"""ORM 基类与公共 Mixin。

约定：
    * 主键统一 id 自增
    * 所有表都带 created_at / updated_at
    * 业务表一律逻辑删除：is_del = 0 表示正常，1 表示已删除
    * 查询正常数据统一写 `Model.alive()`，禁止在 DAO 里手写 `is_del == 1`
      （上一版项目就是把方向写反导致了"查不到刚建的数据"）
"""

from __future__ import annotations

from datetime import datetime
from typing import Any

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

DEL_FLAG_NORMAL: int = 0
DEL_FLAG_DELETED: int = 1


class Base(DeclarativeBase):
    """SQLAlchemy 2.0 DeclarativeBase。"""

    def to_dict(self, exclude: set[str] | None = None) -> dict[str, Any]:
        exclude = exclude or set()
        return {
            c.name: getattr(self, c.name)
            for c in self.__table__.columns
            if c.name not in exclude
        }

    def __repr__(self) -> str:  # pragma: no cover - 调试用
        pk = getattr(self, "id", None)
        return f"<{self.__class__.__name__} id={pk}>"


class TimestampMixin:
    created_at: Mapped[datetime] = mapped_column(
        DateTime, default=datetime.now, nullable=False, comment="创建时间"
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime, default=datetime.now, onupdate=datetime.now, nullable=False, comment="更新时间"
    )


class SoftDeleteMixin:
    is_del: Mapped[int] = mapped_column(
        SmallInteger,
        default=DEL_FLAG_NORMAL,
        server_default="0",
        nullable=False,
        index=True,
        comment="逻辑删除：0=正常 1=已删除",
    )

    @classmethod
    def alive(cls):
        """正常数据的过滤条件，供 select().where() 使用。"""
        return cls.is_del == DEL_FLAG_NORMAL

    def soft_delete(self) -> None:
        self.is_del = DEL_FLAG_DELETED