//===----------------------------------------------------------------------===//
//
// 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) 2023-24 NVIDIA CORPORATION & AFFILIATES.
//
//===----------------------------------------------------------------------===//

// Modifications Copyright (c) 2025 Advanced Micro Devices, Inc.
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#ifndef _LIBCUDACXX___ALGORITHM_COPY_H
#define _LIBCUDACXX___ALGORITHM_COPY_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/iterator_operations.h>
#include <cuda/std/__algorithm/unwrap_iter.h>
#include <cuda/std/__type_traits/enable_if.h>
#include <cuda/std/__type_traits/is_constant_evaluated.h>
#include <cuda/std/__type_traits/is_same.h>
#include <cuda/std/__type_traits/is_trivially_copyable.h>
#include <cuda/std/__type_traits/remove_const.h>
#include <cuda/std/cstdint>
#include <cuda/std/cstdlib>
#include <cuda/std/cstring> // memmove

_LIBCUDACXX_BEGIN_NAMESPACE_STD

_CCCL_EXEC_CHECK_DISABLE
template <class _AlgPolicy, class _InputIterator, class _OutputIterator>
_LIBCUDACXX_HIDE_FROM_ABI constexpr pair<_InputIterator, _OutputIterator>
__copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
{
  for (; __first != __last; ++__first, (void) ++__result)
  {
    *__result = *__first;
  }
  return {__last, __result};
}

_CCCL_EXEC_CHECK_DISABLE
template <class _Tp, class _Up>
_LIBCUDACXX_HIDE_FROM_ABI constexpr bool __dispatch_memmove(_Up* __result, _Tp* __first, const size_t __n)
{
#if defined(_CCCL_BUILTIN_MEMMOVE)
  _CCCL_BUILTIN_MEMMOVE(__result, __first, __n * sizeof(_Up));
  return true;
#else // ^^^ _CCCL_BUILTIN_MEMMOVE ^^^ / vvv !_CCCL_BUILTIN_MEMMOVE vvv
  if (!_CUDA_VSTD::__cccl_default_is_constant_evaluated())
  {
    _CUDA_VSTD::memmove(__result, __first, __n * sizeof(_Up));
    return true;
  }

  return false;
#endif // ^^^ !_CCCL_BUILTIN_MEMMOVE ^^^
}

_CCCL_EXEC_CHECK_DISABLE
template <class _Tp, class _Up>
_LIBCUDACXX_HIDE_FROM_ABI constexpr bool __constexpr_tail_overlap_fallback(_Tp* __first, _Up* __needle, _Tp* __last)
{
  while (__first != __last)
  {
    if (__first == __needle)
    {
      return true;
    }
    ++__first;
  }
  return false;
}

_CCCL_EXEC_CHECK_DISABLE
template <class _Tp, class _Up>
_LIBCUDACXX_HIDE_FROM_ABI constexpr bool __constexpr_tail_overlap(_Tp* __first, _Up* __needle, _Tp* __last)
{
  _LIBCUDACXX_UNUSED_VAR(__last);
#if defined(_CCCL_BUILTIN_CONSTANT_P)
  NV_IF_ELSE_TARGET(NV_IS_HOST_LIBHIPCXX,
                    (return _CCCL_BUILTIN_CONSTANT_P(__first < __needle) && __first < __needle;),
                    (return __constexpr_tail_overlap_fallback(__first, __needle, __last);))
#else // ^^^ _CCCL_BUILTIN_CONSTANT_P ^^^ / vvv !_CCCL_BUILTIN_CONSTANT_P vvv
  return __constexpr_tail_overlap_fallback(__first, __needle, __last);
#endif // !_CCCL_BUILTIN_CONSTANT_P
}

_CCCL_EXEC_CHECK_DISABLE
template <class _AlgPolicy,
          class _Tp,
          class _Up,
          enable_if_t<_CCCL_TRAIT(is_same, remove_const_t<_Tp>, _Up), int> = 0,
          enable_if_t<_CCCL_TRAIT(is_trivially_copyable, _Up), int>        = 0>
_LIBCUDACXX_HIDE_FROM_ABI constexpr pair<_Tp*, _Up*> __copy(_Tp* __first, _Tp* __last, _Up* __result)
{
  const ptrdiff_t __n = __last - __first;
  if (__n > 0)
  {
    if (__dispatch_memmove(__result, __first, __n))
    {
      return {__last, __result + __n};
    }
    if ((!_CUDA_VSTD::is_constant_evaluated() && __first < __result)
        || __constexpr_tail_overlap(__first, __result, __last))
    {
      for (ptrdiff_t __i = __n; __i > 0; --__i)
      {
        *(__result + __i - 1) = *(__first + __i - 1);
      }
    }
    else
    {
      for (ptrdiff_t __i = 0; __i < __n; ++__i)
      {
        *(__result + __i) = *(__first + __i);
      }
    }
  }
  return {__last, __result + __n};
}

template <class _InputIterator, class _OutputIterator>
_LIBCUDACXX_HIDE_FROM_ABI constexpr _OutputIterator
copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
{
  return _CUDA_VSTD::__copy<_ClassicAlgPolicy>(
           _CUDA_VSTD::__unwrap_iter(__first), _CUDA_VSTD::__unwrap_iter(__last), _CUDA_VSTD::__unwrap_iter(__result))
    .second;
}

_LIBCUDACXX_END_NAMESPACE_STD

#endif // _LIBCUDACXX___ALGORITHM_COPY_H
