from datetime import UTC, datetime, timedelta

import pytest
from django.db import transaction

from portal.accounts import throttle
from portal.accounts.models import ThrottleCounter

T0 = datetime(2026, 1, 1, 12, 0, tzinfo=UTC)
EP = "sign-in"

pytestmark = pytest.mark.django_db(transaction=True)


def fail(n, at=T0, **kw):
    for _ in range(n):
        throttle.hit(EP, clock=lambda: at, **kw)


def test_below_limit_passes():
    fail(4, user="alice")
    throttle.check(EP, user="alice", clock=lambda: T0)


def test_user_is_throttled_but_others_pass():
    fail(5, user="Alice", ip="1.1.1.1")
    with pytest.raises(throttle.Throttled) as exc:
        throttle.check(EP, user="alice", clock=lambda: T0)
    assert exc.value.retry_after == 900
    throttle.check(EP, user="bob", ip="2.2.2.2", clock=lambda: T0)


def test_ip_is_throttled_across_users():
    fail(5, user="a", ip="1.1.1.1")
    with pytest.raises(throttle.Throttled):
        throttle.check(EP, user="other", ip="1.1.1.1", clock=lambda: T0)
    throttle.check(EP, user="other", ip="3.3.3.3", clock=lambda: T0)


def test_other_endpoint_is_unaffected():
    fail(5, user="alice")
    throttle.check("password-change", user="alice", clock=lambda: T0)


def test_pause_elapses():
    fail(5, user="alice")
    later = T0 + timedelta(seconds=901)
    throttle.check(EP, user="alice", clock=lambda: later)
    # a new failure after the pause starts a fresh count
    throttle.hit(EP, user="alice", clock=lambda: later)
    assert ThrottleCounter.objects.get(subject="user:alice").count == 1


def test_stale_window_restarts_count():
    fail(4, user="alice")
    later = T0 + timedelta(minutes=16)
    throttle.hit(EP, user="alice", clock=lambda: later)
    assert ThrottleCounter.objects.get().count == 1


def test_reset_clears_user_but_never_the_ip():
    fail(5, user="alice", ip="1.1.1.1")
    throttle.reset(EP, user="alice")
    throttle.check(EP, user="alice", clock=lambda: T0)
    with pytest.raises(throttle.Throttled):
        throttle.check(EP, ip="1.1.1.1", clock=lambda: T0)


def test_reset_has_no_ip_parameter():
    with pytest.raises(TypeError):
        throttle.reset(EP, user="alice", ip="1.1.1.1")


def test_hit_inside_transaction_raises_and_counts_nothing():
    with pytest.raises(RuntimeError), transaction.atomic():
        throttle.hit(EP, user="alice", clock=lambda: T0)
    assert ThrottleCounter.objects.count() == 0


def test_no_subject_raises_for_all_functions():
    with pytest.raises(ValueError):
        throttle.check(EP)
    with pytest.raises(ValueError):
        throttle.hit(EP)
    with pytest.raises(ValueError):
        throttle.reset(EP, user="")


def test_check_never_writes():
    throttle.check(EP, user="alice", ip="1.1.1.1", clock=lambda: T0)
    assert ThrottleCounter.objects.count() == 0