private void SetLessonButtonAsEnabledOrDisabled(Button lessonButton) { int.TryParse(lessonButton.Content.ToString().Replace(GlobalVariables.lessonNumberPartialText, ""), out int buttonLessonNumber); var lessonsDone = _lessonService.GetDoneLessonsNumbersByUser(_user); if (buttonLessonNumber != 0 && lessonsDone != null && lessonsDone.Count > 0 && (lessonsDone.Contains(buttonLessonNumber) || lessonsDone.Max() + 1 == buttonLessonNumber)) { lessonButton.IsEnabled = true; } else if (buttonLessonNumber != 0 && buttonLessonNumber == _lessonService.GetFirstLessonNumber(_user)) { lessonButton.IsEnabled = true; } else { lessonButton.IsEnabled = false; } }