#!/usr/bin/env python
# -*- coding: utf-8 -*-
# $Id: test_maximal_independent_set.py 577 2011-03-01 06:07:53Z lleeoo $
#    Copyright (C) 2004-2019 by
#    Leo Lopes <leo.lopes@monash.edu>
#    Aric Hagberg <hagberg@lanl.gov>
#    Dan Schult <dschult@colgate.edu>
#    Pieter Swart <swart@lanl.gov>
#    All rights reserved.
#    BSD license.
#
# Author: Leo Lopes <leo.lopes@monash.edu>
"""
Tests for maximal (not maximum) independent sets.

"""

import pytest
import networkx as nx
import random


class TestMaximalIndependantSet(object):
    def setup(self):
        self.florentine = nx.Graph()
        self.florentine.add_edge('Acciaiuoli', 'Medici')
        self.florentine.add_edge('Castellani', 'Peruzzi')
        self.florentine.add_edge('Castellani', 'Strozzi')
        self.florentine.add_edge('Castellani', 'Barbadori')
        self.florentine.add_edge('Medici', 'Barbadori')
        self.florentine.add_edge('Medici', 'Ridolfi')
        self.florentine.add_edge('Medici', 'Tornabuoni')
        self.florentine.add_edge('Medici', 'Albizzi')
        self.florentine.add_edge('Medici', 'Salviati')
        self.florentine.add_edge('Salviati', 'Pazzi')
        self.florentine.add_edge('Peruzzi', 'Strozzi')
        self.florentine.add_edge('Peruzzi', 'Bischeri')
        self.florentine.add_edge('Strozzi', 'Ridolfi')
        self.florentine.add_edge('Strozzi', 'Bischeri')
        self.florentine.add_edge('Ridolfi', 'Tornabuoni')
        self.florentine.add_edge('Tornabuoni', 'Guadagni')
        self.florentine.add_edge('Albizzi', 'Ginori')
        self.florentine.add_edge('Albizzi', 'Guadagni')
        self.florentine.add_edge('Bischeri', 'Guadagni')
        self.florentine.add_edge('Guadagni', 'Lamberteschi')

    def test_random_seed(self):
        G = nx.complete_graph(5)
        for node in G:
            assert nx.maximal_independent_set(G, [node], seed=1) == [node]

    def test_K5(self):
        """Maximal independent set: K5"""
        G = nx.complete_graph(5)
        for node in G:
            assert nx.maximal_independent_set(G, [node]) == [node]

    def test_K55(self):
        """Maximal independent set: K55"""
        G = nx.complete_graph(55)
        for node in G:
            assert nx.maximal_independent_set(G, [node]) == [node]

    def test_exception(self):
        """Bad input should raise exception."""
        G = self.florentine
        pytest.raises(nx.NetworkXUnfeasible,
                      nx.maximal_independent_set, G, ["Smith"])
        pytest.raises(nx.NetworkXUnfeasible,
                      nx.maximal_independent_set, G, ["Salviati", "Pazzi"])

    def test_digraph_exception(self):
        G = nx.DiGraph([(1, 2), (3, 4)])
        pytest.raises(nx.NetworkXNotImplemented, nx.maximal_independent_set, G)

    def test_florentine_family(self):
        G = self.florentine
        indep = nx.maximal_independent_set(G, ["Medici", "Bischeri"])
        assert (sorted(indep) ==
                     sorted(["Medici", "Bischeri", "Castellani", "Pazzi",
                             "Ginori", "Lamberteschi"]))

    def test_bipartite(self):
        G = nx.complete_bipartite_graph(12, 34)
        indep = nx.maximal_independent_set(G, [4, 5, 9, 10])
        assert sorted(indep) == list(range(12))

    def test_random_graphs(self):
        """Generate 50 random graphs of different types and sizes and
        make sure that all sets are independent and maximal."""
        for i in range(0, 50, 10):
            G = nx.random_graphs.erdos_renyi_graph(i * 10 + 1, random.random())
            IS = nx.maximal_independent_set(G)
            assert not list(G.subgraph(IS).edges())
            neighbors_of_MIS = set.union(*(set(G.neighbors(v)) for v in IS))
            for v in set(G.nodes()).difference(IS):
                assert v in neighbors_of_MIS
