Week 04 Coding in Class Snapshot

Menu.cs

public static class Menu
{
	/// <summary>
	/// Displays a menu of options on the console and waits for the user to make a selection.
	/// </summary>
	/// <param name="x">The x-coordinate of the top-left corner of the menu box.</param>
	/// <param name="y">The y-coordinate of the top-left corner of the menu box.</param>
	/// <param name="items">The options to display in the menu.</param>
	/// <returns>The selected option as a string.</returns>
	public static void Draw(int x, int y, string current, string[] items)
	{
        foreach (var item in items)
        {
            if (item == current)
            {
                Screen.WriteAt(item, x, y++, ConsoleColor.Black, ConsoleColor.White);
            }
            else
            {
                Screen.WriteAt(item, x, y++, ConsoleColor.White, ConsoleColor.Black);
            }
        }
    }
}

Program.cs

using System;

internal class Program
{
    private static async Task Main(string[] args)
    {
        Setup();

        var items = new[] { "Clear the directory", "Create files", "Arrange files" };

        var current = items[0];

        while (true)
        {
            Menu.Draw(0, 0, current, items);

            var key = Console.ReadKey(true).Key;

            if (key == ConsoleKey.UpArrow)
            {
                if (current != items.First())
                {
                    var index = Array.IndexOf(items, current);
                    current = items[index - 1];
                }
            }
            else if (key == ConsoleKey.DownArrow)
            {
                if (current != items.Last())
                {
                    var index = Array.IndexOf(items, current);
                    current = items[index + 1];
                }
            }
            else if (key == ConsoleKey.Enter)
            {
                var l = items.Max(x => x.Length);
                var s = new string(' ', l);

                Screen.WriteAt(s, 0, items.Length, ConsoleColor.White, ConsoleColor.Black);
                Screen.WriteAt(current, 0, items.Length, ConsoleColor.Yellow, ConsoleColor.Blue);
            }
            else
            {
                HandleInvalidKey();
            }

        }

        void HandleInvalidKey()
        {
            var l = items.Max(x => x.Length);
            var s = new string(' ', l);

            Screen.WriteAt(s, 0, items.Length, ConsoleColor.White, ConsoleColor.Black);
            Screen.WriteAt("Invalid selection", 0, items.Length, ConsoleColor.Yellow, ConsoleColor.Blue);
        }

        static void Setup()
        {
            Console.Clear();
            Console.CursorVisible = false;
        }
    }
}

Screen.cs

public static class Screen
{
	/// <summary>
	/// Writes the text to the console at the specified (x, y) position, with optional foreground and background colors.
	/// </summary>
	/// <param name="text">The text to write to the console.</param>
	/// <param name="x">The x-coordinate of the position to write the text.</param>
	/// <param name="y">The y-coordinate of the position to write the text.</param>
	/// <param name="foreground">The foreground color to use for the text. If not specified, the current foreground color will be used.</param>
	/// <param name="background">The background color to use for the text. If not specified, the current background color will be used.</param>
	public static void WriteAt(this string text, int x, int y, ConsoleColor? foreground = null, ConsoleColor? background = null)
	{
		if (foreground is null)
		{
			foreground = ConsoleColor.White;
		}

        Console.ForegroundColor = foreground.Value;

        Console.BackgroundColor = background ?? ConsoleColor.Black;

        Console.SetCursorPosition(left: x, top: y);

        Console.WriteLine(text);

        Console.ResetColor();
    }

	/// <summary>
	/// Listens for a keystroke from the user and returns the first allowed key that is pressed.
	/// </summary>
	/// <param name="allowed">An array of allowed keys to listen for.</param>
	/// <param name="key">The first allowed key that was pressed by the user.</param>
	public static void Listen(this ConsoleKey[] allowed, out ConsoleKey key)
	{
		throw new NotImplementedException();
	}
}

What would that if-then statement look like as a case statement?

    switch (key)
    {
        case ConsoleKey.UpArrow when current != items.First():
            {
                var index = Array.IndexOf(items, current);
                current = items[index - 1];
                break;
            }
        case ConsoleKey.DownArrow when current != items.Last():
            {
                var index = Array.IndexOf(items, current);
                current = items[index + 1];
                break;
            }
        case ConsoleKey.Enter:
            {
                var l = items.Max(x => x.Length);
                var s = new string(' ', l);

                Screen.WriteAt(s, 0, items.Length, ConsoleColor.White, ConsoleColor.Black);
                Screen.WriteAt(current, 0, items.Length, ConsoleColor.Yellow, ConsoleColor.Blue);
                     
                break;
            }
        default:
            HandleInvalidKey();
            break;
    }

Here's another interesting approach that accomplishes the same thing using switch expressions.

    current = key switch
    {
        ConsoleKey.UpArrow when current != items.First() => items[Array.IndexOf(items, current) - 1],
        ConsoleKey.DownArrow when current != items.Last() => items[Array.IndexOf(items, current) + 1],
        _ => current,
    };

    if (key == ConsoleKey.Enter)
    {
        var l = items.Max(x => x.Length);
        var s = new string(' ', l);

        Screen.WriteAt(s, 0, items.Length, ConsoleColor.White, ConsoleColor.Black);
        Screen.WriteAt(current, 0, items.Length, ConsoleColor.Yellow, ConsoleColor.Blue);
    }

To help you out, here's a first draft at Box.Draw().

    public static void Draw(this Rectangle rect, char fill = ' ')
    {
        // Character reference: ┌ ─ ┐ │ └ ─ ┘

        var top = $"┌{new string('─', rect.Width)}┐";
        Screen.WriteAt(top, rect.Left, rect.Top);

        // TODO: middle

        var bottom = $"└{new string('─', rect.Width)}┘";
        Screen.WriteAt(top, rect.Left, rect.Top + rect.Height);
    }

If you want to rewrite the signature to not use Rectangle, you can do that.

    public static void Draw(int x, int y, int height, int width, char fill = ' ')