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#pragma once

#if THRUST_DEVICE_COMPILER == THRUST_DEVICE_COMPILER_HIP
#include <thrust/detail/cstdint.h>
#include <thrust/detail/temporary_array.h>
#include <thrust/distance.h>
#include <thrust/detail/alignment.h>
#include <thrust/iterator/iterator_traits.h>
#include <thrust/iterator/transform_iterator.h>
#include <thrust/system/hip/config.h>
#include <thrust/system/hip/detail/par_to_seq.h>
#include <thrust/system/hip/detail/util.h>

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

THRUST_NAMESPACE_BEGIN

// XXX declare generic copy_if interface
// to avoid circular dependency from thrust/copy.h
template <typename DerivedPolicy,
          typename InputIterator,
          typename OutputIterator,
          typename Predicate>
OutputIterator __host__ __device__
copy_if(const thrust::detail::execution_policy_base<DerivedPolicy>& exec,
        InputIterator                                               first,
        InputIterator                                               last,
        OutputIterator                                              result,
        Predicate                                                   pred);

template <typename DerivedPolicy,
          typename InputIterator1,
          typename InputIterator2,
          typename OutputIterator,
          typename Predicate>
OutputIterator __host__ __device__
copy_if(const thrust::detail::execution_policy_base<DerivedPolicy>& exec,
        InputIterator1                                              first,
        InputIterator1                                              last,
        InputIterator2                                              stencil,
        OutputIterator                                              result,
        Predicate                                                   pred);

namespace hip_rocprim
{
namespace __copy_if
{
    template <typename Derived, typename InputIt, typename OutputIt, typename Predicate>
    THRUST_HIP_RUNTIME_FUNCTION OutputIt
    copy_if(execution_policy<Derived>& policy, InputIt first, InputIt last, OutputIt output, Predicate predicate)
    {
        typedef typename iterator_traits<InputIt>::difference_type size_type;

        size_type   num_items          = thrust::distance(first, 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 output;

        // Determine temporary device storage requirements.
        hip_rocprim::throw_on_error(rocprim::select(NULL,
                                                    temp_storage_bytes,
                                                    first,
                                                    output,
                                                    reinterpret_cast<size_type*>(NULL),
                                                    num_items,
                                                    predicate,
                                                    stream,
                                                    debug_sync),
                                    "copy_if 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_selected_out
		    = reinterpret_cast<size_type*>(reinterpret_cast<char*>(ptr) + temp_storage_bytes);

        hip_rocprim::throw_on_error(rocprim::select(ptr,
                                                    temp_storage_bytes,
                                                    first,
                                                    output,
                                                    d_num_selected_out,
                                                    num_items,
                                                    predicate,
                                                    stream,
                                                    debug_sync),
                                    "copy_if failed on 2nd step");

        size_type num_selected = get_value(policy, d_num_selected_out);

        return output + num_selected;
    }

    template <typename Derived, typename InputIt, typename StencilIt, typename OutputIt, typename Predicate>
    THRUST_HIP_RUNTIME_FUNCTION OutputIt
    copy_if(execution_policy<Derived>& policy,
            InputIt                    first,
            InputIt                    last,
            StencilIt                  stencil,
            OutputIt                   output,
            Predicate                  predicate)
    {
        typedef typename iterator_traits<InputIt>::difference_type size_type;

        size_type   num_items          = thrust::distance(first, 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 output;

        auto flags = thrust::make_transform_iterator(stencil, predicate);

        // Determine temporary device storage requirements.
        hip_rocprim::throw_on_error(rocprim::select(NULL,
                                                    temp_storage_bytes,
                                                    first,
                                                    flags,
                                                    output,
                                                    reinterpret_cast<size_type*>(NULL),
                                                    num_items,
                                                    stream,
                                                    debug_sync),
                                    "copy_if 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_selected_out
		    = reinterpret_cast<size_type*>(reinterpret_cast<char*>(ptr) + temp_storage_bytes);

        hip_rocprim::throw_on_error(rocprim::select(ptr,
                                                    temp_storage_bytes,
                                                    first,
                                                    flags,
                                                    output,
                                                    d_num_selected_out,
                                                    num_items,
                                                    stream,
                                                    debug_sync),
                                    "copy_if failed on 2nd step");

        size_type num_selected = get_value(policy, d_num_selected_out);

        return output + num_selected;
    }

} // namespace __copy_if

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

template <class Derived, class InputIterator, class OutputIterator, class Predicate>
OutputIterator THRUST_HIP_FUNCTION
copy_if(execution_policy<Derived>& policy,
        InputIterator              first,
        InputIterator              last,
        OutputIterator             result,
        Predicate                  pred)
{
    // struct workaround is required for HIP-clang
    struct workaround
    {
        __host__ static OutputIterator par(execution_policy<Derived>& policy,
                                           InputIterator              first,
                                           InputIterator              last,
                                           OutputIterator             result,
                                           Predicate                  pred)
        {
            return __copy_if::copy_if(policy, first, last, result, pred);
        }
        __device__ static OutputIterator seq(execution_policy<Derived>& policy,
                                             InputIterator              first,
                                             InputIterator              last,
                                             OutputIterator             result,
                                             Predicate                  pred)
        {
            return thrust::copy_if(cvt_to_seq(derived_cast(policy)), first, last, result, pred);
        }
  };

  #if __THRUST_HAS_HIPRT__
    return workaround::par(policy, first, last, result, pred);
  #else
    return workaround::seq(policy, first, last, result, pred);
  #endif



} // func copy_if

template <class Derived,
          class InputIterator,
          class StencilIterator,
          class OutputIterator,
          class Predicate>
OutputIterator THRUST_HIP_FUNCTION
copy_if(execution_policy<Derived>& policy,
        InputIterator              first,
        InputIterator              last,
        StencilIterator            stencil,
        OutputIterator             result,
        Predicate                  pred)
{

    // struct workaround is required for HIP-clang
    struct workaround
    {
        __host__ static OutputIterator par(execution_policy<Derived>& policy,
                                           InputIterator              first,
                                           InputIterator              last,
                                           StencilIterator            stencil,
                                           OutputIterator             result,
                                           Predicate                  pred)
        {
            return __copy_if::copy_if(policy, first, last, stencil, result, pred);
        }
        __device__ static OutputIterator seq(execution_policy<Derived>& policy,
                                             InputIterator              first,
                                             InputIterator              last,
                                             StencilIterator            stencil,
                                             OutputIterator             result,
                                             Predicate                  pred)
        {
            return thrust::copy_if(
                cvt_to_seq(derived_cast(policy)), first, last, stencil, result, pred);
        }
  };

#if __THRUST_HAS_HIPRT__
    return workaround::par(policy, first, last, stencil, result, pred);
#else
    return workaround::seq(policy, first, last, stencil, result, pred);
#endif
} // func copy_if

} // namespace hip_rocprim
THRUST_NAMESPACE_END

#include <thrust/copy.h>
#endif
