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

from plasmapy.plasma.sources import plasma3d


@pytest.mark.parametrize(
    ("grid_dimensions", "expected_size"),
    [
        pytest.param((100, 1, 1), 100, marks=pytest.mark.slow),  # Test 1D setup
        pytest.param((128, 128, 1), 16384, marks=pytest.mark.slow),  # 2D
        pytest.param((64, 64, 64), 262144, marks=pytest.mark.slow),  # 3D
    ],
)
def test_Plasma3D_setup(grid_dimensions, expected_size):
    r"""Function to test basic setup of the Plasma3D object.

    Tests that a Plasma3D object initiated with a particular
    specification behaves in the correct way.

    Parameters
    ----------
    grid_dimensions : tuple of ints
        Grid size of the Plasma3D object to test. Must be a tuple of
        length 3, indicating length of the grid in x, y, and z
        directions respectively. Directions not needed should have a
        length of 1.

    expected_size : int
        Product of grid dimensions.
    """
    x, y, z = grid_dimensions
    test_plasma = plasma3d.Plasma3D(
        domain_x=np.linspace(0, 1, x) * u.m,
        domain_y=np.linspace(0, 1, y) * u.m,
        domain_z=np.linspace(0, 1, z) * u.m,
    )

    # Basic grid setup
    assert test_plasma.x.size == x
    assert test_plasma.y.size == y
    assert test_plasma.z.size == z
    assert test_plasma.grid.size == 3 * expected_size

    # Core variable units and shapes
    assert test_plasma.density.size == expected_size
    assert test_plasma.density.si.unit == u.kg / u.m**3

    assert test_plasma.momentum.size == 3 * expected_size
    assert test_plasma.momentum.si.unit == u.kg / (u.m**2 * u.s)

    assert test_plasma.pressure.size == expected_size
    assert test_plasma.pressure.si.unit == u.Pa

    assert test_plasma.magnetic_field.size == 3 * expected_size
    assert test_plasma.magnetic_field.si.unit == u.T

    assert test_plasma.electric_field.size == 3 * expected_size
    assert test_plasma.electric_field.si.unit == u.V / u.m


@pytest.mark.slow()
def test_Plasma3D_derived_vars():
    r"""Function to test derived variables of the Plasma3D class.

    Tests the shapes, units and values of variables derived from core
    variables.  The core variables are set with arbitrary uniform
    values.
    """
    test_plasma = plasma3d.Plasma3D(
        domain_x=np.linspace(0, 1, 64) * u.m,
        domain_y=np.linspace(0, 1, 64) * u.m,
        domain_z=np.linspace(0, 1, 1) * u.m,
    )

    # Set an arbitrary uniform values throughout the plasma
    test_plasma.density[...] = 2.0 * u.kg / u.m**3
    test_plasma.momentum[...] = 10.0 * u.kg / (u.m**2 * u.s)
    test_plasma.pressure[...] = 1 * u.Pa
    test_plasma.magnetic_field[...] = 0.01 * u.T
    test_plasma.electric_field[...] = 0.01 * u.V / u.m

    # Test derived variable units and shapes
    assert test_plasma.velocity.shape == test_plasma.momentum.shape
    assert (test_plasma.velocity == 5.0 * u.m / u.s).all()

    assert (
        test_plasma.magnetic_field_strength.shape
        == test_plasma.magnetic_field.shape[1:]
    )
    assert test_plasma.magnetic_field_strength.si.unit == u.T
    assert np.allclose(test_plasma.magnetic_field_strength.value, 0.017320508)

    assert (
        test_plasma.electric_field_strength.shape
        == test_plasma.electric_field.shape[1:]
    )
    assert test_plasma.electric_field_strength.si.unit == u.V / u.m

    assert test_plasma.alfven_speed.shape == test_plasma.density.shape
    assert test_plasma.alfven_speed.unit.si == u.m / u.s
    assert np.allclose(test_plasma.alfven_speed.value, 10.92548431)
