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#include "nvbench_helper.cuh"

#include <thrust/device_vector.h>
#include <thrust/execution_policy.h>
#include <thrust/partition.h>

template <class T>
struct less_then_t 
{
  T m_val;

  __host__ __device__ bool operator()(const T &val) const { return val < m_val; }
};

template <typename T>
T value_from_entropy(double percentage) 
{
  if (percentage == 1) 
  {
    return std::numeric_limits<T>::max();
  }
  
  const auto max_val = static_cast<double>(std::numeric_limits<T>::max());
  const auto min_val = static_cast<double>(std::numeric_limits<T>::lowest());
  const auto result = min_val + percentage * max_val - percentage * min_val;
  return static_cast<T>(result);
}

template <typename T>
static void basic(nvbench::state &state,
                  nvbench::type_list<T>)
{
  using select_op_t = less_then_t<T>;

  const auto elements       = static_cast<std::size_t>(state.get_int64("Elements"));
  const bit_entropy entropy = str_to_entropy(state.get_string("Entropy"));

  T val = value_from_entropy<T>(entropy_to_probability(entropy));
  select_op_t select_op{val};

  thrust::device_vector<T> input = generate(elements);
  thrust::device_vector<T> output(elements);

  state.add_element_count(elements);
  state.add_global_memory_reads<T>(elements);
  state.add_global_memory_writes<T>(elements);

  state.exec(nvbench::exec_tag::no_batch | nvbench::exec_tag::sync, [&](nvbench::launch & /* launch */) {
    thrust::partition_copy(input.cbegin(),
                           input.cend(),
                           output.begin(),
                           thrust::make_reverse_iterator(output.begin() + elements),
                           select_op);
  });
}

NVBENCH_BENCH_TYPES(basic, NVBENCH_TYPE_AXES(fundamental_types))
  .set_name("base")
  .set_type_axes_names({"T{ct}"})
  .add_int64_power_of_two_axis("Elements", nvbench::range(16, 28, 4))
  .add_string_axis("Entropy", {"1.000", "0.544", "0.000"});
