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 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
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#pragma once

#if THRUST_DEVICE_COMPILER == THRUST_DEVICE_COMPILER_HIP
#include <thrust/system/hip/config.h>

#include <thrust/detail/config.h>
#include <thrust/pair.h>

#include <thrust/detail/cstdint.h>
#include <thrust/detail/temporary_array.h>
#include <thrust/detail/alignment.h>
#include <thrust/detail/minmax.h>
#include <thrust/detail/raw_reference_cast.h>
#include <thrust/detail/type_traits/iterator/is_output_iterator.h>
#include <thrust/system/hip/detail/get_value.h>
#include <thrust/system/hip/detail/par_to_seq.h>
#include <thrust/system/hip/detail/util.h>
#include <thrust/device_vector.h>
#include <thrust/distance.h>
#include <thrust/functional.h>

// rocprim include
#include <rocprim/rocprim.hpp>

THRUST_NAMESPACE_BEGIN

template <typename DerivedPolicy,
          typename InputIterator1,
          typename InputIterator2,
          typename OutputIterator1,
          typename OutputIterator2,
          typename BinaryPredicate>
__host__ __device__ thrust::pair<OutputIterator1, OutputIterator2>
reduce_by_key(const thrust::detail::execution_policy_base<DerivedPolicy>& exec,
              InputIterator1                                              keys_first,
              InputIterator1                                              keys_last,
              InputIterator2                                              values_first,
              OutputIterator1                                             keys_output,
              OutputIterator2                                             values_output,
              BinaryPredicate                                             binary_pred);

namespace hip_rocprim
{
namespace __reduce_by_key
{
    template <typename Derived,
              typename KeysInputIt,
              typename ValuesInputIt,
              typename KeysOutputIt,
              typename ValuesOutputIt,
              typename EqualityOp,
              typename ReductionOp>
    THRUST_HIP_RUNTIME_FUNCTION
    pair<KeysOutputIt, ValuesOutputIt>
    reduce_by_key(execution_policy<Derived>& policy,
                  KeysInputIt                keys_first,
                  KeysInputIt                keys_last,
                  ValuesInputIt              values_first,
                  KeysOutputIt               keys_output,
                  ValuesOutputIt             values_output,
                  EqualityOp                 equality_op,
                  ReductionOp                reduction_op)
    {
        typedef size_t size_type;
        size_type   num_items = static_cast<size_type>(thrust::distance(keys_first, keys_last));
        size_t      temp_storage_bytes = 0;
        hipStream_t stream             = hip_rocprim::stream(policy);
        bool        debug_sync         = THRUST_HIP_DEBUG_SYNC_FLAG;

        if(num_items == 0)
            return thrust::make_pair(keys_output, values_output);

        hip_rocprim::throw_on_error(rocprim::reduce_by_key(NULL,
                                                           temp_storage_bytes,
                                                           keys_first,
                                                           values_first,
                                                           num_items,
                                                           keys_output,
                                                           values_output,
                                                           reinterpret_cast<size_type*>(NULL),
                                                           reduction_op,
                                                           equality_op,
                                                           stream,
                                                           debug_sync),
                                    "reduce_by_key failed on 1st step");

        size_t storage_size = temp_storage_bytes + sizeof(size_type);

        // Allocate temporary storage.
        thrust::detail::temporary_array<thrust::detail::uint8_t, Derived>
            tmp(policy, storage_size);
        void *ptr = static_cast<void*>(tmp.data().get());

        size_type* d_num_runs_out = reinterpret_cast<size_type*>(
            reinterpret_cast<char*>(ptr) + temp_storage_bytes);

        hip_rocprim::throw_on_error(rocprim::reduce_by_key(ptr,
                                                           temp_storage_bytes,
                                                           keys_first,
                                                           values_first,
                                                           num_items,
                                                           keys_output,
                                                           values_output,
                                                           d_num_runs_out,
                                                           reduction_op,
                                                           equality_op,
                                                           stream,
                                                           debug_sync),
                                    "reduce_by_key failed on 2nd step");

        size_type num_runs_out = hip_rocprim::get_value(policy, d_num_runs_out);

        return thrust::make_pair(keys_output + num_runs_out, values_output + num_runs_out);
    }

} // namespace __reduce_by_key

//-------------------------
// Thrust API entry points
//-------------------------

__thrust_exec_check_disable__ template <class Derived,
                                        class KeyInputIt,
                                        class ValInputIt,
                                        class KeyOutputIt,
                                        class ValOutputIt,
                                        class BinaryPred,
                                        class BinaryOp>
THRUST_HIP_FUNCTION
pair<KeyOutputIt, ValOutputIt>
reduce_by_key(execution_policy<Derived>& policy,
              KeyInputIt                 keys_first,
              KeyInputIt                 keys_last,
              ValInputIt                 values_first,
              KeyOutputIt                keys_output,
              ValOutputIt                values_output,
              BinaryPred                 binary_pred,
              BinaryOp                   binary_op)
{
  struct workaround
  {
      __host__
      static pair<KeyOutputIt, ValOutputIt> par(
        execution_policy<Derived>& policy,
        KeyInputIt                 keys_first,
        KeyInputIt                 keys_last,
        ValInputIt                 values_first,
        KeyOutputIt                keys_output,
        ValOutputIt                values_output,
        BinaryPred                 binary_pred,
        BinaryOp                   binary_op)
      {
      #if __HCC__ && __HIP_DEVICE_COMPILE__
      THRUST_HIP_PRESERVE_KERNELS_WORKAROUND(
          (__reduce_by_key::reduce_by_key<Derived, KeyInputIt, ValInputIt, KeyOutputIt, ValOutputIt, BinaryPred, BinaryOp>)
      );
      #else
      return __reduce_by_key::reduce_by_key(
        policy,
        keys_first,
        keys_last,
        values_first,
        keys_output,
        values_output,
        binary_pred,
        binary_op
      );
      #endif
      }
      __device__
      static pair<KeyOutputIt, ValOutputIt> seq(
        execution_policy<Derived>& policy,
        KeyInputIt                 keys_first,
        KeyInputIt                 keys_last,
        ValInputIt                 values_first,
        KeyOutputIt                keys_output,
        ValOutputIt                values_output,
        BinaryPred                 binary_pred,
        BinaryOp                   binary_op)
      {
        return thrust::reduce_by_key(cvt_to_seq(derived_cast(policy)),
                                     keys_first,
                                     keys_last,
                                     values_first,
                                     keys_output,
                                     values_output,
                                     binary_pred,
                                     binary_op
                                     );
      }
  };
  #if __THRUST_HAS_HIPRT__
    return workaround::par(policy,  keys_first, keys_last, values_first, keys_output, values_output, binary_pred, binary_op);
  #else
    return workaround::seq(policy,  keys_first, keys_last, values_first, keys_output, values_output, binary_pred, binary_op);
  #endif

}

__thrust_exec_check_disable__ template <class Derived,
                                        class KeyInputIt,
                                        class ValInputIt,
                                        class KeyOutputIt,
                                        class ValOutputIt,
                                        class BinaryPred>
THRUST_HIP_FUNCTION pair<KeyOutputIt, ValOutputIt>
reduce_by_key(execution_policy<Derived>& policy,
              KeyInputIt                 keys_first,
              KeyInputIt                 keys_last,
              ValInputIt                 values_first,
              KeyOutputIt                keys_output,
              ValOutputIt                values_output,
              BinaryPred                 binary_pred)
{
    typedef typename thrust::detail::eval_if<thrust::detail::is_output_iterator<ValOutputIt>::value,
                                             thrust::iterator_value<ValInputIt>,
                                             thrust::iterator_value<ValOutputIt>>::type value_type;

    return hip_rocprim::reduce_by_key(policy,
                                      keys_first,
                                      keys_last,
                                      values_first,
                                      keys_output,
                                      values_output,
                                      binary_pred,
                                      plus<value_type>());
}

__thrust_exec_check_disable__ template <class Derived,
                                        class KeyInputIt,
                                        class ValInputIt,
                                        class KeyOutputIt,
                                        class ValOutputIt>
THRUST_HIP_FUNCTION pair<KeyOutputIt, ValOutputIt>
reduce_by_key(execution_policy<Derived>& policy,
              KeyInputIt                 keys_first,
              KeyInputIt                 keys_last,
              ValInputIt                 values_first,
              KeyOutputIt                keys_output,
              ValOutputIt                values_output)
{
    typedef typename thrust::iterator_value<KeyInputIt>::type KeyT;
    return hip_rocprim::reduce_by_key(policy,
                                      keys_first,
                                      keys_last,
                                      values_first,
                                      keys_output,
                                      values_output,
                                      equal_to<KeyT>());
}

} // namespace  hip_rocprim
THRUST_NAMESPACE_END

#endif