#include <torch/extension.h>

#include <ATen/CPUFloatType.h>
#include <ATen/Type.h>
#include <ATen/core/VariableHooksInterface.h>
#include <ATen/detail/ComplexHooksInterface.h>

#include "ATen/Allocator.h"
#include "ATen/CPUGenerator.h"
#include "ATen/DeviceGuard.h"
#include "ATen/NativeFunctions.h"
#include "ATen/TensorImpl.h"
#include "ATen/core/UndefinedTensorImpl.h"
#include "ATen/Utils.h"
#include "ATen/WrapDimUtils.h"
#include "ATen/core/Half.h"
#include "ATen/core/optional.h"

#include <cstddef>
#include <functional>
#include <memory>
#include <utility>

#include "ATen/Config.h"

namespace at {

struct CPUComplexFloatType : public at::CPUTypeDefault {
  CPUComplexFloatType()
      : CPUTypeDefault(
            CPUTensorId(),
            /*is_variable=*/false,
            /*is_undefined=*/false) {}

  ScalarType scalarType() const override;
  caffe2::TypeMeta typeMeta() const override;
  Backend backend() const override;
  const char* toString() const override;
  size_t elementSizeInBytes() const override;
  TypeID ID() const override;
  Tensor& s_copy_(Tensor& self, const Tensor& src, bool non_blocking)
      const override;
  Tensor& _s_copy_from(const Tensor& self, Tensor& dst, bool non_blocking)
      const override;

  Tensor tensor(IntList size) const override {
    // TODO: Upstream this
    int64_t numel = 1;
    for (auto s : size) {
      numel *= s;
    }
    Storage s{c10::make_intrusive<StorageImpl>(
        scalarTypeToTypeMeta(ScalarType::ComplexFloat),
        numel,
        getCPUAllocator(),
        /* resizable */ true)};
    Tensor t{c10::make_intrusive<TensorImpl, UndefinedTensorImpl>(
        std::move(s),
        at::CPUTensorId(),
        /* is_variable */ false)};
    return t;
  }
};

struct ComplexHooks : public at::ComplexHooksInterface {
  ComplexHooks(ComplexHooksArgs) {}
  void registerComplexTypes(Context* context) const override {
    context->registerType(
        Backend::CPU, ScalarType::ComplexFloat, new CPUComplexFloatType());
  }
};

ScalarType CPUComplexFloatType::scalarType() const {
  return ScalarType::ComplexFloat;
}

caffe2::TypeMeta CPUComplexFloatType::typeMeta() const {
  return scalarTypeToTypeMeta(ScalarType::ComplexFloat);
}

Backend CPUComplexFloatType::backend() const {
  return Backend::CPU;
}

const char* CPUComplexFloatType::toString() const {
  return "CPUComplexFloatType";
}

TypeID CPUComplexFloatType::ID() const {
  return TypeID::CPUComplexFloat;
}

size_t CPUComplexFloatType::elementSizeInBytes() const {
  return sizeof(float);
}

Tensor& CPUComplexFloatType::s_copy_(
    Tensor& dst,
    const Tensor& src,
    bool non_blocking) const {
  AT_ERROR("not yet supported");
}

Tensor& CPUComplexFloatType::_s_copy_from(
    const Tensor& src,
    Tensor& dst,
    bool non_blocking) const {
  AT_ERROR("not yet supported");
}

REGISTER_COMPLEX_HOOKS(ComplexHooks);

} // namespace at

PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) { }
