/* -*- mode: C -*-  */
/* 
   IGraph library.
   Copyright (C) 2006  Gabor Csardi <csardi@rmki.kfki.hu>
   MTA RMKI, Konkoly-Thege Miklos st. 29-33, Budapest 1121, Hungary
   
   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>
#include <stdlib.h>

void free_complist(igraph_vector_ptr_t *complist) {
  long int i;
  for (i=0; i<igraph_vector_ptr_size(complist); i++) {
    igraph_destroy(VECTOR(*complist)[i]);
    free(VECTOR(*complist)[i]);
  }
}

int main() {
  
  igraph_t ring, g;
  igraph_vector_ptr_t complist;
  long int i;
  igraph_real_t edges[]= { 0,1,1,2,2,0,
		    3,4,4,5,5,6,
		    8,9,9,10 };
  igraph_vector_t v;
  igraph_vector_t idvect;

  /* A ring, a single component */
  igraph_ring(&ring, 10, IGRAPH_UNDIRECTED, 0, 1);
  
  igraph_vector_ptr_init(&complist, 0);
  igraph_decompose(&ring, &complist, IGRAPH_WEAK, -1, 0);
  igraph_write_graph_edgelist(VECTOR(complist)[0], stdout);
  free_complist(&complist);
  igraph_destroy(&ring);
  
  /* random graph with a giant component */
  igraph_erdos_renyi_game(&g, IGRAPH_ERDOS_RENYI_GNP, 100, 4.0/100, 
			  IGRAPH_UNDIRECTED, 0);
  igraph_decompose(&g, &complist, IGRAPH_WEAK, -1, 20);
  if (igraph_vector_ptr_size(&complist) != 1) { 
    return 1;
  }
  free_complist(&complist);
  igraph_destroy(&g);
  
  /* a toy graph, three components maximum, with at least 2 vertices each */
  igraph_create(&g, 
		igraph_vector_view(&v, edges, sizeof(edges)/sizeof(igraph_real_t)), 
		0, IGRAPH_DIRECTED);
  igraph_decompose(&g, &complist, IGRAPH_WEAK, 3, 2);
  for (i=0; i<igraph_vector_ptr_size(&complist); i++) {
    igraph_write_graph_edgelist(VECTOR(complist)[i], stdout);
  }
  free_complist(&complist);
  igraph_destroy(&g);

  /* The same graph, this time with vertex attributes */
/*   igraph_vector_init_seq(&idvect, 0, igraph_vcount(&g)-1); */
/*   igraph_add_vertex_attribute(&g, "id", IGRAPH_ATTRIBUTE_NUM); */
/*   igraph_set_vertex_attributes(&g, "id", IGRAPH_VS_ALL(&g), &idvect); */
/*   igraph_vector_destroy(&idvect); */

/*   igraph_decompose(&g, &complist, IGRAPH_WEAK, 3, 2); */
/*   for (i=0; i<igraph_vector_ptr_size(&complist); i++) { */
/*     igraph_t *comp=VECTOR(complist)[i]; */
/*     igraph_es_t es; */
/*     igraph_es_all(comp, &es); */
/*     while (!igraph_es_end(comp, &es)) { */
/*       igraph_real_t *from, *to;  */
/*       igraph_get_vertex_attribute(comp, "id", igraph_es_from(comp, &es), */
/* 				  (void**) &from, 0); */
/*       igraph_get_vertex_attribute(comp, "id", igraph_es_to(comp, &es), */
/* 				  (void**) &to, 0); */
/*       printf("%li %li\n", (long int) *from, (long int) *to); */
/*       igraph_es_next(comp, &es); */
/*     } */
/*   } */
  
/*   free_complist(&complist); */
/*   igraph_destroy(&g);   */
  
  igraph_vector_ptr_destroy(&complist);

  return 0;
}