from unittest.mock import sentinel

import pytest

from bonobo.constants import BEGIN
from bonobo.structs.graphs import Graph

identity = lambda x: x


def test_graph_outputs_of():
    g = Graph()

    # default graph only node
    assert len(g.outputs_of(BEGIN)) == 0

    # unexisting node
    with pytest.raises(KeyError):
        g.outputs_of(0)

    # create node
    assert len(g.outputs_of(0, create=True)) == 0
    assert len(g.outputs_of(0)) == 0


def test_graph_add_component():
    g = Graph()

    assert len(g.nodes) == 0

    g.add_node(identity)
    assert len(g.nodes) == 1

    g.add_node(identity)
    assert len(g.nodes) == 2


def test_graph_add_chain():
    g = Graph()

    assert len(g.nodes) == 0

    g.add_chain(identity, identity, identity)
    assert len(g.nodes) == 3
    assert len(g.outputs_of(BEGIN)) == 1


def test_graph_topological_sort():
    g = Graph()

    g.add_chain(sentinel.a1, sentinel.a2, sentinel.a3, _input=None, _output=None)

    assert g.topologically_sorted_indexes == (0, 1, 2)
    assert g[0] == sentinel.a1
    assert g[1] == sentinel.a2
    assert g[2] == sentinel.a3

    g.add_chain(sentinel.b1, sentinel.b2, _output=sentinel.a2)

    assert g.topologically_sorted_indexes[-2:] == (1, 2)
    assert g.topologically_sorted_indexes.index(3) < g.topologically_sorted_indexes.index(4)
    assert g[3] == sentinel.b1
    assert g[4] == sentinel.b2


def test_copy():
    g1 = Graph()
    g2 = g1.copy()

    assert g1 is not g2

    assert len(g1) == 0
    assert len(g2) == 0

    g1.add_chain([])

    assert len(g1) == 1
    assert len(g2) == 0

    g2.add_chain([], identity)

    assert len(g1) == 1
    assert len(g2) == 2