/* -*- c++ -*- ----------------------------------------------------------
   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
   http://lammps.sandia.gov, Sandia National Laboratories
   Steve Plimpton, sjplimp@sandia.gov

   Copyright (2003) Sandia Corporation.  Under the terms of Contract
   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
   certain rights in this software.  This software is distributed under
   the GNU General Public License.

   See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */

#ifndef LMP_NEIGH_LIST_KOKKOS_H
#define LMP_NEIGH_LIST_KOKKOS_H

#include "pointers.h"
#include "neigh_list.h"
#include "kokkos_type.h"

namespace LAMMPS_NS {

enum{FULL=1u,HALFTHREAD=2u,HALF=4u,N2=8u};

class AtomNeighbors
{
 public:
  const int num_neighs;

  KOKKOS_INLINE_FUNCTION
  AtomNeighbors(int* const & firstneigh, const int & _num_neighs,
                const int & stride):
  num_neighs(_num_neighs), _firstneigh(firstneigh), _stride(stride) {};
  KOKKOS_INLINE_FUNCTION
  int& operator()(const int &i) const {
    return _firstneigh[i*_stride];
  }

 private:
  int* const _firstneigh;
  const int _stride;
};

class AtomNeighborsConst
{
 public:
  const int* const _firstneigh;
  const int num_neighs;

  KOKKOS_INLINE_FUNCTION
  AtomNeighborsConst(int* const & firstneigh, const int & _num_neighs,
                     const int & stride):
  _firstneigh(firstneigh), num_neighs(_num_neighs), _stride(stride) {};
  KOKKOS_INLINE_FUNCTION
  const int& operator()(const int &i) const {
    return _firstneigh[i*_stride];
  }

 private:
  //const int* const _firstneigh;
  const int _stride;
};

template<class Device>
class NeighListKokkos: public NeighList {
  int _stride;

public:
  int maxneighs;

  void clean_copy();
  void grow(int nmax);
  typename ArrayTypes<Device>::t_neighbors_2d d_neighbors;
  typename DAT::tdual_int_1d k_ilist;   // local indices of I atoms
  typename ArrayTypes<Device>::t_int_1d d_ilist;
  typename ArrayTypes<Device>::t_int_1d d_numneigh; // # of J neighs for each I

  NeighListKokkos(class LAMMPS *lmp):
  NeighList(lmp) {_stride = 1; maxneighs = 16; kokkos = 1; maxatoms = 0;
                  execution_space = ExecutionSpaceFromDevice<Device>::space;
  };
  ~NeighListKokkos() {numneigh = NULL; ilist = NULL;};

  KOKKOS_INLINE_FUNCTION
  AtomNeighbors get_neighbors(const int &i) const {
    return AtomNeighbors(&d_neighbors(i,0),d_numneigh(i),
                         &d_neighbors(i,1)-&d_neighbors(i,0));
  }

  KOKKOS_INLINE_FUNCTION
  AtomNeighborsConst get_neighbors_const(const int &i) const {
    return AtomNeighborsConst(&d_neighbors(i,0),d_numneigh(i),
                              &d_neighbors(i,1)-&d_neighbors(i,0));
  }

  KOKKOS_INLINE_FUNCTION
  int& num_neighs(const int & i) const {
    return d_numneigh(i);
  }
 private:
  int maxatoms;
};

}

#endif
