import unittest
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 TrackrefTestCase(unittest.TestCase):
    def setUp(self):
        trackref.live_refs.clear()

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

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

        self.assertEqual(
            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()
        self.assertEqual(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()
        self.assertEqual(
            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
        self.assertIs(trackref.get_oldest("Foo"), o1)
        self.assertIs(trackref.get_oldest("Bar"), o2)
        self.assertIsNone(trackref.get_oldest("XXX"))

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