from typing import List, Optional

from sqlalchemy.orm import Session

from app.crud.base import CRUDBase
from app.models.cart import CartItem
from app.schemas.cart import CartItemCreate, CartItemUpdate


class CRUDCartItem(CRUDBase[CartItem, CartItemCreate, CartItemUpdate]):
    def get_by_user_and_product(
        self, db: Session, *, user_id: int, product_id: int
    ) -> Optional[CartItem]:
        """
        Get a cart item by user ID and product ID.

        Args:
            db: Database session
            user_id: User ID
            product_id: Product ID

        Returns:
            The cart item or None if not found
        """
        return (
            db.query(self.model)
            .filter(self.model.user_id == user_id, self.model.product_id == product_id)
            .first()
        )

    def get_user_cart(self, db: Session, *, user_id: int) -> List[CartItem]:
        """
        Get all cart items for a user.

        Args:
            db: Database session
            user_id: User ID

        Returns:
            List of cart items
        """
        return db.query(self.model).filter(self.model.user_id == user_id).all()

    def create_or_update(
        self, db: Session, *, user_id: int, obj_in: CartItemCreate
    ) -> CartItem:
        """
        Create a new cart item or update the quantity if it already exists.

        Args:
            db: Database session
            user_id: User ID
            obj_in: Cart item data

        Returns:
            The created or updated cart item
        """
        cart_item = self.get_by_user_and_product(
            db, user_id=user_id, product_id=obj_in.product_id
        )

        if cart_item:
            # Update existing cart item
            cart_item.quantity += obj_in.quantity
            db.add(cart_item)
            db.commit()
            db.refresh(cart_item)
            return cart_item
        else:
            # Create new cart item
            db_obj = CartItem(
                user_id=user_id, product_id=obj_in.product_id, quantity=obj_in.quantity
            )
            db.add(db_obj)
            db.commit()
            db.refresh(db_obj)
            return db_obj

    def clear_cart(self, db: Session, *, user_id: int) -> None:
        """
        Remove all cart items for a user.

        Args:
            db: Database session
            user_id: User ID
        """
        db.query(self.model).filter(self.model.user_id == user_id).delete()
        db.commit()


cart_item = CRUDCartItem(CartItem)