//@HEADER
// ************************************************************************
//
//                        Kokkos v. 4.0
//       Copyright (2022) National Technology & Engineering
//               Solutions of Sandia, LLC (NTESS).
//
// Under the terms of Contract DE-NA0003525 with NTESS,
// the U.S. Government retains certain rights in this software.
//
// Part of Kokkos, under the Apache License v2.0 with LLVM Exceptions.
// See https://kokkos.org/LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//@HEADER

#include <TestStdAlgorithmsCommon.hpp>

namespace Test {
namespace stdalgos {
namespace TeamCopy_n {

namespace KE = Kokkos::Experimental;

template <class SourceViewType, class DestViewType, class DistancesViewType,
          class IntraTeamSentinelView>
struct TestFunctorA {
  SourceViewType m_sourceView;
  DestViewType m_destView;
  DistancesViewType m_distancesView;
  IntraTeamSentinelView m_intraTeamSentinelView;
  std::size_t m_copyCount;
  int m_apiPick;

  TestFunctorA(const SourceViewType fromView, const DestViewType destView,
               const DistancesViewType distancesView,
               const IntraTeamSentinelView intraTeamSentinelView,
               std::size_t copyCount, int apiPick)
      : m_sourceView(fromView),
        m_destView(destView),
        m_distancesView(distancesView),
        m_intraTeamSentinelView(intraTeamSentinelView),
        m_copyCount(copyCount),
        m_apiPick(apiPick) {}

  template <class MemberType>
  KOKKOS_INLINE_FUNCTION void operator()(const MemberType& member) const {
    const auto myRowIndex = member.league_rank();
    auto myRowViewFrom =
        Kokkos::subview(m_sourceView, myRowIndex, Kokkos::ALL());
    auto myRowViewDest = Kokkos::subview(m_destView, myRowIndex, Kokkos::ALL());
    ptrdiff_t resultDist = 0;

    if (m_apiPick == 0) {
      auto it    = KE::copy_n(member, KE::begin(myRowViewFrom), m_copyCount,
                           KE::begin(myRowViewDest));
      resultDist = KE::distance(KE::begin(myRowViewDest), it);
      Kokkos::single(Kokkos::PerTeam(member), [=, *this]() {
        m_distancesView(myRowIndex) = resultDist;
      });
    } else if (m_apiPick == 1) {
      auto it = KE::copy_n(member, myRowViewFrom, m_copyCount, myRowViewDest);
      resultDist = KE::distance(KE::begin(myRowViewDest), it);
      Kokkos::single(Kokkos::PerTeam(member), [=, *this]() {
        m_distancesView(myRowIndex) = resultDist;
      });
    }

    // store result of checking if all members have their local
    // values matching the one stored in m_distancesView
    member.team_barrier();
    const bool intraTeamCheck = team_members_have_matching_result(
        member, resultDist, m_distancesView(myRowIndex));
    Kokkos::single(Kokkos::PerTeam(member), [=, *this]() {
      m_intraTeamSentinelView(myRowIndex) = intraTeamCheck;
    });
  }
};

template <class LayoutTag, class ValueType>
void test_A(std::size_t numTeams, std::size_t numCols, std::size_t copyCount,
            int apiId) {
  /* description:
     randomly fill a source view and copy a copyCount set of values
     for each row into a destination view. The operation is done via
     a team parfor with one row per team.
   */

  // -----------------------------------------------
  // prepare data
  // -----------------------------------------------
  // create a view in the memory space associated with default exespace
  // with as many rows as the number of teams and fill it with random
  // values from an arbitrary range
  auto [sourceView, cloneOfSourceViewBeforeOp_h] =
      create_random_view_and_host_clone(
          LayoutTag{}, numTeams, numCols,
          Kokkos::pair<ValueType, ValueType>{11, 523}, "sourceView");

  // -----------------------------------------------
  // launch kokkos kernel
  // -----------------------------------------------
  using space_t = Kokkos::DefaultExecutionSpace;
  Kokkos::TeamPolicy<space_t> policy(numTeams, Kokkos::AUTO());
  // create the destination view
  Kokkos::View<ValueType**> destView("destView", numTeams, numCols);
  // make a host copy of destView, should be unchanged after the op
  auto destViewBeforeOp_h = create_host_space_copy(destView);

  // copy_n returns an iterator so to verify that it is correct
  // each team stores the distance of the returned iterator from the
  // beginning of the interval that team operates on and then we check
  // that these distances match the expectation
  Kokkos::View<std::size_t*> distancesView("distancesView", numTeams);
  // sentinel to check if all members of the team compute the same result
  Kokkos::View<bool*> intraTeamSentinelView("intraTeamSameResult", numTeams);

  // use CTAD for functor
  TestFunctorA fnc(sourceView, destView, distancesView, intraTeamSentinelView,
                   copyCount, apiId);
  Kokkos::parallel_for(policy, fnc);

  // -----------------------------------------------
  // check
  // -----------------------------------------------
  auto distancesView_h         = create_host_space_copy(distancesView);
  auto intraTeamSentinelView_h = create_host_space_copy(intraTeamSentinelView);
  auto destViewAfterOp_h       = create_host_space_copy(destView);
  for (std::size_t i = 0; i < destViewBeforeOp_h.extent(0); ++i) {
    ASSERT_TRUE(intraTeamSentinelView_h(i));
    for (std::size_t j = 0; j < copyCount; ++j) {
      ASSERT_EQ(destViewAfterOp_h(i, j), cloneOfSourceViewBeforeOp_h(i, j));
    }
    for (std::size_t j = copyCount; j < numCols; ++j) {
      EXPECT_TRUE(destViewAfterOp_h(i, j) == destViewBeforeOp_h(i, j));
    }
    // each team should return an iterator past the last column
    EXPECT_TRUE(distancesView_h(i) == copyCount);
  }
}

template <class Tag, class ValueType>
void run_all_scenarios() {
  // prepare a map where, for a given set of num cols
  // we provide a list of counts of elements to copy
  // key = num of columns,
  // value = list of num of elemenents to copy
  const std::map<int, std::vector<int>> scenarios = {
      {0, {0}},
      {2, {0, 1, 2}},
      {6, {0, 1, 2, 5}},
      {13, {0, 1, 2, 8, 11}},
      {56, {0, 1, 2, 8, 11, 33, 56}},
      {123, {0, 1, 11, 33, 56, 89, 112}}};

  for (int numTeams : teamSizesToTest) {
    for (const auto& scenario : scenarios) {
      const std::size_t numCols = scenario.first;
      for (int copyCount : scenario.second) {
        for (int apiId : {0, 1}) {
          test_A<Tag, ValueType>(numTeams, numCols, copyCount, apiId);
        }
      }
    }
  }
}

TEST(std_algorithms_copy_n_team_test, test) {
  run_all_scenarios<DynamicTag, double>();
  run_all_scenarios<StridedTwoRowsTag, int>();
  run_all_scenarios<StridedThreeRowsTag, unsigned>();
}

}  // namespace TeamCopy_n
}  // namespace stdalgos
}  // namespace Test