/* ----------------------------------------------------------------------
   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.
------------------------------------------------------------------------- */

#include "neighbor.h"
#include "neigh_list.h"
#include "atom.h"
#include "domain.h"
#include "error.h"

using namespace LAMMPS_NS;

/* ----------------------------------------------------------------------
   binned neighbor list construction with partial Newton's 3rd law
   each owned atom i checks own bin and other bins in stencil
   pair stored once if i,j are both owned and i < j
   pair stored by me if j is ghost (also stored by proc owning j)
------------------------------------------------------------------------- */

void Neighbor::half_bin_no_newton(NeighList *list)
{
  int i,j,k,n,itype,jtype,ibin,which;
  double xtmp,ytmp,ztmp,delx,dely,delz,rsq;
  int *neighptr;

  // bin local & ghost atoms

  bin_atoms();

  // loop over each atom, storing neighbors

  int **special = atom->special;
  int **nspecial = atom->nspecial;
  int *tag = atom->tag;

  double **x = atom->x;
  int *type = atom->type;
  int *mask = atom->mask;
  int *molecule = atom->molecule;
  int nlocal = atom->nlocal;
  if (includegroup) nlocal = atom->nfirst;
  int molecular = atom->molecular;

  int *ilist = list->ilist;
  int *numneigh = list->numneigh;
  int **firstneigh = list->firstneigh;
  int **pages = list->pages;
  int nstencil = list->nstencil;
  int *stencil = list->stencil;

  int inum = 0;
  int npage = 0;
  int npnt = 0;

  for (i = 0; i < nlocal; i++) {

    if (pgsize - npnt < oneatom) {
      npnt = 0;
      npage++;
      if (npage == list->maxpage) pages = list->add_pages();
    }

    neighptr = &pages[npage][npnt];
    n = 0;

    itype = type[i];
    xtmp = x[i][0];
    ytmp = x[i][1];
    ztmp = x[i][2];

    // loop over all atoms in other bins in stencil including self
    // only store pair if i < j
    // stores own/own pairs only once
    // stores own/ghost pairs on both procs

    ibin = coord2bin(x[i]);

    for (k = 0; k < nstencil; k++) {
      for (j = binhead[ibin+stencil[k]]; j >= 0; j = bins[j]) {
        if (j <= i) continue;

        jtype = type[j];
        if (exclude && exclusion(i,j,itype,jtype,mask,molecule)) continue;

        delx = xtmp - x[j][0];
        dely = ytmp - x[j][1];
        delz = ztmp - x[j][2];
        rsq = delx*delx + dely*dely + delz*delz;

        if (rsq <= cutneighsq[itype][jtype]) {
          if (molecular) {
            which = find_special(special[i],nspecial[i],tag[j]);
            if (which == 0) neighptr[n++] = j;
            else if (domain->minimum_image_check(delx,dely,delz))
              neighptr[n++] = j;
            else if (which > 0) neighptr[n++] = j ^ (which << SBBITS);
          } else neighptr[n++] = j;
        }
      }
    }

    ilist[inum++] = i;
    firstneigh[i] = neighptr;
    numneigh[i] = n;
    npnt += n;
    if (n > oneatom)
      error->one(FLERR,"Neighbor list overflow, boost neigh_modify one");
  }

  list->inum = inum;
}

/* ----------------------------------------------------------------------
   binned neighbor list construction with partial Newton's 3rd law
   include neighbors of ghost atoms, but no "special neighbors" for ghosts
   owned and ghost atoms check own bin and other bins in stencil
   pair stored once if i,j are both owned and i < j
   pair stored by me if i owned and j ghost (also stored by proc owning j)
   pair stored once if i,j are both ghost and i < j
------------------------------------------------------------------------- */

void Neighbor::half_bin_no_newton_ghost(NeighList *list)
{
  int i,j,k,n,itype,jtype,ibin,which;
  double xtmp,ytmp,ztmp,delx,dely,delz,rsq;
  int xbin,ybin,zbin,xbin2,ybin2,zbin2;
  int *neighptr;

  // bin local & ghost atoms

  bin_atoms();

  // loop over each atom, storing neighbors

  int **special = atom->special;
  int **nspecial = atom->nspecial;
  int *tag = atom->tag;

  double **x = atom->x;
  int *type = atom->type;
  int *mask = atom->mask;
  int *molecule = atom->molecule;
  int nlocal = atom->nlocal;
  int nall = nlocal + atom->nghost;
  int molecular = atom->molecular;

  int *ilist = list->ilist;
  int *numneigh = list->numneigh;
  int **firstneigh = list->firstneigh;
  int **pages = list->pages;
  int nstencil = list->nstencil;
  int *stencil = list->stencil;
  int **stencilxyz = list->stencilxyz;

  int inum = 0;
  int npage = 0;
  int npnt = 0;

  for (i = 0; i < nall; i++) {

    if (pgsize - npnt < oneatom) {
      npnt = 0;
      npage++;
      if (npage == list->maxpage) pages = list->add_pages();
    }

    neighptr = &pages[npage][npnt];
    n = 0;

    itype = type[i];
    xtmp = x[i][0];
    ytmp = x[i][1];
    ztmp = x[i][2];

    // loop over all atoms in other bins in stencil including self
    // when i is a ghost atom, must check if stencil bin is out of bounds
    // only store pair if i < j
    // stores own/own pairs only once
    // stores own/ghost pairs with owned atom only, on both procs
    // stores ghost/ghost pairs only once

    if (i < nlocal) {
      ibin = coord2bin(x[i]);

      for (k = 0; k < nstencil; k++) {
        for (j = binhead[ibin+stencil[k]]; j >= 0; j = bins[j]) {
          if (j <= i) continue;

          jtype = type[j];
          if (exclude && exclusion(i,j,itype,jtype,mask,molecule)) continue;

          delx = xtmp - x[j][0];
          dely = ytmp - x[j][1];
          delz = ztmp - x[j][2];
          rsq = delx*delx + dely*dely + delz*delz;
          
          if (rsq <= cutneighsq[itype][jtype]) {
            if (molecular) {
              which = find_special(special[i],nspecial[i],tag[j]);
              if (which == 0) neighptr[n++] = j;
              else if (domain->minimum_image_check(delx,dely,delz))
                neighptr[n++] = j;
              else if (which > 0) neighptr[n++] = j ^ (which << SBBITS);
            } else neighptr[n++] = j;
          }
        }
      }

    } else {
      ibin = coord2bin(x[i],xbin,ybin,zbin);
      for (k = 0; k < nstencil; k++) {
        xbin2 = xbin + stencilxyz[k][0];
        ybin2 = ybin + stencilxyz[k][1];
        zbin2 = zbin + stencilxyz[k][2];
        if (xbin2 < 0 || xbin2 >= mbinx ||
            ybin2 < 0 || ybin2 >= mbiny ||
            zbin2 < 0 || zbin2 >= mbinz) continue;
        for (j = binhead[ibin+stencil[k]]; j >= 0; j = bins[j]) {
          if (j <= i) continue;

          jtype = type[j];
          if (exclude && exclusion(i,j,itype,jtype,mask,molecule)) continue;

          delx = xtmp - x[j][0];
          dely = ytmp - x[j][1];
          delz = ztmp - x[j][2];
          rsq = delx*delx + dely*dely + delz*delz;

          if (rsq <= cutneighghostsq[itype][jtype])
            neighptr[n++] = j;
        }
      }
    }

    ilist[inum++] = i;
    firstneigh[i] = neighptr;
    numneigh[i] = n;
    npnt += n;
    if (n > oneatom)
      error->one(FLERR,"Neighbor list overflow, boost neigh_modify one");
  }

  list->inum = atom->nlocal;
  list->gnum = inum - atom->nlocal;
}

/* ----------------------------------------------------------------------
   binned neighbor list construction with full Newton's 3rd law
   each owned atom i checks its own bin and other bins in Newton stencil
   every pair stored exactly once by some processor
------------------------------------------------------------------------- */

void Neighbor::half_bin_newton(NeighList *list)
{
  int i,j,k,n,itype,jtype,ibin,which;
  double xtmp,ytmp,ztmp,delx,dely,delz,rsq;
  int *neighptr;

  // bin local & ghost atoms

  bin_atoms();

  // loop over each atom, storing neighbors

  int **special = atom->special;
  int **nspecial = atom->nspecial;
  int *tag = atom->tag;

  double **x = atom->x;
  int *type = atom->type;
  int *mask = atom->mask;
  int *molecule = atom->molecule;
  int nlocal = atom->nlocal;
  if (includegroup) nlocal = atom->nfirst;
  int molecular = atom->molecular;

  int *ilist = list->ilist;
  int *numneigh = list->numneigh;
  int **firstneigh = list->firstneigh;
  int **pages = list->pages;
  int nstencil = list->nstencil;
  int *stencil = list->stencil;

  int inum = 0;
  int npage = 0;
  int npnt = 0;

  for (i = 0; i < nlocal; i++) {

    if (pgsize - npnt < oneatom) {
      npnt = 0;
      npage++;
      if (npage == list->maxpage) pages = list->add_pages();
    }

    neighptr = &pages[npage][npnt];
    n = 0;

    itype = type[i];
    xtmp = x[i][0];
    ytmp = x[i][1];
    ztmp = x[i][2];

    // loop over rest of atoms in i's bin, ghosts are at end of linked list
    // if j is owned atom, store it, since j is beyond i in linked list
    // if j is ghost, only store if j coords are "above and to the right" of i

    for (j = bins[i]; j >= 0; j = bins[j]) {
      if (j >= nlocal) {
        if (x[j][2] < ztmp) continue;
        if (x[j][2] == ztmp) {
          if (x[j][1] < ytmp) continue;
          if (x[j][1] == ytmp && x[j][0] < xtmp) continue;
        }
      }

      jtype = type[j];
      if (exclude && exclusion(i,j,itype,jtype,mask,molecule)) continue;

      delx = xtmp - x[j][0];
      dely = ytmp - x[j][1];
      delz = ztmp - x[j][2];
      rsq = delx*delx + dely*dely + delz*delz;

      if (rsq <= cutneighsq[itype][jtype]) {
        if (molecular) {
          which = find_special(special[i],nspecial[i],tag[j]);
          if (which == 0) neighptr[n++] = j;
          else if (domain->minimum_image_check(delx,dely,delz))
            neighptr[n++] = j;
          else if (which > 0) neighptr[n++] = j ^ (which << SBBITS);
          // OLD: if (which >= 0) neighptr[n++] = j ^ (which << SBBITS);
        } else neighptr[n++] = j;
      }
    }

    // loop over all atoms in other bins in stencil, store every pair

    ibin = coord2bin(x[i]);
    for (k = 0; k < nstencil; k++) {
      for (j = binhead[ibin+stencil[k]]; j >= 0; j = bins[j]) {
        jtype = type[j];
        if (exclude && exclusion(i,j,itype,jtype,mask,molecule)) continue;

        delx = xtmp - x[j][0];
        dely = ytmp - x[j][1];
        delz = ztmp - x[j][2];
        rsq = delx*delx + dely*dely + delz*delz;

        if (rsq <= cutneighsq[itype][jtype]) {
          if (molecular) {
            which = find_special(special[i],nspecial[i],tag[j]);
            if (which == 0) neighptr[n++] = j;
            else if (domain->minimum_image_check(delx,dely,delz))
              neighptr[n++] = j;
            else if (which > 0) neighptr[n++] = j ^ (which << SBBITS);
            // OLD: if (which >= 0) neighptr[n++] = j ^ (which << SBBITS);
          } else neighptr[n++] = j;
        }
      }
    }

    ilist[inum++] = i;
    firstneigh[i] = neighptr;
    numneigh[i] = n;
    npnt += n;
    if (n > oneatom)
      error->one(FLERR,"Neighbor list overflow, boost neigh_modify one");
  }

  list->inum = inum;
}

/* ----------------------------------------------------------------------
   binned neighbor list construction with Newton's 3rd law for triclinic
   each owned atom i checks its own bin and other bins in triclinic stencil
   every pair stored exactly once by some processor
------------------------------------------------------------------------- */

void Neighbor::half_bin_newton_tri(NeighList *list)
{
  int i,j,k,n,itype,jtype,ibin,which;
  double xtmp,ytmp,ztmp,delx,dely,delz,rsq;
  int *neighptr;

  // bin local & ghost atoms

  bin_atoms();

  // loop over each atom, storing neighbors

  int **special = atom->special;
  int **nspecial = atom->nspecial;
  int *tag = atom->tag;

  double **x = atom->x;
  int *type = atom->type;
  int *mask = atom->mask;
  int *molecule = atom->molecule;
  int nlocal = atom->nlocal;
  if (includegroup) nlocal = atom->nfirst;
  int molecular = atom->molecular;

  int *ilist = list->ilist;
  int *numneigh = list->numneigh;
  int **firstneigh = list->firstneigh;
  int **pages = list->pages;
  int nstencil = list->nstencil;
  int *stencil = list->stencil;

  int inum = 0;
  int npage = 0;
  int npnt = 0;

  for (i = 0; i < nlocal; i++) {

    if (pgsize - npnt < oneatom) {
      npnt = 0;
      npage++;
      if (npage == list->maxpage) pages = list->add_pages();
    }

    neighptr = &pages[npage][npnt];
    n = 0;

    itype = type[i];
    xtmp = x[i][0];
    ytmp = x[i][1];
    ztmp = x[i][2];

    // loop over all atoms in bins in stencil
    // pairs for atoms j "below" i are excluded
    // below = lower z or (equal z and lower y) or (equal zy and lower x)
    //         (equal zyx and j <= i)
    // latter excludes self-self interaction but allows superposed atoms

    ibin = coord2bin(x[i]);
    for (k = 0; k < nstencil; k++) {
      for (j = binhead[ibin+stencil[k]]; j >= 0; j = bins[j]) {
        if (x[j][2] < ztmp) continue;
        if (x[j][2] == ztmp) {
          if (x[j][1] < ytmp) continue;
          if (x[j][1] == ytmp) {
            if (x[j][0] < xtmp) continue;
            if (x[j][0] == xtmp && j <= i) continue;
          }
        }

        jtype = type[j];
        if (exclude && exclusion(i,j,itype,jtype,mask,molecule)) continue;

        delx = xtmp - x[j][0];
        dely = ytmp - x[j][1];
        delz = ztmp - x[j][2];
        rsq = delx*delx + dely*dely + delz*delz;

        if (rsq <= cutneighsq[itype][jtype]) {
          if (molecular) {
            which = find_special(special[i],nspecial[i],tag[j]);
            if (which == 0) neighptr[n++] = j;
            else if (domain->minimum_image_check(delx,dely,delz))
              neighptr[n++] = j;
            else if (which > 0) neighptr[n++] = j ^ (which << SBBITS);
          } else neighptr[n++] = j;
        }
      }
    }

    ilist[inum++] = i;
    firstneigh[i] = neighptr;
    numneigh[i] = n;
    npnt += n;
    if (n > oneatom)
      error->one(FLERR,"Neighbor list overflow, boost neigh_modify one");
  }

  list->inum = inum;
}