/* -*- mode: C -*-  */
/* 
   IGraph library.
   Copyright (C) 2006-2012  Gabor Csardi <csardi.gabor@gmail.com>
   334 Harvard street, Cambridge, MA 02139 USA
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc.,  51 Franklin Street, Fifth Floor, Boston, MA 
   02110-1301 USA

*/

#include <igraph.h>

int main() {
  
  igraph_t orig, sub, diff;
  igraph_vector_t v;

  /* Subtract from itself */
  printf("subtract itself\n");
  igraph_vector_init_int_end(&v, -1, 0,1,1,2,2,1,4,5, -1);
  igraph_create(&orig, &v, 0, IGRAPH_DIRECTED);
  igraph_vector_destroy(&v);
  
  igraph_difference(&diff, &orig, &orig);
  igraph_write_graph_edgelist(&diff, stdout);
  if (igraph_ecount(&diff) != 0 ||
      igraph_vcount(&diff) != igraph_vcount(&orig)) {
    return 1;
  }
  
  igraph_destroy(&orig);
  igraph_destroy(&diff);

  /* Same for undirected graph */
  printf("subtract itself, undirected\n");
  igraph_vector_init_int_end(&v, -1, 0,1,1,2,2,1,4,5, -1);
  igraph_create(&orig, &v, 0, IGRAPH_UNDIRECTED);
  igraph_vector_destroy(&v);

  igraph_vector_init_int_end(&v, -1, 1,0,1,2,2,1,4,5, -1);
  igraph_create(&sub, &v, 0, IGRAPH_UNDIRECTED);
  igraph_vector_destroy(&v);
  
  igraph_difference(&diff, &orig, &sub);
  igraph_write_graph_edgelist(&diff, stdout);
  if (igraph_ecount(&diff) != 0 ||
      igraph_vcount(&diff) != igraph_vcount(&orig)) {
    return 2;
  }
  
  igraph_destroy(&orig);
  igraph_destroy(&sub);
  igraph_destroy(&diff);
  
  /* Subtract the empty graph */
  printf("subtract empty\n");
  igraph_vector_init_int_end(&v, -1, 0,1,1,2,2,1,4,5, -1);
  igraph_create(&orig, &v, 0, IGRAPH_DIRECTED);
  igraph_vector_destroy(&v);

  igraph_empty(&sub, 3, IGRAPH_DIRECTED);
  igraph_difference(&diff, &orig, &sub);
  igraph_write_graph_edgelist(&diff, stdout);
  if (igraph_ecount(&diff) != igraph_ecount(&orig) ||
      igraph_vcount(&diff) != igraph_vcount(&orig)) {
    return 3;
  }

  igraph_destroy(&orig);
  igraph_destroy(&sub);
  igraph_destroy(&diff);

  /* A `real' example */
  printf("real example\n");
  igraph_vector_init_int_end(&v, -1, 0,1,1,2,2,1,4,5,8,9, -1);
  igraph_create(&orig, &v, 0, IGRAPH_DIRECTED);
  igraph_vector_destroy(&v);

  igraph_vector_init_int_end(&v, -1, 0,1,5,4,2,1,6,7, -1);
  igraph_create(&sub, &v, 0, IGRAPH_DIRECTED);
  igraph_vector_destroy(&v);
  
  igraph_difference(&diff, &orig, &sub);
  igraph_write_graph_edgelist(&diff, stdout);

  igraph_destroy(&diff);
  igraph_destroy(&orig);
  igraph_destroy(&sub);  

  /* undirected version */
  printf("real example, undirected\n");
  igraph_vector_init_int_end(&v, -1, 0,1,1,2,2,1,4,5,8,9,8,10,8,13,8,11,8,12, -1);
  igraph_create(&orig, &v, 0, IGRAPH_UNDIRECTED);
  igraph_vector_destroy(&v);

  igraph_vector_init_int_end(&v, -1, 0,1,5,4,2,1,6,7,8,10,8,13, -1);
  igraph_create(&sub, &v, 0, IGRAPH_UNDIRECTED);
  igraph_vector_destroy(&v);

  igraph_difference(&diff, &orig, &sub);
  igraph_write_graph_edgelist(&diff, stdout);

  igraph_destroy(&diff);
  igraph_destroy(&orig);
  igraph_destroy(&sub);  
  
  return 0;
}
