/*
 * 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 <cmath>

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

namespace torch {
namespace executor {
namespace native {

using exec_aten::Tensor;

Tensor& logit_out(
    KernelRuntimeContext& ctx,
    const Tensor& in,
    exec_aten::optional<double> eps,
    Tensor& out) {
  (void)ctx;

  // Resize for dynamic shape
  ET_KERNEL_CHECK(
      ctx, resize_tensor(out, in.sizes()) == Error::Ok, InvalidArgument, out);

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

  ET_KERNEL_CHECK(ctx, tensor_is_floating_type(out), InvalidArgument, out);

  ScalarType in_type = in.scalar_type();
  ScalarType out_type = out.scalar_type();
  ET_SWITCH_REAL_TYPES_AND(Bool, in_type, ctx, "logit.out", CTYPE_IN, [&] {
    ET_SWITCH_FLOAT_TYPES(out_type, ctx, "logit.out", CTYPE_OUT, [&] {
      apply_unary_map_fn(
          [eps](const CTYPE_IN val_in) {
            CTYPE_OUT xi = static_cast<CTYPE_OUT>(val_in);
            if (eps.has_value()) {
              if (xi < eps.value()) {
                xi = eps.value();
              } else if (xi > 1 - eps.value()) {
                xi = 1 - eps.value();
              }
            }
            return static_cast<CTYPE_OUT>(
                log(xi / (static_cast<CTYPE_OUT>(1.0) - xi)));
          },
          in.const_data_ptr<CTYPE_IN>(),
          out.mutable_data_ptr<CTYPE_OUT>(),
          in.numel());
    });
  });
  return out;
}

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