<TelerikScheduler Data="@Appointments"
                  OnUpdate="@UpdateAppointment"
                  OnCreate="@AddAppointment"
                  OnDelete="@DeleteAppointment"
                  OnEdit="@EditHandler" OnCancel="@CancelHandler"
                  AllowCreate="true" AllowDelete="true" AllowUpdate="true"
                  @bind-Date="@StartDate" Height="600px" @bind-View="@CurrView">
    <SchedulerViews>
        <SchedulerDayView StartTime="@DayStart" />
        <SchedulerWeekView StartTime="@DayStart" />
        <SchedulerMultiDayView StartTime="@DayStart" NumberOfDays="10" />
    </SchedulerViews>
</TelerikScheduler>

@code {
    private SchedulerView CurrView { get; set; } = SchedulerView.Week;
    private DateTime StartDate { get; set; } = new DateTime(2019, 12, 2);
    private DateTime DayStart { get; set; } = new DateTime(2000, 1, 1, 8, 0, 0);

    private List<SchedulerAppointment> Appointments { get; set; }

    private async Task UpdateAppointment(SchedulerUpdateEventArgs args)
    {
        SchedulerAppointment item = (SchedulerAppointment)args.Item;

        await MyService.Update(item);

        await GetSchedulerData();
    }

    private async Task AddAppointment(SchedulerCreateEventArgs args)
    {
        SchedulerAppointment item = args.Item as SchedulerAppointment;

        await MyService.Create(item);

        await GetSchedulerData();
    }

    private async Task DeleteAppointment(SchedulerDeleteEventArgs args)
    {
        SchedulerAppointment item = (SchedulerAppointment)args.Item;

        await MyService.Delete(item);

        await GetSchedulerData();
    }

    private void EditHandler(SchedulerEditEventArgs args)
    {
        SchedulerAppointment item = args.Item as SchedulerAppointment;
        if (!args.IsNew) // an edit operation, otherwise - an insert operation
        {
            if (item.Title.Contains("vet", StringComparison.InvariantCultureIgnoreCase))
            {
                args.IsCancelled = true;
            }
        }
        else
        {
            DateTime SlotStart = args.Start; // the start of the slot the user clicked
            DateTime SlotEnd = args.End; // the start of the slot the user clicked
            bool InsertInAllDay = args.IsAllDay; // whether the user started insertion in the All Day row
        }
    }

    private void CancelHandler(SchedulerCancelEventArgs args)
    {
        SchedulerAppointment item = args.Item as SchedulerAppointment;
    }

    public class SchedulerAppointment
    {
        public Guid Id { get; set; }
        public string Title { get; set; }
        public string Description { get; set; }
        public DateTime Start { get; set; }
        public DateTime End { get; set; }
        public bool IsAllDay { get; set; }
        public string RecurrenceRule { get; set; }
        public List<DateTime> RecurrenceExceptions { get; set; }
        public Guid? RecurrenceId { get; set; }

        public SchedulerAppointment()
        {
            Id = Guid.NewGuid();
        }
    }

    private async Task GetSchedulerData()
    {
        Appointments = await MyService.Read();
    }

    protected override async Task OnInitializedAsync()
    {
        await GetSchedulerData();
    }

    private static class MyService
    {
        private static List<SchedulerAppointment> _data { get; set; } = new List<SchedulerAppointment>()
        {
            new SchedulerAppointment
            {
                Title = "Board meeting",
                Description = "Q4 is coming to a close, review the details.",
                Start = new DateTime(2019, 12, 5, 10, 00, 0),
                End = new DateTime(2019, 12, 5, 11, 30, 0)
            },

            new SchedulerAppointment
            {
                Title = "Vet visit",
                Description = "The cat needs vaccinations and her teeth checked.",
                Start = new DateTime(2019, 12, 2, 11, 30, 0),
                End = new DateTime(2019, 12, 2, 12, 0, 0)
            },

            new SchedulerAppointment
            {
                Title = "Planning meeting",
                Description = "Kick off the new project.",
                Start = new DateTime(2019, 12, 6, 9, 30, 0),
                End = new DateTime(2019, 12, 6, 12, 45, 0)
            },

            new SchedulerAppointment
            {
                Title = "Trip to Hawaii",
                Description = "An unforgettable holiday!",
                IsAllDay = true,
                Start = new DateTime(2019, 11, 27),
                End = new DateTime(2019, 12, 05)
            },

            new SchedulerAppointment
            {
                Title = "Morning run",
                Description = "Some time to clear the head and exercise.",
                Start = new DateTime(2019, 11, 27, 9, 0, 0),
                End = new DateTime(2019, 11, 27, 9, 30, 0),
                RecurrenceRule = "FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR"
            }
        };

        public static async Task Create(SchedulerAppointment itemToInsert)
        {
            itemToInsert.Id = Guid.NewGuid();
            _data.Insert(0, itemToInsert);
        }

        public static async Task<List<SchedulerAppointment>> Read()
        {
            return await Task.FromResult(_data);
        }

        public static async Task Update(SchedulerAppointment itemToUpdate)
        {
            var index = _data.FindIndex(i => i.Id == itemToUpdate.Id);
            if (index != -1)
            {
                _data[index] = itemToUpdate;
            }
        }

        public static async Task Delete(SchedulerAppointment itemToDelete)
        {
            if (itemToDelete.RecurrenceId != null)
            {
            }

            if (!string.IsNullOrEmpty(itemToDelete.RecurrenceRule) && itemToDelete.RecurrenceExceptions?.Count > 0)
            {
            }

            _data.Remove(itemToDelete);
        }
    }
}