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//                        Kokkos v. 2.0
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#include <Kokkos_Core.hpp>
#include <cstdio>

// See 01_thread_teams for an explanation of a basic TeamPolicy
typedef Kokkos::TeamPolicy<>              team_policy ;
typedef typename team_policy::member_type team_member ;

struct hello_world {
  typedef int value_type; //Specify value type for reduction target, sum
  KOKKOS_INLINE_FUNCTION
  void operator() ( const team_member & thread, int& sum) const {
    sum+=1;
    // When using the TeamPolicy Kokkos allows for nested parallel loops.
    // All three Kokkos parallel patterns are allowed (for, reduce, scan) and they
    // largely follow the same syntax as on the global level.
    // The execution policy for the Thread level nesting (the Vector level is in the next
    // tutorial example) is Kokkos::TeamThreadRange. This means the loop will be executed
    // by all members of the team and the loop count will be split between threads of the
    // team. Its arguments are the team_member, and a loop count.
    // Not every thread will do the same amount of iterations. On a GPU for example with
    // a team_size() larger than 31 only the first 31 threads would actually do anything.
    // On a CPU with 8 threads 7 would execute 4 loop iterations, and 1 thread would do
    // 3. Note also that the mode of splitting the count is architecture dependent similar
    // to what the RangePolicy on a global level does.
    // The call itself is not guaranteed to be synchronous. Also keep in mind that the
    // operator using a team_policy acts like a parallel region for the team. That means
    // that everything outside of the nested parallel_for is also executed by all threads
    // of the team.
    Kokkos::parallel_for(Kokkos::TeamThreadRange(thread,31), [&] (const int& i) {
       printf("Hello World: (%i , %i) executed loop %i \n",thread.league_rank(),thread.team_rank(),i);
    });
  }
};

int main(int narg, char* args[]) {
  Kokkos::initialize(narg,args);

  // Launch 3 teams of the maximum number of threads per team
  const int team_size_max = team_policy(3,1).team_size_max( hello_world(), Kokkos::ParallelReduceTag());
  const team_policy policy( 3 , team_size_max );
  
  int sum = 0;
  Kokkos::parallel_reduce( policy , hello_world() , sum );
  printf("Result %i\n",sum);

  Kokkos::finalize();
}
