/*
   igraph library.
   Copyright (C) 2021  The igraph development team <igraph@igraph.org>

   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, see <https://www.gnu.org/licenses/>.
*/

#include <igraph.h>
#include "test_utilities.h"

int main(void) {
    igraph_t g, g_copy;
    igraph_bool_t same;
    igraph_vector_int_t degrees;
    igraph_vs_t vertices;
    igraph_rng_seed(igraph_rng_default(), 42);

    /*No edges, should just return the same graph*/
    igraph_small(&g, 5, IGRAPH_DIRECTED, -1);
    IGRAPH_ASSERT(igraph_rewire_directed_edges(&g, /*probability*/ 0.1,
                                               /*loops*/ false, /*mode*/ IGRAPH_ALL)
                  == IGRAPH_SUCCESS);
    IGRAPH_ASSERT(igraph_ecount(&g) == 0);
    IGRAPH_ASSERT(igraph_vcount(&g) == 5);
    igraph_destroy(&g);

    /*No rewire*/
    igraph_small(&g, 10, IGRAPH_DIRECTED, 0,1, 0,3, 5,4, 4,8, 9,2, 9,3, 9,7, 7,7, 7,8, -1);
    igraph_copy(&g_copy, &g);
    IGRAPH_ASSERT(igraph_rewire_directed_edges(&g, /*probability*/ 0.0,
                                               /*loops*/ false, /*mode*/ IGRAPH_ALL)
                  == IGRAPH_SUCCESS);
    IGRAPH_ASSERT(igraph_is_same_graph(&g, &g_copy, &same) == IGRAPH_SUCCESS);
    IGRAPH_ASSERT(same);

    /*Rewire*/
    IGRAPH_ASSERT(igraph_rewire_directed_edges(&g, /*probability*/ 0.5,
                                               /*loops*/ true, /*mode*/ IGRAPH_ALL)
                  == IGRAPH_SUCCESS);
    IGRAPH_ASSERT(igraph_is_same_graph(&g, &g_copy, &same) == IGRAPH_SUCCESS);
    IGRAPH_ASSERT(!same); /*guaranteed for this seed*/
    IGRAPH_ASSERT(igraph_ecount(&g) == 9);
    IGRAPH_ASSERT(igraph_vcount(&g) == 10);
    igraph_destroy(&g);
    igraph_destroy(&g_copy);

    /*Out-star remains out-star if outs are moved*/
    igraph_small(&g, 10, IGRAPH_DIRECTED, 0,1, 0,2, 0,3, 0,4, 0,5, 0,6, 0,7, 0,8, 0,9, -1);
    IGRAPH_ASSERT(igraph_rewire_directed_edges(&g, /*probability*/ 1.0,
                                               /*loops*/ false, /*mode*/ IGRAPH_OUT)
                  == IGRAPH_SUCCESS);
    igraph_vector_int_init(&degrees, 0);
    igraph_vs_1(&vertices, 0);
    igraph_degree(&g, &degrees, vertices, IGRAPH_ALL, IGRAPH_NO_LOOPS);
    IGRAPH_ASSERT(VECTOR(degrees)[0] == 9);
    igraph_vector_int_destroy(&degrees);
    igraph_vs_destroy(&vertices);
    igraph_destroy(&g);

    /*Check if multiple edges are created when using mode == IGRAPH_ALL*/
    igraph_small(&g, 5, IGRAPH_DIRECTED, 0,1, 0,2, 0,3, 0,4, 1,2, 1,3, 1,4, 2,3, 2,4, 3,4, -1);
    IGRAPH_ASSERT(igraph_rewire_directed_edges(&g, /*probability*/ 1.0,
                                               /*loops*/ false, /*mode*/ IGRAPH_ALL)
                  == IGRAPH_SUCCESS);
    print_graph_canon(&g);

    /*A few erroneous calls*/
    VERIFY_FINALLY_STACK();
    igraph_set_error_handler(igraph_error_handler_ignore);

    IGRAPH_ASSERT(igraph_rewire_directed_edges(&g, /*probability*/ -0.1, /*loops*/ false, /*mode*/ IGRAPH_ALL) == IGRAPH_EINVAL);
    IGRAPH_ASSERT(igraph_rewire_directed_edges(&g, /*probability*/ 1.1, /*loops*/ false, /*mode*/ IGRAPH_ALL) == IGRAPH_EINVAL);
    igraph_destroy(&g);

    VERIFY_FINALLY_STACK();
    return 0;
}
