import uuid
from datetime import datetime

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


class Base(DeclarativeBase):
    # Fetch server-generated defaults (created_at/updated_at) via RETURNING
    # at flush time — otherwise the async session would need a lazy refresh
    # on attribute access, which raises MissingGreenlet outside a greenlet.
    __mapper_args__ = {"eager_defaults": True}


class UUIDPrimaryKeyMixin:
    id: Mapped[uuid.UUID] = mapped_column(primary_key=True, default=uuid.uuid4)


class TimestampMixin:
    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()
    )