from datetime import date
from decimal import Decimal


def _ensure_rate(day: date, rate: str) -> None:
    from app.database import SessionLocal
    from app.models import ExchangeRate

    db = SessionLocal()
    try:
        if db.get(ExchangeRate, (day, "CHF")) is None:
            db.add(ExchangeRate(date=day, currency="CHF", rate_per_eur=Decimal(rate)))
            db.commit()
    finally:
        db.close()


def test_conversion_and_override(admin):
    from app.database import SessionLocal
    from app.services import currency

    d = date(2026, 1, 15)
    _ensure_rate(d, "0.95")
    db = SessionLocal()
    try:
        assert currency.to_eur_cents(db, 9500, "CHF", d) == 10000  # 9500 / 0.95
        assert currency.from_eur_cents(db, 10000, "CHF", d) == 9500
        assert currency.convert(db, 10000, "EUR", "CHF", d) == 9500
        assert currency.to_eur_cents(db, 5000, "EUR", d) == 5000  # EUR bleibt EUR
        # Manuell gesetzter Kurs hat Vorrang vor dem EZB-Kurs.
        assert currency.to_eur_cents(db, 10000, "CHF", d, fx_rate=2.0) == 5000
    finally:
        db.close()


def test_weekend_fallback(admin):
    from app.database import SessionLocal
    from app.services import currency

    friday = date(2026, 3, 6)
    sunday = date(2026, 3, 8)  # kein Kurs -> Freitag gilt
    _ensure_rate(friday, "0.90")
    db = SessionLocal()
    try:
        assert currency.rate_on(db, "CHF", sunday) == Decimal("0.90")
    finally:
        db.close()


def test_missing_rate_returns_none(admin):
    from app.database import SessionLocal
    from app.services import currency

    db = SessionLocal()
    try:
        # Weit in der Vergangenheit gibt es keinen Kurs -> None.
        assert currency.to_eur_cents(db, 1000, "CHF", date(1990, 1, 1)) is None
    finally:
        db.close()