"""MySQL 通用仓储基类：封装 CRUD（AsyncSession 会话注入，函数内自提交）。"""
from __future__ import annotations

from typing import Any, Sequence

from sqlalchemy import delete as sa_delete
from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession


class BaseRepository:
    """子类只需设 model；主键列固定名为 id。"""

    model: type | None = None

    def __init__(self, db: AsyncSession):
        self.db = db

    async def get(self, pk: int) -> Any | None:
        return await self.db.get(self.model, pk)

    async def list(self, *, where: Sequence | None = None,
                   order_by: Any | None = None, limit: int = 100,
                   offset: int = 0) -> list:
        stmt = select(self.model)
        if where:
            stmt = stmt.where(*where)
        if order_by is not None:
            stmt = stmt.order_by(order_by)
        return list((await self.db.scalars(stmt.limit(limit).offset(offset))).all())

    async def add(self, obj: Any) -> Any:
        """新增并入参刷新出 id 等 DB 生成字段。"""
        self.db.add(obj)
        await self.db.commit()
        await self.db.refresh(obj)
        return obj

    async def delete(self, pk: int) -> bool:
        result = await self.db.execute(sa_delete(self.model).where(self.model.id == pk))
        await self.db.commit()
        return result.rowcount > 0

    async def count(self, *, where: Sequence | None = None) -> int:
        stmt = select(func.count()).select_from(self.model)
        if where:
            stmt = stmt.where(*where)
        return (await self.db.scalar(stmt)) or 0