chore: import upstream snapshot with attribution

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

@@ -0,0 +1,101 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Harness.ConsoleReactiveFramework;
+
+namespace Harness.ConsoleReactiveComponents;
+
+/// <summary>
+/// Props for <see cref="TextInput"/>.
+/// </summary>
+public record TextInputProps : ConsoleReactiveProps
+{
+    /// <summary>Gets the prompt string displayed on the left (e.g. "&gt; " or "user &gt; ").</summary>
+    public string Prompt { get; init; } = "> ";
+
+    /// <summary>Gets the text content to render to the right of the prompt.</summary>
+    public string Text { get; init; } = "";
+
+    /// <summary>Gets the placeholder text shown in dark grey when <see cref="Text"/> is empty.</summary>
+    public string Placeholder { get; init; } = "";
+}
+
+/// <summary>
+/// A component that renders a prompt with text input. Supports multi-line text
+/// where continuation lines are indented to align with the text start position
+/// (i.e. the column after the prompt).
+/// </summary>
+public class TextInput : ConsoleReactiveComponent<TextInputProps, ConsoleReactiveState>
+{
+    /// <summary>
+    /// Calculates the height (in rows) required to render the prompt and text
+    /// given the available width.
+    /// </summary>
+    /// <param name="props">The text input props.</param>
+    /// <param name="availableWidth">The total available width in columns.</param>
+    /// <returns>The number of rows needed.</returns>
+    public static int CalculateHeight(TextInputProps props, int availableWidth)
+    {
+        int promptLength = props.Prompt.Length;
+        int textWidth = availableWidth - promptLength;
+
+        if (textWidth <= 0 || props.Text.Length == 0)
+        {
+            return 1;
+        }
+
+        int lines = 1;
+        int remaining = props.Text.Length - textWidth;
+        while (remaining > 0)
+        {
+            lines++;
+            remaining -= textWidth;
+        }
+
+        return lines;
+    }
+
+    /// <inheritdoc />
+    public override void RenderCore(TextInputProps props, ConsoleReactiveState state)
+    {
+        int promptLength = props.Prompt.Length;
+        int textWidth = props.Width - promptLength;
+        string indent = new(' ', promptLength);
+
+        // First line: prompt + start of text
+        Console.Write(AnsiEscapes.MoveCursor(props.Y, props.X));
+        Console.Write(AnsiEscapes.EraseEntireLine);
+        Console.Write(props.Prompt);
+
+        if (textWidth <= 0 || props.Text.Length == 0)
+        {
+            // Show placeholder if text is empty
+            if (props.Text.Length == 0 && props.Placeholder.Length > 0 && textWidth > 0)
+            {
+                Console.Write(AnsiEscapes.SetForegroundColor(ConsoleColor.DarkGray));
+                Console.Write(" ");
+                Console.Write(props.Placeholder[..Math.Min(props.Placeholder.Length, textWidth - 1)]);
+                Console.Write(AnsiEscapes.ResetAttributes);
+            }
+
+            return;
+        }
+
+        int offset = 0;
+        int firstChunk = Math.Min(textWidth, props.Text.Length);
+        Console.Write(props.Text[offset..firstChunk]);
+        offset = firstChunk;
+
+        // Continuation lines: indented to align with text start
+        int row = 1;
+        while (offset < props.Text.Length)
+        {
+            int chunk = Math.Min(textWidth, props.Text.Length - offset);
+            Console.Write(AnsiEscapes.MoveCursor(props.Y + row, props.X));
+            Console.Write(AnsiEscapes.EraseEntireLine);
+            Console.Write(indent);
+            Console.Write(props.Text[offset..(offset + chunk)]);
+            offset += chunk;
+            row++;
+        }
+    }
+}