/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree.
 */

#include <executorch/kernels/portable/cpu/scalar_utils.h>
#include <executorch/kernels/portable/cpu/util/functional_util.h>
#include <executorch/runtime/kernel/kernel_includes.h>

namespace torch {
namespace executor {
namespace native {

using Scalar = exec_aten::Scalar;
using ScalarType = exec_aten::ScalarType;
using Tensor = exec_aten::Tensor;

Tensor& fill_scalar_out(
    KernelRuntimeContext& ctx,
    const Tensor& a,
    const Scalar& b,
    Tensor& out) {
  (void)ctx;

  ScalarType a_type = a.scalar_type();
  ScalarType b_type = utils::get_scalar_dtype(b);
  ScalarType out_type = out.scalar_type();

  ET_KERNEL_CHECK(ctx, a_type == out_type, InvalidArgument, out);

  ET_KERNEL_CHECK(
      ctx, tensors_have_same_dim_order(a, out), InvalidArgument, out);

  // Resize for dynamic shape
  ET_KERNEL_CHECK_MSG(
      ctx,
      resize_tensor(out, a.sizes()) == Error::Ok,
      InvalidArgument,
      out,
      "Failed to resize output tensor.");

  ET_SWITCH_REAL_TYPES_AND(Bool, a_type, ctx, "fill.Scalar_out", CTYPE_A, [&] {
    CTYPE_A b_casted;
    ET_SWITCH_SCALAR_OBJ_TYPES(b_type, ctx, "fill.Scalar_out", CTYPE_B, [&] {
      CTYPE_B b_val;
      utils::extract_scalar(b, &b_val);
      b_casted = static_cast<CTYPE_A>(b_val);
    });

    apply_unary_map_fn(
        [b_casted](const CTYPE_A val_a) { return b_casted; },
        a.const_data_ptr<CTYPE_A>(),
        out.mutable_data_ptr<CTYPE_A>(),
        out.numel());
  });

  return out;
}

Tensor& fill_tensor_out(
    KernelRuntimeContext& ctx,
    const Tensor& a,
    const Tensor& b,
    Tensor& out) {
  (void)ctx;

  // Assert `b` must be a scalar tensor.
  ET_KERNEL_CHECK(ctx, tensor_is_scalar(b), InvalidArgument, out);

  ET_KERNEL_CHECK(
      ctx, tensors_have_same_dim_order(a, out), InvalidArgument, out);

  ScalarType a_type = a.scalar_type();
  ScalarType b_type = b.scalar_type();
  ScalarType out_type = out.scalar_type();

  ET_KERNEL_CHECK(ctx, a_type == out_type, InvalidArgument, out);

  // Resize for dynamic shape
  ET_KERNEL_CHECK_MSG(
      ctx,
      resize_tensor(out, a.sizes()) == Error::Ok,
      InvalidArgument,
      out,
      "Failed to resize output tensor.");

  ET_SWITCH_REAL_TYPES_AND(Bool, a_type, ctx, "fill.Tensor_out", CTYPE_A, [&] {
    CTYPE_A b_casted;
    ET_SWITCH_REAL_TYPES_AND(
        Bool, b_type, ctx, "fill.Tensor_out", CTYPE_B, [&] {
          CTYPE_B b_val;
          extract_scalar_tensor(b, &b_val);
          b_casted = static_cast<CTYPE_A>(b_val);
        });

    apply_unary_map_fn(
        [b_casted](const CTYPE_A val_a) { return b_casted; },
        a.const_data_ptr<CTYPE_A>(),
        out.mutable_data_ptr<CTYPE_A>(),
        out.numel());
  });

  return out;
}

} // namespace native
} // namespace executor
} // namespace torch