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//                        Kokkos v. 3.0
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#include <iostream>

#include <Kokkos_Core.hpp>

namespace Test {

template <class Space>
class TestUniqueToken {
 public:
  typedef typename Space::execution_space execution_space;
  typedef Kokkos::View<int*, execution_space> view_type;

  Kokkos::Experimental::UniqueToken<
      execution_space, Kokkos::Experimental::UniqueTokenScope::Global>
      tokens;

  view_type verify;
  view_type counts;
  view_type errors;

  KOKKOS_INLINE_FUNCTION
  void operator()(long) const {
    const int32_t t = tokens.acquire();

    bool ok = true;

    ok = ok && 0 <= t;
    ok = ok && t < tokens.size();
    ok = ok && 0 == Kokkos::atomic_fetch_add(&verify(t), 1);

    Kokkos::atomic_fetch_add(&counts(t), 1);

    ok = ok && 1 == Kokkos::atomic_fetch_add(&verify(t), -1);

    if (!ok) {
      Kokkos::atomic_fetch_add(&errors(0), 1);
    }

    tokens.release(t);
  }

  TestUniqueToken()
      : tokens(execution_space()),
        verify("TestUniqueTokenVerify", tokens.size()),
        counts("TestUniqueTokenCounts", tokens.size()),
        errors("TestUniqueTokenErrors", 1) {}

  static void run() {
    using policy = Kokkos::RangePolicy<execution_space>;

    TestUniqueToken self;

    {
      const int duplicate = 100;
      const long n        = duplicate * self.tokens.size();

      Kokkos::parallel_for(policy(0, n), self);
      Kokkos::parallel_for(policy(0, n), self);
      Kokkos::parallel_for(policy(0, n), self);
      Kokkos::fence();
    }

    typename view_type::HostMirror host_counts =
        Kokkos::create_mirror_view(self.counts);

    Kokkos::deep_copy(host_counts, self.counts);

    int32_t max = 0;

    {
      const long n = host_counts.extent(0);
      for (long i = 0; i < n; ++i) {
        if (max < host_counts[i]) max = host_counts[i];
      }
    }

    std::cout << "TestUniqueToken max reuse = " << max << std::endl;

    typename view_type::HostMirror host_errors =
        Kokkos::create_mirror_view(self.errors);

    Kokkos::deep_copy(host_errors, self.errors);

    ASSERT_EQ(host_errors(0), 0);
  }
};

TEST(TEST_CATEGORY, unique_token) { TestUniqueToken<TEST_EXECSPACE>::run(); }

}  // namespace Test