// VisualBoyAdvance - Nintendo Gameboy/GameboyAdvance (TM) emulator.
// Copyright (C) 1999-2003 Forgotten
// Copyright (C) 2004 Forgotten and the VBA development team

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or(at your option)
// any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

#include "../System.h"
#include "../NLS.h"
#include "../Util.h"

#include "gbCheats.h"
#include "gbGlobals.h"

gbCheat gbCheatList[100];
int gbCheatNumber = 0;
bool gbCheatMap[0x10000];

extern bool cheatsEnabled;

#define GBCHEAT_IS_HEX(a) ( ((a)>='A' && (a) <='F') || ((a) >='0' && (a) <= '9'))
#define GBCHEAT_HEX_VALUE(a) ( (a) >= 'A' ? (a) - 'A' + 10 : (a) - '0')

void gbCheatUpdateMap()
{
  memset(gbCheatMap, 0, 0x10000);

  for(int i = 0; i < gbCheatNumber; i++)
    {
      if(gbCheatList[i].enabled)
        gbCheatMap[gbCheatList[i].address] = true;
    }
}

void gbCheatsSaveGame(gzFile gzFile)
{
  utilWriteInt(gzFile, gbCheatNumber);
  if(gbCheatNumber)
    utilGzWrite(gzFile, &gbCheatList[0], sizeof(gbCheat)*gbCheatNumber);
}

void gbCheatsReadGame(gzFile gzFile, int version)
{
  if(version <= 8)
    {
      int gbGgOn = utilReadInt(gzFile);

      if(gbGgOn)
        {
          int n = utilReadInt(gzFile);
          gbXxCheat tmpCheat;
          for(int i = 0; i < n; i++)
            {
              utilGzRead(gzFile,&tmpCheat, sizeof(gbXxCheat));
              gbAddGgCheat(tmpCheat.cheatCode, tmpCheat.cheatDesc);
            }
        }

      int gbGsOn = utilReadInt(gzFile);

      if(gbGsOn)
        {
          int n = utilReadInt(gzFile);
          gbXxCheat tmpCheat;
          for(int i = 0; i < n; i++)
            {
              utilGzRead(gzFile,&tmpCheat, sizeof(gbXxCheat));
              gbAddGsCheat(tmpCheat.cheatCode, tmpCheat.cheatDesc);
            }
        }
    }
  else
    {
      gbCheatNumber = utilReadInt(gzFile);

      if(gbCheatNumber)
        {
          utilGzRead(gzFile, &gbCheatList[0], sizeof(gbCheat)*gbCheatNumber);
        }
    }

  gbCheatUpdateMap();
}

void gbCheatsSaveCheatList(const char *file)
{
  if(gbCheatNumber == 0)
    return;
  FILE* f = fopen(file, "wb");
  if(f == NULL)
    return;
  int version = 1;
  fwrite(&version, 1, sizeof(version), f);
  int type = 1;
  fwrite(&type, 1, sizeof(type), f);
  fwrite(&gbCheatNumber, 1, sizeof(gbCheatNumber), f);
  fwrite(gbCheatList, 1, sizeof(gbCheatList), f);
  fclose(f);
}

bool gbCheatsLoadCheatList(const char *file)
{
  gbCheatNumber = 0;

  gbCheatUpdateMap();

  int count = 0;

  FILE* f = fopen(file, "rb");

  if(f == NULL)
    return false;

  int version = 0;

  if(fread(&version, 1, sizeof(version), f) != sizeof(version))
    {
      fclose(f);
      return false;
    }

  if(version != 1)
    {
      systemMessage(MSG_UNSUPPORTED_CHEAT_LIST_VERSION,
                    N_("Unsupported cheat list version %d"), version);
      fclose(f);
      return false;
    }

  int type = 0;
  if(fread(&type, 1, sizeof(type), f) != sizeof(type))
    {
      fclose(f);
      return false;
    }

  if(type != 1)
    {
      systemMessage(MSG_UNSUPPORTED_CHEAT_LIST_TYPE,
                    N_("Unsupported cheat list type %d"), type);
      fclose(f);
      return false;
    }

  if(fread(&count, 1, sizeof(count), f) != sizeof(count))
    {
      fclose(f);
      return false;
    }

  if(fread(gbCheatList, 1, sizeof(gbCheatList), f) != sizeof(gbCheatList))
    {
      fclose(f);
      return false;
    }

  gbCheatNumber = count;
  gbCheatUpdateMap();

  return true;
}

bool gbVerifyGsCode(const char *code)
{
  int len = strlen(code);

  if(len == 0)
    return true;

  if(len != 8)
    return false;

  for(int i = 0; i < 8; i++)
    if(!GBCHEAT_IS_HEX(code[i]))
      return false;

  int address = GBCHEAT_HEX_VALUE(code[6]) << 12 |
                GBCHEAT_HEX_VALUE(code[7]) << 8 |
                GBCHEAT_HEX_VALUE(code[4]) << 4 |
                GBCHEAT_HEX_VALUE(code[5]);

  if(address < 0xa000 ||
      address > 0xdfff)
    return false;

  return true;
}

void gbAddGsCheat(const char *code, const char *desc)
{
  if(gbCheatNumber > 99)
    {
      systemMessage(MSG_MAXIMUM_NUMBER_OF_CHEATS,
                    N_("Maximum number of cheats reached."));
      return;
    }

  if(!gbVerifyGsCode(code))
    {
      systemMessage(MSG_INVALID_GAMESHARK_CODE,
                    N_("Invalid GameShark code: %s"), code);
      return;
    }

  int i = gbCheatNumber;

  strcpy(gbCheatList[i].cheatCode, code);
  strcpy(gbCheatList[i].cheatDesc, desc);

  gbCheatList[i].code = GBCHEAT_HEX_VALUE(code[0]) << 4 |
                        GBCHEAT_HEX_VALUE(code[1]);

  gbCheatList[i].value = GBCHEAT_HEX_VALUE(code[2]) << 4 |
                         GBCHEAT_HEX_VALUE(code[3]);

  gbCheatList[i].address = GBCHEAT_HEX_VALUE(code[6]) << 12 |
                           GBCHEAT_HEX_VALUE(code[7]) << 8 |
                           GBCHEAT_HEX_VALUE(code[4]) << 4 |
                           GBCHEAT_HEX_VALUE(code[5]);

  gbCheatList[i].compare = 0;

  gbCheatList[i].enabled = true;

  gbCheatMap[gbCheatList[i].address] = true;

  gbCheatNumber++;
}

bool gbVerifyGgCode(const char *code)
{
  int len = strlen(code);

  if(len != 11 &&
      len != 7 &&
      len != 6 &&
      len != 0)
    return false;

  if(len == 0)
    return true;

  if(!GBCHEAT_IS_HEX(code[0]))
    return false;
  if(!GBCHEAT_IS_HEX(code[1]))
    return false;
  if(!GBCHEAT_IS_HEX(code[2]))
    return false;
  if(code[3] != '-')
    return false;
  if(!GBCHEAT_IS_HEX(code[4]))
    return false;
  if(!GBCHEAT_IS_HEX(code[5]))
    return false;
  if(!GBCHEAT_IS_HEX(code[6]))
    return false;
  if(code[7] != 0)
    {
      if(code[7] != '-')
        return false;
      if(code[8] != 0)
        {
          if(!GBCHEAT_IS_HEX(code[8]))
            return false;
          if(!GBCHEAT_IS_HEX(code[9]))
            return false;
          if(!GBCHEAT_IS_HEX(code[10]))
            return false;
        }
    }

  //  int replace = (GBCHEAT_HEX_VALUE(code[0]) << 4) +
  //    GBCHEAT_HEX_VALUE(code[1]);

  int address = (GBCHEAT_HEX_VALUE(code[2]) << 8) +
                (GBCHEAT_HEX_VALUE(code[4]) << 4) +
                (GBCHEAT_HEX_VALUE(code[5])) +
                ((GBCHEAT_HEX_VALUE(code[6]) ^ 0x0f) << 12);

  if(address >= 0x8000 && address <= 0x9fff)
    return false;

  if(address >= 0xc000)
    return false;

  if(code[7] == 0 || code[8] == '0')
    return true;

  int compare = (GBCHEAT_HEX_VALUE(code[8]) << 4) +
                (GBCHEAT_HEX_VALUE(code[10]));
  compare = compare ^ 0xff;
  compare = (compare >> 2) | ( (compare << 6) & 0xc0);
  compare ^= 0x45;

  int cloak = (GBCHEAT_HEX_VALUE(code[8])) ^ (GBCHEAT_HEX_VALUE(code[9]));

  if(cloak >=1 && cloak <= 7)
    return false;

  return true;
}

void gbAddGgCheat(const char *code, const char *desc)
{
  if(gbCheatNumber > 99)
    {
      systemMessage(MSG_MAXIMUM_NUMBER_OF_CHEATS,
                    N_("Maximum number of cheats reached."));
      return;
    }

  if(!gbVerifyGgCode(code))
    {
      systemMessage(MSG_INVALID_GAMEGENIE_CODE,
                    N_("Invalid GameGenie code: %s"), code);
      return;
    }

  int i = gbCheatNumber;

  int len = strlen(code);

  strcpy(gbCheatList[i].cheatCode, code);
  strcpy(gbCheatList[i].cheatDesc, desc);

  gbCheatList[i].code = 1;
  gbCheatList[i].value = (GBCHEAT_HEX_VALUE(code[0]) << 4) +
                         GBCHEAT_HEX_VALUE(code[1]);

  gbCheatList[i].address = (GBCHEAT_HEX_VALUE(code[2]) << 8) +
                           (GBCHEAT_HEX_VALUE(code[4]) << 4) +
                           (GBCHEAT_HEX_VALUE(code[5])) +
                           ((GBCHEAT_HEX_VALUE(code[6]) ^ 0x0f) << 12);

  gbCheatList[i].compare = 0;

  if(len != 7 && len != 8)
    {

      int compare = (GBCHEAT_HEX_VALUE(code[8]) << 4) +
                    (GBCHEAT_HEX_VALUE(code[10]));
      compare = compare ^ 0xff;
      compare = (compare >> 2) | ( (compare << 6) & 0xc0);
      compare ^= 0x45;

      gbCheatList[i].compare = compare;
      gbCheatList[i].code = 0;
    }

  gbCheatList[i].enabled = true;

  gbCheatMap[gbCheatList[i].address] = true;

  gbCheatNumber++;
}

void gbCheatRemove(int i)
{
  if(i < 0 || i >= gbCheatNumber)
    {
      systemMessage(MSG_INVALID_CHEAT_TO_REMOVE,
                    N_("Invalid cheat to remove %d"), i);
      return;
    }

  if((i+1) <  gbCheatNumber)
    {
      memcpy(&gbCheatList[i], &gbCheatList[i+1], sizeof(gbCheat)*
             (gbCheatNumber-i-1));
    }

  gbCheatNumber--;

  gbCheatUpdateMap();
}

void gbCheatRemoveAll()
{
  gbCheatNumber = 0;
  gbCheatUpdateMap();
}

void gbCheatEnable(int i)
{
  if(i >=0 && i < gbCheatNumber)
    {
      if(!gbCheatList[i].enabled)
        {
          gbCheatList[i].enabled = true;
          gbCheatUpdateMap();
        }
    }
}

void gbCheatDisable(int i)
{
  if(i >=0 && i < gbCheatNumber)
    {
      if(gbCheatList[i].enabled)
        {
          gbCheatList[i].enabled = false;
          gbCheatUpdateMap();
        }
    }
}

bool gbCheatReadGSCodeFile(const char *fileName)
{
  FILE* file = fopen(fileName, "rb");

  if(!file)
    {
      systemMessage(MSG_CANNOT_OPEN_FILE, N_("Cannot open file %s"), fileName);
      return false;
    }

  fseek(file, 0x18, SEEK_SET);
  int count = 0;
  fread(&count, 1, 2, file);
  int dummy = 0;
  gbCheatRemoveAll();
  char desc[13];
  char code[9];
  int i;
  for(i = 0; i < count; i++)
    {
      fread(&dummy, 1, 2, file);
      fread(desc, 1, 12, file);
      desc[12] = 0;
      fread(code, 1, 8, file);
      code[8] = 0;
      gbAddGsCheat(code, desc);
    }

  for(i = 0; i < gbCheatNumber; i++)
    gbCheatDisable(i);

  fclose(file);
  return true;
}

u8 gbCheatRead(u16 address)
{
  if(!cheatsEnabled)
    return gbMemoryMap[address>>12][address & 0xFFF];

  for(int i = 0; i < gbCheatNumber; i++)
    {
      if(gbCheatList[i].enabled && gbCheatList[i].address == address)
        {
          switch(gbCheatList[i].code)
            {
            case 0x100: // GameGenie support
              if(gbMemoryMap[address>>12][address&0xFFF] == gbCheatList[i].compare)
                return gbCheatList[i].value;
              break;
            case 0x00:
            case 0x01:
            case 0x80:
              return gbCheatList[i].value;
            case 0x90:
            case 0x91:
            case 0x92:
            case 0x93:
            case 0x94:
            case 0x95:
            case 0x96:
            case 0x97:
              if(address >= 0xd000 && address < 0xe000)
                {
                  if(((gbMemoryMap[0x0d] - gbWram)/0x1000) ==
                      (gbCheatList[i].code - 0x90))
                    return gbCheatList[i].value;
                }
              else
                return gbCheatList[i].value;
            }
        }
    }
  return gbMemoryMap[address>>12][address&0xFFF];
}