/*
 * Copyright(C) 1999-2020 National Technology & Engineering Solutions
 * of Sandia, LLC (NTESS).  Under the terms of Contract DE-NA0003525 with
 * NTESS, the U.S. Government retains certain rights in this software.
 *
 * See packages/seacas/LICENSE for details
 */

#include "structs.h" // for vtx_data
#include <stdlib.h>

/* Compute the terminal constraints for next partition. */
void make_terms_ref(struct vtx_data **graph,       /* data structure for graph */
                    int               using_ewgts, /* are edge weights being used? */
                    int               subnvtxs,    /* number of vtxs in subgraph */
                    int *             loc2glob,    /* mapping from subgraph to graph */
                    int set0, int set1,            /* two processors I'm choosing between */
                    int *  assignment,             /* set for each vertex */
                    int    architecture,           /* 0 => hypercube, 1 => mesh */
                    int    mesh_dims[3],           /* if mesh, size of mesh */
                    float *term_wgts[]             /* terminal weights for each vertex */
)
{
  double term_wgt;             /* terminal weight */
  float  edge_wgt;             /* weight of an edge */
  int    dist0 = 0, dist1 = 0; /* distance from set to set0 and set1 */
  int    set;                  /* set neighbor vtx belongs to */
  int    vtx;                  /* vertex number */
  int    neighbor;             /* neighboring vertex number */
  int    x;                    /* bitwise difference between sets */
  int    i, j;                 /* loop counters */

  /* NOTE: CURRENTLY ONLY WORKING FOR BISECTION. */

  edge_wgt = 1;
  for (i = 1; i <= subnvtxs; i++) {
    term_wgt = 0;
    vtx      = loc2glob[i];

    for (j = 1; j < graph[vtx]->nedges; j++) {
      neighbor = graph[vtx]->edges[j];
      set      = assignment[neighbor];
      if (set != set0 && set != set1) {
        if (architecture == 0) {
          dist0 = 0;
          x     = set ^ set0;
          while (x) {
            if (x & 1) {
              ++dist0;
            }
            x >>= 1;
          }
          dist1 = 0;
          x     = set ^ set1;
          while (x) {
            if (x & 1) {
              ++dist1;
            }
            x >>= 1;
          }
        }

        else if (architecture > 0) {
          dist0 = abs((set % mesh_dims[0]) - (set0 % mesh_dims[0]));
          dist0 +=
              abs(((set / mesh_dims[0]) % mesh_dims[1]) - ((set0 / mesh_dims[0]) % mesh_dims[1]));
          dist0 +=
              abs((set / (mesh_dims[0] * mesh_dims[1])) - (set0 / (mesh_dims[0] * mesh_dims[1])));

          dist1 = abs((set % mesh_dims[0]) - (set1 % mesh_dims[0]));
          dist1 +=
              abs(((set / mesh_dims[0]) % mesh_dims[1]) - ((set1 / mesh_dims[0]) % mesh_dims[1]));
          dist1 +=
              abs((set / (mesh_dims[0] * mesh_dims[1])) - (set1 / (mesh_dims[0] * mesh_dims[1])));
        }

        if (using_ewgts) {
          edge_wgt = graph[vtx]->ewgts[j];
        }
        term_wgt += edge_wgt * (dist0 - dist1);
      }
    }
    (term_wgts[1])[i] = term_wgt;
  }
}