import os.path
import numpy as np
from numpy.testing import assert_allclose
import pytest

from optifik.fft import thickness_from_fft
from optifik.analysis import smooth_intensities
from optifik.io import load_spectrum


def test_FFT():
    FOLDER = os.path.join('tests', 'basic')
    FILE_NAME = '003582.xy'
    expected = 3524.51

    spectrum_path = os.path.join(FOLDER, FILE_NAME)
    lambdas, raw_intensities = load_spectrum(spectrum_path, wavelength_min=450)
    smoothed_intensities = smooth_intensities(raw_intensities)
    r_index =  1.324188 + 3102.060378 / (lambdas**2)

    thickness_FFT = thickness_from_fft(lambdas,
                                       smoothed_intensities,
                                       refractive_index=r_index)
    result = thickness_FFT.thickness

    assert_allclose(result, expected, rtol=1e-1)