#include "sha256.h"

#include <cstring>

namespace roro {

namespace {
const uint32_t K[64] = {
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
    0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
    0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
    0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
    0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
    0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};

inline uint32_t rotr(uint32_t x, int n) { return (x >> n) | (x << (32 - n)); }
}  // namespace

Sha256::Sha256() {
    const uint32_t init[8] = {0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
                              0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19};
    std::memcpy(h_, init, sizeof(h_));
}

void Sha256::block(const uint8_t* p) {
    uint32_t w[64];
    for (int i = 0; i < 16; i++)
        w[i] = (uint32_t(p[4 * i]) << 24) | (uint32_t(p[4 * i + 1]) << 16) | (uint32_t(p[4 * i + 2]) << 8) | p[4 * i + 3];
    for (int i = 16; i < 64; i++) {
        uint32_t s0 = rotr(w[i - 15], 7) ^ rotr(w[i - 15], 18) ^ (w[i - 15] >> 3);
        uint32_t s1 = rotr(w[i - 2], 17) ^ rotr(w[i - 2], 19) ^ (w[i - 2] >> 10);
        w[i] = w[i - 16] + s0 + w[i - 7] + s1;
    }
    uint32_t a = h_[0], b = h_[1], c = h_[2], d = h_[3], e = h_[4], f = h_[5], g = h_[6], h = h_[7];
    for (int i = 0; i < 64; i++) {
        uint32_t t1 = h + (rotr(e, 6) ^ rotr(e, 11) ^ rotr(e, 25)) + ((e & f) ^ (~e & g)) + K[i] + w[i];
        uint32_t t2 = (rotr(a, 2) ^ rotr(a, 13) ^ rotr(a, 22)) + ((a & b) ^ (a & c) ^ (b & c));
        h = g;
        g = f;
        f = e;
        e = d + t1;
        d = c;
        c = b;
        b = a;
        a = t1 + t2;
    }
    h_[0] += a; h_[1] += b; h_[2] += c; h_[3] += d;
    h_[4] += e; h_[5] += f; h_[6] += g; h_[7] += h;
}

void Sha256::update(const uint8_t* data, size_t len) {
    bits_ += static_cast<uint64_t>(len) * 8;
    while (len > 0) {
        size_t take = 64 - used_ < len ? 64 - used_ : len;
        std::memcpy(buf_ + used_, data, take);
        used_ += take;
        data += take;
        len -= take;
        if (used_ == 64) {
            block(buf_);
            used_ = 0;
        }
    }
}

void Sha256::finish(uint8_t out[32]) {
    uint64_t bits = bits_;
    uint8_t pad = 0x80;
    update(&pad, 1);
    uint8_t zero = 0;
    while (used_ != 56) update(&zero, 1);
    uint8_t len[8];
    for (int i = 0; i < 8; i++) len[i] = static_cast<uint8_t>(bits >> (56 - 8 * i));
    update(len, 8);
    for (int i = 0; i < 8; i++) {
        out[4 * i] = h_[i] >> 24;
        out[4 * i + 1] = h_[i] >> 16;
        out[4 * i + 2] = h_[i] >> 8;
        out[4 * i + 3] = h_[i];
    }
}

}  // namespace roro