Show a numbered menu on Linux and macOS instead of crashing

FileDeduplicator.Test/MenuTests.cs

@@ -0,0 +1,94 @@
+// Copyright (c) 2023-2026 ktsu-dev contributors
+
+namespace ktsu.FileDeduplicator.Test;
+
+using DustInTheWind.ConsoleTools.Controls;
+using DustInTheWind.ConsoleTools.Controls.Menus;
+
+using ktsu.FileDeduplicator.Verbs;
+
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+/// <summary>
+/// Tests the interactive menu that runs when no verb is given.
+/// </summary>
+/// <remarks>
+/// Input is always redirected here, so these drive the numbered prompt. That prompt is also the
+/// menu on Linux and macOS, where the scrolling menu crashed reading <c>Console.CursorVisible</c>
+/// (ktsu-dev/FileDeduplicator#161).
+/// </remarks>
+[TestClass]
+[DoNotParallelize]
+public sealed class MenuTests
+{
+	[TestMethod]
+	public void MenuListsTheVerbsAndExitsOnZero()
+	{
+		string output = ConsoleCapture.Run(new Menu(), "0\n", out int exitCode);
+
+		Assert.AreEqual(0, exitCode, output);
+		Assert.Contains("Scan - ", output);
+		Assert.Contains("Deduplicate - ", output);
+		Assert.Contains("0. Exit", output);
+		Assert.DoesNotContain("Menu", output, "The menu offered itself.");
+	}
+
+	[TestMethod]
+	public void MenuExitsAtTheEndOfInput()
+	{
+		_ = ConsoleCapture.Run(new Menu(), string.Empty, out int exitCode);
+
+		Assert.AreEqual(0, exitCode);
+	}
+
+	[TestMethod]
+	public void MenuRunsTheChosenVerbAndOffersTheMenuAgain()
+	{
+		// Arrange
+		using TempTree tree = new();
+		_ = tree.Write("a.txt", "alpha");
+		_ = tree.Write("aa.txt", "alpha");
+		Type[] menuVerbs = [.. Program.Verbs.Where(t => t != typeof(Menu))];
+		int scan = Array.IndexOf(menuVerbs, typeof(Scan)) + 1;
+		Assert.IsGreaterThan(0, scan, "Scan is not on the menu.");
+
+		// Act
+		string output = ConsoleCapture.Run(new Menu(), $"{scan}\n{tree.Root.WeakString}\n0\n", out int exitCode);
+
+		// Assert
+		Assert.AreEqual(0, exitCode, output);
+		Assert.Contains("Found 1 group(s) of duplicate files", output);
+		Assert.AreEqual(2, output.Split("0. Exit").Length - 1, "The menu was not offered again after the verb ran.");
+	}
+
+	[TestMethod]
+	public void MenuRejectsAChoiceThatIsNotOnIt()
+	{
+		string output = ConsoleCapture.Run(new Menu(), "42\n0\n", out int exitCode);
+
+		Assert.AreEqual(0, exitCode, output);
+		Assert.Contains("Not an option: 42", output);
+	}
+
+	/// <summary>
+	/// The scrolling menu used in an interactive Windows console has an Exit item whose command ends
+	/// the display loop, so it can be left without Ctrl+C.
+	/// </summary>
+	[TestMethod]
+	public void ScrollMenuHasAnExitItemThatClosesIt()
+	{
+		// Arrange
+		Menu menu = new();
+		ControlRepeater repeater = menu.BuildScrollMenu(out Menu.ExitCommand exit);
+
+		// Act
+		bool requestedBefore = exit.Requested;
+		exit.Execute();
+
+		// Assert
+		Assert.IsInstanceOfType<ScrollMenu>(repeater.Control);
+		Assert.IsTrue(exit.IsActive);
+		Assert.IsFalse(requestedBefore);
+		Assert.IsTrue(exit.Requested);
+	}
+}

FileDeduplicator/Verbs/Menu.cs

@@ -18,6 +18,37 @@ internal sealed class Menu : BaseVerb<Menu>
 	internal override bool ScansADirectory => false;
 
 	internal override void Run(Menu options)
+	{
+		// ScrollMenu reads Console.CursorVisible, whose getter throws PlatformNotSupportedException on
+		// every platform but Windows, and it needs a real keyboard to drive. Elsewhere, and whenever
+		// input is piped in, the menu is a numbered prompt read a line at a time.
+		if (OperatingSystem.IsWindows() && !Console.IsInputRedirected)
+		{
+			RunScrollMenu();
+		}
+		else
+		{
+			RunNumberedMenu();
+		}
+	}
+
+	private Type[] MenuVerbs => [.. Program.Verbs.Where(verb => verb != GetType())];
+
+	private void RunScrollMenu()
+	{
+		ControlRepeater menuRepeater = BuildScrollMenu(out ExitCommand exit);
+		while (!exit.Requested)
+		{
+			menuRepeater.Display();
+		}
+	}
+
+	/// <summary>
+	/// Builds the scrolling menu: one item per verb, then Exit.
+	/// </summary>
+	/// <param name="exit">The Exit item's command, which says when the menu has been left.</param>
+	/// <returns>The repeater that displays the menu until Exit is chosen.</returns>
+	internal ControlRepeater BuildScrollMenu(out ExitCommand exit)
 	{
 		ScrollMenu scrollMenu = new()
 		{
@@ -31,32 +62,84 @@ internal override void Run(Menu options)
 			Control = scrollMenu,
 		};
 
-		LabelMenuItem[] menuItems = [.. Program.Verbs
-			.Where(verb => verb != GetType())
-			.Select(CreateMenuItem)];
+		exit = new(menuRepeater);
+		LabelMenuItem[] menuItems = [.. MenuVerbs.Select(CreateMenuItem)];
 
 		scrollMenu.AddItems(menuItems);
+		scrollMenu.AddItems([new LabelMenuItem() { Text = "Exit", Command = exit, IsEnabled = true }]);
+
+		return menuRepeater;
+	}
+
+	private void RunNumberedMenu()
+	{
+		BaseVerb[] verbs = [.. MenuVerbs.Select(CreateVerb)];
+		string[] texts = [.. MenuVerbs.Select(DescribeVerb)];
 
 		while (true)
 		{
-			menuRepeater.Display();
+			Console.WriteLine();
+			for (int i = 0; i < verbs.Length; i++)
+			{
+				Console.WriteLine($"  {i + 1}. {texts[i]}");
+			}
+
+			Console.WriteLine("  0. Exit");
+			Console.Write("Choose an option: ");
+
+			// End of input is an exit too, so a piped script cannot leave the menu waiting forever.
+			string? input = Console.ReadLine()?.Trim();
+			if (input is null or "0")
+			{
+				return;
+			}
+
+			if (int.TryParse(input, out int choice) && choice >= 1 && choice <= verbs.Length)
+			{
+				verbs[choice - 1].Execute();
+			}
+			else
+			{
+				Console.WriteLine($"Not an option: {input}");
+			}
 		}
 	}
 
-	private static LabelMenuItem CreateMenuItem(Type verbType)
+	private static BaseVerb CreateVerb(Type verbType)
 	{
 		BaseVerb? verb = Activator.CreateInstance(verbType) as BaseVerb;
 		Debug.Assert(verb != null);
+		return verb;
+	}
 
+	private static string DescribeVerb(Type verbType)
+	{
 		string name = verbType.Name;
 		string? helpText = verbType.GetCustomAttribute<VerbAttribute>()?.HelpText;
-		string text = string.IsNullOrEmpty(helpText) ? name : $"{name} - {helpText}";
+		return string.IsNullOrEmpty(helpText) ? name : $"{name} - {helpText}";
+	}
+
+	private static LabelMenuItem CreateMenuItem(Type verbType) => new()
+	{
+		Text = DescribeVerb(verbType),
+		Command = CreateVerb(verbType),
+		IsEnabled = true,
+	};
+
+	/// <summary>
+	/// The menu item that leaves the menu, which otherwise could only be left with Ctrl+C.
+	/// </summary>
+	/// <param name="repeater">The repeater to stop, which otherwise redisplays the menu indefinitely.</param>
+	internal sealed class ExitCommand(ControlRepeater repeater) : ICommand
+	{
+		internal bool Requested { get; private set; }
+
+		public bool IsActive => true;
 
-		return new LabelMenuItem()
+		public void Execute()
 		{
-			Text = text,
-			Command = verb,
-			IsEnabled = true,
-		};
+			Requested = true;
+			repeater.RequestClose();
+		}
 	}
 }

README.md

@@ -30,6 +30,9 @@ Run without arguments to launch the interactive menu:
 FileDeduplicator
 ```
 
+On Windows the menu is navigated with the arrow keys. On Linux and macOS, and whenever input is piped
+in, it is a numbered list: type the number of a command, or `0` to exit.
+
 ### Commands
 
 ```sh