#include <botan/blake2b.h>
#include <botan/exceptn.h>
#include <botan/mem_ops.h>
#include <botan/loadstor.h>
#include <algorithm>

namespace Botan {

namespace {
  const u64bit blake2b_IV[BLAKE2B_IVU64COUNT] = {
    0x6a09e667f3bcc908ULL, 0xbb67ae8584caa73bULL,
    0x3c6ef372fe94f82bULL, 0xa54ff53a5f1d36f1ULL,
    0x510e527fade682d1ULL, 0x9b05688c2b3e6c1fULL,
    0x1f83d9abfb41bd6bULL, 0x5be0cd19137e2179ULL
  };

  const u64bit blake2b_sigma[12][16] = {
    {  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15 } ,
    { 14, 10,  4,  8,  9, 15, 13,  6,  1, 12,  0,  2, 11,  7,  5,  3 } ,
    { 11,  8, 12,  0,  5,  2, 15, 13, 10, 14,  3,  6,  7,  1,  9,  4 } ,
    {  7,  9,  3,  1, 13, 12, 11, 14,  2,  6,  5, 10,  4,  0, 15,  8 } ,
    {  9,  0,  5,  7,  2,  4, 10, 15, 14,  1, 11, 12,  6,  8,  3, 13 } ,
    {  2, 12,  6, 10,  0, 11,  8,  3,  4, 13,  7,  5, 15, 14,  1,  9 } ,
    { 12,  5,  1, 15, 14, 13,  4, 10,  0,  7,  6,  3,  9,  2,  8, 11 } ,
    { 13, 11,  7, 14, 12,  1,  3,  9,  5,  0, 15,  4,  8,  6,  2, 10 } ,
    {  6, 15, 14,  9, 11,  3,  0,  8, 12,  2, 13,  7,  1,  4, 10,  5 } ,
    { 10,  2,  8,  4,  7,  6,  1,  5, 15, 11,  9, 14,  3, 12, 13 , 0 } ,
    {  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15 } ,
    { 14, 10,  4,  8,  9, 15, 13,  6,  1, 12,  0,  2, 11,  7,  5,  3 }
  };
}

Blake2b* Blake2b::make(const Spec& spec) {
  return new Blake2b(spec.arg_as_integer(0, 512));
}

Blake2b::Blake2b(size_t output_bits) :
      m_output_bits(output_bits),
      m_buffer(BLAKE2B_BLOCKBYTES),
      m_buflen(0),
      m_H(BLAKE2B_IVU64COUNT),
      m_T{0},
      m_F{0} {
  if(output_bits == 0 || output_bits % 8 != 0
    || output_bits / 8 > BLAKE2B_OUTBYTES) {
      throw Invalid_Argument("Bad output bits size for Blake2b");
  }
  
  state_init();
}

inline void Blake2b::state_init() {
  std::copy(std::begin(blake2b_IV), std::end(blake2b_IV), m_H.begin());
  m_H[0] ^= 0x01010000 ^ static_cast<byte>(output_length());
}

void Blake2b::compress(bool lastblock) {
  u64bit m[16];
  u64bit v[16];
  u64bit* const H = m_H.data();
  const byte* const block = m_buffer.data();

  if(lastblock) {
    m_F[0] = ~0ULL;
  }

  for(int i = 0; i < 16; i++) {
    m[i] = load_le<u64bit>(block, i);
  }

  for(int i = 0; i < 8; i++) {
    v[i] = H[i];
    v[i + 8] = blake2b_IV[i];
  }

  v[12] ^= m_T[0];
  v[13] ^= m_T[1];
  v[14] ^= m_F[0];
  v[15] ^= m_F[1];

#define rotr64(w, c) (((w) >> c) ^ ((w) << (64 - c)))

#define G(r, i, a, b, c, d) \
  do { \
    a = a + b + m[blake2b_sigma[r][2 * i + 0]]; \
    d = rotr64(d ^ a, 32); \
    c = c + d; \
    b = rotr64(b ^ c, 24); \
    a = a + b + m[blake2b_sigma[r][2 * i + 1]]; \
    d = rotr64(d ^ a, 16); \
    c = c + d; \
    b = rotr64(b ^ c, 63); \
  } while(0)

#define ROUND(r)  \
  do { \
    G(r, 0, v[0], v[4], v[8], v[12]); \
    G(r, 1, v[1], v[5], v[9], v[13]); \
    G(r, 2, v[2], v[6], v[10], v[14]); \
    G(r, 3, v[3], v[7], v[11], v[15]); \
    G(r, 4, v[0], v[5], v[10], v[15]); \
    G(r, 5, v[1], v[6], v[11], v[12]); \
    G(r, 6, v[2], v[7], v[8], v[13]); \
    G(r, 7, v[3], v[4], v[9], v[14]); \
  } while(0)

  ROUND(0);
  ROUND(1);
  ROUND(2);
  ROUND(3);
  ROUND(4);
  ROUND(5);
  ROUND(6);
  ROUND(7);
  ROUND(8);
  ROUND(9);
  ROUND(10);
  ROUND(11);

  for(int i = 0; i < 8; i++) {
    H[i] ^= v[i] ^ v[i + 8];
  }

#undef G
#undef ROUND
#undef rotr64
}

inline void Blake2b::increment_counter(const u64bit inc) {
  m_T[0] += inc;
  if(m_T[0] < inc) {
      m_T[1]++;
  }
}

void Blake2b::add_data(const byte input[], size_t length) {
  if(!input || length == 0) {
    return;
  }

  byte* const buffer = m_buffer.data();

  while(length > 0) {
    size_t fill = BLAKE2B_BLOCKBYTES - m_buflen;

    if(length <= fill) {
      std::memcpy(buffer + m_buflen, input, length);
      m_buflen += length;
      return;
    }

    std::memcpy(buffer + m_buflen, input, fill);
    increment_counter(BLAKE2B_BLOCKBYTES);
    compress();

    m_buflen = 0;
    input += fill;
    length -= fill;
  }
}

void Blake2b::final_result(byte output[]) {
  if(!output) {
    return;
  }

  byte* const buffer = m_buffer.data();
  const u64bit* const H = static_cast<const u64bit*>(m_H.data());
  u16bit outlen = static_cast<u16bit>(output_length());

  std::memset(buffer + m_buflen, 0, BLAKE2B_BLOCKBYTES - m_buflen);
  increment_counter(m_buflen);
  compress(true);

  for (u16bit i = 0; i < outlen; i++) {
    output[i] = (H[i >> 3] >> (8 * (i & 7))) & 0xFF;
  }

  clear();
}

std::string Blake2b::name() const {
  return "Blake2b(" + std::to_string(m_output_bits) + ")";
}

HashFunction* Blake2b::clone() const {
  return new Blake2b(m_output_bits);
}

void Blake2b::clear() {
  zeroise(m_H);
  zeroise(m_buffer);
  m_buflen = 0;
  m_T[0] = m_T[1] = 0;
  m_F[0] = m_F[1] = 0;
  state_init();
}

}