// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// SPDX-FileCopyrightText: Copyright Contributors to the Kokkos project

#include <gtest/gtest.h>

#include <Kokkos_Macros.hpp>
#ifdef KOKKOS_ENABLE_EXPERIMENTAL_CXX20_MODULES
import kokkos.core;
#else
#include <Kokkos_Core.hpp>
#endif
#include <sstream>
#include <iostream>

namespace Test {

template <class Space>
struct NestedView {
  Kokkos::View<int *, Space> member;

 public:
  KOKKOS_INLINE_FUNCTION
  NestedView() : member() {}

  KOKKOS_INLINE_FUNCTION
  NestedView &operator=(const Kokkos::View<int *, Space> &lhs) {
    member = lhs;
    if (member.extent(0)) Kokkos::atomic_add(&member(0), 1);
    return *this;
  }

  KOKKOS_DEFAULTED_FUNCTION NestedView(const NestedView &)            = default;
  KOKKOS_DEFAULTED_FUNCTION NestedView(NestedView &&)                 = default;
  KOKKOS_DEFAULTED_FUNCTION NestedView &operator=(const NestedView &) = default;
  KOKKOS_DEFAULTED_FUNCTION NestedView &operator=(NestedView &&)      = default;

  KOKKOS_INLINE_FUNCTION
  ~NestedView() {
    if (member.extent(0)) {
      Kokkos::atomic_add(&member(0), -1);
    }
  }
};

// Workaround for clang 19/20/21/22 MachineLICM ICE: NestedView::operator=(View)
// crashes MachineLICM when inlined into cuda_parallel_launch_local_memory. A
// noinline wrapper breaks the chain.
template <class Space>
#if defined(KOKKOS_COMPILER_CLANG) && defined(KOKKOS_ENABLE_CUDA)
KOKKOS_FUNCTION
    __attribute__((noinline))
#else
KOKKOS_FUNCTION
#endif
    void
    assign_nested_view(NestedView<Space> &dst,
                       const Kokkos::View<int *, Space> &src) {
  dst = src;
}

template <class Space>
struct NestedViewFunctor {
  Kokkos::View<NestedView<Space> *, Space> nested;
  Kokkos::View<int *, Space> array;

  NestedViewFunctor(const Kokkos::View<NestedView<Space> *, Space> &arg_nested,
                    const Kokkos::View<int *, Space> &arg_array)
      : nested(arg_nested), array(arg_array) {}

  KOKKOS_INLINE_FUNCTION
  void operator()(int i) const { assign_nested_view(nested[i], array); }
};

template <class Space>
void view_nested_view() {
  Kokkos::View<int *, Space> tracking("tracking", 1);

  typename Kokkos::View<int *, Space>::host_mirror_type host_tracking =
      Kokkos::create_mirror(tracking);

  {
    Kokkos::View<NestedView<Space> *, Space> a("a_nested_view", 2);

    Kokkos::parallel_for(Kokkos::RangePolicy<Space>(0, 2),
                         NestedViewFunctor<Space>(a, tracking));
    Kokkos::deep_copy(host_tracking, tracking);
    ASSERT_EQ(2, host_tracking(0));

    Kokkos::View<NestedView<Space> *, Space> b("b_nested_view", 2);
    Kokkos::parallel_for(Kokkos::RangePolicy<Space>(0, 2),
                         NestedViewFunctor<Space>(b, tracking));
    Kokkos::deep_copy(host_tracking, tracking);
    ASSERT_EQ(4, host_tracking(0));
  }

  Kokkos::deep_copy(host_tracking, tracking);

  ASSERT_EQ(0, host_tracking(0));
}

TEST(TEST_CATEGORY, view_nested_view) { view_nested_view<TEST_EXECSPACE>(); }

}  // namespace Test
