#include <torch/torch.h>

#if defined(USING_TORCH_V1)
#include <ATen/BatchedTensorImpl.h>
#else
#include <ATen/LegacyBatchedTensorImpl.h>
#endif

#include <atomic>
#include <iostream>

#include "nx_nif_utils.hpp"

std::map<const std::string, const torch::ScalarType> dtypes = {{"byte", torch::kByte}, {"char", torch::kChar}, {"short", torch::kShort}, {"int", torch::kInt}, {"long", torch::kLong}, {"float8_e5m2", torch::kFloat8_e5m2}, {"half", torch::kHalf}, {"brain", torch::kBFloat16}, {"float", torch::kFloat}, {"double", torch::kDouble}, {"bool", torch::kBool}, {"complex", at::ScalarType::ComplexFloat}, {"complex_double", at::ScalarType::ComplexDouble}};
std::map<const std::string, const int> dtype_sizes = {{"byte", 1}, {"char", 1}, {"short", 2}, {"int", 4}, {"long", 8}, {"float8_e5m2", 1}, {"half", 2}, {"brain", 2}, {"float", 4}, {"double", 8}, {"complex", 8}, {"complex_double", 16}};

inline torch::ScalarType string2type(const std::string &atom) {
  return dtypes[atom];
}

inline const std::string *type2string(const torch::ScalarType type) {
  for (std::map<const std::string, const torch::ScalarType>::iterator i = dtypes.begin(); i != dtypes.end(); ++i) {
    if (i->second == type)
      return &i->first;
  }
  return nullptr;
}

// the class instance to manage the refcount of Tensor
class TensorP {
 public:
  TensorP(ErlNifEnv *env, const ERL_NIF_TERM arg) : ptr(nullptr) {
    // setup
    if (!enif_get_resource(env, arg, TENSOR_TYPE, (void **)&ptr)) {
      err = nx::nif::error(env, "Unable to get tensor param in NIF");
      return;
    }

    refcount = (std::atomic<int> *)(ptr + 1);
    deleted = (std::atomic_flag *)(refcount + 1);

    if (refcount->load() == 0) {
      // already deallocated
      ptr = nullptr;
      err = nx::nif::error(env, "Tensor has been deallocated");
      return;
    }

    if (is_valid()) {
      // increase reference count
      ++(*refcount);
    }
  }

  ~TensorP() {
    if (is_valid()) {
      // decrease reference count
      if (refcount->fetch_sub(1) == 0) {
        ptr->~Tensor();
      }
    }
  }

  bool deallocate() {
    if (is_valid() && atomic_flag_test_and_set(deleted) == false) {
      --(*refcount);
      return true;
    } else {
      return false;
    }
  }

  torch::Tensor *data() const {
    return ptr;
  }

  bool is_valid() const {
    return ptr != nullptr;
  }

  ERL_NIF_TERM error() {
    return err;
  }

 private:
  torch::Tensor *ptr;
  std::atomic<int> *refcount;
  std::atomic_flag *deleted;
  ERL_NIF_TERM err;
};

#define NIF(NAME) ERL_NIF_TERM NAME(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])

#define SCALAR_PARAM(ARGN, VAR)                                      \
  torch::Scalar VAR;                                                 \
  VAR.~Scalar();                                                     \
  double double_##VAR;                                               \
  std::vector<double> complex_##VAR;                                 \
  if (nx::nif::get_tuple<double>(env, argv[ARGN], complex_##VAR)) {  \
    new (&VAR) torch::Scalar(c10::complex<double>(                   \
        complex_##VAR[0],                                            \
        complex_##VAR[1]));                                          \
  } else if (enif_get_double(env, argv[ARGN], &double_##VAR) == 0) { \
    int64_t int64_##VAR;                                             \
    enif_get_int64(env, argv[ARGN], (ErlNifSInt64 *)&int64_##VAR);   \
    new (&VAR) torch::Scalar(int64_##VAR);                           \
  } else {                                                           \
    new (&VAR) torch::Scalar(double_##VAR);                          \
  }

#define SHAPE_PARAM(ARGN, VAR) TUPLE_PARAM(ARGN, std::vector<int64_t>, VAR)

#define TYPE_PARAM(ARGN, VAR)  \
  ATOM_PARAM(ARGN, VAR##_atom) \
  torch::ScalarType VAR = string2type(VAR##_atom)

#define DEVICE_PARAM(ARGN, VAR) TUPLE_PARAM(ARGN, std::vector<int64_t>, VAR)

#define DEVICE(DEV_VEC) torch::device(torch::Device((torch::DeviceType)DEV_VEC[0], (torch::DeviceIndex)DEV_VEC[1]))

#define OPTS(TYPE, DEV_VEC) DEVICE(DEV_VEC).dtype(TYPE)

#define TENSOR_PARAM(ARGN, VAR)      \
  TensorP VAR##_tp(env, argv[ARGN]); \
  torch::Tensor *VAR;                \
  if (!VAR##_tp.is_valid()) {        \
    return VAR##_tp.error();         \
  } else {                           \
    VAR = VAR##_tp.data();           \
  }

#define CATCH()                                                  \
  catch (c10::Error & error) {                                   \
    std::ostringstream msg;                                      \
    msg << error.msg() << " in NIF." << __func__ << "/" << argc; \
    return nx::nif::error(env, msg.str().c_str());               \
  }

#define SCALAR(S)                                                       \
  try {                                                                 \
    if (c10::isFloatingType(S.type()))                                  \
      return nx::nif::ok(env, nx::nif::make(env, S.toDouble()));        \
    else                                                                \
      return nx::nif::ok(env, nx::nif::make(env, (int64_t)S.toLong())); \
  }                                                                     \
  CATCH()

#define TENSOR(T)                                            \
  try {                                                      \
    return nx::nif::ok(env, create_tensor_resource(env, T)); \
  }                                                          \
  CATCH()

#define TENSOR_LIST(TL)                                                                        \
  try {                                                                                        \
    const std::vector<torch::Tensor> &tl = TL;                                                 \
    std::vector<ERL_NIF_TERM> res_list;                                                        \
    for (torch::Tensor t : tl)                                                                 \
      res_list.push_back(create_tensor_resource(env, t));                                      \
    return nx::nif::ok(env, enif_make_list_from_array(env, res_list.data(), res_list.size())); \
  }                                                                                            \
  CATCH()

#define TENSOR_TUPLE(TT)                                                                        \
  try {                                                                                         \
    const std::tuple<torch::Tensor, torch::Tensor> &tt = TT;                                    \
    std::vector<ERL_NIF_TERM> res_list;                                                         \
    for (torch::Tensor t : {std::get<0>(tt), std::get<1>(tt)})                                  \
      res_list.push_back(create_tensor_resource(env, t));                                       \
    return nx::nif::ok(env, enif_make_tuple_from_array(env, res_list.data(), res_list.size())); \
  }                                                                                             \
  CATCH()

#define TENSOR_TUPLE_3(TT)                                                                      \
  try {                                                                                         \
    const std::tuple<torch::Tensor, torch::Tensor, torch::Tensor> &tt = TT;                     \
    std::vector<ERL_NIF_TERM> res_list;                                                         \
    for (torch::Tensor t : {std::get<0>(tt), std::get<1>(tt), std::get<2>(tt)})                 \
      res_list.push_back(create_tensor_resource(env, t));                                       \
    return nx::nif::ok(env, enif_make_tuple_from_array(env, res_list.data(), res_list.size())); \
  }                                                                                             \
  CATCH()

ERL_NIF_TERM
create_tensor_resource(ErlNifEnv *env, torch::Tensor tensor) {
  ERL_NIF_TERM ret;
  torch::Tensor *tensorPtr;
  std::atomic<int> *refcount;

  tensorPtr = (torch::Tensor *)enif_alloc_resource(TENSOR_TYPE, sizeof(torch::Tensor) + sizeof(std::atomic<int>) + sizeof(std::atomic_flag));
  if (tensorPtr == NULL)
    return enif_make_badarg(env);

  new (tensorPtr) torch::Tensor(tensor.variable_data());
  refcount = new (tensorPtr + 1) std::atomic<int>(1);
  new (refcount + 1) std::atomic_flag();

  ret = enif_make_resource(env, tensorPtr);
  enif_release_resource(tensorPtr);

  return ret;
}

NIF(delete_tensor) {
  TensorP tensor(env, argv[0]);

  return tensor.deallocate() ? nx::nif::ok(env) : enif_make_badarg(env);
}

uint64_t elem_count(std::vector<int64_t> shape) {
  return std::accumulate(shape.begin(), shape.end(), 1, std::multiplies<>{});
}

NIF(from_blob) {
  BINARY_PARAM(0, blob);
  SHAPE_PARAM(1, shape);
  TYPE_PARAM(2, type);
  DEVICE_PARAM(3, device);

  if (blob.size / dtype_sizes[type_atom] < elem_count(shape))
    return nx::nif::error(env, "Binary size is too small for the requested shape");

  auto tensor = torch::from_blob(blob.data, shape, torch::device(torch::kCPU).dtype(type));

  if (DEVICE(device).device().type() == torch::kCPU) {
    TENSOR(tensor.clone());
  } else {
    TENSOR(tensor.to(DEVICE(device)));
  }
}

NIF(to_blob) {
  ERL_NIF_TERM result;
  TENSOR_PARAM(0, t);
  size_t byte_size = t->nbytes();
  int64_t limit = 0;

  bool has_received_limit = (argc == 2);

  if (has_received_limit) {
    PARAM(1, int64_t, param_limit);
    limit = param_limit;
    byte_size = limit * t->itemsize();
  }

  torch::optional<torch::Device> device = torch::device_of(*t);
  // flatten the tensor to compensate for operations which return
  // a column-major tensor. t->flatten() is a no-op if the tensor
  // is already row-major, which was verified by printing t->data_ptr
  // and reshaped.data_ptr and confirming they had the same value.
  // We also slice if a limit was received and it doesn't encompass the full tensor.
  torch::Tensor reshaped = (has_received_limit && byte_size < t->nbytes()) ? t->flatten().slice(0, 0, limit) : t->flatten();
  void *data_ptr = reshaped.data_ptr();

  if (device.has_value() && device.value().type() == torch::kCPU && data_ptr == t->data_ptr()) {
    // case where we own the data_ptr and the data is in the CPU already
    return nx::nif::ok(env, enif_make_resource_binary(env, t, data_ptr, byte_size));
  } else if (device.has_value() && device.value().type() == torch::kCPU) {
    // case where we don't own the data_ptr but the data is in the CPU already
    void *result_data = (void *)enif_make_new_binary(env, byte_size, &result);
    memcpy(result_data, data_ptr, byte_size);
    return nx::nif::ok(env, result);
  } else {
    // case where the data isn't in the CPU, therefore we don't own the data_ptr
    void *result_data = (void *)enif_make_new_binary(env, byte_size, &result);
    memcpy(result_data, reshaped.to(torch::kCPU).data_ptr(), byte_size);
    return nx::nif::ok(env, result);
  }
}

NIF(item) {
  TENSOR_PARAM(0, t);

  SCALAR(t->item());
}

NIF(scalar_type) {
  TENSOR_PARAM(0, t);

  const std::string *type_name = type2string(t->scalar_type());

  if (type_name != nullptr)
    return nx::nif::ok(env, enif_make_atom(env, type_name->c_str()));
  else
    return nx::nif::error(env, "Could not determine tensor type.");
}

NIF(shape) {
  TENSOR_PARAM(0, t);

  std::vector<ERL_NIF_TERM> sizes;
  for (int64_t dim = 0; dim < t->dim(); dim++)
    sizes.push_back(nx::nif::make(env, (t->size(dim))));

  return nx::nif::ok(env, enif_make_tuple_from_array(env, sizes.data(), sizes.size()));
}

NIF(mps_is_available) {
#ifdef MAC_ARM64
  bool has_mps = at::hasMPS();
#else
  bool has_mps = false;
#endif
  return nx::nif::make(env, has_mps);
}

NIF(cuda_is_available) {
  return nx::nif::make(env, (bool)torch::cuda::is_available());
}

NIF(cuda_device_count) {
  return nx::nif::make(env, (int)torch::cuda::device_count());
}

NIF(nbytes) {
  TENSOR_PARAM(0, t);

  return nx::nif::ok(env, enif_make_int64(env, t->nbytes()));
}

NIF(split) {
  TENSOR_PARAM(0, t);
  PARAM(1, int64_t, batch_size);

  TENSOR_LIST(torch::split(*t, batch_size));
}

NIF(reshape) {
  TENSOR_PARAM(0, t);
  SHAPE_PARAM(1, shape);

  TENSOR(torch::reshape(*t, shape));
}

NIF(to_type) {
  TENSOR_PARAM(0, t);
  TYPE_PARAM(1, type);

  TENSOR(t->toType(type));
}

NIF(to_device) {
  TENSOR_PARAM(0, t);
  DEVICE_PARAM(1, device);

  TENSOR(t->to(DEVICE(device)));
}

NIF(squeeze) {
  TENSOR_PARAM(0, t);

  if (argc == 2) {
    PARAM(1, int64_t, dim);
    TENSOR(torch::squeeze(*t, dim));
  } else
    TENSOR(torch::squeeze(*t));
}

NIF(broadcast_to) {
  TENSOR_PARAM(0, t);
  SHAPE_PARAM(1, shape);

  TENSOR(torch::broadcast_to(*t, shape).clone());
}

NIF(transpose) {
  TENSOR_PARAM(0, t);
  PARAM(1, int64_t, dim0);
  PARAM(2, int64_t, dim1);

  TENSOR(torch::transpose(*t, dim0, dim1));
}

NIF(slice) {
  TENSOR_PARAM(0, input);
  LIST_PARAM(1, std::vector<int64_t>, starts);
  LIST_PARAM(2, std::vector<int64_t>, lengths);
  LIST_PARAM(3, std::vector<int64_t>, strides);

  torch::Tensor output;
  torch::Tensor destination = *input;

  auto shape = input->sizes();
  size_t dim = 0;
  for (dim = 0; dim < starts.size(); dim++) {
    auto start = starts[dim];
    auto stride = strides[dim];
    auto length = lengths[dim];
    auto end = std::min(start + length, shape[dim]);  // Ensuring we don't go out of bounds

    // arguments are dimension, start index, NON-INCLUSIVE end index and stride
    destination = destination.slice(dim, start, end, stride);
    if (dim == starts.size() - 1) {
      output = destination.clone();
    }
  }

  TENSOR(output);
}

NIF(concatenate) {
  LIST_PARAM(0, std::vector<torch::Tensor>, tensors);

  PARAM(1, int64_t, axis);

  TENSOR(torch::cat(tensors, axis));
}

NIF(gather) {
  TENSOR_PARAM(0, input);
  TENSOR_PARAM(1, indices);
  PARAM(2, int64_t, axis);

  TENSOR(torch::gather(*input, axis, *indices));
}

NIF(index_put) {
  TENSOR_PARAM(0, input);
  LIST_PARAM(1, std::vector<torch::Tensor>, indices);
  TENSOR_PARAM(2, updates);
  PARAM(3, bool, accumulate);

  c10::List<c10::optional<at::Tensor>> convertedList;
  for (const torch::Tensor &tensor : indices) {
    convertedList.push_back(tensor);
  }

  TENSOR(torch::index_put(*input, convertedList, *updates, accumulate));
}

NIF(index) {
  TENSOR_PARAM(0, input);
  LIST_PARAM(1, std::vector<torch::Tensor>, indices);

  c10::List<c10::optional<at::Tensor>> convertedList;
  for (const torch::Tensor &tensor : indices) {
    convertedList.push_back(tensor);
  }

  TENSOR(torch::index(*input, convertedList));
}

NIF(argsort) {
  TENSOR_PARAM(0, input);
  PARAM(1, bool, stable);
  PARAM(2, int64_t, axis);
  PARAM(3, bool, is_descending);

  TENSOR(torch::argsort(*input, stable, axis, is_descending));
}

NIF(top_k) {
  TENSOR_PARAM(0, input);
  PARAM(1, int64_t, k);

  TENSOR_TUPLE(at::topk(*input, k));
}

NIF(flip) {
  TENSOR_PARAM(0, input);
  LIST_PARAM(1, std::vector<int64_t>, dims);

  TENSOR(torch::flip(*input, dims));
}

NIF(unfold) {
  TENSOR_PARAM(0, input);
  PARAM(1, int64_t, dim);
  PARAM(2, int64_t, size);
  PARAM(3, int64_t, step);

  TENSOR(at::native::unfold(*input, dim, size, step));
}

NIF(put) {
  TENSOR_PARAM(0, input);
  LIST_PARAM(1, std::vector<int64_t>, indices);
  TENSOR_PARAM(2, source);

  torch::Tensor output = input->clone();
  torch::Tensor destination = output;

  auto source_shape = source->sizes();

  size_t dim = 0;
  for (dim = 0; dim < indices.size() - 1; dim++) {
    auto start = indices[dim];
    // arguments are dimension, start index and NON-INCLUSIVE end index
    destination = destination.slice(dim, start, start + source_shape[dim]);
  }

  auto start = indices[dim];
  destination.slice(dim, start, start + source_shape[dim]) = *source;

  TENSOR(output);
}

NIF(permute) {
  TENSOR_PARAM(0, t);
  LIST_PARAM(1, std::vector<int64_t>, dims);

  TENSOR(t->permute(dims).contiguous());
}

/* Creation */

NIF(scalar_tensor) {
  SCALAR_PARAM(0, scalar);
  TYPE_PARAM(1, type);
  DEVICE_PARAM(2, device);

  TENSOR(torch::scalar_tensor(scalar, OPTS(type, device)));
}

NIF(randint) {
  PARAM(0, int64_t, min);
  PARAM(1, int64_t, max);
  SHAPE_PARAM(2, shape);
  TYPE_PARAM(3, type);
  DEVICE_PARAM(4, device);

  TENSOR(torch::randint(min, max, shape, OPTS(type, device)));
}

NIF(rand) {
  PARAM(0, double, min);
  PARAM(1, double, max);
  SHAPE_PARAM(2, shape);
  TYPE_PARAM(3, type);
  DEVICE_PARAM(4, device);

  TENSOR(min + torch::rand(shape, OPTS(type, device)) * (max - min));
}

NIF(normal) {
  PARAM(0, double, mean);
  PARAM(1, double, std);
  SHAPE_PARAM(2, shape);
  TYPE_PARAM(3, type);
  DEVICE_PARAM(4, device);

  TENSOR(torch::normal(mean, std, shape, c10::nullopt, OPTS(type, device)));
}

NIF(arange) {
  PARAM(0, int64_t, start);
  PARAM(1, int64_t, end);
  PARAM(2, int64_t, step);
  TYPE_PARAM(3, type);
  DEVICE_PARAM(4, device);

  if (argc == 6) {
    SHAPE_PARAM(5, shape);
    TENSOR(torch::reshape(torch::arange((double)start, (double)end, (double)step, OPTS(type, device)), shape));
  } else {
    TENSOR(torch::arange((double)start, (double)end, (double)step, OPTS(type, device)));
  }
}

NIF(ones) {
  SHAPE_PARAM(0, shape);
  TYPE_PARAM(1, type);
  DEVICE_PARAM(2, device);

  TENSOR(torch::ones(shape, OPTS(type, device)));
}

NIF(eye) {
  PARAM(0, int64_t, m);
  PARAM(1, int64_t, n);
  TYPE_PARAM(2, type);
  DEVICE_PARAM(3, device);

  TENSOR(torch::eye(m, n, OPTS(type, device)));
}

NIF(full) {
  SHAPE_PARAM(0, shape);
  SCALAR_PARAM(1, scalar);
  TYPE_PARAM(2, type);
  DEVICE_PARAM(3, device);

  TENSOR(torch::full(shape, scalar, OPTS(type, device)));
}

/* Binary Ops */

#define BINARY_OP(OP) BINARY_OP2(OP, OP)

#define BINARY_OP2(OP, NATIVE_OP)     \
  NIF(OP) {                           \
    TENSOR_PARAM(0, a);               \
    TENSOR_PARAM(1, b);               \
                                      \
    TENSOR(torch::NATIVE_OP(*a, *b)); \
  }

#define BINARY_OPB(OP)                                       \
  NIF(OP) {                                                  \
    TENSOR_PARAM(0, a);                                      \
    TENSOR_PARAM(1, b);                                      \
                                                             \
    nx::nif::ok(env, nx::nif::make(env, torch::OP(*a, *b))); \
  }

#define UNARY_OP(OP) UNARY_OP2(OP, OP)

#define UNARY_OP2(OP, NATIVE)  \
  NIF(OP) {                    \
    TENSOR_PARAM(0, a);        \
    TENSOR(torch::NATIVE(*a)); \
  }

BINARY_OP(bitwise_and)
BINARY_OP(bitwise_or)
BINARY_OP(bitwise_xor)
BINARY_OP2(left_shift, __lshift__)
BINARY_OP2(right_shift, __rshift__)

BINARY_OP2(equal, eq)
BINARY_OP(not_equal)
BINARY_OP(greater)
BINARY_OP(less)
BINARY_OP(greater_equal)
BINARY_OP(less_equal)

BINARY_OP(logical_and)
BINARY_OP(logical_or)
BINARY_OP(logical_xor)

BINARY_OP(add)
BINARY_OP(subtract)
BINARY_OP(divide)
BINARY_OP(remainder)
BINARY_OP(multiply)
BINARY_OP(matmul)
BINARY_OP2(pow, pow)
BINARY_OP(atan2)
BINARY_OP(min)
BINARY_OP(max)

NIF(fmod) {
  TENSOR_PARAM(0, a);
  TENSOR_PARAM(1, b);
  TENSOR(at::fmod(*a, *b));
}

NIF(quotient) {
  TENSOR_PARAM(0, a);
  TENSOR_PARAM(1, b);
  TENSOR(torch::divide(*a, *b, "trunc"));
}

NIF(tensordot) {
  TENSOR_PARAM(0, t1);
  TENSOR_PARAM(1, t2);
  LIST_PARAM(2, std::vector<int64_t>, axes1);
  LIST_PARAM(3, std::vector<int64_t>, batch_axes1);
  LIST_PARAM(4, std::vector<int64_t>, axes2);
  LIST_PARAM(5, std::vector<int64_t>, batch_axes2);

  bool is_batched = batch_axes1.size() > 0 || batch_axes2.size() > 0;

  torch::Tensor result;

  if (is_batched) {
    // if any of the tensors is batched, we need to apply some transformations
    // on the inputs and on the result to wrap the batched APIs that torch exposes
    std::vector<at::BatchDim> batch_dims1, batch_dims2;
    int64_t vmap_level = 0;

    for (auto dim : batch_axes1) {
      batch_dims1.push_back(at::BatchDim(vmap_level++, dim));
    }
    torch::Tensor batched_1 = at::makeBatched(*t1, at::BatchDims(batch_dims1.begin(), batch_dims1.end()));

    vmap_level = 0;

    for (auto dim : batch_axes2) {
      batch_dims2.push_back(at::BatchDim(vmap_level++, dim));
    }
    torch::Tensor batched_2 = at::makeBatched(*t2, at::BatchDims(batch_dims2.begin(), batch_dims2.end()));

    torch::Tensor batched_result = torch::tensordot(batched_1, batched_2, axes1, axes2);
    auto impl = at::maybeGetBatchedImpl(batched_result);
    if (!impl) {
      return nx::nif::error(env, "unable to get tensordot result");
    }
    result = torch::clone(impl->value());
  } else {
    result = torch::tensordot(*t1, *t2, axes1, axes2);
  }

  TENSOR(result);
}

/* Unary Ops */

UNARY_OP(abs)
UNARY_OP(ceil)
UNARY_OP(floor)
UNARY_OP2(negate, negative)
UNARY_OP(round)
UNARY_OP(sign)
UNARY_OP(exp)
UNARY_OP(expm1)
UNARY_OP(sqrt)
UNARY_OP(rsqrt)
UNARY_OP(log)
UNARY_OP(log1p)
UNARY_OP(bitwise_not)
UNARY_OP(logical_not)
UNARY_OP2(sigmoid, sigmoid)

UNARY_OP(sin)
UNARY_OP(asin)
UNARY_OP(sinh)
UNARY_OP(asinh)
UNARY_OP(cos)
UNARY_OP(acos)
UNARY_OP(cosh)
UNARY_OP(acosh)
UNARY_OP(tan)
UNARY_OP(atan)
UNARY_OP(tanh)
UNARY_OP(atanh)
UNARY_OP(erf)
UNARY_OP(erfc)
UNARY_OP2(erf_inv, erfinv)

NIF(view_as_real) {
  TENSOR_PARAM(0, tensor);
  TENSOR(torch::view_as_real(*tensor));
}

NIF(conjugate) {
  TENSOR_PARAM(0, tensor);
  at::Tensor conjugated = tensor->conj();
  TENSOR(conjugated.clone(conjugated.suggest_memory_format()));
}

NIF(triangular_solve) {
  TENSOR_PARAM(0, a);
  TENSOR_PARAM(1, b);
  PARAM(2, bool, transpose);
  PARAM(3, bool, upper);

  auto ts_a = *a;
  if (transpose) {
    auto num_dims = a->dim();
    ts_a = torch::transpose(*a, num_dims - 2, num_dims - 1);
    upper = !upper;
  }

  torch::Tensor result = torch::linalg_solve_triangular(ts_a, *b, upper, true, false);

  TENSOR(result);
}

NIF(determinant) {
  TENSOR_PARAM(0, t);

  TENSOR(t->det());
}

NIF(sort) {
  TENSOR_PARAM(0, t);
  PARAM(1, bool, stable);
  PARAM(2, int64_t, axis);
  PARAM(3, bool, descending);

  std::tuple<torch::Tensor, torch::Tensor> result = t->sort(stable, axis, descending);
  TENSOR(std::get<0>(result));
}

NIF(clip) {
  TENSOR_PARAM(0, t);
  TENSOR_PARAM(1, min);
  TENSOR_PARAM(2, max);

  TENSOR(torch::clip(*t, *min, *max));
}

NIF(where) {
  TENSOR_PARAM(0, pred);
  TENSOR_PARAM(1, on_true);
  TENSOR_PARAM(2, on_false);

  TENSOR(torch::where(*pred, *on_true, *on_false));
}

/* Aggregates */

NIF(sum) {
  TENSOR_PARAM(0, t);
  LIST_PARAM(1, std::vector<int64_t>, dims);
  PARAM(2, bool, keep_dim);

  TENSOR(torch::sum(*t, dims, keep_dim));
}

NIF(product) {
  TENSOR_PARAM(0, t);

  if (argc == 1) {
    TENSOR(torch::prod(*t));
  }

  PARAM(1, int64_t, dim);
  PARAM(2, bool, keep_dim);

  TENSOR(torch::prod(*t, dim, keep_dim));
}

NIF(argmax) {
  TENSOR_PARAM(0, t);
  PARAM(1, int64_t, dim);
  PARAM(2, bool, keep_dim);

  if (dim == -1) {
    TENSOR(torch::argmax(*t));
  } else {
    TENSOR(torch::argmax(*t, dim, keep_dim));
  }
}

NIF(argmin) {
  TENSOR_PARAM(0, t);
  PARAM(1, int64_t, dim);
  PARAM(2, bool, keep_dim);

  if (dim == -1) {
    TENSOR(torch::argmin(*t));
  } else {
    TENSOR(torch::argmin(*t, dim, keep_dim));
  }
}

NIF(cbrt) {
  TENSOR_PARAM(0, tensor);

  if (tensor->scalar_type() == torch::kDouble) {
    TENSOR(torch::pow(*tensor, 1.0 / 3));
  } else {
    TENSOR(torch::pow(*tensor, 1.0f / 3));
  }
}
NIF(fft) {
  TENSOR_PARAM(0, tensor);
  PARAM(1, int64_t, length);
  PARAM(2, int64_t, axis);
  TENSOR(torch::fft::fft(*tensor, length, axis));
}

NIF(ifft) {
  TENSOR_PARAM(0, tensor);
  PARAM(1, int64_t, length);
  PARAM(2, int64_t, axis);
  TENSOR(torch::fft::ifft(*tensor, length, axis));
}

NIF(fft2) {
  TENSOR_PARAM(0, tensor);
  LIST_PARAM(1, std::vector<int64_t>, lengths);
  LIST_PARAM(2, std::vector<int64_t>, axes);
  TENSOR(torch::fft::fft2(*tensor, lengths, axes));
}

NIF(ifft2) {
  TENSOR_PARAM(0, tensor);
  LIST_PARAM(1, std::vector<int64_t>, lengths);
  LIST_PARAM(2, std::vector<int64_t>, axes);
  TENSOR(torch::fft::ifft2(*tensor, lengths, axes));
}

NIF(is_nan) {
  TENSOR_PARAM(0, tensor);

  TENSOR(torch::isnan(*tensor));
}

NIF(is_infinity) {
  TENSOR_PARAM(0, tensor);

  TENSOR(torch::isinf(*tensor));
}

NIF(all) {
  TENSOR_PARAM(0, t);

  if (argc == 1) {
    TENSOR(torch::all(*t));
  } else {
    PARAM(1, int64_t, axis);
    PARAM(2, bool, keep_dim);

    TENSOR(torch::all(*t, axis, keep_dim));
  }
}

NIF(any) {
  TENSOR_PARAM(0, t);

  if (argc == 1) {
    TENSOR(torch::any(*t));
  } else {
    PARAM(1, int64_t, axis);
    PARAM(2, bool, keep_dim);

    TENSOR(torch::any(*t, axis, keep_dim));
  }
}

NIF(all_close) {
  TENSOR_PARAM(0, a);
  TENSOR_PARAM(1, b);
  PARAM(2, double, rtol);
  PARAM(3, double, atol);
  PARAM(4, bool, equal_nan);

  bool all_close = torch::allclose(*a, *b, rtol, atol, equal_nan);

  auto init_opts = torch::device(torch::kCPU).dtype(torch::kBool);
  TENSOR(torch::scalar_tensor(all_close, init_opts));
}

NIF(cumulative_sum) {
  TENSOR_PARAM(0, t);
  PARAM(1, int64_t, axis);

  TENSOR(torch::cumsum(*t, axis));
}

NIF(cumulative_product) {
  TENSOR_PARAM(0, t);
  PARAM(1, int64_t, axis);

  TENSOR(torch::cumprod(*t, axis));
}

NIF(cumulative_min) {
  TENSOR_PARAM(0, t);
  PARAM(1, int64_t, axis);

  const std::tuple<torch::Tensor, torch::Tensor> &tt = torch::cummin(*t, axis);
  TENSOR(std::get<0>(tt));
}

NIF(cumulative_max) {
  TENSOR_PARAM(0, t);
  PARAM(1, int64_t, axis);

  const std::tuple<torch::Tensor, torch::Tensor> &tt = torch::cummax(*t, axis);
  TENSOR(std::get<0>(tt));
}

NIF(cholesky) {
  TENSOR_PARAM(0, t);
  bool upper = false;

  if (argc == 2) {
    GET(1, upper);
  }

  if (upper) {
    TENSOR(torch::cholesky(*t).mH());
  }

  TENSOR(torch::cholesky(*t));
}

NIF(pad) {
  TENSOR_PARAM(0, tensor);
  TENSOR_PARAM(1, constant);
  LIST_PARAM(2, std::vector<int64_t>, config);

  TENSOR(torch::constant_pad_nd(*tensor, config, constant->item()));
}

/* Transformations */

NIF(qr) {
  TENSOR_PARAM(0, t);
  bool reduced = true;

  if (argc == 2) {
    GET(1, reduced);
  }

  TENSOR_TUPLE(torch::linalg_qr(*t, reduced ? "reduced" : "complete"));
}

NIF(svd) {
  TENSOR_PARAM(0, t);
  bool full_matrices = true;

  if (argc == 2) {
    GET(1, full_matrices);
  }

  TENSOR_TUPLE_3(torch::linalg_svd(*t, full_matrices));
}

NIF(lu) {
  TENSOR_PARAM(0, t);

  std::tuple<torch::Tensor, torch::Tensor> lu_result = torch::linalg_lu_factor(*t);
  std::tuple<torch::Tensor, torch::Tensor, torch::Tensor> plu = torch::lu_unpack(std::get<0>(lu_result), std::get<1>(lu_result));

  TENSOR_TUPLE_3(plu);
}

NIF(amax) {
  TENSOR_PARAM(0, tensor);
  LIST_PARAM(1, std::vector<int64_t>, axes);
  PARAM(2, bool, keep_axes);

  TENSOR(at::amax(*tensor, axes, keep_axes));
}

NIF(amin) {
  TENSOR_PARAM(0, tensor);
  LIST_PARAM(1, std::vector<int64_t>, axes);
  PARAM(2, bool, keep_axes);

  TENSOR(at::amin(*tensor, axes, keep_axes));
}

NIF(eigh) {
  TENSOR_PARAM(0, tensor);

  TENSOR_TUPLE(torch::linalg_eigh(*tensor));
}

NIF(solve) {
  TENSOR_PARAM(0, tensorA);
  TENSOR_PARAM(1, tensorB);

  TENSOR(torch::linalg_solve(*tensorA, *tensorB));
}

NIF(conv) {
  TENSOR_PARAM(0, tensor);
  TENSOR_PARAM(1, kernel);

  LIST_PARAM(2, std::vector<int64_t>, stride);
  LIST_PARAM(3, std::vector<int64_t>, padding);
  LIST_PARAM(4, std::vector<int64_t>, dilation);
  PARAM(5, bool, transposed);
  PARAM(6, int64_t, groups);

  c10::optional<at::Tensor> bias_tensor;

  std::vector<int64_t> output_padding;
  output_padding.push_back(0);

  // aten::convolution(Tensor input, Tensor weight, Tensor? bias,
  //      int[] stride, int[] padding, int[] dilation, bool transposed,
  //      int[] output_padding, int groups) -> Tensor
  TENSOR(at::convolution(*tensor, *kernel, bias_tensor,
                         stride, padding, dilation, transposed, output_padding, groups));
}

NIF(max_pool_3d) {
  TENSOR_PARAM(0, tensor);
  LIST_PARAM(1, std::vector<int64_t>, kernel_size);
  LIST_PARAM(2, std::vector<int64_t>, strides);
  LIST_PARAM(3, std::vector<int64_t>, padding);
  LIST_PARAM(4, std::vector<int64_t>, dilation);

  TENSOR(at::max_pool3d(*tensor, kernel_size, strides, padding, dilation));
}

void free_tensor(ErlNifEnv *env, void *obj) {
  torch::Tensor *tensor = reinterpret_cast<torch::Tensor *>(obj);
  std::atomic<int> *refcount = reinterpret_cast<std::atomic<int> *>(tensor + 1);
  std::atomic_flag *deleted = reinterpret_cast<std::atomic_flag *>(refcount + 1);

  if (atomic_flag_test_and_set(deleted) == false) {
    tensor->~Tensor();
  }

  deleted->~atomic_flag();
  refcount->~atomic<int>();
}

static int
open_resource_type(ErlNifEnv *env) {
  const char *name = "Tensor";
  ErlNifResourceFlags flags = (ErlNifResourceFlags)(ERL_NIF_RT_CREATE | ERL_NIF_RT_TAKEOVER);

  TENSOR_TYPE = enif_open_resource_type(env, NULL, name, free_tensor, flags, NULL);
  if (TENSOR_TYPE == NULL)
    return -1;
  return 0;
}

int upgrade(ErlNifEnv *env, void **priv_data, void **old_priv_data, ERL_NIF_TERM load_info) {
  // Silence "unused var" warnings.
  (void)(env);
  (void)(priv_data);
  (void)(old_priv_data);
  (void)(load_info);

  return 0;
}

int load(ErlNifEnv *env, void **priv_data, ERL_NIF_TERM load_info) {
  if (open_resource_type(env) == -1)
    return -1;

  // Silence "unused var" warnings.
  (void)(priv_data);
  (void)(load_info);

  return 0;
}

#define F(NAME, ARITY)    \
  {                       \
#NAME, ARITY, NAME, 0 \
  }

#define DF(NAME, ARITY)                                     \
  {#NAME "_cpu", ARITY, NAME, ERL_NIF_DIRTY_JOB_CPU_BOUND}, \
  {                                                         \
#NAME "_io", ARITY, NAME, ERL_NIF_DIRTY_JOB_IO_BOUND    \
  }

static ErlNifFunc nif_functions[] = {
    DF(randint, 5),
    DF(rand, 5),
    DF(normal, 5),
    DF(arange, 5),
    DF(arange, 6),
    DF(scalar_tensor, 3),
    DF(ones, 3),
    DF(eye, 4),
    DF(full, 4),

    DF(item, 1),
    DF(from_blob, 4),
    DF(to_blob, 1),
    DF(to_blob, 2),
    DF(delete_tensor, 1),
    DF(reshape, 2),
    DF(split, 2),
    DF(to_type, 2),
    DF(to_device, 2),
    DF(squeeze, 2),
    DF(squeeze, 1),
    DF(broadcast_to, 2),
    DF(transpose, 3),
    DF(permute, 2),
    DF(slice, 4),
    DF(concatenate, 2),
    DF(gather, 3),
    DF(index, 2),
    DF(index_put, 4),
    DF(argsort, 4),
    DF(top_k, 2),
    DF(flip, 2),
    DF(unfold, 4),
    DF(put, 3),

    DF(add, 2),
    DF(subtract, 2),
    DF(divide, 2),
    DF(remainder, 2),
    DF(fmod, 2),
    DF(quotient, 2),
    DF(multiply, 2),
    DF(pow, 2),
    DF(atan2, 2),
    DF(min, 2),
    DF(max, 2),
    DF(solve, 2),

    DF(bitwise_and, 2),
    DF(bitwise_or, 2),
    DF(bitwise_xor, 2),
    DF(left_shift, 2),
    DF(right_shift, 2),

    DF(equal, 2),
    DF(not_equal, 2),
    DF(greater, 2),
    DF(less, 2),
    DF(greater_equal, 2),
    DF(less_equal, 2),

    DF(logical_and, 2),
    DF(logical_or, 2),
    DF(logical_xor, 2),
    DF(logical_not, 1),

    DF(sum, 3),
    DF(product, 1),
    DF(product, 3),
    DF(argmax, 3),
    DF(argmin, 3),
    DF(any, 1),
    DF(any, 3),
    DF(all, 1),
    DF(all, 3),
    DF(all_close, 5),

    DF(cumulative_sum, 2),
    DF(cumulative_product, 2),
    DF(cumulative_min, 2),
    DF(cumulative_max, 2),

    DF(abs, 1),
    DF(ceil, 1),
    DF(floor, 1),
    DF(negate, 1),
    DF(round, 1),
    DF(sign, 1),
    DF(exp, 1),
    DF(expm1, 1),
    DF(sqrt, 1),
    DF(rsqrt, 1),
    DF(log, 1),
    DF(log1p, 1),
    DF(bitwise_not, 1),
    DF(sigmoid, 1),
    DF(sin, 1),
    DF(asin, 1),
    DF(sinh, 1),
    DF(asinh, 1),
    DF(view_as_real, 1),
    DF(conjugate, 1),
    DF(cos, 1),
    DF(acos, 1),
    DF(cosh, 1),
    DF(acosh, 1),
    DF(tan, 1),
    DF(atan, 1),
    DF(tanh, 1),
    DF(atanh, 1),
    DF(erf, 1),
    DF(erfc, 1),
    DF(erf_inv, 1),
    DF(cbrt, 1),
    DF(is_nan, 1),
    DF(is_infinity, 1),
    DF(fft, 3),
    DF(ifft, 3),
    DF(fft2, 3),
    DF(ifft2, 3),

    DF(tensordot, 6),
    DF(matmul, 2),
    DF(pad, 3),

    DF(cholesky, 1),
    DF(cholesky, 2),
    DF(eigh, 1),
    DF(qr, 1),
    DF(qr, 2),
    DF(svd, 1),
    DF(svd, 2),
    DF(lu, 1),
    DF(triangular_solve, 4),
    DF(determinant, 1),
    DF(sort, 4),
    DF(clip, 3),
    DF(where, 3),
    DF(amax, 3),
    DF(amin, 3),

    DF(conv, 7),
    DF(max_pool_3d, 5),

    F(mps_is_available, 0),
    F(cuda_is_available, 0),
    F(cuda_device_count, 0),
    F(scalar_type, 1),
    F(shape, 1),
    F(nbytes, 1)};

ERL_NIF_INIT(Elixir.Torchx.NIF, nif_functions, load, NULL, upgrade, NULL)