adding missing validations

lib/dynamics/ghla/Ghla.Quantower.cs

@@ -0,0 +1,50 @@
+using System.Drawing;
+using System.Runtime.CompilerServices;
+using TradingPlatform.BusinessLayer;
+
+namespace QuanTAlib;
+
+[SkipLocalsInit]
+public sealed class GhlaIndicator : Indicator, IWatchlistIndicator
+{
+    [InputParameter("Period", sortIndex: 1, 1, 1000, 1, 0)]
+    public int Period { get; set; } = 13;
+
+    [InputParameter("Show cold values", sortIndex: 21)]
+    public bool ShowColdValues { get; set; } = true;
+
+    private Ghla _ghla = null!;
+    private readonly LineSeries _ghlaSeries;
+
+    public static int MinHistoryDepths => 0;
+    int IWatchlistIndicator.MinHistoryDepths => MinHistoryDepths;
+
+    public override string ShortName => $"GHLA {Period}";
+    public override string SourceCodeLink => "https://github.com/mihakralj/QuanTAlib/blob/main/lib/dynamics/ghla/Ghla.Quantower.cs";
+
+    public GhlaIndicator()
+    {
+        OnBackGround = true;
+        SeparateWindow = false; // Overlay indicator — plots on price chart
+        Name = "GHLA - Gann High-Low Activator";
+        Description = "SMA(High)/SMA(Low) alternating trailing stop with hysteresis trend detection";
+
+        _ghlaSeries = new LineSeries(name: "GHLA", color: Color.Yellow, width: 2, style: LineStyle.Solid);
+        AddLineSeries(_ghlaSeries);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected override void OnInit()
+    {
+        _ghla = new Ghla(Period);
+        base.OnInit();
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected override void OnUpdate(UpdateArgs args)
+    {
+        TBar bar = this.GetInputBar(args);
+        TValue result = _ghla.Update(bar, args.IsNewBar());
+        _ghlaSeries.SetValue(result.Value, _ghla.IsHot, ShowColdValues);
+    }
+}