#include <stdlib.h>
#include <stdint.h>

#include "scrypt.h"
#include "pbkdf2.h"

#include "util.h"
#include "net.h"

#define SCRYPT_BUFFER_SIZE (131072 + 63)

extern "C" void scrypt_core(unsigned int *X, unsigned int *V);

/* cpu and memory intensive function to transform a 80 byte buffer into a 32 byte output
   scratchpad size needs to be at least 63 + (128 * r * p) + (256 * r + 64) + (128 * r * N) bytes
   r = 1, p = 1, N = 1024
 */

uint256 scrypt_nosalt(const void* input, size_t inputlen, void *scratchpad)
{
    unsigned int *V;
    unsigned int X[32];
    uint256 result = 0;
    V = (unsigned int *)(((uintptr_t)(scratchpad) + 63) & ~ (uintptr_t)(63));

    PBKDF2_SHA256((const uint8_t*)input, inputlen, (const uint8_t*)input, inputlen, 1, (uint8_t *)X, 128);
    scrypt_core(X, V);
    PBKDF2_SHA256((const uint8_t*)input, inputlen, (uint8_t *)X, 128, 1, (uint8_t*)&result, 32);

    return result;
}

uint256 scrypt(const void* data, size_t datalen, const void* salt, size_t saltlen, void *scratchpad)
{
    unsigned int *V;
    unsigned int X[32];
    uint256 result = 0;
    V = (unsigned int *)(((uintptr_t)(scratchpad) + 63) & ~ (uintptr_t)(63));

    PBKDF2_SHA256((const uint8_t*)data, datalen, (const uint8_t*)salt, saltlen, 1, (uint8_t *)X, 128);
    scrypt_core(X, V);
    PBKDF2_SHA256((const uint8_t*)data, datalen, (uint8_t *)X, 128, 1, (uint8_t*)&result, 32);

    return result;
}

uint256 scrypt_hash(const void* input, size_t inputlen)
{
    unsigned char scratchpad[SCRYPT_BUFFER_SIZE];
    return scrypt_nosalt(input, inputlen, scratchpad);
}

uint256 scrypt_salted_hash(const void* input, size_t inputlen, const void* salt, size_t saltlen)
{
    unsigned char scratchpad[SCRYPT_BUFFER_SIZE];
    return scrypt(input, inputlen, salt, saltlen, scratchpad);
}

uint256 scrypt_salted_multiround_hash(const void* input, size_t inputlen, const void* salt, size_t saltlen, const unsigned int nRounds)
{
    uint256 resultHash = scrypt_salted_hash(input, inputlen, salt, saltlen);
    uint256 transitionalHash = resultHash;

    for(unsigned int i = 1; i < nRounds; i++)
    {
        resultHash = scrypt_salted_hash(input, inputlen, (const void*)&transitionalHash, 32);
        transitionalHash = resultHash;
    }

    return resultHash;
}

uint256 scrypt_blockhash(const void* input)
{
    unsigned char scratchpad[SCRYPT_BUFFER_SIZE];
    return scrypt_nosalt(input, 80, scratchpad);
}