"""Deklarative Basisklasse und gemeinsame Spaltentypen."""

from datetime import UTC, datetime
from decimal import Decimal

from sqlalchemy import DateTime, MetaData, Numeric
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column

# Feste Namenskonventionen, damit Alembic stabile Constraint-Namen erzeugt.
NAMING_CONVENTION = {
    "ix": "ix_%(column_0_label)s",
    "uq": "uq_%(table_name)s_%(column_0_name)s",
    "ck": "ck_%(table_name)s_%(constraint_name)s",
    "fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
    "pk": "pk_%(table_name)s",
}

# Alle Geldbeträge einheitlich als NUMERIC(12,2) -> Decimal.
Money = Numeric(12, 2, asdecimal=True)


def utcnow() -> datetime:
    """Zeitstempel in UTC – die Anzeige rechnet nach Europe/Berlin um."""
    return datetime.now(UTC)


class Base(DeclarativeBase):
    metadata = MetaData(naming_convention=NAMING_CONVENTION)

    type_annotation_map = {  # noqa: RUF012
        Decimal: Money,
    }


class TimestampMixin:
    """created_at/updated_at für Tabellen mit Änderungsverfolgung."""

    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), default=utcnow, nullable=False
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), default=utcnow, onupdate=utcnow, nullable=False
    )


class CreatedAtMixin:
    """Nur created_at für rein additive Tabellen."""

    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), default=utcnow, nullable=False
    )