/****************************************************************************
 * Copyright (c) 2023 by the ArborX authors                                 *
 * All rights reserved.                                                     *
 *                                                                          *
 * This file is part of the ArborX library. ArborX is                       *
 * distributed under a BSD 3-clause license. For the licensing terms see    *
 * the LICENSE file in the top-level directory.                             *
 *                                                                          *
 * SPDX-License-Identifier: BSD-3-Clause                                    *
 ****************************************************************************/

#ifndef ARBORX_DETAILS_LEGACY_HPP
#define ARBORX_DETAILS_LEGACY_HPP

#include <ArborX_Config.hpp>

#include <ArborX_AccessTraits.hpp>
#include <ArborX_PairValueIndex.hpp>

namespace ArborX::Details
{

template <typename Primitives, typename BoundingVolume>
class LegacyValues
{
  Primitives _primitives;
  using Access = AccessTraits<Primitives, PrimitivesTag>;

public:
  using memory_space = typename Access::memory_space;
  using index_type = unsigned;
  using value_type = PairValueIndex<BoundingVolume, index_type>;
  using size_type =
      Kokkos::detected_t<Details::AccessTraitsSizeArchetypeExpression, Access,
                         Primitives>;

  LegacyValues(Primitives const &primitives)
      : _primitives(primitives)
  {}

  KOKKOS_FUNCTION
  auto operator()(size_type i) const
  {
    using Primitive = std::decay_t<decltype(Access::get(_primitives, i))>;
    if constexpr (std::is_same_v<BoundingVolume, Primitive>)
    {
      return value_type{Access::get(_primitives, i), (index_type)i};
    }
    else
    {
      BoundingVolume bounding_volume{};
      expand(bounding_volume, Access::get(_primitives, i));
      return value_type{bounding_volume, (index_type)i};
    }
#if (defined(KOKKOS_COMPILER_NVCC) && (KOKKOS_COMPILER_NVCC < 1150)) ||        \
    (defined(KOKKOS_COMPILER_INTEL) && (KOKKOS_COMPILER_INTEL <= 2021))
    // FIXME_NVCC, FIXME_INTEL: workaround for spurios "missing return
    // statement at end of non-void function" warning
    return value_type{};
#endif
  }

  KOKKOS_FUNCTION
  size_type size() const { return Access::size(_primitives); }
};

template <typename Primitives, typename BoundingVolume>
class AccessValuesI<LegacyValues<Primitives, BoundingVolume>, PrimitivesTag>
    : public LegacyValues<Primitives, BoundingVolume>
{
public:
  using self_type = LegacyValues<Primitives, BoundingVolume>;
};

template <typename Callback>
struct LegacyCallbackWrapper
{
  Callback _callback;

  template <typename Predicate, typename Value, typename Index>
  KOKKOS_FUNCTION auto
  operator()(Predicate const &predicate,
             PairValueIndex<Value, Index> const &value) const
  {
    return _callback(predicate, value.index);
  }

  template <typename Predicate, typename Value, typename Index, typename Output>
  KOKKOS_FUNCTION void operator()(Predicate const &predicate,
                                  PairValueIndex<Value, Index> const &value,
                                  Output const &out) const
  {
    // APIv1 callback has the signature operator()(Query, int)
    // As we store PairValueIndex with potentially non int index (like
    // unsigned), we explicitly cast it here.
    _callback(predicate, (int)value.index, out);
  }
};

struct LegacyDefaultCallback
{
  template <typename Query, typename Value, typename Index,
            typename OutputFunctor>
  KOKKOS_FUNCTION void operator()(Query const &,
                                  PairValueIndex<Value, Index> const &value,
                                  OutputFunctor const &output) const
  {
    // APIv1 callback has the signature operator()(Query, int)
    // As we store PairValueIndex with potentially non int index (like
    // unsigned), we explicitly cast it here.
    output((int)value.index);
  }
};

struct LegacyDefaultTemplateValue
{};

} // namespace ArborX::Details

template <>
struct ArborX::GeometryTraits::dimension<
    ArborX::Details::LegacyDefaultTemplateValue>
{
  static constexpr int value = 3;
};
template <>
struct ArborX::GeometryTraits::tag<ArborX::Details::LegacyDefaultTemplateValue>
{
  using type = BoxTag;
};
template <>
struct ArborX::GeometryTraits::coordinate_type<
    ArborX::Details::LegacyDefaultTemplateValue>
{
  using type = float;
};

template <typename Primitives, typename BoundingVolume>
struct ArborX::AccessTraits<
    ArborX::Details::LegacyValues<Primitives, BoundingVolume>,
    ArborX::PrimitivesTag>
{
  using Values = ArborX::Details::LegacyValues<Primitives, BoundingVolume>;

  using memory_space = typename Values::memory_space;
  using size_type = typename Values::size_type;
  using value_type = typename Values::value_type;

  KOKKOS_FUNCTION static size_type size(Values const &values)
  {
    return values.size();
  }
  KOKKOS_FUNCTION static decltype(auto) get(Values const &values, size_type i)
  {
    return values(i);
  }
};

#endif