"""Tests para acf_pacf."""

import numpy as np

from acf_pacf import acf_pacf


def _ar1(phi: float, n: int, seed: int) -> list:
    rng = np.random.default_rng(seed)
    series = [0.0]
    for _ in range(n):
        series.append(phi * series[-1] + rng.normal(0, 1))
    return series


def test_ruido_blanco_no_autocorrelado():
    rng = np.random.default_rng(0)
    ruido = rng.normal(0, 1, 500).tolist()
    res = acf_pacf(ruido)
    assert res["is_autocorrelated"] is False


def test_ar1_es_autocorrelado():
    ar = _ar1(0.8, 500, seed=1)
    res = acf_pacf(ar)
    assert res["is_autocorrelated"] is True


def test_lag1_significativo_en_ar1():
    # En un AR(1) la PACF corta tras el lag 1: lag 1 debe ser significativo.
    ar = _ar1(0.8, 500, seed=2)
    res = acf_pacf(ar)
    assert 1 in res["significant_pacf_lags"]
    assert 1 in res["significant_acf_lags"]


def test_muestra_insuficiente_devuelve_nota():
    res = acf_pacf([1, 2, 3, 4, 5])
    assert res["n"] == 5
    assert res["note"] == "datos insuficientes"
    assert res["is_autocorrelated"] is None


def test_descarta_none_y_nan():
    rng = np.random.default_rng(3)
    base = rng.normal(0, 1, 200).tolist()
    sucio = []
    for i, v in enumerate(base):
        sucio.append(v)
        if i % 25 == 0:
            sucio.append(None)
            sucio.append(float("nan"))
    res = acf_pacf(sucio)
    assert res["n"] == 200


def test_recorta_nlags_a_limites():
    # Serie de 20 puntos con nlags=40: debe recortar a < n/2.
    rng = np.random.default_rng(4)
    serie = rng.normal(0, 1, 20).tolist()
    res = acf_pacf(serie, nlags=40)
    assert res["nlags"] < 20 // 2
    assert len(res["acf"]) == res["nlags"] + 1


def test_acf_lag0_es_uno():
    rng = np.random.default_rng(5)
    serie = rng.normal(0, 1, 100).tolist()
    res = acf_pacf(serie)
    assert abs(res["acf"][0] - 1.0) < 1e-9
    assert abs(res["pacf"][0] - 1.0) < 1e-9