from typing import Generic, TypeVar, Type, Optional, List, Dict, Any
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, update, delete
from sqlalchemy.orm import selectinload
from app.db.base import BaseModel

ModelType = TypeVar("ModelType", bound=BaseModel)


class CRUDBase(Generic[ModelType]):
    def __init__(self, model: Type[ModelType]):
        self.model = model
    
    async def get(self, db: AsyncSession, id: str) -> Optional[ModelType]:
        """Получить объект по ID"""
        result = await db.execute(select(self.model).where(self.model.id == id))
        return result.scalar_one_or_none()
    
    async def get_multi(
        self,
        db: AsyncSession,
        skip: int = 0,
        limit: int = 100,
        filters: Optional[Dict[str, Any]] = None
    ) -> List[ModelType]:
        """Получить список объектов"""
        query = select(self.model)
        
        if filters:
            for key, value in filters.items():
                if hasattr(self.model, key):
                    query = query.where(getattr(self.model, key) == value)
        
        query = query.offset(skip).limit(limit)
        result = await db.execute(query)
        return result.scalars().all()
    
    async def create(self, db: AsyncSession, obj_in: Dict[str, Any]) -> ModelType:
        """Создать объект"""
        db_obj = self.model(**obj_in)
        db.add(db_obj)
        await db.commit()
        await db.refresh(db_obj)
        return db_obj
    
    async def update(
        self,
        db: AsyncSession,
        db_obj: ModelType,
        obj_in: Dict[str, Any]
    ) -> ModelType:
        """Обновить объект"""
        for field, value in obj_in.items():
            if hasattr(db_obj, field) and value is not None:
                setattr(db_obj, field, value)
        
        await db.commit()
        await db.refresh(db_obj)
        return db_obj
    
    async def delete(self, db: AsyncSession, id: str) -> bool:
        """Удалить объект"""
        result = await db.execute(delete(self.model).where(self.model.id == id))
        await db.commit()
        return result.rowcount > 0