from pathlib import Path

import numpy as np

from femsurrogate.fea.benchmark import cantilever_tip_displacement
from femsurrogate.fea.io import read_beam_example, read_expected_displacements
from femsurrogate.fea.solver import solve_linear_static

ROOT = Path(__file__).resolve().parents[1]
INPUT_PATH = ROOT / "BeamExamples" / "CantileverBeam.txt"
EXPECTED_PATH = ROOT / "BeamExamples" / "CantileverBeam_Displacements.txt"


def test_solver_matches_cantilever_fixture_displacements():
    model = read_beam_example(INPUT_PATH)
    actual = solve_linear_static(model)
    expected = read_expected_displacements(EXPECTED_PATH)

    assert set(actual) == set(expected)
    for node_id, expected_displacement in expected.items():
        actual_displacement = actual[node_id]
        np.testing.assert_allclose(
            [actual_displacement.ux, actual_displacement.uy, actual_displacement.rz],
            [expected_displacement.ux, expected_displacement.uy, expected_displacement.rz],
            atol=5e-7,
            rtol=1e-6,
        )


def test_tip_displacement_matches_analytical_cantilever_magnitude():
    model = read_beam_example(INPUT_PATH)
    actual_tip_uy = solve_linear_static(model)[6].uy
    node_x = [node.x for node in model.nodes.values()]
    length = max(node_x) - min(node_x)
    analytical_tip_uy = cantilever_tip_displacement(
        force_y=model.nodal_loads[6].fy,
        length=length,
        E=model.metadata["ElasticModulus"],
        Izz=model.metadata["Izz"],
    )

    np.testing.assert_allclose(abs(actual_tip_uy), abs(analytical_tip_uy), rtol=1e-9, atol=0.0)