"""Column mixins shared by the ORM models."""

from datetime import datetime

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


class TimestampMixin:
    """Adds ``created_at`` / ``updated_at`` to a model.

    Timestamps are generated by the database on insert and refreshed by the
    ORM on update, so a row written by any client carries a server clock value.
    """

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