"""Unit test della normalizzazione quaternion server-side."""
from __future__ import annotations

import math
import numpy as np
import pytest

from presa_mano.geometry import normalize_quaternion


def test_already_normalized_is_unchanged():
    q = [0.0, 0.0, 0.0, 1.0]
    out = normalize_quaternion(q)
    assert np.allclose(out, q)


def test_not_normalized_gets_normalized_to_unit_length():
    # scala 2.0
    q = [0.0, 0.0, 0.0, 2.0]
    out = normalize_quaternion(q)
    norm = math.sqrt(sum(x*x for x in out))
    assert abs(norm - 1.0) < 1e-9


def test_degenerate_zero_quat_raises():
    with pytest.raises(ValueError, match="degenerate"):
        normalize_quaternion([0.0, 0.0, 0.0, 0.0])


def test_near_zero_quat_raises():
    with pytest.raises(ValueError, match="degenerate"):
        normalize_quaternion([1e-9, 0.0, 0.0, 1e-9])