from pathlib import Path
import importlib.util
import math

import pytest


HERE = Path(__file__).resolve().parent

spec = importlib.util.spec_from_file_location("concrete_beam_calc", HERE / "calc.py")
assert spec is not None and spec.loader is not None
calc_module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(calc_module)
compute = calc_module.compute


def _load(name: str, filename: str):
    spec = importlib.util.spec_from_file_location(name, HERE / filename)
    assert spec is not None and spec.loader is not None
    module = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(module)
    return module


@pytest.fixture
def result():
    import yaml

    with (HERE / "input.yaml").open(encoding="utf-8") as handle:
        return compute(yaml.safe_load(handle))


def test_example_demands(result):
    v = result["values"]
    assert v["self_weight"] == pytest.approx(0.1)
    assert v["wu"] == pytest.approx(0.7325)
    assert v["Mu"] == pytest.approx(23.44)
    assert v["Vu"] == pytest.approx(5.86)


def test_example_flexure(result):
    v = result["values"]
    assert v["a"] == pytest.approx(1.823529, rel=1e-5)
    assert v["et"] == pytest.approx(0.010283, rel=1e-3)
    assert v["phi"] == pytest.approx(0.9)
    assert v["phiMn"] == pytest.approx(23.961176, rel=1e-5)
    assert result["checks"]["flexure"]["ok"] is True


def test_example_min_steel_and_shear(result):
    v = result["values"]
    assert v["As_min"] == pytest.approx(0.253333, rel=1e-4)
    assert v["phiVc"] == pytest.approx(6.244016, rel=1e-4)
    assert result["checks"]["minimum_steel"]["ok"] is True
    assert result["checks"]["shear"]["ok"] is True


def test_reinforcement_geometry(result):
    v = result["values"]
    assert v["cover"] == pytest.approx(1.5)
    assert v["stirrup_size"] == 3
    assert v["stirrup_db"] == pytest.approx(0.375)
    assert v["stirrup_spacing"] == pytest.approx(6.0)
    assert v["bar_size"] == 5
    assert v["n_bars"] == 2
    assert v["bar_db"] == pytest.approx(0.625)
    assert v["top_bar_size"] == 4
    assert v["n_top_bars"] == 2
    assert v["top_bar_db"] == pytest.approx(0.5)
    assert v["As_bars"] == pytest.approx(2 * math.pi * 0.625**2 / 4.0, rel=1e-6)


def test_rejects_depth_without_room_for_bars():
    import yaml

    with (HERE / "input.yaml").open(encoding="utf-8") as handle:
        inp = yaml.safe_load(handle)
    inp["d"] = "11.9 in"
    with pytest.raises(ValueError):
        compute(inp)


def test_section_fragment_is_current(result):
    module = _load("beam_section", "beam_section.py")
    expected = module.render(result["values"])
    actual = (HERE / "assets" / "beam-section.typ").read_text(encoding="utf-8")
    assert actual == expected