/*
 *  Copyright 2008-2021 NVIDIA Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

/*! \file
 *  \brief Algorithms for asynchronously copying a range.
 */

#pragma once

#include <thrust/detail/config.h>

#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 <thrust/detail/cpp14_required.h>

#if _CCCL_STD_VER >= 2014

#  include <thrust/detail/select_system.h>
#  include <thrust/detail/static_assert.h>
#  include <thrust/event.h>
#  include <thrust/system/detail/adl/async/copy.h>
#  include <thrust/type_traits/remove_cvref.h>

THRUST_NAMESPACE_BEGIN

namespace async
{

/*! \cond
 */

namespace unimplemented
{

template <typename FromPolicy, typename ToPolicy, typename ForwardIt, typename Sentinel, typename OutputIt>
_CCCL_HOST event<FromPolicy> async_copy(
  thrust::execution_policy<FromPolicy>& from_exec,
  thrust::execution_policy<ToPolicy>& to_exec,
  ForwardIt first,
  Sentinel last,
  OutputIt output)
{
  THRUST_STATIC_ASSERT_MSG((thrust::detail::depend_on_instantiation<ForwardIt, false>::value),
                           "this algorithm is not implemented for the specified system");
  return {};
}

} // namespace unimplemented

namespace copy_detail
{

using thrust::async::unimplemented::async_copy;

struct copy_fn final
{
  template <typename FromPolicy, typename ToPolicy, typename ForwardIt, typename Sentinel, typename OutputIt>
  _CCCL_HOST static auto
  call(thrust::detail::execution_policy_base<FromPolicy> const& from_exec,
       thrust::detail::execution_policy_base<ToPolicy> const& to_exec,
       ForwardIt&& first,
       Sentinel&& last,
       OutputIt&& output)
    // ADL dispatch.
    THRUST_RETURNS(async_copy(
      thrust::detail::derived_cast(thrust::detail::strip_const(from_exec)),
      thrust::detail::derived_cast(thrust::detail::strip_const(to_exec)),
      THRUST_FWD(first),
      THRUST_FWD(last),
      THRUST_FWD(output)))

      template <typename DerivedPolicy, typename ForwardIt, typename Sentinel, typename OutputIt>
      _CCCL_HOST static auto call(thrust::detail::execution_policy_base<DerivedPolicy> const& exec,
                                  ForwardIt&& first,
                                  Sentinel&& last,
                                  OutputIt&& output)
        THRUST_RETURNS(copy_fn::call(
          thrust::detail::derived_cast(thrust::detail::strip_const(exec))
          // Synthesize a suitable new execution policy, because we don't want to
          // try and extract twice from the one we were passed.
          ,
          typename remove_cvref_t<decltype(thrust::detail::derived_cast(thrust::detail::strip_const(exec)))>::tag_type{},
          THRUST_FWD(first),
          THRUST_FWD(last),
          THRUST_FWD(output)))

          template <typename ForwardIt, typename Sentinel, typename OutputIt>
          _CCCL_HOST static auto call(ForwardIt&& first, Sentinel&& last, OutputIt&& output)
            THRUST_RETURNS(copy_fn::call(
              thrust::detail::select_system(typename thrust::iterator_system<remove_cvref_t<ForwardIt>>::type{}),
              thrust::detail::select_system(typename thrust::iterator_system<remove_cvref_t<OutputIt>>::type{}),
              THRUST_FWD(first),
              THRUST_FWD(last),
              THRUST_FWD(output)))

              template <typename... Args>
              _CCCL_NODISCARD _CCCL_HOST auto operator()(Args&&... args) const THRUST_RETURNS(call(THRUST_FWD(args)...))
};

} // namespace copy_detail

THRUST_INLINE_CONSTANT copy_detail::copy_fn copy{};

/*! \endcond
 */

} // namespace async

THRUST_NAMESPACE_END

#endif
