"""Exact-boundary latest catch-up admits one occurrence, not two (R4/F3).

The scan-cap/latest branch used exclusive ``prev_before(now)`` for an
inclusive latest-due query and let admission move the consumed watermark
backwards, so a poll exactly at a due instant admitted the previous tick
and the next poll admitted the due tick. The fix selects the latest
eligible occurrence <= now (one bounded forward probe reusing the adapter)
and never moves the consumed watermark backwards.
"""

from __future__ import annotations

from datetime import UTC, datetime, timedelta
from pathlib import Path
from typing import Any, cast

from tests.scheduling.controlled import (
    DictDeployments,
    ScriptedDispatcher,
    fixture_environment,
)
from wf_artifacts.runs.store import FileRunStore
from wf_scheduling.calendar import CronSource
from wf_scheduling.models import Schedule
from wf_scheduling.ownership import SchedulerOwnership
from wf_scheduling.poll import SCAN_CAP, Scheduler
from wf_scheduling.prepare import SchedulePreparer
from wf_scheduling.store import FileScheduleStore


def ts(y: int, mo: int, d: int, h: int = 0, mi: int = 0, s: int = 0) -> datetime:
    return datetime(y, mo, d, h, mi, s, tzinfo=UTC)


class CountingCron:
    """CronSource wrapper counting bounded-lookup calls."""

    def __init__(self, expression: str, zone: str) -> None:
        self._source = CronSource(expression, zone)
        self.next_calls = 0
        self.prev_calls = 0

    def next_after(self, instant: datetime) -> datetime | None:
        self.next_calls += 1
        return self._source.next_after(instant)

    def prev_before(self, instant: datetime) -> datetime | None:
        self.prev_calls += 1
        return self._source.prev_before(instant)


def _sched_model(sid: str, **kw: Any) -> Schedule:
    now = ts(2026, 9, 8, 12, 0)
    base: dict[str, Any] = {
        "id": sid,
        "deployment_id": "dep-1",
        "trigger": {"kind": "cron", "expression": "* * * * *", "timezone": "UTC"},
        "input_bindings": [],
        "created_at": now.isoformat(),
        "updated_at": now.isoformat(),
    }
    base.update(kw)
    return Schedule.model_validate(base)


def _harness(
    root: Path,
    ownership: SchedulerOwnership,
    *,
    capacity: int = 4,
    script: dict | None = None,
) -> tuple[Scheduler, FileScheduleStore, FileRunStore, dict]:
    sched_store = FileScheduleStore(root / "sched")
    run_store = FileRunStore(root / "runs")
    sources: dict = {}
    sched = Scheduler(
        schedule_store=sched_store,
        run_store=run_store,
        sources=sources,
        capacity=capacity,
        preparer=SchedulePreparer(
            DictDeployments({"dep-1": {"rev": 1, "required": []}}),
            fixture_environment,
        ),
        dispatcher=ScriptedDispatcher(script),
        ownership=ownership,
    )
    return sched, sched_store, run_store, sources


def _admitted(store: FileScheduleStore, sid: str) -> list[dict[str, Any]]:
    page = store.list_occurrences(sid, limit=100)
    return [
        r
        for r in cast(list[dict[str, Any]], page["occurrences"])
        if r["kind"] == "admitted"
    ]


def test_exact_boundary_admits_latest_once(tmp_path: Path) -> None:
    ownership = SchedulerOwnership(tmp_path / "sched", owner="test").acquire()
    try:
        sched, store, runs, sources = _harness(
            tmp_path, ownership, script={"*": "hang"}
        )
        now = ts(2026, 9, 8, 12, 0)
        store.create_schedule(
            _sched_model("m", misfire="latest", overlap="parallel", max_active_runs=4)
        )
        store.save_consumed("m", now - timedelta(days=3))
        sources["m"] = CronSource("* * * * *", "UTC")
        sched.poll(now)
        assert len(runs.list_runs()) == 1
        admitted = _admitted(store, "m")
        assert len(admitted) == 1
        assert datetime.fromisoformat(admitted[0]["resolved_at"]) == now
        assert store.get_consumed("m") == now
    finally:
        ownership.release()


def test_second_poll_at_same_instant_admits_nothing(tmp_path: Path) -> None:
    ownership = SchedulerOwnership(tmp_path / "sched", owner="test").acquire()
    try:
        sched, store, runs, sources = _harness(
            tmp_path, ownership, script={"*": "hang"}
        )
        now = ts(2026, 9, 8, 12, 0)
        store.create_schedule(
            _sched_model("m", misfire="latest", overlap="parallel", max_active_runs=4)
        )
        store.save_consumed("m", now - timedelta(days=3))
        sources["m"] = CronSource("* * * * *", "UTC")
        sched.poll(now)
        sched.poll(now)
        assert len(runs.list_runs()) == 1
        assert len(_admitted(store, "m")) == 1
    finally:
        ownership.release()


def test_between_ticks_admits_latest(tmp_path: Path) -> None:
    ownership = SchedulerOwnership(tmp_path / "sched", owner="test").acquire()
    try:
        sched, store, runs, sources = _harness(
            tmp_path, ownership, script={"*": "hang"}
        )
        now = ts(2026, 9, 8, 12, 0, 30)
        store.create_schedule(
            _sched_model("m", misfire="latest", overlap="parallel", max_active_runs=4)
        )
        store.save_consumed("m", now - timedelta(days=3))
        sources["m"] = CronSource("* * * * *", "UTC")
        sched.poll(now)
        admitted = _admitted(store, "m")
        assert len(admitted) == 1
        assert datetime.fromisoformat(admitted[0]["resolved_at"]) == ts(
            2026, 9, 8, 12, 0
        )
    finally:
        ownership.release()


def test_restart_after_catchup_admits_nothing(tmp_path: Path) -> None:
    now = ts(2026, 9, 8, 12, 0)
    ownership = SchedulerOwnership(tmp_path / "sched", owner="test").acquire()
    try:
        sched, store, _, sources = _harness(tmp_path, ownership, script={"*": "hang"})
        store.create_schedule(
            _sched_model("m", misfire="latest", overlap="parallel", max_active_runs=4)
        )
        store.save_consumed("m", now - timedelta(days=3))
        sources["m"] = CronSource("* * * * *", "UTC")
        sched.poll(now)
    finally:
        ownership.release()
    ownership2 = SchedulerOwnership(tmp_path / "sched", owner="test2").acquire()
    try:
        sched2, store2, runs2, sources2 = _harness(
            tmp_path, ownership2, script={"*": "hang"}
        )
        sources2["m"] = CronSource("* * * * *", "UTC")
        sched2.poll(now)
        assert len(runs2.list_runs()) == 1
        assert len(_admitted(store2, "m")) == 1
    finally:
        ownership2.release()


def test_long_catchup_stays_bounded(tmp_path: Path) -> None:
    ownership = SchedulerOwnership(tmp_path / "sched", owner="test").acquire()
    try:
        sched, store, runs, sources = _harness(
            tmp_path, ownership, script={"*": "complete"}
        )
        now = ts(2026, 9, 8, 12, 0)
        store.create_schedule(_sched_model("m", misfire="latest"))
        store.save_consumed("m", now - timedelta(days=3))
        src = CountingCron("* * * * *", "UTC")
        sources["m"] = src
        sched.poll(now)
        assert src.next_calls + src.prev_calls <= SCAN_CAP + 2
        assert len(_admitted(store, "m")) == 1
    finally:
        ownership.release()


def test_skip_policy_exact_boundary_spans_without_admission(
    tmp_path: Path,
) -> None:
    ownership = SchedulerOwnership(tmp_path / "sched", owner="test").acquire()
    try:
        sched, store, runs, sources = _harness(
            tmp_path, ownership, script={"*": "hang"}
        )
        now = ts(2026, 9, 8, 12, 0)
        store.create_schedule(_sched_model("s", misfire="skip"))
        store.save_consumed("s", now - timedelta(days=3))
        sources["s"] = CronSource("* * * * *", "UTC")
        sched.poll(now)
        assert runs.list_runs() == []
        assert _admitted(store, "s") == []
        assert store.get_consumed("s") == now
        sched.poll(now)
        assert runs.list_runs() == []
        assert _admitted(store, "s") == []
    finally:
        ownership.release()


def test_overlap_skip_exact_boundary_skips_once(tmp_path: Path) -> None:
    ownership = SchedulerOwnership(tmp_path / "sched", owner="test").acquire()
    try:
        sched, store, runs, sources = _harness(
            tmp_path, ownership, script={"*": "hang"}
        )
        now = ts(2026, 9, 8, 12, 0)
        store.create_schedule(_sched_model("o", misfire="latest", overlap="skip"))
        store.save_consumed("o", now - timedelta(minutes=1))
        sources["o"] = CronSource("* * * * *", "UTC")
        # Poll exactly at the due instant: timely admission of 12:00.
        sched.poll(now)
        assert len(runs.list_runs()) == 1
        # Exactly at the next due instant with the first run still active:
        # one terminal skip, no candidate resurrection afterwards.
        sched.poll(now + timedelta(minutes=1))
        page = store.list_occurrences("o", limit=100)
        kinds = [r["kind"] for r in cast(list[dict[str, Any]], page["occurrences"])]
        assert kinds.count("skipped-overlap") == 1
        assert store.get_candidate("o") is None
        sched.poll(now + timedelta(minutes=1))
        page = store.list_occurrences("o", limit=100)
        kinds = [r["kind"] for r in cast(list[dict[str, Any]], page["occurrences"])]
        assert kinds.count("skipped-overlap") == 1
    finally:
        ownership.release()