"""Week helpers and WeeklyClock schedule arithmetic."""

from __future__ import annotations

from datetime import date, datetime, timedelta
from zoneinfo import ZoneInfo

import pytest

from sebrief.week import WeeklyClock, parse_hhmm, week_id, week_range

KST = ZoneInfo("Asia/Seoul")


# ------------------------------------------------------------------------- week id / range
def test_week_id_and_range_roundtrip():
    assert week_id(date(2026, 8, 31)) == "2026-W36"
    assert week_id(date(2026, 9, 6)) == "2026-W36"
    assert week_range("2026-W36") == (date(2026, 8, 31), date(2026, 9, 6))


def test_week_id_uses_iso_year_at_boundaries():
    # 2026-01-01 is a Thursday -> belongs to ISO 2026-W01 starting Mon 2025-12-29
    assert week_id(date(2025, 12, 29)) == "2026-W01"
    assert week_range("2026-W01")[0] == date(2025, 12, 29)


@pytest.mark.parametrize("bad", ["2026-36", "2026-W99", "2026W36", "abcd-W01", "2026-W1"])
def test_week_range_rejects_invalid(bad):
    with pytest.raises(ValueError):
        week_range(bad)


@pytest.mark.parametrize("bad", ["8:", "25:00", "08:60", "abc", "0820"])
def test_parse_hhmm_rejects_invalid(bad):
    with pytest.raises(ValueError):
        parse_hhmm(bad)


def test_parse_hhmm_ok():
    assert parse_hhmm("07:00") == (7, 0)
    assert parse_hhmm(" 7:05 ") == (7, 5)


# ------------------------------------------------------------------------------ WeeklyClock
def test_clock_rejects_bad_config():
    with pytest.raises(ValueError):
        WeeklyClock(run_weekday=7)
    with pytest.raises(ValueError):
        WeeklyClock(run_time="25:00")


def test_next_run_before_and_after_the_weekly_slot():
    clock = WeeklyClock(0, "07:00")
    before = datetime(2026, 9, 7, 6, 59, tzinfo=KST)  # Monday, one minute before the run
    week, run_at = clock.next_run(before)
    assert (week, run_at) == ("2026-W36", datetime(2026, 9, 7, 7, 0, tzinfo=KST))

    after = datetime(2026, 9, 7, 7, 0, tzinfo=KST)  # exactly at the slot -> next week's run
    week, run_at = clock.next_run(after)
    assert (week, run_at) == ("2026-W37", datetime(2026, 9, 14, 7, 0, tzinfo=KST))


def test_next_run_midweek_and_custom_weekday():
    wed = datetime(2026, 9, 9, 12, 0, tzinfo=KST)
    assert WeeklyClock(0, "07:00").next_run(wed) == (
        "2026-W37",
        datetime(2026, 9, 14, 7, 0, tzinfo=KST),
    )
    # Thursday 08:30 runs cover the week that ended the previous Sunday
    assert WeeklyClock(3, "08:30").next_run(wed) == (
        "2026-W36",
        datetime(2026, 9, 10, 8, 30, tzinfo=KST),
    )


def test_next_run_requires_tz_aware():
    with pytest.raises(ValueError):
        WeeklyClock().next_run(datetime(2026, 9, 7, 12, 0))  # noqa: DTZ001 - naive on purpose


def test_run_at_for_is_consistent_with_next_run():
    clock = WeeklyClock(0, "07:00")
    assert clock.run_at_for("2026-W36") == datetime(2026, 9, 7, 7, 0, tzinfo=KST)
    clock2 = WeeklyClock(3, "08:30")
    assert clock2.run_at_for("2026-W36") == datetime(2026, 9, 10, 8, 30, tzinfo=KST)


def test_last_run_and_latest_completed_week():
    clock = WeeklyClock(0, "07:00")
    monday_noon = datetime(2026, 9, 7, 12, 0, tzinfo=KST)
    assert clock.last_run(monday_noon) == ("2026-W36", datetime(2026, 9, 7, 7, 0, tzinfo=KST))
    assert clock.latest_completed_week(monday_noon) == "2026-W36"
    # mid-week: the last run is still the past Monday
    wed = datetime(2026, 9, 9, 9, 0, tzinfo=KST)
    assert clock.last_run(wed) == ("2026-W36", datetime(2026, 9, 7, 7, 0, tzinfo=KST))


@pytest.mark.parametrize(
    ("now_delta", "expected"),
    [
        (timedelta(hours=1), "2026-W36"),  # 1h after the slot: inside the window
        (timedelta(hours=71), "2026-W36"),  # still inside the 72h window
        (timedelta(hours=73), None),  # outside
    ],
)
def test_catchup_candidate_window(now_delta, expected):
    clock = WeeklyClock(0, "07:00")
    run_at = datetime(2026, 9, 7, 7, 0, tzinfo=KST)
    assert clock.catchup_candidate(run_at + now_delta, 72) == expected


def test_covered_week():
    clock = WeeklyClock(0, "07:00")
    assert clock.covered_week(date(2026, 9, 7)) == "2026-W36"
    assert clock.covered_week(date(2026, 9, 14)) == "2026-W37"