import pytest

from app.models import BaseUnit, Product
from app.services.units import UnitError, base_to_packages, to_base_quantity


def test_base_unit_passthrough(rice):
    assert to_base_quantity(rice, 200, "g") == 200
    assert to_base_quantity(rice, 200, "gramm") == 200


def test_package_conversion(rice):
    # 3 Packungen * 500 g = 1500 g
    assert to_base_quantity(rice, 3, "package") == 1500
    assert to_base_quantity(rice, 2, "packung") == 1000


def test_wrong_unit_rejected(rice):
    with pytest.raises(UnitError):
        to_base_quantity(rice, 1, "ml")


def test_package_without_size_rejected():
    product = Product(name="Ei", base_unit=BaseUnit.piece, package_size=None)
    with pytest.raises(UnitError):
        to_base_quantity(product, 1, "package")


def test_non_positive_quantity_rejected(rice):
    with pytest.raises(UnitError):
        to_base_quantity(rice, 0, "g")


def test_base_to_packages(rice):
    assert base_to_packages(rice, 1500) == 3
    product = Product(name="Ei", base_unit=BaseUnit.piece, package_size=None)
    assert base_to_packages(product, 10) is None