from typing import Generic, TypeVar, Type, List, Optional
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from app.database import Base

T = TypeVar("T", bound=Base)

class BaseRepository(Generic[T]):
    def __init__(self, model: Type[T], db: AsyncSession):
        self.model = model
        self.db = db

    async def get_by_id(self, id: any) -> Optional[T]:
        result = await self.db.execute(select(self.model).filter(self.model.id == id))
        return result.scalars().first()

    async def get_all(self, skip: int = 0, limit: int = 100) -> List[T]:
        result = await self.db.execute(select(self.model).offset(skip).limit(limit))
        return list(result.scalars().all())

    async def create(self, obj: T) -> T:
        self.db.add(obj)
        await self.db.flush()
        return obj

    async def update(self, obj: T) -> T:
        self.db.add(obj)
        await self.db.flush()
        return obj

    async def delete(self, obj: T) -> None:
        await self.db.delete(obj)
        await self.db.flush()