#include "erl_nif.h"

/*-----------------------------------------------------------------------------
 * MurmurHash3 was written by Austin Appleby, and is placed in the public
 * domain. The author hereby disclaims copyright to this source code.
 */

//-----------------------------------------------------------------------------
// Platform-specific functions and macros

// Microsoft Visual Studio

#if defined(_MSC_VER)

typedef unsigned char uint8_t;
typedef unsigned long uint32_t;
typedef unsigned __int64 uint64_t;

typedef char int8_t;
typedef long int32_t;
typedef __int64 int64_t;

#define FORCE_INLINE	__forceinline

#include <stdlib.h>

#define ROTL32(x,y)	_rotl(x,y)
#define ROTL64(x,y)	_rotl64(x,y)

#define BIG_CONSTANT(x) (x)

// Other compilers

#else	// defined(_MSC_VER)

#include <stdint.h>

#define	FORCE_INLINE inline __attribute__((always_inline))

inline uint32_t rotl32 ( int32_t x, int8_t r )
{
  // cast to unsigned for logical right bitshift (to match C* MM3 implementation)
  return (x << r) | ((int32_t) (((uint32_t) x) >> (32 - r)));
}

inline int64_t rotl64 ( int64_t x, int8_t r )
{
  // cast to unsigned for logical right bitshift (to match C* MM3 implementation)
  return (x << r) | ((int64_t) (((uint64_t) x) >> (64 - r)));
}

#define ROTL32(x,y)	rotl32(x,y)
#define ROTL64(x,y)	rotl64(x,y)

#define BIG_CONSTANT(x) (x##LL)

#endif // !defined(_MSC_VER)

//-----------------------------------------------------------------------------
// Block read - if your platform needs to do endian-swapping or can only
// handle aligned reads, do the conversion here

FORCE_INLINE int64_t getblock ( const int64_t * p, int i )
{
  return p[i];
}

//-----------------------------------------------------------------------------
// Finalization mix - force all bits of a hash block to avalanche

FORCE_INLINE int64_t fmix ( int64_t k )
{
  // cast to unsigned for logical right bitshift (to match C* MM3 implementation)
  k ^= ((uint64_t) k) >> 33;
  k *= BIG_CONSTANT(0xff51afd7ed558ccd);
  k ^= ((uint64_t) k) >> 33;
  k *= BIG_CONSTANT(0xc4ceb9fe1a85ec53);
  k ^= ((uint64_t) k) >> 33;

  return k;
}

int64_t x64_128 (const void * key, const int len,
                              const uint32_t seed)
{
  const int8_t * data = (const int8_t*)key;
  const int nblocks = len / 16;

  int64_t h1 = seed;
  int64_t h2 = seed;

  int64_t c1 = BIG_CONSTANT(0x87c37b91114253d5);
  int64_t c2 = BIG_CONSTANT(0x4cf5ad432745937f);
  int64_t k1 = 0;
  int64_t k2 = 0;

  const int64_t * blocks = (const int64_t *)(data);
  const int8_t * tail = (const int8_t*)(data + nblocks*16);

  // ---------- body -----------

  int i;
  for(i = 0; i < nblocks; i++)
  {
    int64_t k1 = getblock(blocks,i*2+0);
    int64_t k2 = getblock(blocks,i*2+1);

    k1 *= c1; k1  = ROTL64(k1,31); k1 *= c2; h1 ^= k1;

    h1 = ROTL64(h1,27); h1 += h2; h1 = h1*5+0x52dce729;

    k2 *= c2; k2  = ROTL64(k2,33); k2 *= c1; h2 ^= k2;

    h2 = ROTL64(h2,31); h2 += h1; h2 = h2*5+0x38495ab5;
  }

  //---------- tail ----------

  switch(len & 15)
  {
    case 15: k2 ^= ((int64_t) (tail[14])) << 48;
    case 14: k2 ^= ((int64_t) (tail[13])) << 40;
    case 13: k2 ^= ((int64_t) (tail[12])) << 32;
    case 12: k2 ^= ((int64_t) (tail[11])) << 24;
    case 11: k2 ^= ((int64_t) (tail[10])) << 16;
    case 10: k2 ^= ((int64_t) (tail[ 9])) << 8;
    case  9: k2 ^= ((int64_t) (tail[ 8])) << 0;
             k2 *= c2; k2  = ROTL64(k2,33); k2 *= c1; h2 ^= k2;

    case  8: k1 ^= ((int64_t) (tail[ 7])) << 56;
    case  7: k1 ^= ((int64_t) (tail[ 6])) << 48;
    case  6: k1 ^= ((int64_t) (tail[ 5])) << 40;
    case  5: k1 ^= ((int64_t) (tail[ 4])) << 32;
    case  4: k1 ^= ((int64_t) (tail[ 3])) << 24;
    case  3: k1 ^= ((int64_t) (tail[ 2])) << 16;
    case  2: k1 ^= ((int64_t) (tail[ 1])) << 8;
    case  1: k1 ^= ((int64_t) (tail[ 0])) << 0;
             k1 *= c1; k1  = ROTL64(k1,31); k1 *= c2; h1 ^= k1;
  };

  // ---------- finalization ---------

  h1 ^= len; h2 ^= len;

  h1 += h2;
  h2 += h1;

  h1 = fmix(h1);
  h2 = fmix(h2);

  h1 += h2;
  h2 += h1;

  return h1;
}

static ERL_NIF_TERM x64_128_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
  int cell;
  int64_t ret;
  int8_t * key;
  uint32_t seed, len;
  ERL_NIF_TERM head, tail;

  tail = argv[0];

  if (argc != 2 ||
      !enif_get_list_length(env, tail, &len) ||
      !enif_get_uint(env, argv[1], &seed)) {
    return enif_make_badarg(env);
  }
  key = malloc(len * sizeof(int8_t));
  for (uint32_t i = 0; i < len; i++) {
    if (!enif_get_list_cell(env, tail, &head, &tail) ||
        !enif_get_int(env, head, &cell)) {
      return enif_make_badarg(env);
    }
    key[i] = (int8_t) cell;
  }
  ret = x64_128((void *) key, len, seed);
  return enif_make_int64(env, ret);
}

static ErlNifFunc nif_funcs[] = {
  {"native_x64_128", 2, x64_128_nif, 0}
};

int load (ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info) {
  (void) env;
  (void) priv_data;
  (void) load_info;
  return 0;
}

int upgrade (ErlNifEnv* env, void** priv_data, void** old_priv_data, ERL_NIF_TERM load_info) {
  (void) env;
  (void) priv_data;
  (void) old_priv_data;
  (void) load_info;
  return 0;
}

void unload (ErlNifEnv* env, void* priv_data) {
  (void) env;
  (void) priv_data;
}

ERL_NIF_INIT(Elixir.Cassandra.Murmur3, nif_funcs, load, load, upgrade, unload)