from io import StringIO
from time import sleep, time
from unittest import mock

from twisted.trial.unittest import SkipTest

from scrapy.utils import trackref


class Foo(trackref.object_ref):
    pass


class Bar(trackref.object_ref):
    pass


class TestTrackref:
    def setup_method(self):
        trackref.live_refs.clear()

    def test_format_live_refs(self):
        o1 = Foo()  # noqa: F841
        o2 = Bar()  # noqa: F841
        o3 = Foo()  # noqa: F841
        assert (
            trackref.format_live_refs()
            == """\
Live References

Bar                                 1   oldest: 0s ago
Foo                                 2   oldest: 0s ago
"""
        )

        assert (
            trackref.format_live_refs(ignore=Foo)
            == """\
Live References

Bar                                 1   oldest: 0s ago
"""
        )

    @mock.patch("sys.stdout", new_callable=StringIO)
    def test_print_live_refs_empty(self, stdout):
        trackref.print_live_refs()
        assert stdout.getvalue() == "Live References\n\n\n"

    @mock.patch("sys.stdout", new_callable=StringIO)
    def test_print_live_refs_with_objects(self, stdout):
        o1 = Foo()  # noqa: F841
        trackref.print_live_refs()
        assert (
            stdout.getvalue()
            == """\
Live References

Foo                                 1   oldest: 0s ago\n\n"""
        )

    def test_get_oldest(self):
        o1 = Foo()

        o1_time = time()

        o2 = Bar()

        o3_time = time()
        if o3_time <= o1_time:
            sleep(0.01)
            o3_time = time()
        if o3_time <= o1_time:
            raise SkipTest("time.time is not precise enough")

        o3 = Foo()  # noqa: F841
        assert trackref.get_oldest("Foo") is o1
        assert trackref.get_oldest("Bar") is o2
        assert trackref.get_oldest("XXX") is None

    def test_iter_all(self):
        o1 = Foo()
        o2 = Bar()  # noqa: F841
        o3 = Foo()
        assert set(trackref.iter_all("Foo")) == {o1, o3}