// SPDX-FileCopyrightText: Copyright (c) 2025, NVIDIA CORPORATION. All rights reserved.
// SPDX-License-Identifier: BSD-3-Clause

#include <cub/device/device_merge.cuh>

#include <thrust/detail/raw_pointer_cast.h>

#include <cuda/std/utility>

#include <cstdint>

#include <nvbench_helper.cuh>

#include "merge_common.cuh"

// %RANGE% TUNE_TRANSPOSE trp 0:1:1
// %RANGE% TUNE_LOAD ld 0:3:1
// %RANGE% TUNE_ITEMS_PER_THREAD ipt 7:24:1
// %RANGE% TUNE_THREADS_PER_BLOCK_POW2 tpb 6:10:1

template <typename KeyT>
void keys(nvbench::state& state, nvbench::type_list<KeyT>)
{
  using offset_t     = int64_t;
  using compare_op_t = less_t;

  // Retrieve axis parameters
  const auto elements       = static_cast<std::size_t>(state.get_int64("Elements{io}"));
  const bit_entropy entropy = str_to_entropy(state.get_string("Entropy"));

  const auto num_items_lhs  = elements / 2;
  const auto num_items_rhs  = elements - num_items_lhs;
  auto [keys_lhs, keys_rhs] = generate_lhs_rhs<KeyT>(num_items_lhs, num_items_rhs, entropy);

  thrust::device_vector<KeyT> keys_out(elements, thrust::no_init);
  KeyT* d_keys_lhs = thrust::raw_pointer_cast(keys_lhs.data());
  KeyT* d_keys_rhs = thrust::raw_pointer_cast(keys_rhs.data());
  KeyT* d_keys_out = thrust::raw_pointer_cast(keys_out.data());

  // Enable throughput calculations and add "Size" column to results.
  state.add_element_count(elements);
  state.add_global_memory_reads<KeyT>(elements);
  state.add_global_memory_writes<KeyT>(elements);

  caching_allocator_t alloc;
  state.exec(nvbench::exec_tag::gpu | nvbench::exec_tag::no_batch, [&](nvbench::launch& launch) {
    auto env = cub_bench_env(
      alloc,
      launch
#if !TUNE_BASE
      ,
      cuda::execution::tune(bench_policy_selector<key_t>{})
#endif // !TUNE_BASE
    );
    _CCCL_TRY_CUDA_API(
      cub::DeviceMerge::MergeKeys,
      "MergePairs failed",
      d_keys_lhs,
      static_cast<offset_t>(num_items_lhs),
      d_keys_rhs,
      static_cast<offset_t>(num_items_rhs),
      d_keys_out,
      compare_op_t{},
      env);
  });
}

#ifdef TUNE_KeyT
using key_types = nvbench::type_list<TUNE_KeyT>;
#else // !defined(TUNE_KeyT)
using key_types = fundamental_types;
#endif // TUNE_KeyT

NVBENCH_BENCH_TYPES(keys, NVBENCH_TYPE_AXES(key_types))
  .set_name("base")
  .set_type_axes_names({"KeyT{ct}"})
  .add_int64_power_of_two_axis("Elements{io}", nvbench::range(16, 28, 4))
  .add_string_axis("Entropy", {"1.000", "0.201"});