import unittest
from unittest.mock import Mock

from IPython.core import events
import IPython.testing.tools as tt


@events._define_event
def ping_received():
    pass


@events._define_event
def event_with_argument(argument):
    pass


class CallbackTests(unittest.TestCase):
    def setUp(self):
        self.em = events.EventManager(
            get_ipython(),
            {
                "ping_received": ping_received,
                "event_with_argument": event_with_argument,
            },
        )

    def test_register_unregister(self):
        cb = Mock()

        self.em.register("ping_received", cb)
        self.em.trigger("ping_received")
        self.assertEqual(cb.call_count, 1)

        self.em.unregister("ping_received", cb)
        self.em.trigger("ping_received")
        self.assertEqual(cb.call_count, 1)

    def test_bare_function_missed_unregister(self):
        def cb1(): ...

        def cb2(): ...

        self.em.register("ping_received", cb1)
        self.assertRaises(ValueError, self.em.unregister, "ping_received", cb2)
        self.em.unregister("ping_received", cb1)

    def test_cb_error(self):
        cb = Mock(side_effect=ValueError)
        self.em.register("ping_received", cb)
        with tt.AssertPrints("Error in callback"):
            self.em.trigger("ping_received")

    def test_cb_keyboard_interrupt(self):
        cb = Mock(side_effect=KeyboardInterrupt)
        self.em.register("ping_received", cb)
        with tt.AssertPrints("Error in callback"):
            self.em.trigger("ping_received")

    def test_unregister_during_callback(self):
        invoked = [False] * 3

        def func1(*_):
            invoked[0] = True
            self.em.unregister("ping_received", func1)
            self.em.register("ping_received", func3)

        def func2(*_):
            invoked[1] = True
            self.em.unregister("ping_received", func2)

        def func3(*_):
            invoked[2] = True

        self.em.register("ping_received", func1)
        self.em.register("ping_received", func2)

        self.em.trigger("ping_received")
        self.assertEqual([True, True, False], invoked)
        self.assertEqual([func3], self.em.callbacks["ping_received"])
