//@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 <Kokkos_Core.hpp>
#include <Kokkos_Random.hpp>

template <class Scalar>
struct RunGather<Scalar, UNROLL> {
  static void run(int N, int K, int D, int R, int F) {
    Kokkos::View<int**> connectivity("Connectivity", N, K);
    Kokkos::View<Scalar*> A_in("Input", N);
    Kokkos::View<Scalar*> B_in("Input", N);
    Kokkos::View<Scalar*> C("Output", N);

    Kokkos::Random_XorShift64_Pool<> rand_pool(12313);

    Kokkos::deep_copy(A_in, 1.5);
    Kokkos::deep_copy(B_in, 2.0);

    Kokkos::View<const Scalar*, Kokkos::MemoryTraits<Kokkos::RandomAccess> > A(
        A_in);
    Kokkos::View<const Scalar*, Kokkos::MemoryTraits<Kokkos::RandomAccess> > B(
        B_in);

    Kokkos::parallel_for(
        "InitKernel", N, KOKKOS_LAMBDA(const int& i) {
          auto rand_gen = rand_pool.get_state();
          for (int jj = 0; jj < K; jj++) {
            connectivity(i, jj) = (rand_gen.rand(D) + i - D / 2 + N) % N;
          }
          rand_pool.free_state(rand_gen);
        });
    Kokkos::fence();

    Kokkos::Timer timer;
    for (int r = 0; r < R; r++) {
      Kokkos::parallel_for(
          "BenchmarkKernel", N, KOKKOS_LAMBDA(const int& i) {
            Scalar c = Scalar(0.0);
            for (int jj = 0; jj < K; jj++) {
              const int j    = connectivity(i, jj);
              Scalar a1      = A(j);
              const Scalar b = B(j);
#if (UNROLL > 1)
              Scalar a2 = a1 * Scalar(1.3);
#endif
#if (UNROLL > 2)
              Scalar a3 = a2 * Scalar(1.1);
#endif
#if (UNROLL > 3)
              Scalar a4 = a3 * Scalar(1.1);
#endif
#if (UNROLL > 4)
              Scalar a5 = a4 * Scalar(1.3);
#endif
#if (UNROLL > 5)
              Scalar a6 = a5 * Scalar(1.1);
#endif
#if (UNROLL > 6)
              Scalar a7 = a6 * Scalar(1.1);
#endif
#if (UNROLL > 7)
              Scalar a8 = a7 * Scalar(1.1);
#endif

              for (int f = 0; f < F; f++) {
                a1 += b * a1;
#if (UNROLL > 1)
                a2 += b * a2;
#endif
#if (UNROLL > 2)
                a3 += b * a3;
#endif
#if (UNROLL > 3)
                a4 += b * a4;
#endif
#if (UNROLL > 4)
                a5 += b * a5;
#endif
#if (UNROLL > 5)
                a6 += b * a6;
#endif
#if (UNROLL > 6)
                a7 += b * a7;
#endif
#if (UNROLL > 7)
                a8 += b * a8;
#endif
              }
#if (UNROLL == 1)
              c += a1;
#endif
#if (UNROLL == 2)
              c += a1 + a2;
#endif
#if (UNROLL == 3)
              c += a1 + a2 + a3;
#endif
#if (UNROLL == 4)
              c += a1 + a2 + a3 + a4;
#endif
#if (UNROLL == 5)
              c += a1 + a2 + a3 + a4 + a5;
#endif
#if (UNROLL == 6)
              c += a1 + a2 + a3 + a4 + a5 + a6;
#endif
#if (UNROLL == 7)
              c += a1 + a2 + a3 + a4 + a5 + a6 + a7;
#endif
#if (UNROLL == 8)
              c += a1 + a2 + a3 + a4 + a5 + a6 + a7 + a8;
#endif
            }
            C(i) = c;
          });
      Kokkos::fence();
    }
    double seconds = timer.seconds();

    double bytes = 1.0 * N * K * R * (2 * sizeof(Scalar) + sizeof(int)) +
                   1.0 * N * R * sizeof(Scalar);
    double flops      = 1.0 * N * K * R * (F * 2 * UNROLL + 2 * (UNROLL - 1));
    double gather_ops = 1.0 * N * K * R * 2;
    printf(
        "SNKDRUF: %i %i %i %i %i %i %i Time: %lfs Bandwidth: %lfGiB/s GFlop/s: "
        "%lf GGather/s: %lf\n",
        static_cast<int>(sizeof(Scalar) / 4), N, K, D, R, UNROLL, F, seconds,
        1.0 * bytes / seconds / 1024 / 1024 / 1024, 1.e-9 * flops / seconds,
        1.e-9 * gather_ops / seconds);
  }
};
