"""Tests for the regime quadrant classification + hysteresis (anti-flicker)."""

from __future__ import annotations

from app.services.alert_service import _classify_quadrant


# Quadrant ids: 1=① hot&brittle (regime low, warning high), 2=② transition
# (both high), 3=③ healthy (both low), 4=④ real downturn (regime high, warning low).
# Dividers: regime 40, early-warning 60; margin 5.


def test_fresh_classification():
    assert _classify_quadrant(20, 90, None) == "1"   # low regime, high warning
    assert _classify_quadrant(70, 90, None) == "2"   # both high
    assert _classify_quadrant(20, 30, None) == "3"   # both low
    assert _classify_quadrant(70, 30, None) == "4"   # high regime, low warning


def test_hysteresis_holds_inside_deadband():
    # From ③ (both low): early-warning nudging just past 60 stays ③ until it
    # clears 60 + margin (65).
    assert _classify_quadrant(20, 62, prev="3") == "3"   # within deadband → no flip
    assert _classify_quadrant(20, 66, prev="3") == "1"   # clears 65 → flips to ①


def test_hysteresis_sticky_when_already_high():
    # From ① (warning high): a dip below 60 keeps ① until it drops past 60 - margin (55).
    assert _classify_quadrant(20, 58, prev="1") == "1"   # still high (deadband)
    assert _classify_quadrant(20, 54, prev="1") == "3"   # drops past 55 → back to ③


def test_hysteresis_on_regime_axis():
    # From ③: regime rising past 40 stays ③ until it clears 45.
    assert _classify_quadrant(43, 30, prev="3") == "3"
    assert _classify_quadrant(46, 30, prev="3") == "4"
    # From ④: regime easing keeps ④ until below 35.
    assert _classify_quadrant(37, 30, prev="4") == "4"
    assert _classify_quadrant(34, 30, prev="4") == "3"


def test_boundary_sitting_does_not_flip():
    # A point parked exactly on both dividers keeps whatever quadrant it had.
    for q in ("1", "2", "3", "4"):
        assert _classify_quadrant(40, 60, prev=q) == q