MainWindowViewModel

using Margo.UI.Utilities;

namespace Margo.UI.ViewModel
{
    internal class MainWindowViewModel : BaseViewModel
    {

        private BaseViewModel _currentViewModel;

        private readonly AddProductViewModel _addProductViewModel = new AddProductViewModel();
        private readonly ProductsViewModel _productsViewModel = new ProductsViewModel();
        private readonly ShoppingListViewModel _shoppingListViewModel = new ShoppingListViewModel();

        public MainWindowViewModel()
        {
            CurrentViewModel = _shoppingListViewModel;
            NavCommand = new RelayCommand<string>(OnNav);
            _shoppingListViewModel.AddProductRequested += NavToAddProduct;
        }

        private void NavToAddProduct()
        {
            CurrentViewModel = _addProductViewModel;
        }

        public RelayCommand<string> NavCommand { get; private set; }

        public BaseViewModel CurrentViewModel
        {
            get { return _currentViewModel; }
            set { SetProperty(ref _currentViewModel, value); }
        }

        private void OnNav(string destination)
        {
            switch (destination)
            {
                case "shoppingList":
                    CurrentViewModel = _shoppingListViewModel;
                    break;
                case "products":
                    CurrentViewModel = _productsViewModel;
                    break;
            }
        }
    }
}