# -*- coding: utf-8 -*-
"""Unit tests: SAX transformation primitives."""
import numpy as np
import pytest

from src.sax import transform as sx


def test_znorm_zero_std():
    a = sx.z_normalize([5.0, 5.0, 5.0])
    assert np.allclose(a, 0.0)


def test_znorm_standard():
    a = sx.z_normalize([1.0, 2.0, 3.0, 4.0])
    assert abs(np.mean(a)) < 1e-9
    assert abs(np.std(a) - 1.0) < 1e-9


def test_paa_reduces_length():
    res = sx.to_paa(np.arange(10, dtype=float), 4)
    assert res.shape[0] == 4


def test_paa_preserves_mean():
    xs = np.linspace(0, 9, 10)
    assert abs(np.mean(sx.to_paa(xs, 2)) - np.mean(xs)) < 1e-9


def test_sax_encode_length_and_alphabet():
    word = sx.sax_encode(np.random.default_rng(0).uniform(-1, 1, 24), 8, 5)
    assert len(word) == 8
    assert all(ch in "abcde" for ch in word)


def test_sax_alphabet_error():
    with pytest.raises(ValueError):
        sx.sax_encode(np.arange(24, dtype=float), 8, 2)  # 2 not supported


def test_mindist_same_word_zero():
    w = "baccd"
    assert sx.mindist_mid(w, w, 5) == 0.0


def test_mindist_symmetric():
    a, b = "aabbc", "ccbbd"
    assert sx.mindist_mid(a, b, 5) == sx.mindist_mid(b, a, 5)


def test_mindist_monotonic_symbol_distance():
    d1 = sx.mindist_mid("a", "b", 5)
    d2 = sx.mindist_mid("a", "e", 5)
    assert d2 > d1