import pytest

from app.models import BaseUnit, Product
from app.services.conversion import ConversionError, to_base


def test_base_unit(db, rice):
    assert to_base(db, rice, 200, "Gramm") == 200
    assert to_base(db, rice, 200, "g") == 200  # Kürzel-Alias


def test_kilogram_converts_to_grams(db, rice):
    assert to_base(db, rice, 1, "Kilogramm") == 1000
    assert to_base(db, rice, 2.5, "kg") == 2500


def test_package_uses_package_size(db, rice):
    # rice: package_size = 500 g
    assert to_base(db, rice, 3, "package") == 1500


def test_wrong_kind_rejected(db, rice):
    # rice ist ein Gewichts-Produkt -> Volumeneinheit passt nicht
    with pytest.raises(ConversionError):
        to_base(db, rice, 1, "Liter")


def test_unknown_unit_rejected(db, rice):
    with pytest.raises(ConversionError):
        to_base(db, rice, 1, "Eimer")


def test_volume_product(db):
    milk = Product(name="Milch", base_unit=BaseUnit.milliliter, package_size=1000)
    db.add(milk)
    db.commit()
    assert to_base(db, milk, 1, "Liter") == 1000
    assert to_base(db, milk, 500, "ml") == 500


def test_non_positive_quantity_rejected(db, rice):
    with pytest.raises(ConversionError):
        to_base(db, rice, 0, "Gramm")