/* Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License. */

#pragma once

#include <array>
#include <cstdint>
#include <type_traits>
#include <vector>

#include "paddle/phi/common/memory_utils.h"
#include "paddle/phi/common/place.h"
#include "paddle/phi/core/dense_tensor.h"
#include "paddle/phi/kernels/funcs/math_function.h"
#include "paddle/phi/kernels/funcs/stride_utils.h"

namespace phi {
namespace funcs {

constexpr int MAX_DIMS = DDim::kMaxRank;

template <int N>
struct alignas(N) OpaqueType {
  char data[N];
};

template <typename IndexT>
std::array<char*, DDim::kMaxRank> GetIndexDataPtrs(
    const std::vector<const DenseTensor*>& index) {
  std::array<char*, DDim::kMaxRank> index_ptrs{};

  PADDLE_ENFORCE_LE(index.size(),
                    DDim::kMaxRank,
                    "The number of index tensors exceeds the maximum rank.");

  for (size_t i = 0; i < index.size(); ++i) {
    const IndexT* p_index = index[i]->data<IndexT>();

    PADDLE_ENFORCE_NOT_NULL(
        p_index,
        ::common::errors::InvalidArgument(
            "The pointer p_index is nullptr, "
            "please check whether the index tensor is valid and "
            "its data is correctly initialized."));

    index_ptrs[i] = reinterpret_cast<char*>(const_cast<IndexT*>(p_index));
  }

  return index_ptrs;
}

}  // namespace funcs
}  // namespace phi