flutter scoped model

// scoped-models/products.dart
import 'package:scoped_model/scoped_model.dart';

import '../models/product.dart';

class ProductsModel extends Model {
  List<Product> _products = [];
  int? _selectedProductIndex; // if we changed from var => int ?
  bool _showFavorites = false;

  List<Product> get products {
    return List.from(_products);
  }

  List<Product> get displayedProducts {
    if (_showFavorites) {
      return _products.where((Product product) => product.isFavourite).toList();
    }
    return List.from(_products);
  }

  int get selectedProductIndex{
    return _selectedProductIndex!.toInt();
  }

  Product get selectedProduct {
    // Error gone here :)
    // But need to dive ..
    //return _selectedProductIndex;
    //If i uncomment underline :: Error happened
    return _products[_selectedProductIndex!.toInt()];
  }

  bool get displayFavoritesOnly {
    return _showFavorites;
  }

  void addProduct(Product product) {
    _products.add(product);
    //Chnaged to  null frrom 0
    // _selectedProductIndex = null;
    notifyListeners();
  }

  void updateProduct(Product product) {
    _products[_selectedProductIndex!.toInt()] = product;
    //_selectedProductIndex = null;
    notifyListeners();
  }

  void deleteProduct() {
    _products.removeAt(_selectedProductIndex!.toInt());
    //_selectedProductIndex = null;
    notifyListeners();
  }

  void toggleProductFavoriteStatus() {
    final bool isCurrenltyFavorite = selectedProduct.isFavourite;

    final bool newFavoriteStatus = !isCurrenltyFavorite;

    final Product updateProduct = Product(
        title: selectedProduct.title,
        description: selectedProduct.description,
        price: selectedProduct.price,
        image: selectedProduct.image,
        isFavourite: newFavoriteStatus);
    _products[selectedProductIndex] = updateProduct;
    notifyListeners();
  }

  void selectProduct(int index) {
    _selectedProductIndex = index;
    notifyListeners();
  }

  void toggleDisplayMode() {
    _showFavorites = !_showFavorites;
    notifyListeners();
  }
}