"""Tests for `CalendarService` (§3.4 + §3.8: röda dagar / klämdagar API).

Covers: year-window pagination (fixed 4-year page, out-of-range rejection),
override merging (workspace DayOverrides layered on top of the statutory
calendar), and the exact-name holiday-matching trap (§4.2: Easter Sunday
comes back from the `holidays` library as the combined string
"Påskdagen; Söndag" — a naive `"Söndag" in name` filter would misclassify it
as a bare weekend).
"""

from datetime import date, datetime
from uuid import uuid4

import pytest

from app.entities.day_override import DayOverride
from app.services.calendar_service import MAX_WINDOW_YEARS, CalendarService
from app.services.day_override_service import DayOverrideService
from app.utils.errors import ValidationError
from app.utils.holidays import cached_year_bounds
from tests.conftest import SeededIds


@pytest.fixture
def calendar_service(day_override_service: DayOverrideService) -> CalendarService:
    return CalendarService(day_override_service)


class TestYearWindowPagination:
    async def test_default_window_is_four_years(self, calendar_service: CalendarService) -> None:
        window = await calendar_service.get_calendar_window(workspace_id=uuid4(), start_year=2026)
        assert window.start_year == 2026
        assert window.end_year == 2029
        years_seen = {d.date.year for d in window.days}
        assert years_seen == {2026, 2027, 2028, 2029}

    async def test_second_page_starts_where_first_left_off(
        self, calendar_service: CalendarService
    ) -> None:
        first = await calendar_service.get_calendar_window(workspace_id=uuid4(), start_year=2026)
        second = await calendar_service.get_calendar_window(
            workspace_id=uuid4(), start_year=first.end_year + 1
        )
        assert second.start_year == 2030
        assert second.end_year == 2033

    async def test_years_over_max_window_is_rejected(
        self, calendar_service: CalendarService
    ) -> None:
        with pytest.raises(ValidationError):
            await calendar_service.get_calendar_window(
                workspace_id=uuid4(), start_year=2026, years=MAX_WINDOW_YEARS + 1
            )

    async def test_start_year_outside_cache_is_rejected(
        self, calendar_service: CalendarService
    ) -> None:
        bounds = cached_year_bounds()
        assert bounds is not None, "cache file must exist for this repo's test suite"
        _, max_year = bounds

        with pytest.raises(ValidationError):
            await calendar_service.get_calendar_window(
                workspace_id=uuid4(), start_year=max_year + 1
            )

    async def test_full_10_year_cache_is_never_returned_in_one_call(
        self, calendar_service: CalendarService
    ) -> None:
        bounds = cached_year_bounds()
        assert bounds is not None
        min_year, _ = bounds

        window = await calendar_service.get_calendar_window(
            workspace_id=uuid4(), start_year=min_year
        )
        years_seen = {d.date.year for d in window.days}
        assert len(years_seen) == MAX_WINDOW_YEARS

    async def test_window_reaching_max_year_is_clamped_not_rejected(
        self, calendar_service: CalendarService
    ) -> None:
        """§ bug: `GET /days?start_year=<max_year>&years=4` used to happily
        report `end_year = max_year + 3` and silently serve the extra years
        from the degraded `holidays`-library fallback. The window must be
        clamped to the cache instead, and `end_year` must report the ACTUAL
        range served — never a range that wasn't returned.
        """
        bounds = cached_year_bounds()
        assert bounds is not None
        _, max_year = bounds

        window = await calendar_service.get_calendar_window(
            workspace_id=uuid4(), start_year=max_year, years=MAX_WINDOW_YEARS
        )

        assert window.start_year == max_year
        assert window.end_year == max_year, "must clamp end_year to the cache, not overshoot it"
        years_seen = {d.date.year for d in window.days}
        assert years_seen == {max_year}, "no day may come from a year beyond the cache"

    async def test_a_middle_page_that_would_overshoot_is_also_clamped(
        self, calendar_service: CalendarService
    ) -> None:
        """Same clamp, exercised one page before the very last year (e.g. the
        `start_year=max_year-1, years=4` case from real paging, which would
        overshoot the cache's end by two years without the clamp)."""
        bounds = cached_year_bounds()
        assert bounds is not None
        _, max_year = bounds
        start_year = max_year - 1

        window = await calendar_service.get_calendar_window(
            workspace_id=uuid4(), start_year=start_year, years=MAX_WINDOW_YEARS
        )

        assert window.end_year == max_year
        years_seen = {d.date.year for d in window.days}
        assert years_seen == {start_year, max_year}
        assert max(years_seen) <= max_year


class TestNoDegradedDataAcrossTheServedRange:
    """§4.2/§6: the fallback `holidays` library only knows formal röda dagar
    and misses de facto days (Julafton, Nyårsafton, Midsommarafton). This is
    exactly the regression that shipped: years past the cache silently lost
    those days. Assert they're present for EVERY year the endpoint can ever
    serve, and that no year is silently poorer than its neighbours.
    """

    @staticmethod
    async def _all_cached_years_red_days(
        calendar_service: CalendarService,
    ) -> dict[int, dict[date, str]]:
        bounds = cached_year_bounds()
        assert bounds is not None
        min_year, max_year = bounds

        by_year: dict[int, dict[date, str]] = {}
        start = min_year
        while start <= max_year:
            window = await calendar_service.get_calendar_window(
                workspace_id=uuid4(), start_year=start
            )
            for day in window.days:
                if day.day_type == "red_day":
                    by_year.setdefault(day.date.year, {})[day.date] = day.name or ""
            start = window.end_year + 1
        return by_year

    async def test_julafton_nyarsafton_and_midsommarafton_are_red_days_every_year(
        self, calendar_service: CalendarService
    ) -> None:
        by_year = await self._all_cached_years_red_days(calendar_service)
        bounds = cached_year_bounds()
        assert bounds is not None
        min_year, max_year = bounds
        assert set(by_year) == set(range(min_year, max_year + 1)), (
            "every cached year must be reachable via pagination"
        )

        for year, red_days in by_year.items():
            names_by_date = {d: name.lower() for d, name in red_days.items()}

            julafton = [d for d, n in names_by_date.items() if d.month == 12 and d.day == 24]
            assert julafton and "julafton" in names_by_date[julafton[0]], (
                f"{year}: Julafton (12-24) must be a red day"
            )

            nyarsafton = [d for d, n in names_by_date.items() if d.month == 12 and d.day == 31]
            assert nyarsafton and "nyårsafton" in names_by_date[nyarsafton[0]], (
                f"{year}: Nyårsafton (12-31) must be a red day"
            )

            midsommarafton = [d for d, n in names_by_date.items() if "midsommarafton" in n]
            assert midsommarafton, f"{year}: Midsommarafton must be a red day"

    async def test_red_day_count_is_consistent_across_every_served_year(
        self, calendar_service: CalendarService
    ) -> None:
        """No year may be silently poorer than its neighbours (the fallback's
        signature: 18 real red days in-cache vs. 13 once it kicks in).

        The one legitimate exception in a ~30-year range: Pingstdagen
        (Easter + 49 days) occasionally lands on Sveriges nationaldag (fixed
        June 6), e.g. 2049 and 2055. That's 17 *distinct* red dates, not a
        degradation — both holidays genuinely share one calendar date, and
        the API itself reports 17 for that year. Assert the exception is
        exactly this coincidence, by name, rather than loosely allowing any
        two counts.
        """
        by_year = await self._all_cached_years_red_days(calendar_service)
        for year, red_days in by_year.items():
            names_by_date = {d: name.lower() for d, name in red_days.items()}
            june_6_name = next(
                (n for d, n in names_by_date.items() if d.month == 6 and d.day == 6), ""
            )
            pingst_meets_nationaldag = "pingstdagen" in june_6_name and "nationaldag" in june_6_name
            expected = 17 if pingst_meets_nationaldag else 18
            assert len(red_days) == expected, (
                f"{year}: expected {expected} red dates "
                f"({'Pingstdagen/Nationaldagen coincide' if pingst_meets_nationaldag else 'normal year'}), "
                f"got {len(red_days)} — a year may be degraded: {sorted(red_days)}"
            )


class TestOverrideMerging:
    async def test_worked_override_flips_a_statutory_red_day_to_not_free(
        self,
        calendar_service: CalendarService,
        day_override_repo,
        seeded_ids: SeededIds,
    ) -> None:
        # 2026-12-25 (Juldagen) is a statutory red day; the workspace marks it
        # a working day via an override.
        christmas = date(2026, 12, 25)
        await day_override_repo.create(
            DayOverride(
                id=uuid4(),
                workspace_id=seeded_ids.workspace_id,
                date=christmas,
                is_working_day=True,
                created_at=datetime.now(),
                updated_at=datetime.now(),
            )
        )

        window = await calendar_service.get_calendar_window(
            workspace_id=seeded_ids.workspace_id, start_year=2026
        )
        by_date = {d.date: d for d in window.days}
        christmas_day = by_date[christmas]

        assert christmas_day.day_type == "red_day", "statutory classification must not change"
        assert christmas_day.is_override is True
        assert christmas_day.override_is_working_day is True
        assert christmas_day.is_free is False, "the override must win over the statutory calendar"

    async def test_off_override_flips_an_ordinary_working_day_to_free(
        self,
        calendar_service: CalendarService,
        day_override_repo,
        seeded_ids: SeededIds,
    ) -> None:
        # 2026-01-02 is a bridge_day (klämdag) - an ordinary working day the
        # employer happens to give off here.
        ordinary_bridge_day = date(2026, 1, 2)
        await day_override_repo.create(
            DayOverride(
                id=uuid4(),
                workspace_id=seeded_ids.workspace_id,
                date=ordinary_bridge_day,
                is_working_day=False,
                created_at=datetime.now(),
                updated_at=datetime.now(),
            )
        )

        window = await calendar_service.get_calendar_window(
            workspace_id=seeded_ids.workspace_id, start_year=2026
        )
        by_date = {d.date: d for d in window.days}
        day = by_date[ordinary_bridge_day]

        assert day.day_type == "klamdag"
        assert day.is_override is True
        assert day.override_is_working_day is False
        assert day.is_free is True

    async def test_days_without_an_override_are_unaffected(
        self, calendar_service: CalendarService, seeded_ids: SeededIds
    ) -> None:
        window = await calendar_service.get_calendar_window(
            workspace_id=seeded_ids.workspace_id, start_year=2026
        )
        assert all(not d.is_override and d.override_is_working_day is None for d in window.days)


class TestExactNameHolidayMatching:
    """§4.2: the `holidays` library combines a fixed holiday with "Söndag"
    when it lands on a Sunday, e.g. "Påskdagen; Söndag". A naive
    `"Söndag" in name` filter would wrongly classify these as bare weekends.
    """

    async def test_easter_sunday_is_classified_as_red_day_even_when_it_reads_sondag(
        self, calendar_service: CalendarService
    ) -> None:
        # Easter Sunday always falls on a Sunday by definition, so in every
        # cached year its cache/library name is combined with "Söndag".
        window = await calendar_service.get_calendar_window(workspace_id=uuid4(), start_year=2026)
        easter_sundays = [d for d in window.days if d.name and "påskdagen" in d.name.lower()]
        assert easter_sundays, "expected an Easter Sunday in the 2026 window"

        for day in easter_sundays:
            assert day.day_type == "red_day"
            assert day.name != "Söndag", "must carry the real holiday name, not the bare marker"

    async def test_bare_sundays_are_never_classified_as_red_days(
        self, calendar_service: CalendarService
    ) -> None:
        window = await calendar_service.get_calendar_window(workspace_id=uuid4(), start_year=2026)
        # 2026-01-04 is an ordinary Sunday with no coinciding holiday.
        plain_sunday = date(2026, 1, 4)
        by_date = {d.date: d for d in window.days}
        day = by_date[plain_sunday]

        assert day.day_type == "weekend"
        assert day.name is None
        assert day.is_free is True