#include "utils.h"

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

#include "mbedtls/sha256.h"

#ifndef bswap_16
#define bswap_16(a) ((((uint16_t)(a) << 8) & 0xff00) | (((uint16_t)(a) >> 8) & 0xff))
#endif

#ifndef bswap_32
#define bswap_32(a) ((((uint32_t)(a) << 24) & 0xff000000) | \
                     (((uint32_t)(a) << 8) & 0xff0000) |    \
                     (((uint32_t)(a) >> 8) & 0xff00) |      \
                     (((uint32_t)(a) >> 24) & 0xff))
#endif

/*
 * General byte order swapping functions.
 */
#define bswap16(x) __bswap16(x)
#define bswap32(x) __bswap32(x)
#define bswap64(x) __bswap64(x)

uint32_t swab32(uint32_t v)
{
    return bswap_32(v);
}

// takes 80 bytes and flips every 4 bytes
void flip80bytes(void *dest_p, const void *src_p)
{
    uint32_t *dest = dest_p;
    const uint32_t *src = src_p;
    int i;

    for (i = 0; i < 20; i++)
        dest[i] = swab32(src[i]);
}

void flip64bytes(void *dest_p, const void *src_p)
{
    uint32_t *dest = dest_p;
    const uint32_t *src = src_p;
    int i;

    for (i = 0; i < 16; i++)
        dest[i] = swab32(src[i]);
}

void flip32bytes(void *dest_p, const void *src_p)
{
    uint32_t *dest = dest_p;
    const uint32_t *src = src_p;
    int i;

    for (i = 0; i < 8; i++)
        dest[i] = swab32(src[i]);
}

int hex2char(uint8_t x, char *c)
{
    if (x <= 9)
    {
        *c = x + '0';
    }
    else if (x <= 15)
    {
        *c = x - 10 + 'a';
    }
    else
    {
        return -1;
    }

    return 0;
}

size_t bin2hex(const uint8_t *buf, size_t buflen, char *hex, size_t hexlen)
{
    if ((hexlen + 1) < buflen * 2)
    {
        return 0;
    }

    for (size_t i = 0; i < buflen; i++)
    {
        if (hex2char(buf[i] >> 4, &hex[2 * i]) < 0)
        {
            return 0;
        }
        if (hex2char(buf[i] & 0xf, &hex[2 * i + 1]) < 0)
        {
            return 0;
        }
    }

    hex[2 * buflen] = '\0';
    return 2 * buflen;
}

uint8_t hex2val(char c)
{
    if (c >= '0' && c <= '9')
    {
        return c - '0';
    }
    else if (c >= 'a' && c <= 'f')
    {
        return c - 'a' + 10;
    }
    else if (c >= 'A' && c <= 'F')
    {
        return c - 'A' + 10;
    }
    else
    {
        return 0;
    }
}

size_t hex2bin(const char *hex, uint8_t *bin, size_t bin_len)
{
    size_t len = 0;

    while (*hex && len < bin_len)
    {
        bin[len] = hex2val(*hex++) << 4;

        if (!*hex)
        {
            len++;
            break;
        }

        bin[len++] |= hex2val(*hex++);
    }

    return len;
}

void print_hex(const uint8_t *b, size_t len,
               const size_t in_line, const char *prefix)
{
    size_t i = 0;
    const uint8_t *end = b + len;

    if (prefix == NULL)
    {
        prefix = "";
    }

    printf("%s", prefix);
    while (b < end)
    {
        if (++i > in_line)
        {
            printf("\n%s", prefix);
            i = 1;
        }
        printf("%02X ", (uint8_t)*b++);
    }
    printf("\n");
    fflush(stdout);
}

char *double_sha256(const char *hex_string)
{
    size_t bin_len = strlen(hex_string) / 2;
    uint8_t *bin = malloc(bin_len);
    hex2bin(hex_string, bin, bin_len);

    unsigned char first_hash_output[32], second_hash_output[32];

    mbedtls_sha256(bin, bin_len, first_hash_output, 0);
    mbedtls_sha256(first_hash_output, 32, second_hash_output, 0);

    free(bin);

    char *output_hash = malloc(64 + 1);
    bin2hex(second_hash_output, 32, output_hash, 65);
    return output_hash;
}

uint8_t *double_sha256_bin(const uint8_t *data, const size_t data_len)
{
    uint8_t first_hash_output[32];
    uint8_t *second_hash_output = malloc(32);

    mbedtls_sha256(data, data_len, first_hash_output, 0);
    mbedtls_sha256(first_hash_output, 32, second_hash_output, 0);

    return second_hash_output;
}

void single_sha256_bin(const uint8_t *data, const size_t data_len, uint8_t *dest)
{
    // mbedtls_sha256(data, data_len, dest, 0);

    // Initialize SHA256 context
    mbedtls_sha256_context sha256_ctx;
    mbedtls_sha256_init(&sha256_ctx);
    mbedtls_sha256_starts(&sha256_ctx, 0);

    // Compute first SHA256 hash of header
    mbedtls_sha256_update(&sha256_ctx, data, 64);
    unsigned char hash[32];
    mbedtls_sha256_finish(&sha256_ctx, hash);

    // Compute midstate from hash
    memcpy(dest, hash, 32);
}

void midstate_sha256_bin(const uint8_t *data, const size_t data_len, uint8_t *dest)
{
    mbedtls_sha256_context midstate;

    // Calculate midstate
    mbedtls_sha256_init(&midstate);
    mbedtls_sha256_starts(&midstate, 0);
    mbedtls_sha256_update(&midstate, data, 64);

    // memcpy(dest, midstate.state, 32);
    flip32bytes(dest, midstate.state);
}

void swap_endian_words(const char *hex_words, uint8_t *output)
{
    size_t hex_length = strlen(hex_words);
    if (hex_length % 8 != 0)
    {
        fprintf(stderr, "Must be 4-byte word aligned\n");
        exit(EXIT_FAILURE);
    }

    size_t binary_length = hex_length / 2;

    for (size_t i = 0; i < binary_length; i += 4)
    {
        for (int j = 0; j < 4; j++)
        {
            unsigned int byte_val;
            sscanf(hex_words + (i + j) * 2, "%2x", &byte_val);
            output[i + (3 - j)] = byte_val;
        }
    }
}

void reverse_bytes(uint8_t *data, size_t len)
{
    for (int i = 0; i < len / 2; ++i)
    {
        uint8_t temp = data[i];
        data[i] = data[len - 1 - i];
        data[len - 1 - i] = temp;
    }
}

// static const double truediffone = 26959535291011309493156476344723991336010898738574164086137773096960.0;
static const double bits192 = 6277101735386680763835789423207666416102355444464034512896.0;
static const double bits128 = 340282366920938463463374607431768211456.0;
static const double bits64 = 18446744073709551616.0;

/* Converts a little endian 256 bit value to a double */
double le256todouble(const void *target)
{
    uint64_t *data64;
    double dcut64;

    data64 = (uint64_t *)(target + 24);
    dcut64 = *data64 * bits192;

    data64 = (uint64_t *)(target + 16);
    dcut64 += *data64 * bits128;

    data64 = (uint64_t *)(target + 8);
    dcut64 += *data64 * bits64;

    data64 = (uint64_t *)(target);
    dcut64 += *data64;

    return dcut64;
}

void prettyHex(unsigned char *buf, int len)
{
    int i;
    printf("[");
    for (i = 0; i < len - 1; i++)
    {
        printf("%02X ", buf[i]);
    }
    printf("%02X]\n", buf[len - 1]);
}

uint32_t flip32(uint32_t val)
{
    uint32_t ret = 0;
    ret |= (val & 0xFF) << 24;
    ret |= (val & 0xFF00) << 8;
    ret |= (val & 0xFF0000) >> 8;
    ret |= (val & 0xFF000000) >> 24;
    return ret;
}