"""Scheduler poll loop against real file stores (T08)."""

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.models import StoredRunStatus
from wf_artifacts.runs.store import FileRunStore
from wf_scheduling.calendar import OneShotSource
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

UTC_TZ = UTC


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_TZ)


class PeriodicSource:
    def __init__(self, period: timedelta, start: datetime) -> None:
        self.period = period
        self.start = start
        self.next_calls = 0
        self.prev_calls = 0

    def next_after(self, instant: datetime) -> datetime | None:
        self.next_calls += 1
        if instant < self.start:
            return self.start
        n = (instant - self.start) // self.period + 1
        return self.start + n * self.period

    def prev_before(self, instant: datetime) -> datetime | None:
        self.prev_calls += 1
        if instant <= self.start:
            return None
        n = (instant - self.start - timedelta(microseconds=1)) // self.period
        return self.start + n * self.period


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


def _harness(
    tmp_path: Path,
    *,
    capacity: int = 4,
    script: dict | None = None,
    deployments: dict[str, dict] | None = None,
) -> tuple[Scheduler, FileScheduleStore, FileRunStore, dict]:
    sched_store = FileScheduleStore(tmp_path / "sched")
    run_store = FileRunStore(tmp_path / "runs")
    sources: dict = {}
    preparer = SchedulePreparer(
        DictDeployments(
            deployments
            if deployments is not None
            else {"dep-1": {"rev": 1, "required": []}}
        ),
        fixture_environment,
    )
    sched = Scheduler(
        schedule_store=sched_store,
        run_store=run_store,
        sources=sources,
        capacity=capacity,
        preparer=preparer,
        dispatcher=ScriptedDispatcher(script),
        ownership=SchedulerOwnership(tmp_path / "sched", owner="test").acquire(),
    )
    return sched, sched_store, run_store, sources


def _add(
    sched: Scheduler,
    store: FileScheduleStore,
    sources: dict,
    sid: str,
    src: Any,
    consumed: datetime,
    **kw: Any,
) -> Any:
    model = _sched_model(sid, **kw)
    store.create_schedule(model)
    store.save_consumed(sid, consumed)
    sources[sid] = src
    return store.get_schedule(sid)


def _history(store: FileScheduleStore, sid: str) -> list[dict]:
    page = store.list_occurrences(sid, limit=100)
    return page["occurrences"]  # type: ignore[return-value]


def test_overlap_skip_blocks_and_late_drops() -> None:
    import tempfile

    with tempfile.TemporaryDirectory() as tmp:
        root = Path(tmp)
        sched, store, runs, sources = _harness(root, capacity=4, script={"*": "hang"})
        t0 = ts(2026, 9, 8, 12, 0)
        _add(
            sched,
            store,
            sources,
            "a",
            PeriodicSource(timedelta(minutes=10), t0),
            t0 - timedelta(minutes=10),
        )
        sched.poll(t0)
        assert len(runs.list_runs()) == 1
        sched.poll(t0 + timedelta(minutes=10))
        kinds = [(r["kind"], r["resolved_at"]) for r in _history(store, "a")]
        assert any(k == "skipped-overlap" and "12:10" in str(v) for k, v in kinds)
        sched.poll(t0 + timedelta(minutes=30))
        kinds = [(r["kind"], r["resolved_at"]) for r in _history(store, "a")]
        assert any(k == "skipped-misfire" for k, _ in kinds)
        sched.ownership.release()


def test_latest_coalesces_to_one_candidate_and_no_double_admit() -> None:
    import tempfile

    with tempfile.TemporaryDirectory() as tmp:
        root = Path(tmp)
        sched, store, runs, sources = _harness(root, capacity=0)
        _add(
            sched,
            store,
            sources,
            "h",
            PeriodicSource(timedelta(hours=1), ts(2026, 9, 8, 9, 0)),
            ts(2026, 9, 8, 9, 0),
            misfire="latest",
        )
        sched.poll(ts(2026, 9, 8, 12, 20))
        cand = store.get_candidate("h")
        assert cand is not None and cand.intended_at == ts(2026, 9, 8, 12, 0)
        assert [r for r in _history(store, "h") if r["kind"] == "admitted"] == []
        # Capacity returns at 13:00 while 13:00 is also due: exactly one
        # admission for 13:00, 12:00 superseded, never both.
        sched.capacity = 4
        cast(ScriptedDispatcher, sched.dispatcher).script = {"*": "complete"}
        sched.poll(ts(2026, 9, 8, 13, 0))
        admitted = [r for r in _history(store, "h") if r["kind"] == "admitted"]
        assert len(admitted) == 1
        assert datetime.fromisoformat(admitted[0]["resolved_at"]) == ts(
            2026, 9, 8, 13, 0
        )
        assert store.get_candidate("h") is None
        sched.ownership.release()


def test_parallel_limits_and_interrupted_slots() -> None:
    import tempfile

    with tempfile.TemporaryDirectory() as tmp:
        root = Path(tmp)
        sched, store, runs, sources = _harness(root, capacity=4, script={"*": "hang"})
        t0 = ts(2026, 9, 8, 12, 0)
        _add(
            sched,
            store,
            sources,
            "p",
            PeriodicSource(timedelta(minutes=5), t0),
            t0 - timedelta(minutes=5),
            overlap="parallel",
            max_active_runs=2,
        )
        sched.poll(t0)
        assert sched._task_load() == 1
        first = runs.list_runs()[0]
        runs.save_run(first.model_copy(update={"status": StoredRunStatus.INTERRUPTED}))
        assert sched._task_load() == 0
        sched.poll(t0 + timedelta(minutes=5))
        assert len(runs.list_runs()) == 2
        sched.poll(t0 + timedelta(minutes=10))
        assert any(r["kind"] == "skipped-overlap" for r in _history(store, "p"))
        # Lowering the limit never cancels; blocks new admission instead.
        sched_model = store.get_schedule("p")
        sched_model.max_active_runs = 1
        store.save_schedule(sched_model)
        second = [r for r in runs.list_runs() if r.id != first.id][0]
        runs.save_run(second.model_copy(update={"status": StoredRunStatus.INTERRUPTED}))
        sched.poll(t0 + timedelta(minutes=15))
        assert any(
            r["kind"] == "skipped-overlap" and "12:15" in str(r["resolved_at"])
            for r in _history(store, "p")
        )
        sched.ownership.release()


def test_pause_is_not_downtime() -> None:
    import tempfile

    with tempfile.TemporaryDirectory() as tmp:
        root = Path(tmp)
        sched, store, runs, sources = _harness(
            root, capacity=4, script={"*": "complete"}
        )
        _add(
            sched,
            store,
            sources,
            "a",
            PeriodicSource(timedelta(hours=1), ts(2026, 9, 8, 9, 0)),
            ts(2026, 9, 8, 9, 0),
            misfire="latest",
        )
        sched.poll(ts(2026, 9, 8, 9, 0))
        model = store.get_schedule("a")
        model.paused = True
        store.save_schedule(model)
        sched.poll(ts(2026, 9, 8, 10, 30))
        assert store.get_candidate("a") is None
        sched.resume_schedule("a", ts(2026, 9, 8, 12, 30))
        sched.poll(ts(2026, 9, 8, 12, 30))
        admitted = [
            r["resolved_at"] for r in _history(store, "a") if r["kind"] == "admitted"
        ]
        assert "2026-09-08T10:00:00+00:00" not in admitted
        assert "2026-09-08T11:00:00+00:00" not in admitted
        sched.ownership.release()


def test_long_downtime_is_bounded(tmp_path: Path) -> None:
    sched, store, runs, sources = _harness(
        tmp_path, capacity=4, script={"*": "complete"}
    )
    src = PeriodicSource(timedelta(minutes=1), ts(2023, 9, 8, 12, 0))
    _add(sched, store, sources, "m", src, ts(2023, 9, 8, 12, 0), misfire="latest")
    sched.poll(ts(2026, 9, 8, 12, 0, 0))
    assert src.next_calls + src.prev_calls <= SCAN_CAP + 2
    admitted = [r for r in _history(store, "m") if r["kind"] == "admitted"]
    assert len(admitted) == 1
    assert datetime.fromisoformat(admitted[0]["resolved_at"]) == ts(2026, 9, 8, 11, 59)
    assert (
        len([r for r in _history(store, "m") if r["kind"] == "interval-summary"]) == 1
    )
    sched.ownership.release()


def test_fairness_slow_schedule_not_starved(tmp_path: Path) -> None:
    sched, store, runs, sources = _harness(tmp_path, capacity=1, script={"*": "hang"})
    t0 = ts(2026, 9, 8, 12, 0)
    _add(
        sched,
        store,
        sources,
        "fast",
        PeriodicSource(timedelta(minutes=1), t0),
        t0 - timedelta(minutes=1),
    )
    _add(sched, store, sources, "slow", OneShotSource(t0), t0 - timedelta(hours=1))
    sched.poll(t0)
    assert any(
        r["kind"] == "admitted" and r["schedule_id"] == "fast"
        for r in _history(store, "fast")
    )
    for run in runs.list_runs():
        runs.save_run(run.model_copy(update={"status": StoredRunStatus.COMPLETED}))
    sched.poll(t0 + timedelta(seconds=30))
    assert any(r["kind"] == "admitted" for r in _history(store, "slow"))
    sched.ownership.release()


def test_capacity_wait_then_expire_for_skip(tmp_path: Path) -> None:
    sched, store, runs, sources = _harness(tmp_path, capacity=0)
    t0 = ts(2026, 9, 8, 12, 0)
    _add(sched, store, sources, "a", OneShotSource(t0), t0 - timedelta(hours=1))
    assert sched.poll(t0) == {"a": "admit:held-undecided"}
    assert store.get_candidate("a") is None
    sched.capacity = 1
    cast(ScriptedDispatcher, sched.dispatcher).script = {"*": "complete"}
    sched.poll(t0 + timedelta(seconds=30))
    assert len([r for r in _history(store, "a") if r["kind"] == "admitted"]) == 1
    sched.ownership.release()