/* [[file:nauty.note::8adb819f][8adb819f]] */
/* Adopted from nautyex6.c */
#include<assert.h>
#include "lib/nauty.h"

/*
  n: number of nodes
  nedges: number of edges
  lab: labels
  ptn: partitions
*/
int dwim(int n, int nedges, int *edges_i, int *edges_j, int *lab, int *ptn) {
  /* DYNALLSTAT declares a pointer variable (to hold an array when it is
   allocated) and a size variable to remember how big the array is. Nothing is
   allocated yet. */
  DYNALLSTAT(graph, g, g_sz);
  DYNALLSTAT(int, orbits, orbits_sz);

  /* Default options for undirected graphs in dense nauty */
  DEFAULTOPTIONS_GRAPH(options);
  statsblk stats;

  /* Select option for canonical labelling */
  /* options.getcanon = TRUE; */
  /* We want to set node colours using `lab` and `ptn` */
  options.defaultptn = FALSE;

  if (n > 0) {
    /* The nauty parameter m is a value such that an array of m setwords is
    sufficient to hold n bits. The type setword is defined in nauty.h. The
    number of bits in a setword is WORDSIZE, which is 16, 32 or 64. Here we
    calculate m = ceiling(n/WORDSIZE). */
    int m = SETWORDSNEEDED(n);

    /* The following optional call verifies that we are linking to compatible
       versions of the nauty routines. */
    nauty_check(WORDSIZE, m, n, NAUTYVERSIONID);

    /* Now that we know how big the graph will be, we allocate space for the
     * graph and the other arrays we need. */
    DYNALLOC1(int, orbits, orbits_sz, n, "malloc");
    DYNALLOC2(graph, g, g_sz, n, m, "malloc");

    /* start with no edges */
    EMPTYGRAPH(g, m, n);

    /* add edges from edges_i, edges_j arrays */
    for (int i = 0; i < nedges; ++i) {
      int e1 = edges_i[i];
      int e2 = edges_j[i];
      if (e1 < e2) {
        ADDONEEDGE(g, e1, e2, m);
      } else {
        return -2;
      }
    }

    /* Create canonical graphs */
    densenauty(g, lab, ptn, orbits, &options, &stats, m, n, NULL);
    assert(stats.errstatus == 0);

    /* frees any allocated array */
    DYNFREE(orbits, orbits_sz);
    DYNFREE(g, g_sz);

    return 0;
  } else {
    return -1;
  }
}
/* 8adb819f ends here */