{
// Alphanumeric filter for text<->bin conversion
static const char* filter = "0123456789ABCDEFGHJKMNPQRTUVWXYZILOS";

static u32 genseeds[0x20];

static const u8 gentable0[0x38] = {
    0x39, 0x31, 0x29, 0x21, 0x19, 0x11, 0x09, 0x01, 0x3A, 0x32, 0x2A, 0x22, 0x1A, 0x12,
    0x0A, 0x02, 0x3B, 0x33, 0x2B, 0x23, 0x1B, 0x13, 0x0B, 0x03, 0x3C, 0x34, 0x2C, 0x24,
    0x3F, 0x37, 0x2F, 0x27, 0x1F, 0x17, 0x0F, 0x07, 0x3E, 0x36, 0x2E, 0x26, 0x1E, 0x16,
    0x0E, 0x06, 0x3D, 0x35, 0x2D, 0x25, 0x1D, 0x15, 0x0D, 0x05, 0x1C, 0x14, 0x0C, 0x04,
};
static const u8 gentable1[0x08] = {
    0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01,
};
static const u8 gentable2[0x10] = {
    0x01, 0x02, 0x04, 0x06, 0x08, 0x0A, 0x0C, 0x0E, 0x0F, 0x11, 0x13, 0x15, 0x17, 0x19, 0x1B, 0x1C,
};
static const u8 gentable3[0x30] = {
    0x0E, 0x11, 0x0B, 0x18, 0x01, 0x05, 0x03, 0x1C, 0x0F, 0x06, 0x15, 0x0A, 0x17, 0x13, 0x0C, 0x04,
    0x1A, 0x08, 0x10, 0x07, 0x1B, 0x14, 0x0D, 0x02, 0x29, 0x34, 0x1F, 0x25, 0x2F, 0x37, 0x1E, 0x28,
    0x33, 0x2D, 0x21, 0x30, 0x2C, 0x31, 0x27, 0x38, 0x22, 0x35, 0x2E, 0x2A, 0x32, 0x24, 0x1D, 0x20,
};

static const u16 crctable0[0x10] = {
    0x0000, 0x1081, 0x2102, 0x3183, 0x4204, 0x5285, 0x6306, 0x7387,
    0x8408, 0x9489, 0xA50A, 0xB58B, 0xC60C, 0xD68D, 0xE70E, 0xF78F,
};
static const u16 crctable1[0x10] = {
    0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
    0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
};

static const u8 gensubtable[0x08] = {
    0x34, 0x1C, 0x84, 0x9E, 0xFD, 0xA4, 0xB6, 0x7B,
};

static const u32 table0[0x40] = {
    0x01010400, 0x00000000, 0x00010000, 0x01010404, 0x01010004, 0x00010404, 0x00000004, 0x00010000,
    0x00000400, 0x01010400, 0x01010404, 0x00000400, 0x01000404, 0x01010004, 0x01000000, 0x00000004,
    0x00000404, 0x01000400, 0x01000400, 0x00010400, 0x00010400, 0x01010000, 0x01010000, 0x01000404,
    0x00010004, 0x01000004, 0x01000004, 0x00010004, 0x00000000, 0x00000404, 0x00010404, 0x01000000,
    0x00010000, 0x01010404, 0x00000004, 0x01010000, 0x01010400, 0x01000000, 0x01000000, 0x00000400,
    0x01010004, 0x00010000, 0x00010400, 0x01000004, 0x00000400, 0x00000004, 0x01000404, 0x00010404,
    0x01010404, 0x00010004, 0x01010000, 0x01000404, 0x01000004, 0x00000404, 0x00010404, 0x01010400,
    0x00000404, 0x01000400, 0x01000400, 0x00000000, 0x00010004, 0x00010400, 0x00000000, 0x01010004,
};
static const u32 table1[0x40] = {
    0x80108020, 0x80008000, 0x00008000, 0x00108020, 0x00100000, 0x00000020, 0x80100020, 0x80008020,
    0x80000020, 0x80108020, 0x80108000, 0x80000000, 0x80008000, 0x00100000, 0x00000020, 0x80100020,
    0x00108000, 0x00100020, 0x80008020, 0x00000000, 0x80000000, 0x00008000, 0x00108020, 0x80100000,
    0x00100020, 0x80000020, 0x00000000, 0x00108000, 0x00008020, 0x80108000, 0x80100000, 0x00008020,
    0x00000000, 0x00108020, 0x80100020, 0x00100000, 0x80008020, 0x80100000, 0x80108000, 0x00008000,
    0x80100000, 0x80008000, 0x00000020, 0x80108020, 0x00108020, 0x00000020, 0x00008000, 0x80000000,
    0x00008020, 0x80108000, 0x00100000, 0x80000020, 0x00100020, 0x80008020, 0x80000020, 0x00100020,
    0x00108000, 0x00000000, 0x80008000, 0x00008020, 0x80000000, 0x80100020, 0x80108020, 0x00108000,
};
static const u32 table2[0x40] = {
    0x00000208, 0x08020200, 0x00000000, 0x08020008, 0x08000200, 0x00000000, 0x00020208, 0x08000200,
    0x00020008, 0x08000008, 0x08000008, 0x00020000, 0x08020208, 0x00020008, 0x08020000, 0x00000208,
    0x08000000, 0x00000008, 0x08020200, 0x00000200, 0x00020200, 0x08020000, 0x08020008, 0x00020208,
    0x08000208, 0x00020200, 0x00020000, 0x08000208, 0x00000008, 0x08020208, 0x00000200, 0x08000000,
    0x08020200, 0x08000000, 0x00020008, 0x00000208, 0x00020000, 0x08020200, 0x08000200, 0x00000000,
    0x00000200, 0x00020008, 0x08020208, 0x08000200, 0x08000008, 0x00000200, 0x00000000, 0x08020008,
    0x08000208, 0x00020000, 0x08000000, 0x08020208, 0x00000008, 0x00020208, 0x00020200, 0x08000008,
    0x08020000, 0x08000208, 0x00000208, 0x08020000, 0x00020208, 0x00000008, 0x08020008, 0x00020200,
};
static const u32 table3[0x40] = {
    0x00802001, 0x00002081, 0x00002081, 0x00000080, 0x00802080, 0x00800081, 0x00800001, 0x00002001,
    0x00000000, 0x00802000, 0x00802000, 0x00802081, 0x00000081, 0x00000000, 0x00800080, 0x00800001,
    0x00000001, 0x00002000, 0x00800000, 0x00802001, 0x00000080, 0x00800000, 0x00002001, 0x00002080,
    0x00800081, 0x00000001, 0x00002080, 0x00800080, 0x00002000, 0x00802080, 0x00802081, 0x00000081,
    0x00800080, 0x00800001, 0x00802000, 0x00802081, 0x00000081, 0x00000000, 0x00000000, 0x00802000,
    0x00002080, 0x00800080, 0x00800081, 0x00000001, 0x00802001, 0x00002081, 0x00002081, 0x00000080,
    0x00802081, 0x00000081, 0x00000001, 0x00002000, 0x00800001, 0x00002001, 0x00802080, 0x00800081,
    0x00002001, 0x00002080, 0x00800000, 0x00802001, 0x00000080, 0x00800000, 0x00002000, 0x00802080,
};
static const u32 table4[0x40] = {
    0x00000100, 0x02080100, 0x02080000, 0x42000100, 0x00080000, 0x00000100, 0x40000000, 0x02080000,
    0x40080100, 0x00080000, 0x02000100, 0x40080100, 0x42000100, 0x42080000, 0x00080100, 0x40000000,
    0x02000000, 0x40080000, 0x40080000, 0x00000000, 0x40000100, 0x42080100, 0x42080100, 0x02000100,
    0x42080000, 0x40000100, 0x00000000, 0x42000000, 0x02080100, 0x02000000, 0x42000000, 0x00080100,
    0x00080000, 0x42000100, 0x00000100, 0x02000000, 0x40000000, 0x02080000, 0x42000100, 0x40080100,
    0x02000100, 0x40000000, 0x42080000, 0x02080100, 0x40080100, 0x00000100, 0x02000000, 0x42080000,
    0x42080100, 0x00080100, 0x42000000, 0x42080100, 0x02080000, 0x00000000, 0x40080000, 0x42000000,
    0x00080100, 0x02000100, 0x40000100, 0x00080000, 0x00000000, 0x40080000, 0x02080100, 0x40000100,
};
static const u32 table5[0x40] = {
    0x20000010, 0x20400000, 0x00004000, 0x20404010, 0x20400000, 0x00000010, 0x20404010, 0x00400000,
    0x20004000, 0x00404010, 0x00400000, 0x20000010, 0x00400010, 0x20004000, 0x20000000, 0x00004010,
    0x00000000, 0x00400010, 0x20004010, 0x00004000, 0x00404000, 0x20004010, 0x00000010, 0x20400010,
    0x20400010, 0x00000000, 0x00404010, 0x20404000, 0x00004010, 0x00404000, 0x20404000, 0x20000000,
    0x20004000, 0x00000010, 0x20400010, 0x00404000, 0x20404010, 0x00400000, 0x00004010, 0x20000010,
    0x00400000, 0x20004000, 0x20000000, 0x00004010, 0x20000010, 0x20404010, 0x00404000, 0x20400000,
    0x00404010, 0x20404000, 0x00000000, 0x20400010, 0x00000010, 0x00004000, 0x20400000, 0x00404010,
    0x00004000, 0x00400010, 0x20004010, 0x00000000, 0x20404000, 0x20000000, 0x00400010, 0x20004010,
};
static const u32 table6[0x40] = {
    0x00200000, 0x04200002, 0x04000802, 0x00000000, 0x00000800, 0x04000802, 0x00200802, 0x04200800,
    0x04200802, 0x00200000, 0x00000000, 0x04000002, 0x00000002, 0x04000000, 0x04200002, 0x00000802,
    0x04000800, 0x00200802, 0x00200002, 0x04000800, 0x04000002, 0x04200000, 0x04200800, 0x00200002,
    0x04200000, 0x00000800, 0x00000802, 0x04200802, 0x00200800, 0x00000002, 0x04000000, 0x00200800,
    0x04000000, 0x00200800, 0x00200000, 0x04000802, 0x04000802, 0x04200002, 0x04200002, 0x00000002,
    0x00200002, 0x04000000, 0x04000800, 0x00200000, 0x04200800, 0x00000802, 0x00200802, 0x04200800,
    0x00000802, 0x04000002, 0x04200802, 0x04200000, 0x00200800, 0x00000000, 0x00000002, 0x04200802,
    0x00000000, 0x00200802, 0x04200000, 0x00000800, 0x04000002, 0x04000800, 0x00000800, 0x00200002,
};
static const u32 table7[0x40] = {
    0x10001040, 0x00001000, 0x00040000, 0x10041040, 0x10000000, 0x10001040, 0x00000040, 0x10000000,
    0x00040040, 0x10040000, 0x10041040, 0x00041000, 0x10041000, 0x00041040, 0x00001000, 0x00000040,
    0x10040000, 0x10000040, 0x10001000, 0x00001040, 0x00041000, 0x00040040, 0x10040040, 0x10041000,
    0x00001040, 0x00000000, 0x00000000, 0x10040040, 0x10000040, 0x10001000, 0x00041040, 0x00040000,
    0x00041040, 0x00040000, 0x10041000, 0x00001000, 0x00000040, 0x10040040, 0x00001000, 0x00041040,
    0x10001000, 0x00000040, 0x10000040, 0x10040000, 0x10040040, 0x10000000, 0x00040000, 0x10001040,
    0x00000000, 0x10041040, 0x00040040, 0x10000040, 0x10040000, 0x10001000, 0x10001040, 0x00000000,
    0x10041040, 0x00041000, 0x00041000, 0x00001040, 0x00001040, 0x00040040, 0x10000000, 0x10041000,
};

static void generateseeds(u32* seeds, const u8* seedtable, u8 doreverse)
{
  u32 tmp3;
  u8 array0[0x38], array1[0x38], array2[0x08];
  u8 tmp, tmp2;

  for (int i = 0; i < 0x38; ++i)
  {
    tmp = (gentable0[i] - 1);
    array0[i] = ((u32)(0 - (seedtable[tmp >> 3] & gentable1[tmp & 7])) >> 31);
  }

  for (int i = 0; i < 0x10; ++i)
  {
    memset(array2, 0, 8);
    tmp2 = gentable2[i];

    for (int j = 0; j < 0x38; j++)
    {
      tmp = (tmp2 + j);

      if (j > 0x1B)
      {
        if (tmp > 0x37)
        {
          tmp -= 0x1C;
        }
      }
      else if (tmp > 0x1B)
      {
        tmp -= 0x1C;
      }

      array1[j] = array0[tmp];
    }
    for (int j = 0; j < 0x30; j++)
    {
      if (!array1[gentable3[j] - 1])
      {
        continue;
      }
      tmp = (((j * 0x2AAB) >> 16) - (j >> 0x1F));
      array2[tmp] |= (gentable1[j - (tmp * 6)] >> 2);
    }
    seeds[i << 1] = ((array2[0] << 24) | (array2[2] << 16) | (array2[4] << 8) | array2[6]);
    seeds[(i << 1) + 1] = ((array2[1] << 24) | (array2[3] << 16) | (array2[5] << 8) | array2[7]);
  }

  if (!doreverse)
  {
    int j = 0x1F;
    for (int i = 0; i < 16; i += 2)
    {
      tmp3 = seeds[i];
      seeds[i] = seeds[j - 1];
      seeds[j - 1] = tmp3;

      tmp3 = seeds[i + 1];
      seeds[i + 1] = seeds[j];
      seeds[j] = tmp3;
      j -= 2;
    }
  }
}

static void buildseeds()
{
  generateseeds(genseeds, gensubtable, 0);
}

static void getcode(const u32* src, u32* addr, u32* val)
{
  *addr = Common::swap32(src[0]);
  *val = Common::swap32(src[1]);
}

static void setcode(u32* dst, u32 addr, u32 val)
{
  dst[0] = Common::swap32(addr);
  dst[1] = Common::swap32(val);
}

static u16 gencrc16(const u32* codes, u16 size)
{
  u16 ret = 0;

  if (size > 0)
  {
    for (u8 tmp = 0; tmp < size; ++tmp)
    {
      for (int i = 0; i < 4; ++i)
      {
        u8 tmp2 = ((codes[tmp] >> (i << 3)) ^ ret);
        ret = ((crctable0[(tmp2 >> 4) & 0x0F] ^ crctable1[tmp2 & 0x0F]) ^ (ret >> 8));
      }
    }
  }
  return ret;
}

static u8 verifycode(const u32* codes, u16 size)
{
  u16 tmp = gencrc16(codes, size);
  return (((tmp >> 12) ^ (tmp >> 8) ^ (tmp >> 4) ^ tmp) & 0x0F);
}

static void unscramble1(u32* addr, u32* val)
{
  u32 tmp;

  *val = Common::RotateLeft(*val, 4);

  tmp = ((*addr ^ *val) & 0xF0F0F0F0);
  *addr ^= tmp;
  *val = Common::RotateRight((*val ^ tmp), 0x14);

  tmp = ((*addr ^ *val) & 0xFFFF0000);
  *addr ^= tmp;
  *val = Common::RotateRight((*val ^ tmp), 0x12);

  tmp = ((*addr ^ *val) & 0x33333333);
  *addr ^= tmp;
  *val = Common::RotateRight((*val ^ tmp), 6);

  tmp = ((*addr ^ *val) & 0x00FF00FF);
  *addr ^= tmp;
  *val = Common::RotateLeft((*val ^ tmp), 9);

  tmp = ((*addr ^ *val) & 0xAAAAAAAA);
  *addr = Common::RotateLeft((*addr ^ tmp), 1);
  *val ^= tmp;
}

static void unscramble2(u32* addr, u32* val)
{
  u32 tmp;

  *val = Common::RotateRight(*val, 1);

  tmp = ((*addr ^ *val) & 0xAAAAAAAA);
  *val ^= tmp;
  *addr = Common::RotateRight((*addr ^ tmp), 9);

  tmp = ((*addr ^ *val) & 0x00FF00FF);
  *val ^= tmp;
  *addr = Common::RotateLeft((*addr ^ tmp), 6);

  tmp = ((*addr ^ *val) & 0x33333333);
  *val ^= tmp;
  *addr = Common::RotateLeft((*addr ^ tmp), 0x12);

  tmp = ((*addr ^ *val) & 0xFFFF0000);
  *val ^= tmp;
  *addr = Common::RotateLeft((*addr ^ tmp), 0x14);

  tmp = ((*addr ^ *val) & 0xF0F0F0F0);
  *val ^= tmp;
  *addr = Common::RotateRight((*addr ^ tmp), 4);
}

static void decryptcode(const u32* seeds, u32* code)
{
  u32 addr, val;
  u32 tmp, tmp2;
  int i = 0;

  getcode(code, &addr, &val);
  unscramble1(&addr, &val);
  while (i < 32)
  {
    tmp = (Common::RotateRight(val, 4) ^ seeds[i++]);
    tmp2 = (val ^ seeds[i++]);
    addr ^= (table6[tmp & 0x3F] ^ table4[(tmp >> 8) & 0x3F] ^ table2[(tmp >> 16) & 0x3F] ^
             table0[(tmp >> 24) & 0x3F] ^ table7[tmp2 & 0x3F] ^ table5[(tmp2 >> 8) & 0x3F] ^
             table3[(tmp2 >> 16) & 0x3F] ^ table1[(tmp2 >> 24) & 0x3F]);

    tmp = (Common::RotateRight(addr, 4) ^ seeds[i++]);
    tmp2 = (addr ^ seeds[i++]);
    val ^= (table6[tmp & 0x3F] ^ table4[(tmp >> 8) & 0x3F] ^ table2[(tmp >> 16) & 0x3F] ^
            table0[(tmp >> 24) & 0x3F] ^ table7[tmp2 & 0x3F] ^ table5[(tmp2 >> 8) & 0x3F] ^
            table3[(tmp2 >> 16) & 0x3F] ^ table1[(tmp2 >> 24) & 0x3F]);
  }
  unscramble2(&addr, &val);
  setcode(code, val, addr);
}

static bool getbitstring(u32* ctrl, u32* out, u8 len)
{
  u32 tmp = (ctrl[0] + (ctrl[1] << 2));

  *out = 0;
  while (len--)
  {
    if (ctrl[2] > 0x1F)
    {
      ctrl[2] = 0;
      ctrl[1]++;
      tmp = (ctrl[0] + (ctrl[1] << 2));
    }
    if (ctrl[1] >= ctrl[3])
    {
      return false;
    }
    *out = ((*out << 1) | ((tmp >> (0x1F - ctrl[2])) & 1));
    ctrl[2]++;
  }
  return true;
}

static bool batchdecrypt(u32* codes, u16 size)
{
  u32 tmp, *ptr = codes;
  u32 tmparray[4] = {0}, tmparray2[8] = {0};

  // Not required
  // if (size & 1) return 0;
  // if (!size) return 0;

  tmp = (size >> 1);
  while (tmp--)
  {
    decryptcode(genseeds, ptr);
    ptr += 2;
  }

  tmparray[0] = *codes;
  tmparray[1] = 0;
  tmparray[2] = 4;  // Skip crc
  tmparray[3] = size;
  getbitstring(tmparray, tmparray2 + 1, 11);  // Game id
  getbitstring(tmparray, tmparray2 + 2, 17);  // Code id
  getbitstring(tmparray, tmparray2 + 3, 1);   // Master code
  getbitstring(tmparray, tmparray2 + 4, 1);   // Unknown
  getbitstring(tmparray, tmparray2 + 5, 2);   // Region

  // Grab gameid and region from the last decrypted code
  // TODO: Maybe check this against Dolphin's GameID? - "code is for wrong game" type msg
  // gameid = tmparray2[1];
  // region = tmparray2[5];

  tmp = codes[0];
  codes[0] &= 0x0FFFFFFF;
  if ((tmp >> 28) != verifycode(codes, size))
  {
    return false;
  }

  return true;

  // Unfinished (so says Parasyte :p )
}

static int GetVal(const char* flt, char chr)
{
  int ret = (int)(strchr(flt, chr) - flt);
  switch (ret)
  {
  case 32:  // 'I'
  case 33:  // 'L'
    ret = 1;
    break;
  case 34:  // 'O'
    ret = 0;
    break;
  case 35:  // 'S'
    ret = 5;
    break;
  }
  return ret;
}

static int alphatobin(u32* dst, const std::vector<std::string>& alpha, int size)
{
  int j = 0;
  int ret = 0;
  int org = size + 1;
  u32 bin[2];
  u8 parity;

  for (; size; --size)
  {
    bin[0] = 0;
    for (int i = 0; i < 6; i++)
    {
      bin[0] |= (GetVal(filter, alpha[j >> 1][i]) << (((5 - i) * 5) + 2));
    }
    bin[0] |= (GetVal(filter, alpha[j >> 1][6]) >> 3);
    dst[j++] = bin[0];

    bin[1] = 0;
    for (int i = 0; i < 6; i++)
    {
      bin[1] |= (GetVal(filter, alpha[j >> 1][i + 6]) << (((5 - i) * 5) + 4));
    }
    bin[1] |= (GetVal(filter, alpha[j >> 1][12]) >> 1);
    dst[j++] = bin[1];

    // verify parity bit
    int k = 0;
    parity = 0;
    for (int i = 0; i < 64; i++)
    {
      if (i == 32)
      {
        k++;
      }
      parity ^= (bin[k] >> (i - (k << 5)));
    }
    if ((parity & 1) != (GetVal(filter, alpha[(j - 2) >> 1][12]) & 1))
    {
      ret = (org - size);
    }
  }

  return ret;
}

void DecryptARCode(std::vector<std::string> vCodes, std::vector<AREntry>* ops)
{
  // The almighty buildseeds() function!! without this, the crypto routines are useless
  buildseeds();

  u32 uCodes[1200];
  u32 ret;

  for (std::string& s : vCodes)
  {
    std::transform(s.begin(), s.end(), s.begin(), toupper);
  }

  ret = alphatobin(uCodes, vCodes, (int)vCodes.size());
  if (ret)
  {
    // Return value is index + 1, 0 being the success flag value.
    PanicAlertT("Action Replay Code Decryption Error:\nParity Check Failed\n\nCulprit Code:\n%s",
                vCodes[ret - 1].c_str());
  }
  else if (!batchdecrypt(uCodes, (u16)vCodes.size() << 1))
  {
    // Commented out since we just send the code anyways and hope for the best XD
    // PanicAlert("Action Replay Code Decryption Error:\nCRC Check Failed\n\n"
    // "First Code in Block(should be verification code):\n%s", vCodes[0].c_str());

    for (size_t i = 0; i < (vCodes.size() << 1); i += 2)
    {
      ops->emplace_back(uCodes[i], uCodes[i + 1]);
      // PanicAlert("Decrypted AR Code without verification code:\n%08X %08X", uCodes[i],
      // uCodes[i+1]);
    }
  }
  else
  {
    // Skip passing the verification code back
    for (size_t i = 2; i < (vCodes.size() << 1); i += 2)
    {
      ops->emplace_back(uCodes[i], uCodes[i + 1]);
      // PanicAlert("Decrypted AR Code:\n%08X %08X", uCodes[i], uCodes[i+1]);
    }
  }
}

}  // namespace ActionReplay