from collections.abc import Iterator
from datetime import datetime, timedelta

import pytest

from app.config import Settings
from app.core import clock


@pytest.fixture(autouse=True)
def _fresh_clock(monkeypatch: pytest.MonkeyPatch) -> Iterator[None]:
    monkeypatch.setattr(clock, "get_settings", lambda: Settings(_env_file=None, demo_clock=True))
    clock.register_persistence(None, None)
    clock.reset()
    yield
    clock.register_persistence(None, None)
    clock.reset()


def _close(a: datetime, b: datetime) -> bool:
    return abs(a - b) < timedelta(seconds=5)


def test_now_is_tz_aware_in_settings_tz() -> None:
    now = clock.now()
    assert now.tzinfo is not None
    assert now.utcoffset() == timedelta(hours=3)  # Europe/Moscow


def test_advance_shifts_time() -> None:
    before = clock.now()
    after = clock.advance(days=1, hours=2, minutes=30)
    assert _close(after, before + timedelta(days=1, hours=2, minutes=30))
    assert clock.offset() == timedelta(days=1, hours=2, minutes=30)
    assert clock.today() == clock.now().date()


def test_set_now_and_reset() -> None:
    target = datetime(2026, 10, 20, 9, 0)
    assert _close(clock.set_now(target), target.replace(tzinfo=clock.now().tzinfo))
    clock.reset()
    assert clock.offset() == timedelta(0)
    assert _close(clock.now(), clock._real_now())


def test_persistence_hook_loads_and_saves() -> None:
    saved: list[timedelta] = []
    clock.register_persistence(lambda: timedelta(days=5), saved.append)
    assert clock.offset() == timedelta(days=5)
    clock.advance(days=1)
    assert saved[-1] == timedelta(days=6)
    clock.reset()
    assert saved[-1] == timedelta(0)


def test_persistence_load_none_keeps_offset() -> None:
    clock.advance(hours=3)
    clock.register_persistence(lambda: None, None)
    assert clock.offset() == timedelta(hours=3)


def test_real_mode_ignores_offset_and_forbids_moving(monkeypatch: pytest.MonkeyPatch) -> None:
    clock.advance(days=3)
    monkeypatch.setattr(clock, "get_settings", lambda: Settings(_env_file=None, demo_clock=False))
    assert clock.offset() == timedelta(0)
    assert _close(clock.now(), clock._real_now())
    with pytest.raises(RuntimeError):
        clock.advance(days=1)
    with pytest.raises(RuntimeError):
        clock.set_now(datetime(2026, 1, 1))