RSI bigger timeframe

using cAlgo.API;
using cAlgo.API.Internals;
using cAlgo.API.Indicators;
using cAlgo.Indicators;

namespace cAlgo
{
    [Levels(30, 50, 70)]
    [Indicator(IsOverlay = false, TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
    public class mRSIbtf : Indicator
    {
        [Parameter("Working TimeFrame", DefaultValue = "H4")]
        public TimeFrame inpTF1 { get; set; }
        [Parameter("DrawMode (slope)", DefaultValue = enumDrawMode.DrawModeSlope)]
        public enumDrawMode inpDrawMode { get; set; }
        [Parameter("Periods (14)", DefaultValue = 14)]
        public int inpPeriods { get; set; }

        [Output("RSIbtf", LineColor = "Black", PlotType = PlotType.Line, LineStyle = LineStyle.Solid, Thickness = 1)]
        public IndicatorDataSeries outRSI { get; set; }

        private Bars _barsTF1;
        private RelativeStrengthIndex _rsi;

        protected override void Initialize()
        {
            _barsTF1 = MarketData.GetBars(inpTF1);

            while (_barsTF1.OpenTimes[0] > Bars.OpenTimes[0])
                _barsTF1.LoadMoreHistory();
                
            _rsi = Indicators.RelativeStrengthIndex(_barsTF1.ClosePrices, inpPeriods);
        }
        
        public override void Calculate(int i)
        {
            int idx = inpTF1 == Chart.TimeFrame ? i : _barsTF1.OpenTimes.GetIndexByTime(Bars.OpenTimes[i]);
            int idx1 = inpTF1 == Chart.TimeFrame ? i-1 : _barsTF1.OpenTimes.GetIndexByTime(Bars.OpenTimes[i-1]);

            outRSI[i] = idx >= 0 ? _rsi.Result[idx] : 50.0;;
            if (idx >= 0 && inpDrawMode == enumDrawMode.DrawModeSlope && inpTF1 != Chart.TimeFrame && Bars.OpenTimes.GetIndexByTime(_barsTF1.OpenTimes[idx]) == Bars.OpenTimes.GetIndexByTime(_barsTF1.OpenTimes[idx1]))
                outRSI[i-1] = double.NaN;
        }
    }

    public enum enumDrawMode
    {
        DrawModeSteps,
        DrawModeSlope
    }
}