public ActionResult AddEditGroup(int? groupId)
        {
            var model = new GroupViewModel { Id = 0 };
            if (groupId.HasValue && groupId.Value > 0)
            {
                var group = _groupStore.GetGroupsWithStories(s => s.Id == groupId.Value).FirstOrDefault();
                if (group != null)
                {
                    model.Id = group.Id;
                    model.Title = group.Title;
                    model.Description = group.Description;
                    model.Content = group.Content;
                    model.Stories = new List<StoryViewModel>((group.Stories ?? new List<Story>()).Select(s => new StoryViewModel
                    {
                        Id = s.Id,
                        Title = s.Title,
                        Description = s.Description,
                        Content = s.Content ?? string.Empty,
                        Groups = null
                    }));
                }
            }

            return View("_AddEditGroup", model);
        }
        public ActionResult SaveGroup(GroupViewModel model)
        {
            if (!ModelState.IsValid)
            {
                return RedirectToAction("AddEditGroup", "Home", new { groupId = model.Id });
            }
            var userId = User.Identity.GetUserId();

            if (model.Id > 0)
            {
                var groupExistent = _groupStore.GetGroup(model.Id, true);
                if (groupExistent != null)
                {
                    groupExistent.Id = model.Id;
                    groupExistent.Title = model.Title;
                    groupExistent.Description = model.Description;
                    groupExistent.Content = model.Content;
                    if (groupExistent.Stories == null)
                        groupExistent.Stories = new List<Story>();
                    _groupStore.UpdateGroup(groupExistent);
                }
            }
            else
            {
                var group = new Group
                {
                    Id = model.Id,
                    Title = model.Title,
                    Description = model.Description,
                    Content = model.Content,
                    Stories = new List<Story>()
                };
                _groupStore.AddGroup(group);
            }

            return RedirectToAction("GroupList", "Home");
        }