"""Pure-function tests for the host_agent seconds_since_seen reconciler."""
from dataclasses import dataclass
from datetime import datetime, timedelta, timezone

from plugins.host_agent.scheduler import seconds_since_seen


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


NOW = datetime(2026, 4, 15, 12, 0, 0, tzinfo=timezone.utc)
NAMES = {"h1": "nas", "h2": "web", "h3": "db"}


def test_seconds_since_each_agent_last_reported():
    regs = [FakeReg("h1", NOW - timedelta(seconds=30), NOW - timedelta(days=9)),
            FakeReg("h2", NOW - timedelta(minutes=10), NOW - timedelta(days=9))]
    assert seconds_since_seen(regs, NAMES, NOW) == [("nas", 30.0), ("web", 600.0)]


def test_an_agent_that_never_reported_counts_from_registration():
    regs = [FakeReg("h3", None, NOW - timedelta(minutes=5))]
    assert seconds_since_seen(regs, NAMES, NOW) == [("db", 300.0)]


def test_a_registration_without_its_host_is_skipped():
    regs = [FakeReg("gone", NOW, NOW)]
    assert seconds_since_seen(regs, NAMES, NOW) == []


def test_a_clock_ahead_of_ours_reads_as_just_seen():
    regs = [FakeReg("h1", NOW + timedelta(seconds=5), NOW)]
    assert seconds_since_seen(regs, NAMES, NOW) == [("nas", 0.0)]


def test_empty_input():
    assert seconds_since_seen([], NAMES, NOW) == []


def test_steward_s_own_outage_is_not_the_agent_s_silence():
    """#5441: agents that last reported 10 minutes ago, while Steward has only
    been back for a minute, are a minute old; an agent heard since then keeps
    its own age."""
    back = NOW - timedelta(minutes=1)
    regs = [FakeReg("h1", NOW - timedelta(minutes=10), NOW - timedelta(days=9)),
            FakeReg("h2", NOW - timedelta(seconds=20), NOW - timedelta(days=9)),
            FakeReg("h3", None, NOW - timedelta(days=9))]
    assert seconds_since_seen(regs, NAMES, NOW, back) == [("nas", 60.0), ("web", 20.0), ("db", 60.0)]


def test_a_post_that_arrived_but_was_not_stored_counts_as_seen():
    """#5514: Steward's storage stalled and dropped the agents' posts, so
    last_seen_at (written with them) stayed old, and agents posting every few
    seconds read as offline. Arriving is the agent's part; the later of the
    two counts. An agent with no arrival keeps its stored age."""
    regs = [FakeReg("h1", NOW - timedelta(minutes=4), NOW - timedelta(days=9)),
            FakeReg("h2", NOW - timedelta(minutes=4), NOW - timedelta(days=9)),
            FakeReg("h3", NOW - timedelta(seconds=10), NOW - timedelta(days=9))]
    arrived = {"h1": NOW - timedelta(seconds=5), "h3": NOW - timedelta(minutes=2)}
    assert seconds_since_seen(regs, NAMES, NOW, arrived=arrived) == [
        ("nas", 5.0), ("web", 240.0), ("db", 10.0)]


def test_arrivals_are_kept_per_app():
    from types import SimpleNamespace
    from plugins.host_agent.scheduler import arrivals
    app, other = SimpleNamespace(), SimpleNamespace()
    arrivals(app)["h1"] = NOW
    assert arrivals(app) == {"h1": NOW} and arrivals(other) == {}


def test_an_agent_already_offline_stays_offline_through_a_restart():
    """#5719: VDNT-Docker03's agent was silent for hours when Steward
    restarted, and counting it from the restart read it as just seen: its
    alert resolved, then fired again three minutes later, two emails a
    restart. An agent already past the offline window keeps its whole
    silence; one that was fine when Steward stopped still counts from the
    restart (#5441)."""
    back = NOW - timedelta(minutes=1)
    regs = [FakeReg("h1", NOW - timedelta(hours=5), NOW - timedelta(days=9)),
            FakeReg("h2", NOW - timedelta(minutes=10), NOW - timedelta(days=9))]
    assert seconds_since_seen(regs, NAMES, NOW, back, already_silent={"nas"}) == [
        ("nas", 5 * 3600.0), ("web", 60.0)]


def test_an_offline_agent_that_reports_after_the_restart_is_back():
    back = NOW - timedelta(minutes=1)
    regs = [FakeReg("h1", NOW - timedelta(seconds=15), NOW - timedelta(days=9))]
    assert seconds_since_seen(regs, NAMES, NOW, back, already_silent={"nas"}) == [("nas", 15.0)]