"""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) == []