/*

   IGraph library.

   Copyright (C) 2021-2024  The igraph development team

   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 <cstdlib>

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {

    igraph_t graph;

    igraph_vector_int_t edges;

    igraph_set_warning_handler(igraph_warning_handler_ignore);

    /* We work with small, up-to 16-vertex graphs, as the algorithms

     * tested here can be slow. Each byte is interpreted as an edge.

     * A simple graph can have at most 120 edges, but we allow up

     * to 240, as the fuzzer usually generates multigraphs. */

    if (Size > 240) {

        return 0;

    }

    igraph_vector_int_init(&edges, 2*Size);

    size_t j = 0;

    for (size_t i=0; i < Size; ++i) {

        VECTOR(edges)[j++] = Data[i] / 16;

        VECTOR(edges)[j++] = Data[i] % 16;

    }

    if (igraph_create(&graph, &edges, 0, IGRAPH_UNDIRECTED) == IGRAPH_SUCCESS) {

        igraph_vector_int_list_t ivl;

        igraph_vector_int_t iv1, iv2;

        igraph_bool_t is_separator, is_minimal_separator;

        igraph_vector_int_list_init(&ivl, 0);

        igraph_vector_int_init(&iv1, 0);

        igraph_vector_int_init(&iv2, 0);

        igraph_all_minimal_st_separators(&graph, &ivl);

        // Check that all returned sets are indeed separators.

        for (igraph_integer_t i=0; i < igraph_vector_int_list_size(&ivl); i++) {

            igraph_is_separator(

                &graph,

                igraph_vss_vector(igraph_vector_int_list_get_ptr(&ivl, i)),

                &is_separator);

            IGRAPH_ASSERT(is_separator);

        }

        igraph_minimum_size_separators(&graph, &ivl);

        // Simplification is necessary for cohesive_blocks() and

        // enables a straightforward check for complete graphs below.

        igraph_simplify(&graph, true, true, NULL);

        const igraph_integer_t vcount = igraph_vcount(&graph);

        const igraph_integer_t ecount = igraph_ecount(&graph);

        if (ecount != vcount*(vcount-1)/2) {

            // minimum_size_separators() returns all size n-1 subsets

            // of the complete graph K_n. is_minimal_separator() does not

            // consider these to be separators. Therefore we skip complete

            // graphs. For non-complete graphs we check that all results

            // are minimal separators.

            for (igraph_integer_t i=0; i < igraph_vector_int_list_size(&ivl); i++) {

                igraph_is_minimal_separator(

                    &graph,

                    igraph_vss_vector(igraph_vector_int_list_get_ptr(&ivl, i)),

                    &is_minimal_separator);

                IGRAPH_ASSERT(is_minimal_separator);

            }

        }

        {

            igraph_t g;

            igraph_cohesive_blocks(&graph, &ivl, &iv1, &iv2, &g);

            igraph_destroy(&g);

        }

        igraph_vector_int_destroy(&iv2);

        igraph_vector_int_destroy(&iv1);

        igraph_vector_int_list_destroy(&ivl);

        igraph_destroy(&graph);

    }

    igraph_vector_int_destroy(&edges);

    IGRAPH_ASSERT(IGRAPH_FINALLY_STACK_EMPTY);

    return 0;  // Non-zero return values are reserved for future use.

}