BollingerBands Trend Flat indicator

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

namespace cAlgo
{
    [Levels(0)]
    [Indicator(IsOverlay = false, AccessRights = AccessRights.None)]
    public class mBBtrendflat : Indicator
    {
        [Parameter("Periods (20)", DefaultValue = 20)]
        public int inpPeriod { get; set; }
        [Parameter("Standard Deviation (2.0)", DefaultValue = 2)]
        public double inpDeviation { get; set; }
        [Parameter("Smooth Type (sma)", DefaultValue = MovingAverageType.Simple)]
        public MovingAverageType inpSmoothType { get; set; }
        [Parameter("Use FIR filter (no)", DefaultValue = false)]
        public bool inpUseFIRfilter { get; set; }

        [Output("Trend Up", LineColor = "Green", PlotType = PlotType.Histogram, LineStyle = LineStyle.Solid, Thickness = 3)]
        public IndicatorDataSeries outUp { get; set; }
        [Output("Trend Down", LineColor = "Red", PlotType = PlotType.Histogram, LineStyle = LineStyle.Solid, Thickness = 3)]
        public IndicatorDataSeries outDown { get; set; }

        private BollingerBands _bbands;
        private IndicatorDataSeries _price, _min, _max;

        protected override void Initialize()
        {
            _price = CreateDataSeries();
            _min = CreateDataSeries();
            _max = CreateDataSeries();
            _bbands = Indicators.BollingerBands(_price, inpPeriod, inpDeviation, inpSmoothType);
        }

        public override void Calculate(int i)
        {
            _price[i] = i>3 && inpUseFIRfilter == true ? (Bars.ClosePrices[i] + 2.0 * Bars.ClosePrices[i-1] + 2.0 * Bars.ClosePrices[i-2] + Bars.ClosePrices[i-3]) / 6.0 : Bars.ClosePrices[i];
            _max[i] = i>inpPeriod ? Math.Max(_bbands.Top.Maximum(inpPeriod), _bbands.Bottom.Maximum(inpPeriod)) : _bbands.Top[i];
            _min[i] = i>inpPeriod ? Math.Min(_bbands.Top.Minimum(inpPeriod), _bbands.Bottom.Minimum(inpPeriod)) : _bbands.Bottom[i];
            
            outUp[i] = _bbands.Top[i] == _max[i] && Bars.ClosePrices[i] > _bbands.Main[i] ? +1 : 0;
            outDown[i] = _bbands.Bottom[i] == _min[i] && Bars.ClosePrices[i] < _bbands.Main[i] ? -1 : 0;
        }
    }
}