chore: import upstream snapshot with attribution

dotnet/samples/02-agents/Harness/ConsoleReactiveComponents/TopBottomRule.cs

@@ -0,0 +1,83 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Harness.ConsoleReactiveFramework;
+
+namespace Harness.ConsoleReactiveComponents;
+
+/// <summary>
+/// Props for <see cref="TopBottomRule"/>.
+/// </summary>
+public record TopBottomRuleProps : ConsoleReactiveProps
+{
+    /// <summary>Gets the foreground color of the horizontal rules. If <c>null</c>, the default terminal color is used.</summary>
+    public ConsoleColor? Color { get; init; }
+}
+
+/// <summary>
+/// A component that renders a top and bottom horizontal rule (─) with children
+/// stacked vertically between them.
+/// </summary>
+public class TopBottomRule : ConsoleReactiveComponent<TopBottomRuleProps, ConsoleReactiveState>
+{
+    /// <summary>
+    /// Calculates the total height including the top rule, children, and bottom rule.
+    /// </summary>
+    /// <param name="props">The component props containing children.</param>
+    /// <returns>2 (for the rules) plus the sum of all children heights.</returns>
+    public static int CalculateHeight(TopBottomRuleProps props)
+    {
+        int childrenHeight = 0;
+        foreach (var child in props.Children)
+        {
+            childrenHeight += child.BaseProps?.Height ?? 0;
+        }
+
+        // Top rule + children + bottom rule
+        return 2 + childrenHeight;
+    }
+
+    /// <inheritdoc />
+    public override void RenderCore(TopBottomRuleProps props, ConsoleReactiveState state)
+    {
+        int ruleWidth = props.Width;
+        string rule = new('─', ruleWidth);
+
+        if (props.Color.HasValue)
+        {
+            Console.Write(AnsiEscapes.SetForegroundColor(props.Color.Value));
+        }
+
+        // Top rule
+        Console.Write(AnsiEscapes.MoveCursor(props.Y, props.X));
+        Console.Write(rule);
+
+        // Render children stacked below the top rule
+        int currentY = props.Y + 1;
+
+        if (props.Color.HasValue)
+        {
+            Console.Write(AnsiEscapes.ResetAttributes);
+        }
+
+        foreach (var child in props.Children)
+        {
+            child.BaseProps = child.BaseProps! with { X = props.X, Y = currentY };
+            child.Render();
+            currentY += child.BaseProps.Height;
+        }
+
+        if (props.Color.HasValue)
+        {
+            Console.Write(AnsiEscapes.SetForegroundColor(props.Color.Value));
+        }
+
+        // Bottom rule
+        Console.Write(AnsiEscapes.MoveCursor(currentY, props.X));
+        Console.Write(rule);
+
+        if (props.Color.HasValue)
+        {
+            Console.Write(AnsiEscapes.ResetAttributes);
+        }
+    }
+}