# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
Tests for the fourier module.
"""

from astropy.modeling.fitting import LevMarLSQFitter
from astropy.modeling.models import Gaussian2D
import numpy as np
from numpy.testing import assert_allclose
import pytest

from ..fourier import create_matching_kernel, resize_psf
from ..windows import SplitCosineBellWindow

try:
    import scipy  # noqa
    HAS_SCIPY = True
except ImportError:
    HAS_SCIPY = False


@pytest.mark.skipif('not HAS_SCIPY')
def test_resize_psf():
    psf1 = np.ones((5, 5))
    psf2 = resize_psf(psf1, 0.1, 0.05)
    assert psf2.shape == (10, 10)


@pytest.mark.skipif('not HAS_SCIPY')
def test_create_matching_kernel():
    """Test with noiseless 2D Gaussians."""

    size = 25
    cen = (size - 1) / 2.
    y, x = np.mgrid[0:size, 0:size]
    std1 = 3.
    std2 = 5.
    gm1 = Gaussian2D(1., cen, cen, std1, std1)
    gm2 = Gaussian2D(1., cen, cen, std2, std2)
    g1 = gm1(x, y)
    g2 = gm2(x, y)
    g1 /= g1.sum()
    g2 /= g2.sum()

    window = SplitCosineBellWindow(0.0, 0.2)
    k = create_matching_kernel(g1, g2, window=window)

    fitter = LevMarLSQFitter()
    gfit = fitter(gm1, x, y, k)
    assert_allclose(gfit.x_stddev, gfit.y_stddev)
    assert_allclose(gfit.x_stddev, np.sqrt(std2**2 - std1**2), 0.06)


def test_create_matching_kernel_shapes():
    """Test with wrong PSF shapes."""
    with pytest.raises(ValueError):
        psf1 = np.ones((5, 5))
        psf2 = np.ones((3, 3))
        create_matching_kernel(psf1, psf2)
