from typing import Type, TypeVar, Generic, List, Optional, Any
from sqlalchemy.orm import Session
from app.db.database import Base
from app.services.service_manager import ServiceManager

T = TypeVar('T')

class BaseService(Generic[T]):
    def __init__(self, model: Type[T]):
        self.model = model
        self.service_manager = ServiceManager()
        self._services = {}

    def get(self, db: Session, id: int) -> Optional[T]:
        return db.query(self.model).filter(self.model.id == id).first()

    def get_all(self, db: Session, skip: int = 0, limit: int = 100) -> List[T]:
        return db.query(self.model).offset(skip).limit(limit).all()

    def create(self, db: Session, obj_in: dict) -> T:
        db_obj = self.model(**obj_in)
        db.add(db_obj)
        db.commit()
        db.refresh(db_obj)
        return db_obj

    def update(self, db: Session, db_obj: T, obj_in: dict) -> T:
        for field in obj_in:
            if hasattr(db_obj, field):
                setattr(db_obj, field, obj_in[field])
        db.add(db_obj)
        db.commit()
        db.refresh(db_obj)
        return db_obj

    def delete(self, db: Session, id: int) -> bool:
        obj = db.query(self.model).filter(self.model.id == id).first()
        if obj:
            db.delete(obj)
            db.commit()
            return True
        return False

    def get_service(self, name: str) -> Any:
        """Get a service by name with lazy loading"""
        if name not in self._services:
            self._services[name] = self.service_manager.get_service(name)
        return self._services[name]

    @property
    def file_service(self):
        """Convenience property for file service"""
        return self.get_service('file')