"""Database base declarations."""

from datetime import datetime, timezone

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


def utc_now() -> datetime:
    """Return the current UTC timestamp."""

    return datetime.now(timezone.utc)


class Base(DeclarativeBase):
    """Shared declarative base."""


class TimestampMixin:
    """Mixin that adds created and updated timestamps."""

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