//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// SPDX-FileCopyrightText: Copyright (c) 2024 NVIDIA CORPORATION & AFFILIATES.
//
//===----------------------------------------------------------------------===//

#ifndef _CUDA_STD___ALGORITHM_SET_UNION_H
#define _CUDA_STD___ALGORITHM_SET_UNION_H

#include <cuda/std/detail/__config>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

#include <cuda/std/__algorithm/comp.h>
#include <cuda/std/__algorithm/comp_ref_type.h>
#include <cuda/std/__algorithm/copy.h>
#include <cuda/std/__algorithm/iterator_operations.h>
#include <cuda/std/__iterator/iterator_traits.h>
#include <cuda/std/__utility/move.h>
#include <cuda/std/__utility/pair.h>

#include <cuda/std/__cccl/prologue.h>

_CCCL_BEGIN_NAMESPACE_CUDA_STD

_CCCL_EXEC_CHECK_DISABLE
template <class _InIter1, class _InIter2, class _OutIter>
struct __set_union_result
{
  _InIter1 __in1_;
  _InIter2 __in2_;
  _OutIter __out_;

  // need a constructor as C++03 aggregate init is hard
  _CCCL_API constexpr __set_union_result(_InIter1&& __in_iter1, _InIter2&& __in_iter2, _OutIter&& __out_iter)
      : __in1_(::cuda::std::move(__in_iter1))
      , __in2_(::cuda::std::move(__in_iter2))
      , __out_(::cuda::std::move(__out_iter))
  {}
};

_CCCL_EXEC_CHECK_DISABLE
template <class _AlgPolicy, class _Compare, class _InIter1, class _Sent1, class _InIter2, class _Sent2, class _OutIter>
_CCCL_API constexpr __set_union_result<_InIter1, _InIter2, _OutIter>
__set_union(_InIter1 __first1, _Sent1 __last1, _InIter2 __first2, _Sent2 __last2, _OutIter __result, _Compare&& __comp)
{
  for (; __first1 != __last1; ++__result)
  {
    if (__first2 == __last2)
    {
      auto __ret1 = ::cuda::std::__copy<_AlgPolicy>(
        ::cuda::std::move(__first1), ::cuda::std::move(__last1), ::cuda::std::move(__result));
      return __set_union_result<_InIter1, _InIter2, _OutIter>(
        ::cuda::std::move(__ret1.first), ::cuda::std::move(__first2), ::cuda::std::move((__ret1.second)));
    }
    if (__comp(*__first2, *__first1))
    {
      *__result = *__first2;
      ++__first2;
    }
    else
    {
      if (!__comp(*__first1, *__first2))
      {
        ++__first2;
      }
      *__result = *__first1;
      ++__first1;
    }
  }
  auto __ret2 = ::cuda::std::__copy<_AlgPolicy>(
    ::cuda::std::move(__first2), ::cuda::std::move(__last2), ::cuda::std::move(__result));
  return __set_union_result<_InIter1, _InIter2, _OutIter>(
    ::cuda::std::move(__first1), ::cuda::std::move(__ret2.first), ::cuda::std::move((__ret2.second)));
}

_CCCL_EXEC_CHECK_DISABLE
template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
_CCCL_API constexpr _OutputIterator set_union(
  _InputIterator1 __first1,
  _InputIterator1 __last1,
  _InputIterator2 __first2,
  _InputIterator2 __last2,
  _OutputIterator __result,
  _Compare __comp)
{
  return ::cuda::std::__set_union<_ClassicAlgPolicy, __comp_ref_type<_Compare>>(
           ::cuda::std::move(__first1),
           ::cuda::std::move(__last1),
           ::cuda::std::move(__first2),
           ::cuda::std::move(__last2),
           ::cuda::std::move(__result),
           __comp)
    .__out_;
}

_CCCL_EXEC_CHECK_DISABLE
template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
_CCCL_API constexpr _OutputIterator set_union(
  _InputIterator1 __first1,
  _InputIterator1 __last1,
  _InputIterator2 __first2,
  _InputIterator2 __last2,
  _OutputIterator __result)
{
  return ::cuda::std::set_union(
    ::cuda::std::move(__first1),
    ::cuda::std::move(__last1),
    ::cuda::std::move(__first2),
    ::cuda::std::move(__last2),
    ::cuda::std::move(__result),
    __less{});
}

_CCCL_END_NAMESPACE_CUDA_STD

#include <cuda/std/__cccl/epilogue.h>

#endif // _CUDA_STD___ALGORITHM_SET_UNION_H
