"""SQLAlchemy declarative base and common mixins."""

from datetime import datetime

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


class Base(DeclarativeBase):
    """Shared declarative base for all models."""

    pass


class TimestampMixin:
    """Adds ``created_at`` and ``updated_at`` columns with server defaults."""

    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        onupdate=func.now(),
    )