#include "erl_nif.h"
#include "mmath.h"

#include <math.h>

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

static int
upgrade(ErlNifEnv* env, void** priv, void** old_priv, ERL_NIF_TERM load_info)
{
  return 0;
}

static ERL_NIF_TERM
to_list(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
  ErlNifBinary a;
  ERL_NIF_TERM *acc;
  ERL_NIF_TERM r;
  ErlNifSInt64* vs;
  ERL_NIF_TERM last = enif_make_int(env, 0);
  ffloat f;
  unsigned count;
  int64_t v;
  int64_t v_overlay;
  if (argc != 1)
    return enif_make_badarg(env);

  GET_BIN(0, a, count, vs);

  acc = malloc(count * sizeof(ERL_NIF_TERM));

  for (unsigned i = 0 ; i < count; i++) {
    switch (TYPE(vs[i])) {
    case EMPTY_TYPE:
      // do nothing
      break;
    case INTEGER_TYPE:
      v = ntohll(vs[i]);
      v_overlay = v & VALUE_MASK;
      if (v & VALUE_SIGN_MASK) {
        v_overlay |= ((int64_t) -1) & ~ VALUE_MASK;
      }
      last = enif_make_int64(env, v_overlay);
      break;
    default:
      f = float_deserialize(vs[i]);
      last = enif_make_double(env, f.value);
    }
    acc[i] = last;
  }
  r = enif_make_list_from_array(env, acc, count);
  free(acc);
  return r;
}

static ERL_NIF_TERM
from_list(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
  ERL_NIF_TERM list;
  ERL_NIF_TERM cell;
  ErlNifSInt64 int_v;
  double float_v;
  ErlNifSInt64* target;
  ERL_NIF_TERM r;
  unsigned count;
  ffloat d;

  if (argc != 1)
    return enif_make_badarg(env);

  list = argv[0];

  if (!enif_get_list_length(env, list, &count))
    return enif_make_badarg(env);

  if (!(target = (ErlNifSInt64*) enif_make_new_binary(env, count * sizeof(ErlNifSInt64), &r)))
    return enif_make_badarg(env); // TODO return propper error

  for (int i = 0; i < count; i++) {
    if (! enif_get_list_cell(env, list, &cell, &list))
      return enif_make_badarg(env); // TODO return propper error
    if (enif_get_int64(env, cell, &int_v)) {
      target[i] = TO_DDB_INT(int_v);
    } else if (enif_get_double(env, cell, &float_v)){
      d = float_from_double(float_v);
      target[i] = float_serialize(d);
    } else {
      return enif_make_badarg(env);}
  }
  return r;
}

static ERL_NIF_TERM
rdatasize(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
  if (argc != 0)
    return enif_make_badarg(env);

  return enif_make_int(env, sizeof(ffloat));
}

static ERL_NIF_TERM
realize(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
  ErlNifBinary a;
  ERL_NIF_TERM r;
  ErlNifSInt64* vs;
  ffloat* target;
  ffloat last = {.value = 0, .confidence = 0};
  int has_last = 0;
  int count;

  if (argc != 1)
    return enif_make_badarg(env);

  GET_BIN(0, a, count, vs);

  if (! (target = (ffloat*) enif_make_new_binary(env, count * sizeof(ffloat), &r)))
    return enif_make_badarg(env); // TODO return propper error

  for (int i = 0; i < count; i++) {
    last.confidence = 0;
    if (IS_SET(vs[i])) {
      last = FROM_DDB(vs[i]);
      if (! has_last) {
        for (int j = 0; j < i; j++) {
          target[j] = last;
          target[j].confidence = 0;
        }
        has_last = 1;
      }
    };
    target[i] = last;
  }
  return r;
}

static ERL_NIF_TERM
derealize(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
  ErlNifBinary a;
  ERL_NIF_TERM r;
  ffloat* vs;
  ErlNifSInt64* target;
  int count;

  if (argc != 1)
    return enif_make_badarg(env);

  GET_BIN(0, a, count, vs);

  if (! (target = (ErlNifSInt64*) enif_make_new_binary(env, count * sizeof(ErlNifSInt64), &r)))
    return enif_make_badarg(env); // TODO return propper error
  for (int i = 0; i < count; i++) {
    target[i] = TO_DDB(vs[i]);
  }
  return r;
}

static ERL_NIF_TERM
replicate(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
  ErlNifBinary bin;
  ERL_NIF_TERM r;
  ffloat* vs;
  ffloat* target;
  ErlNifSInt64 rep_size;    // replication factor
  uint32_t count;
  uint32_t pos;
  uint32_t target_size;

  if (argc != 2)
    return enif_make_badarg(env);

  GET_CHUNK(rep_size);
  GET_BIN(0, bin, count, vs);

  target_size = ceil(count * rep_size * sizeof(ffloat));
  if (! (target = (ffloat*) enif_make_new_binary(env, target_size, &r)))
    return enif_make_badarg(env); // TODO return propper error

  // If we don't have any input data we can return right away.
  if (count == 0)
    return r;

  // We iterate over the input i..count elements, making rep_size copies of each
  for (uint32_t i = 0; i < count; i++) {
    for (uint32_t j = 0; j < rep_size; j++) {
        pos = (i * rep_size) + j;
        target[pos] = vs[i];
    }
  }
  return r;
}


static ERL_NIF_TERM
clean(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
  ErlNifBinary a;
  ERL_NIF_TERM r;
  ErlNifSInt64* vs;
  ErlNifSInt64* target;
  unsigned count;
  unsigned j = 0;

  if (argc != 1)
    return enif_make_badarg(env);

  GET_BIN(0, a, count, vs);

  if (count % 2)
    return enif_make_badarg(env); // TODO return propper error

  if (!(target = (ErlNifSInt64*) enif_make_new_binary(env, (count / 2) * sizeof(ErlNifSInt64), &r)))
    return enif_make_badarg(env); // TODO return propper error

  for (unsigned i = 1 ; i < count; i = i + 2) {
    target[j] = vs[i];
    j++;
  }
  return r;
}

char get_type(ErlNifSInt64 ev) {
  int64_t v = ntohll(ev);
  return (uint8_t)((v & TYPE_MASK) >> 56);
}

static ErlNifFunc nif_funcs[] = {
  {"from_list",    1, from_list},
  {"to_list",      1, to_list},
  {"rdatasize",    0, rdatasize},
  {"realize",      1, realize},
  {"derealize",    1, derealize},
  {"replicate",    2, replicate},
  {"clean",        1, clean}
};

// Initialize this NIF library.
//
// Args: (MODULE, ErlNifFunc funcs[], load, reload, upgrade, unload)
// Docs: http://erlang.org/doc/man/erl_nif.html#ERL_NIF_INIT

ERL_NIF_INIT(mmath_bin, nif_funcs, &load, NULL, &upgrade, NULL);