"""Pure-function tests for host_agent staleness filter."""
from dataclasses import dataclass
from datetime import datetime, timedelta, timezone

from plugins.host_agent.scheduler import _filter_stale


@dataclass
class FakeReg:
    host_id: str
    last_seen_at: datetime | None


NOW = datetime(2026, 4, 15, 12, 0, 0, tzinfo=timezone.utc)


def test_filter_stale_returns_only_old_rows():
    regs = [
        FakeReg("fresh", NOW - timedelta(seconds=30)),
        FakeReg("stale", NOW - timedelta(seconds=600)),
        FakeReg("never", None),
    ]
    stale = _filter_stale(regs, now=NOW, stale_after_seconds=180)
    ids = {r.host_id for r in stale}
    assert ids == {"stale"}


def test_filter_stale_empty_input():
    assert _filter_stale([], now=NOW, stale_after_seconds=180) == []


def test_filter_stale_all_fresh():
    regs = [
        FakeReg("a", NOW - timedelta(seconds=10)),
        FakeReg("b", NOW - timedelta(seconds=30)),
    ]
    assert _filter_stale(regs, now=NOW, stale_after_seconds=60) == []


def test_filter_stale_boundary_exact_cutoff_is_not_stale():
    # A row exactly at the cutoff should not be flagged (strict less-than).
    regs = [FakeReg("edge", NOW - timedelta(seconds=180))]
    assert _filter_stale(regs, now=NOW, stale_after_seconds=180) == []


def test_filter_stale_skips_none_last_seen():
    regs = [FakeReg("never", None)]
    assert _filter_stale(regs, now=NOW, stale_after_seconds=1) == []