/* -*- mode: C -*-  */
/* vim:set ts=4 sw=4 sts=4 et: */
/*
   IGraph library.
   Copyright (C) 2011-2012  Gabor Csardi <csardi.gabor@gmail.com>
   334 Harvard st, 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>
#include <string.h>

int main() {
    igraph_t g;
    igraph_vector_t weights, result;
    igraph_bool_t dag;
    int retval;

    igraph_vector_init(&result, 0);

    igraph_set_error_handler(&igraph_error_handler_printignore);

    /***********************************************************************/
    /* Exact solution with integer programming                             */
    /***********************************************************************/

    /* Simple unweighted graph */
    igraph_small(&g, 0, IGRAPH_DIRECTED, 0, 1, 1, 2, 2, 0, 2, 3, 2, 4, 0, 4, 4, 3, 5, 0, 6, 5, -1);
    retval = igraph_feedback_arc_set(&g, &result, 0, IGRAPH_FAS_EXACT_IP);
    if (retval == IGRAPH_UNIMPLEMENTED) {
        return 77;
    }
    igraph_vector_print(&result);
    igraph_delete_edges(&g, igraph_ess_vector(&result));
    igraph_is_dag(&g, &dag);
    if (!dag) {
        return 1;
    }
    igraph_destroy(&g);

    /* Simple weighted graph */
    igraph_small(&g, 0, IGRAPH_DIRECTED, 0, 1, 1, 2, 2, 0, 2, 3, 2, 4, 0, 4, 4, 3, 5, 0, 6, 5, -1);
    igraph_vector_init_int_end(&weights, -1, 1, 1, 3, 1, 1, 1, 1, 1, 1, -1);
    igraph_feedback_arc_set(&g, &result, &weights, IGRAPH_FAS_EXACT_IP);
    igraph_vector_print(&result);
    igraph_delete_edges(&g, igraph_ess_vector(&result));
    igraph_is_dag(&g, &dag);
    if (!dag) {
        return 2;
    }
    igraph_vector_destroy(&weights);
    igraph_destroy(&g);

    /* Simple unweighted graph with loops */
    igraph_small(&g, 0, IGRAPH_DIRECTED, 0, 1, 1, 2, 2, 0, 2, 3, 2, 4, 0, 4, 4, 3, 5, 0, 6, 5, 1, 1, 4, 4, -1);
    igraph_feedback_arc_set(&g, &result, 0, IGRAPH_FAS_EXACT_IP);
    igraph_vector_print(&result);
    igraph_delete_edges(&g, igraph_ess_vector(&result));
    igraph_is_dag(&g, &dag);
    if (!dag) {
        return 3;
    }
    igraph_destroy(&g);

    /* Disjoint union of two almost identical graphs */
    igraph_small(&g, 0, IGRAPH_DIRECTED,
                 0, 1, 1, 2, 2, 0, 2, 3,  2, 4,  0, 4,  4, 3,    5, 0,  6, 5, 1, 1, 4, 4,
                 7, 8, 8, 9, 9, 7, 9, 10, 9, 11, 7, 11, 11, 10, 12, 7, 13, 12,
                 -1);
    igraph_feedback_arc_set(&g, &result, 0, IGRAPH_FAS_EXACT_IP);
    igraph_vector_print(&result);
    igraph_delete_edges(&g, igraph_ess_vector(&result));
    igraph_is_dag(&g, &dag);
    if (!dag) {
        return 4;
    }
    igraph_destroy(&g);

    /* Graph with lots of isolated vertices */
    igraph_small(&g, 10000, IGRAPH_DIRECTED, 0, 1, -1);
    igraph_feedback_arc_set(&g, &result, 0, IGRAPH_FAS_EXACT_IP);
    igraph_vector_print(&result);
    igraph_delete_edges(&g, igraph_ess_vector(&result));
    igraph_is_dag(&g, &dag);
    if (!dag) {
        return 5;
    }
    igraph_destroy(&g);

    /* Null graph */
    igraph_empty(&g, 0, IGRAPH_DIRECTED);
    igraph_feedback_arc_set(&g, &result, NULL, IGRAPH_FAS_EXACT_IP);
    if (igraph_vector_size(&result) != 0) {
        return 6;
    }
    igraph_destroy(&g);

    /* Singleton graph */
    igraph_empty(&g, 1, IGRAPH_DIRECTED);
    igraph_feedback_arc_set(&g, &result, NULL, IGRAPH_FAS_EXACT_IP);
    if (igraph_vector_size(&result) != 0) {
        return 7;
    }
    igraph_destroy(&g);

    igraph_vector_destroy(&result);

    return 0;
}