@implements IDisposable
@using System.Timers

<TelerikButton OnClick="@DoFastWork">Do fast work (no loader)</TelerikButton>
<TelerikButton OnClick="@DoSlowWork">Do SLOW work (shows loader)</TelerikButton>
@result

<TelerikLoader Visible="@LoaderVisible"></TelerikLoader>

@* NOTE: This is a basic example - if you bash the button you will never see the loader.
    In a real case you may want to take care of that - hide the butotn with a loader container instead, or disable it, or debounce the clicks *@

@code{
    bool LoaderVisible { get; set; }
    Timer theTimer { get; set; }
    int minDelay { get; set; } = 1000;

    string result { get; set; }

    async Task DoFastWork()
    {
        InitTimer();

        await Task.Delay(300); //simulate fast task
        result = DateTime.Now.ToString();

        DisposeTimer();
        LoaderVisible = false;
    }

    async Task DoSlowWork()
    {
        InitTimer();

        await Task.Delay(3000); //simulate SLOW task
        result = DateTime.Now.ToString();

        DisposeTimer();
        LoaderVisible = false;
    }

    // the idea is that we never hit this event if things happen fast enough
    void OnTimedEvent(object source, ElapsedEventArgs e)
    {
        LoaderVisible = true;
        InvokeAsync(StateHasChanged);
    }

    void InitTimer()
    {
        DisposeTimer();

        theTimer = new System.Timers.Timer();
        theTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
        theTimer.Interval = minDelay;
        theTimer.Enabled = true;
    }

    void DisposeTimer()
    {
        try
        {
            if (theTimer != null)
            {
                theTimer.Dispose();
            }
        }
        catch { }
    }


    public void Dispose()
    {
        DisposeTimer();
    }
}