Auto TrendlinesPair with Retest

using System;
using System.Collections.Generic;
using cAlgo.API;
using cAlgo.API.Indicators;
using LittleTrader;
using LittleTrader.Models.PriceActions;
using LittleTrader.Extensions;
using LittleTrader.Huy;

namespace cAlgo.Indicators
{
    [Indicator(IsOverlay = true, AccessRights = AccessRights.None)]
    public class LT_Ind_TrendLinesPair : Indicator
    {
        [Parameter(Group = "Sources")]
        public DataSeries HighSource { get; set; }
        [Parameter(Group = "Sources")]
        public DataSeries LowSource { get; set; }

        [Parameter(Group = "Sources")]
        public DataSeries OscHigh { get; set; }
        [Parameter(Group = "Sources")]
        public DataSeries OscLow { get; set; }

        [Parameter(DefaultValue = 20, MinValue = 1, Group = "SwingsFinder")]
        public int Period { get; set; }

        ChartVerticalLine _shiftLine;
        DateTime _lastShiftLineTime;

        protected override void Initialize()
        {
            Chart.ObjectsUpdated += e =>
            {
                if (_shiftLine != null && _shiftLine.Time != _lastShiftLineTime)
                {
                    _lastShiftLineTime = _shiftLine.Time;
                    var index = Bars.OpenTimes.GetIndexByTime(_shiftLine.Time);
                    RetestAt(index);
                }
            };

            Chart.MouseDown += e =>
            {
                if (e.CtrlKey == true)
                {
                    var index = (int)e.BarIndex;
                    DrawShiftLine(index);
                    RetestAt(index);
                }
            };

            Chart.ObjectsRemoved += e =>
            {
                if (e.ChartObjects[0] == _shiftLine)
                {
                    _shiftLine = null;
                    Print("Shift line removed!");
                    Calculate(Bars.GetLastIndex());
                }
            };
        }

        void RetestAt(int index)
        {
            CalTrendlines(index);
            Print($"Retest at {index}");
        }

        void DrawShiftLine(int index)
        {
            _shiftLine = Chart.DrawVerticalLine("shift", index, Color.Yellow, 1, LineStyle.DotsRare);
            _shiftLine.IsInteractive = true;
        }

        public override void Calculate(int index)
        {
            if (_shiftLine != null) return;
            try
            {
                CalTrendlines(index);
            }
            catch (LTNoDataException)
            {
            }
            catch (Exception ex)
            {
                Print(ex.ToString());
            }
        }

        class TrendData
        {
            public DataSeries High { get; set; }
            public DataSeries Low { get; set; }
            public ChartArea Chart { get; set; }
        }

        void CalTrendlines(int index)
        {
            var list = new List<TrendData>
            {
                new TrendData { High = HighSource, Low = LowSource, Chart = Chart },
                new TrendData { High = OscHigh, Low = OscLow, Chart = IndicatorArea },
            };

            try
            {
                foreach (var item in list)
                {
                    var high = new Trendline(item.High, Swings.High, Period, index);
                    var low = new Trendline(item.Low, Swings.Low, Period, index);
                    high.Draw(item.Chart, "high", 200);
                    low.Draw(item.Chart, "low", 200);
                }
            }

            catch (LTNoDataException)
            { }
        }

    }
}