import astropy.units as u
import numpy as np
import pytest

from gala._cconfig import GSL_ENABLED
from gala.potential.scf import SCFInterpolatedPotential, SCFPotential
from gala.units import galactic

if not GSL_ENABLED:
    pytest.skip("skipping SCF tests: they depend on GSL", allow_module_level=True)


@pytest.mark.parametrize("func_name", ["energy", "density", "gradient"])
def test_simple_compare_noninterp(func_name):
    """
    Compare the interpolated to time-invariant versions for a trivial case
    """
    rng = np.random.default_rng(42)
    nmax = 5
    lmax = 3

    Snlm = rng.uniform(size=(nmax + 1, lmax + 1, lmax + 1))
    Tnlm = np.zeros_like(Snlm)

    tj = np.linspace(0, 1000, 16)
    Sjnlm = np.repeat(Snlm[None], len(tj), axis=0)
    Tjnlm = np.repeat(Tnlm[None], len(tj), axis=0)

    m = 1e9
    r_s = 10.0

    pot_static = SCFPotential(m=m, r_s=r_s, Snlm=Snlm, Tnlm=Tnlm, units=galactic)
    pot_t = SCFInterpolatedPotential(
        m=m,
        r_s=r_s,
        tj=tj,
        Sjnlm=Sjnlm,
        Tjnlm=Tjnlm,
        units=galactic,
        com_xj=np.zeros((3, len(tj))),
        com_vj=np.zeros((3, len(tj))),
    )

    test_xyz = rng.uniform(-10, 10, size=(3, 10))
    test_t = rng.uniform(0, 1000, size=16)
    for t in test_t:
        t_val = getattr(pot_t, func_name)(test_xyz, t=t)
        static_val = getattr(pot_static, func_name)(test_xyz, t=t)
        assert u.allclose(t_val, static_val)
