Refactor. Add data layer

BudgetApp/Components/ToastContainer.razor.cs

@@ -0,0 +1,40 @@
+namespace BudgetApp.Components;
+
+public partial class ToastContainer
+{
+    private readonly List<ToastItem> _toasts = [];
+
+    protected override void OnInitialized()
+    {
+        ToastService.OnShow += ShowToast;
+    }
+
+    private async void ShowToast(string message)
+    {
+        var toast = new ToastItem { Message = message };
+        _toasts.Add(toast);
+        await InvokeAsync(StateHasChanged);
+        _ = DismissAfterDelay(toast);
+    }
+
+    private async Task DismissAfterDelay(ToastItem toast)
+    {
+        await Task.Delay(3500);
+        toast.Dismissing = true;
+        await InvokeAsync(StateHasChanged);
+        await Task.Delay(300);
+        _toasts.Remove(toast);
+        await InvokeAsync(StateHasChanged);
+    }
+
+    public void Dispose()
+    {
+        ToastService.OnShow -= ShowToast;
+    }
+
+    private sealed class ToastItem
+    {
+        public string Message { get; set; } = "";
+        public bool Dismissing { get; set; }
+    }
+}