"""核心基类

Tenant 表无 tenant_id（自身即租户），使用 BaseNoTenant。
其他表继承 Base（含 tenant_id、created_at、updated_at）。
"""
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
from sqlalchemy import TIMESTAMP, func, BigInteger
from typing import Optional


class BaseNoTenant(DeclarativeBase):
    """无 tenant_id 的基类，用于 Tenant 表"""
    __abstract__ = True
    created_at: Mapped[Optional[TIMESTAMP]] = mapped_column(
        TIMESTAMP, nullable=False, server_default=func.now()
    )
    updated_at: Mapped[Optional[TIMESTAMP]] = mapped_column(
        TIMESTAMP, nullable=False, server_default=func.now(), onupdate=func.now()
    )


class Base(BaseNoTenant):
    """带 tenant_id 的基类，所有租户表继承此类"""
    __abstract__ = True
    tenant_id: Mapped[int] = mapped_column(
        BigInteger, nullable=False, default=1, index=True
    )
    created_at: Mapped[Optional[TIMESTAMP]] = mapped_column(
        TIMESTAMP, nullable=False, server_default=func.now()
    )
    updated_at: Mapped[Optional[TIMESTAMP]] = mapped_column(
        TIMESTAMP, nullable=False, server_default=func.now(), onupdate=func.now()
    )


class BaseNoCreatedAt(BaseNoTenant):
    """仅有 tenant_id 和 updated_at，无 created_at（如 user_workloads）"""
    __abstract__ = True
    tenant_id: Mapped[int] = mapped_column(
        BigInteger, nullable=False, default=1, index=True
    )
    updated_at: Mapped[Optional[TIMESTAMP]] = mapped_column(
        TIMESTAMP, nullable=False, server_default=func.now(), onupdate=func.now()
    )