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

void RangerCrypto(unsigned int *data, int size)
{
    unsigned int i; // r5
    unsigned int rand; // ST04_4
    unsigned int h_rand; // r0
    unsigned int s_rand = data[0]; // the initial seed is located before the encrypted data

    for(i = 1; i < size; i++)
    {
        rand = 1566083941 * s_rand;
        h_rand = rand;
        s_rand = 1566083941 * rand;
        data[i] ^= (h_rand & 0xFFFF0000) | (s_rand >> 16);
    }
}

int crc16_table[] =
{
    0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
    0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
    0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
    0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
    0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
    0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
    0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
    0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
    0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
    0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
    0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
    0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
    0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
    0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
    0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
    0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
    0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
    0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
    0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
    0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
    0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
    0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
    0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
    0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
    0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
    0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
    0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
    0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
    0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
    0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
    0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
    0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040
};

unsigned int CRC16(char *data, int size)
{
    unsigned int chk = 0;
    int i;
    for (i = 0; i < size; i++)
    {
        chk = (crc16_table[(data[i] ^ chk) & 0xFF] ^ chk >> 8);
    }
    return chk;
}

int main(int argc, char** argv)
{
	if(argc < 2)
	{
		printf("Argument error!\n");
		return 0;
	}

	FILE *sav = fopen(argv[1], "rwb+");
	if (!sav)
	{
		printf("Reading failed!\n");
		return 0;
	}

	fseek(sav, 0, SEEK_END);
	int size = ftell(sav);
	rewind(sav);

    char *pkr = (char *)malloc(0xC);
    char pkr2[] = { 0x50, 0x4B, 0x52, 0x2D, 0x30, 0x35, 0x39, 0x00, 0x61, 0x30, 0x30, 0x00 }; // PKR-059 a00
    fread(pkr, 1, 0xC, sav);
	rewind(sav);

	if((size == 0x40000 || size == 0x4007A || size == 0x10000 || size == 0x1007A) && !strcmp(pkr, pkr2)) // Jap: 256kb, EU/US: 65kb
    {
        unsigned int *saveinfo = (unsigned int *)malloc(0x1F4);
        fseek(sav, 0xC, SEEK_SET);
        fread(saveinfo, 1, 0x1F4, sav);

        if(saveinfo[1] >> 16 != 0)
        {
            RangerCrypto(saveinfo, 0x7D);
            fseek(sav, 0xC, SEEK_SET);
            fwrite(saveinfo, 1, 0x1F4, sav);
        }
        else
        {
            unsigned int *tmp = (unsigned int *)malloc(0x1F4);
            memcpy(tmp, saveinfo, 0x1F4);

            if(tmp[1] >> 16 == 0) // if decrypted fix checksum before encrypting
            {
                tmp[1] = CRC16((char*)tmp+8, 0x1EC);
            }

            RangerCrypto(tmp, 0x7D);
            fseek(sav, 0xC, SEEK_SET);
            fwrite(tmp, 1, 0x1F4, sav);
            free(tmp);
        }

        unsigned int *saveinfo2 = (unsigned int *)malloc(0x1F4);
        fseek(sav, 0x20C, SEEK_SET);
        fread(saveinfo2, 1, 0x1F4, sav);

        if(saveinfo2[1] >> 16 == 0) // if decrypted fix checksum before encrypting
        {
            saveinfo2[1] = CRC16((char*)saveinfo2+8, 0x1EC);
        }

        RangerCrypto(saveinfo2, 0x7D);
        fseek(sav, 0x20C, SEEK_SET);
        fwrite(saveinfo2, 1, 0x1F4, sav);
        free(saveinfo2);

        int c;
        for(c = 0; c < 10; c++)
        {
            unsigned int chunknumber = saveinfo[0xC + (c*0xC)] >> 16 & 0xFF;
            unsigned int chunkoffset = saveinfo[0xD + (c*0xC)];
            unsigned int datasize = saveinfo[0xE + (c*0xC)];
            unsigned int chunksize = saveinfo[0xF + (c*0xC)] / chunknumber;

            if(chunkoffset != 0 && chunksize <= 0x40000)
            {
                int i;
                for(i = 0; (i < chunknumber) && (i < 3); i++)
                {
                    unsigned int *chunk = (unsigned int *)malloc(chunksize);

                    fseek(sav, chunkoffset + (chunksize*i), SEEK_SET);
                    fread(chunk, 1, chunksize, sav);

                    if(chunk[1] >> 16 == 0 && chunk[1] & 0xFFFF != 0) // if decrypted fix checksum before encrypting
                    {
                        chunk[1] = CRC16((char*)chunk+0x18, datasize);
                    }

                    RangerCrypto(chunk, ((datasize+0x18)/4));

                    fseek(sav, chunkoffset + (chunksize*i), SEEK_SET);
                    fwrite(chunk, 1, chunksize, sav);

                    free(chunk);
                }
            }
        }

        free(saveinfo);
    }

	fclose(sav);
	
	printf("Done!\n");

	return 0;
}