import math
import pytest
from pygui.backend.frame_stats import compute_stats, Stats


def test_basic_stat():
    s = compute_stats([148.0, 150.0, 149.0])
    assert s.min == 148.0 and s.min_index == 0
    assert s.max == 150.0 and s.max_index == 1
    assert s.diff == pytest.approx(2.0)
    assert s.avg == pytest.approx(149.0)
    assert s.sigma == pytest.approx(math.sqrt(2 / 3))
    assert s.three_sigma == pytest.approx(3 * math.sqrt(2 / 3))


def test_empty_values_returns_zeros():
    s = compute_stats([])
    assert s == Stats(0.0, -1, 0.0, -1, 0.0, 0.0, 0.0, 0.0)


def test_ignores_nan():
    s = compute_stats([149.0, float("nan"), 151.0])