import pytest
from ase.spacegroup import crystal
from ase.data import atomic_numbers, atomic_masses
from ase.optimize import QuasiNewton
from ase.constraints import UnitCellFilter
from numpy.testing import assert_allclose


@pytest.mark.calculator_lite
@pytest.mark.calculator('lammpsrun')
def test_NaCl_minimize(factory):
    a = 6.15
    n = 4
    nacl = crystal(['Na', 'Cl'], [(0, 0, 0), (0.5, 0.5, 0.5)], spacegroup=225,
                   cellpar=[a, a, a, 90, 90, 90]).repeat((n, n, n))

    # Buckingham parameters from
    # https://physics.stackexchange.com/questions/250018

    pair_style = 'buck/coul/long 12.0'
    pair_coeff = ['1 1 3796.9 0.2603 124.90']
    pair_coeff += ['2 2 1227.2 0.3214 124.90']
    pair_coeff += ['1 2 4117.9 0.3048 0.0']
    masses = ['1 {}'.format(atomic_masses[atomic_numbers['Na']]),
              '2 {}'.format(atomic_masses[atomic_numbers['Cl']])]

    with factory.calc(
            specorder=['Na', 'Cl'],
            pair_style=pair_style,
            pair_coeff=pair_coeff,
            masses=masses,
            atom_style='charge',
            kspace_style='pppm 1.0e-5',
            keep_tmp_files=True,
    ) as calc:

        for a in nacl:
            if a.symbol == 'Na':
                a.charge = +1.
            else:
                a.charge = -1.

        nacl.calc = calc

        assert_allclose(nacl.get_potential_energy(), -1896.216737561538,
                        atol=1e-4, rtol=1e-4)

        nacl.get_potential_energy()

        ucf = UnitCellFilter(nacl)
        with QuasiNewton(ucf, force_consistent=False) as dyn:
            dyn.run(fmax=1.0E-2)

        assert_allclose(nacl.get_potential_energy(), -1897.208861729178,
                        atol=1e-4, rtol=1e-4)
