import pytest
import networkx as nx


class TestMCS:
    @classmethod
    def setup_class(cls):
        # simple graph
        connected_chordal_G = nx.Graph()
        connected_chordal_G.add_edges_from(
            [
                (1, 2),
                (1, 3),
                (2, 3),
                (2, 4),
                (3, 4),
                (3, 5),
                (3, 6),
                (4, 5),
                (4, 6),
                (5, 6),
            ]
        )
        cls.connected_chordal_G = connected_chordal_G

        chordal_G = nx.Graph()
        chordal_G.add_edges_from(
            [
                (1, 2),
                (1, 3),
                (2, 3),
                (2, 4),
                (3, 4),
                (3, 5),
                (3, 6),
                (4, 5),
                (4, 6),
                (5, 6),
                (7, 8),
            ]
        )
        chordal_G.add_node(9)
        cls.chordal_G = chordal_G

        non_chordal_G = nx.Graph()
        non_chordal_G.add_edges_from([(1, 2), (1, 3), (2, 4), (2, 5), (3, 4), (3, 5)])
        cls.non_chordal_G = non_chordal_G

        self_loop_G = nx.Graph()
        self_loop_G.add_edges_from([(1, 1)])
        cls.self_loop_G = self_loop_G

    @pytest.mark.parametrize("G", (nx.DiGraph(), nx.MultiGraph(), nx.MultiDiGraph()))
    def test_is_chordal_not_implemented(self, G):
        with pytest.raises(nx.NetworkXNotImplemented):
            nx.is_chordal(G)

    def test_is_chordal(self):
        assert not nx.is_chordal(self.non_chordal_G)
        assert nx.is_chordal(self.chordal_G)
        assert nx.is_chordal(self.connected_chordal_G)
        assert nx.is_chordal(nx.complete_graph(3))
        assert nx.is_chordal(nx.cycle_graph(3))
        assert not nx.is_chordal(nx.cycle_graph(5))
        with pytest.raises(nx.NetworkXError, match="Input graph is not chordal"):
            nx.is_chordal(self.self_loop_G)

    def test_induced_nodes(self):
        G = nx.generators.classic.path_graph(10)
        Induced_nodes = nx.find_induced_nodes(G, 1, 9, 2)
        assert Induced_nodes == {1, 2, 3, 4, 5, 6, 7, 8, 9}
        pytest.raises(
            nx.NetworkXTreewidthBoundExceeded, nx.find_induced_nodes, G, 1, 9, 1
        )
        Induced_nodes = nx.find_induced_nodes(self.chordal_G, 1, 6)
        assert Induced_nodes == {1, 2, 4, 6}
        pytest.raises(nx.NetworkXError, nx.find_induced_nodes, self.non_chordal_G, 1, 5)

    def test_graph_treewidth(self):
        with pytest.raises(nx.NetworkXError, match="Input graph is not chordal"):
            nx.chordal_graph_treewidth(self.non_chordal_G)

    def test_chordal_find_cliques(self):
        cliques = {
            frozenset([9]),
            frozenset([7, 8]),
            frozenset([1, 2, 3]),
            frozenset([2, 3, 4]),
            frozenset([3, 4, 5, 6]),
        }
        assert nx.chordal_graph_cliques(self.chordal_G) == cliques
        with pytest.raises(nx.NetworkXError, match="Input graph is not chordal"):
            nx.chordal_graph_cliques(self.non_chordal_G)
        with pytest.raises(nx.NetworkXError, match="Input graph is not chordal"):
            nx.chordal_graph_cliques(self.self_loop_G)

    def test_chordal_find_cliques_path(self):
        G = nx.path_graph(10)
        cliqueset = nx.chordal_graph_cliques(G)
        for (u, v) in G.edges():
            assert frozenset([u, v]) in cliqueset or frozenset([v, u]) in cliqueset

    def test_chordal_find_cliquesCC(self):
        cliques = {frozenset([1, 2, 3]), frozenset([2, 3, 4]), frozenset([3, 4, 5, 6])}
        cgc = nx.chordal_graph_cliques
        assert cgc(self.connected_chordal_G) == cliques

    def test_complete_to_chordal_graph(self):
        fgrg = nx.fast_gnp_random_graph
        test_graphs = [
            nx.barbell_graph(6, 2),
            nx.cycle_graph(15),
            nx.wheel_graph(20),
            nx.grid_graph([10, 4]),
            nx.ladder_graph(15),
            nx.star_graph(5),
            nx.bull_graph(),
            fgrg(20, 0.3, seed=1),
        ]
        for G in test_graphs:
            H, a = nx.complete_to_chordal_graph(G)
            assert nx.is_chordal(H)
            assert len(a) == H.number_of_nodes()
            if nx.is_chordal(G):
                assert G.number_of_edges() == H.number_of_edges()
                assert set(a.values()) == {0}
            else:
                assert len(set(a.values())) == H.number_of_nodes()