"""Occurrence identity and UTC persistence helpers (T02)."""

from __future__ import annotations

from datetime import datetime, timezone

import pytest

from wf_scheduling.calendar import CronSource
from wf_scheduling.occurrences import (
    Occurrence,
    is_already_consumed,
    monotonic_ns,
    occurrence_id,
    scheduled_at_str,
    wall_now_utc,
)


def utc(*args: int) -> datetime:
    return datetime(*args, tzinfo=timezone.utc)


def test_occurrence_id_is_deterministic_utc_pair() -> None:
    at = utc(2026, 9, 8, 13, 0, 0)
    assert occurrence_id("sched-1", at) == occurrence_id("sched-1", at)
    assert occurrence_id("sched-1", at) != occurrence_id("sched-2", at)
    assert occurrence_id("sched-1", at) != occurrence_id(
        "sched-1", utc(2026, 9, 8, 14, 0, 0)
    )
    assert "sched-1" in occurrence_id("sched-1", at)


def test_occurrence_id_rejects_naive() -> None:
    with pytest.raises(ValueError, match="aware"):
        occurrence_id("s", datetime(2026, 9, 8, 12, 0))


def test_scheduled_at_serializes_as_utc_rfc3339() -> None:
    from datetime import timedelta

    at = datetime(2026, 9, 8, 12, 0, tzinfo=timezone(timedelta(hours=2)))
    assert scheduled_at_str(at) == "2026-09-08T10:00:00+00:00"
    with pytest.raises(ValueError, match="aware"):
        scheduled_at_str(datetime(2026, 9, 8, 12, 0))


def test_occurrence_model_exposes_contract_fields() -> None:
    occ = Occurrence(schedule_id="s", scheduled_at=utc(2026, 9, 8, 13, 0, 0))
    assert occ.schedule_id == "s"
    assert occ.occurrence_id == occurrence_id("s", utc(2026, 9, 8, 13, 0, 0))
    assert occ.scheduled_at == utc(2026, 9, 8, 13, 0, 0)
    payload = occ.to_binding_dict()
    assert payload["schedule_id"] == "s"
    assert payload["scheduled_at"] == "2026-09-08T13:00:00+00:00"


def test_calendar_identities_are_unique_and_increasing() -> None:
    src = CronSource("30 9 * * *", "UTC")
    cursor = utc(2026, 9, 1, 0, 0, 0)
    seen: set[str] = set()
    prev: datetime | None = None
    for _ in range(10):
        nxt = src.next_after(cursor)
        assert nxt is not None
        ident = occurrence_id("s", nxt)
        assert ident not in seen
        seen.add(ident)
        if prev is not None:
            assert nxt > prev
        prev = nxt
        cursor = nxt


def test_rollback_guard_never_readmits_consumed() -> None:
    consumed = utc(2026, 9, 8, 12, 20, 0)
    assert is_already_consumed(utc(2026, 9, 8, 12, 0, 0), consumed)
    assert is_already_consumed(consumed, consumed)
    assert not is_already_consumed(utc(2026, 9, 8, 12, 30, 0), consumed)


def test_wall_and_monotonic_clocks_split() -> None:
    wall = wall_now_utc()
    assert wall.tzinfo is not None
    assert wall.utcoffset() is not None
    first = monotonic_ns()
    second = monotonic_ns()
    assert second >= first