!--------------------------------------------------------------------------------------------------!
!   CP2K: A general program to perform molecular dynamics simulations                              !
!   Copyright (C) 2000 - 2017  CP2K developers group                                               !
!--------------------------------------------------------------------------------------------------!

! **************************************************************************************************
!> \par History
!>      JGH (20-12-2000) : Parallel data layout
!> \author APSI
! **************************************************************************************************
MODULE pw_grid_types

   USE kinds,                           ONLY: dp,&
                                              int_8
#include "../base/base_uses.f90"

   IMPLICIT NONE

   PRIVATE
   PUBLIC :: pw_grid_type, map_pn

   ! (only for reciprocal grid:) fill in half or full space
   INTEGER, PARAMETER, PUBLIC :: HALFSPACE = 211, FULLSPACE = 212
   INTEGER, PARAMETER, PUBLIC :: PW_MODE_LOCAL = 0, PW_MODE_DISTRIBUTED = 1

   ! maps to positive and negative g-vectors
! **************************************************************************************************
   TYPE map_pn
      INTEGER, DIMENSION(:), POINTER :: pos, neg
   END TYPE map_pn

! info on parallelisation
   ! contains only significant information if mode == PW_MODE_DISTRIBUTED
! **************************************************************************************************
   TYPE pw_para_type
      INTEGER :: mode ! 0 = local = PW_MODE_LOCAL ; 1 = distributed = PW_MODE_DISTRIBUTED
      LOGICAL :: ray_distribution ! block or pencil distribution
      LOGICAL :: blocked ! block or pencil distribution
      INTEGER :: group ! MPI group id
      INTEGER :: my_pos ! Position within group
      INTEGER :: group_size ! # of Processors in group
      LOGICAL :: group_head ! Master process within group
      INTEGER :: group_head_id ! Id of group_head
      INTEGER, DIMENSION(:, :, :), POINTER :: yzp ! g-space rays (xy,k,pe)
      INTEGER, DIMENSION(:, :), POINTER :: yzq ! local inverse pointer of yzp
      INTEGER, DIMENSION(:), POINTER :: nyzray ! number of g-space rays (pe)
      INTEGER :: rs_group ! real space group (2-dim cart)
      INTEGER :: rs_mpo ! real space group position
      INTEGER, DIMENSION(2) :: rs_dims ! real space group dimensions
      INTEGER, DIMENSION(2) :: rs_pos ! real space group positions in grid
      INTEGER, DIMENSION(:, :, :, :), POINTER :: bo ! list of axis distribution
      INTEGER, DIMENSION(:), POINTER :: pos_of_x ! what my_pos holds a given x plane....should go: hard-codes to plane distributed
   END TYPE pw_para_type

   ! all you always wanted to know about grids, but were...
! **************************************************************************************************
   TYPE pw_grid_type
      INTEGER(int_8) :: ngpts ! # grid points
      INTEGER(int_8) :: ngpts_cut ! # grid points within cutoff
      INTEGER, DIMENSION(2, 3) :: bounds ! lower and upper bounds
      INTEGER, DIMENSION(3) :: npts ! # point in all directions
      INTEGER :: ngpts_local ! # grid points
      INTEGER :: ngpts_cut_local ! # grid points within cutoff
      INTEGER, DIMENSION(2, 3) :: bounds_local ! bounds on local process
      INTEGER, DIMENSION(3) :: npts_local ! local version of npts
      REAL(KIND=dp), DIMENSION(3) :: dr ! grid spacing
      REAL(KIND=dp), DIMENSION(3, 3) :: dh ! incremental cell matrix
      REAL(KIND=dp), DIMENSION(3, 3) :: dh_inv ! inverse incremental cell matrix
      LOGICAL :: orthorhombic ! cell symmetry
      REAL(KIND=dp) :: dvol, vol ! volume element, volume
      REAL(KIND=dp) :: cutoff ! cutoff in a.u.
      TYPE(map_pn) :: mapl, mapm, mapn ! mapping 1D => 3D
      TYPE(pw_para_type) :: para ! information on parallelisation
      REAL(KIND=dp), DIMENSION(:, :), POINTER :: g ! grid point vectors
      REAL(KIND=dp), DIMENSION(:), POINTER :: gsq ! squared vector lengths
      INTEGER, DIMENSION(:, :), POINTER :: g_hat ! grid point indices (Miller)
      INTEGER, DIMENSION(:, :), POINTER :: g_hatmap ! mapped grid point indices (Miller) [CUDA]
      INTEGER :: grid_span ! type HALFSPACE/FULLSPACE
      LOGICAL :: have_g0 ! whether I have G = [0,0,0]
      INTEGER :: first_gne0 ! first g index /= 0 [1/2]
      INTEGER :: id_nr ! tag of this grid
      INTEGER :: reference ! reference grid identifier
      INTEGER, DIMENSION(:), POINTER :: gidx ! ref grid index
      INTEGER :: ref_count ! reference count
      LOGICAL :: spherical ! spherical cutoff?
      COMPLEX(KIND=dp), DIMENSION(:, :), POINTER :: grays ! used by parallel 3D FFT routine
   END TYPE pw_grid_type

END MODULE pw_grid_types

