"""Unit-Tests Adaptive Quality (PLAN.md §5.2)."""

from __future__ import annotations

from hms_adaptive import AdaptiveQualityController, QualityLevel


def _fast_controller() -> AdaptiveQualityController:
    """Regler ohne echte Wartezeiten für deterministische Tests."""
    return AdaptiveQualityController(min_hold_ms=0, downgrade_intervals=2, upgrade_intervals=6)


def test_starts_at_high() -> None:
    assert _fast_controller().level is QualityLevel.HIGH


def test_single_bad_interval_does_not_downgrade() -> None:
    c = _fast_controller()
    assert c.step(30.0) is QualityLevel.HIGH  # 1 schlechtes Intervall genügt nicht


def test_downgrades_one_level_per_interval_not_more() -> None:
    c = _fast_controller()
    c.step(30.0)
    c.step(30.0)
    assert c.level is QualityLevel.MEDIUM  # genau eine Stufe (Hysterese, §5.2)
    c.step(30.0)
    c.step(30.0)
    assert c.level is QualityLevel.LOW
    assert c.step(30.0) is QualityLevel.LOW  # Untergrenze


def test_upgrade_needs_sustained_reserve() -> None:
    c = _fast_controller()
    for _ in range(4):
        c.step(30.0)
    assert c.level is QualityLevel.LOW
    for _ in range(5):  # 5 gute Intervalle genügen nicht (Upgrade träger)
        c.step(1.0)
    assert c.level is QualityLevel.LOW
    c.step(1.0)  # 6. gutes Intervall → eine Stufe hoch
    assert c.level is QualityLevel.MEDIUM


def test_upgrade_slower_than_downgrade() -> None:
    c = _fast_controller()
    assert c.downgrade_intervals < c.upgrade_intervals


def test_no_pumping_on_alternating_load() -> None:
    c = _fast_controller()
    levels = []
    for _ in range(60):
        levels.append(c.step(30.0))  # Dauerlast → LOW
    assert c.level is QualityLevel.LOW
    for _ in range(3):
        c.step(1.0)  # kurze Erholung darf kein Pumpen erzeugen
        c.step(30.0)
    assert c.level is QualityLevel.LOW  # keine Aufwertung bei alternierender Last


def test_reason_is_recorded() -> None:
    c = _fast_controller()
    c.step(30.0)
    c.step(30.0)
    assert "p99" in c.last_reason and "budget" in c.last_reason


def test_default_min_hold_prevents_rapid_changes(monkeypatch) -> None:

    c = AdaptiveQualityController()  # min_hold_ms=2000 (Produktionswert)
    c.step(30.0)
    c.step(30.0)
    assert c.level is QualityLevel.HIGH  # Mindesthaltezeit noch nicht vergangen