"""Unit tests for the :mod:`networkx.generators.interval_graph` module.

"""
import math
import pytest

import networkx as nx
from networkx.generators.interval_graph import interval_graph
from networkx.testing import assert_edges_equal


class TestIntervalGraph:
    """Unit tests for :func:`networkx.generators.interval_graph.interval_graph`"""

    def test_empty(self):
        """ Tests for trivial case of empty input"""
        assert len(interval_graph([])) == 0

    def test_interval_graph_check_invalid(self):
        """ Tests for conditions that raise Exceptions """

        invalids_having_none = [None, (1, 2)]
        with pytest.raises(TypeError):
            interval_graph(invalids_having_none)

        invalids_having_set = [{1, 2}]
        with pytest.raises(TypeError):
            interval_graph(invalids_having_set)

        invalids_having_seq_but_not_length2 = [(1, 2, 3)]
        with pytest.raises(TypeError):
            interval_graph(invalids_having_seq_but_not_length2)

        invalids_interval = [[3, 2]]
        with pytest.raises(ValueError):
            interval_graph(invalids_interval)

    def test_interval_graph_0(self):
        intervals = [(1, 2), (1, 3)]

        expected_graph = nx.Graph()
        expected_graph.add_edge(*intervals)

        actual_g = interval_graph(intervals)

        assert set(actual_g.nodes) == set(expected_graph.nodes)
        assert_edges_equal(expected_graph, actual_g)

    def test_interval_graph_1(self):
        intervals = [(1, 2), (2, 3), (3, 4), (1, 4)]

        expected_graph = nx.Graph()
        expected_graph.add_nodes_from(intervals)
        e1 = ((1, 4), (1, 2))
        e2 = ((1, 4), (2, 3))
        e3 = ((1, 4), (3, 4))
        e4 = ((3, 4), (2, 3))
        e5 = ((1, 2), (2, 3))

        expected_graph.add_edges_from([e1, e2, e3, e4, e5])

        actual_g = interval_graph(intervals)

        assert set(actual_g.nodes) == set(expected_graph.nodes)
        assert_edges_equal(expected_graph, actual_g)

    def test_interval_graph_2(self):
        intervals = [(1, 2), [3, 5], [6, 8], (9, 10)]

        expected_graph = nx.Graph()
        expected_graph.add_nodes_from([(1, 2), (3, 5), (6, 8), (9, 10)])

        actual_g = interval_graph(intervals)

        assert set(actual_g.nodes) == set(expected_graph.nodes)
        assert_edges_equal(expected_graph, actual_g)

    def test_interval_graph_3(self):
        intervals = [(1, 4), [3, 5], [2.5, 4]]

        expected_graph = nx.Graph()
        expected_graph.add_nodes_from([(1, 4), (3, 5), (2.5, 4)])
        e1 = ((1, 4), (3, 5))
        e2 = ((1, 4), (2.5, 4))
        e3 = ((3, 5), (2.5, 4))

        expected_graph.add_edges_from([e1, e2, e3])

        actual_g = interval_graph(intervals)

        assert set(actual_g.nodes) == set(expected_graph.nodes)
        assert_edges_equal(expected_graph, actual_g)

    def test_interval_graph_4(self):
        """ test all possible overlaps """
        intervals = [
            (0, 2),
            (-2, -1),
            (-2, 0),
            (-2, 1),
            (-2, 2),
            (-2, 3),
            (0, 1),
            (0, 2),
            (0, 3),
            (1, 2),
            (1, 3),
            (2, 3),
            (3, 4),
        ]

        expected_graph = nx.Graph()
        expected_graph.add_nodes_from(intervals)
        expected_nbrs = {
            (-2, 0),
            (-2, 1),
            (-2, 2),
            (-2, 3),
            (0, 1),
            (0, 2),
            (0, 3),
            (1, 2),
            (1, 3),
            (2, 3),
        }
        actual_g = nx.interval_graph(intervals)
        actual_nbrs = nx.neighbors(actual_g, (0, 2))

        assert set(actual_nbrs) == expected_nbrs

    def test_interval_graph_5(self):
        """ this test is to see that an interval supports infinite number"""
        intervals = {(-math.inf, 0), (-1, -1), (0.5, 0.5), (1, 1), (1, math.inf)}

        expected_graph = nx.Graph()
        expected_graph.add_nodes_from(intervals)
        e1 = ((-math.inf, 0), (-1, -1))
        e2 = ((1, 1), (1, math.inf))

        expected_graph.add_edges_from([e1, e2])
        actual_g = interval_graph(intervals)

        assert set(actual_g.nodes) == set(expected_graph.nodes)
        assert_edges_equal(expected_graph, actual_g)
