ansi-fahrplan/UiElements/TopMenu.cs

using SCI.CursesWrapper;
using Mindmagma.Curses;

namespace ANSI_Fahrplan.UiElements;

public class TopMenu : UiElement {
	private List<MenuItem> _menuItems = new List<MenuItem> ();
	public List<MenuItem> MenuItems {
		get {
			return _menuItems;
		}
		set {
			UnregisterItemEventHandlers ();
			_menuItems = value;
			RegisterItemEventHandlers ();
			DrawMenu ();
		}
	}

	private MenuItem? activeMenuItem;

	public TopMenu (nint screen, List<MenuItem> menuItems) : base (screen) {
		NCurses.GetMaxYX (screen, out _, out int width);		
		innerWindow = NCurses.NewWindow (1, width, 0, 0);
		
		var colorSchemeNormal = ColorSchemes.TopMenuNormal ();
		NCurses.WindowBackground (innerWindow, colorSchemeNormal);
		NCurses.WindowAttributeOn (innerWindow, colorSchemeNormal);

		MenuItems = menuItems;
	}

	/// <summary>
	/// Register key event handlers for each menu item
	/// </summary>
	private void RegisterItemEventHandlers () {
		foreach (var item in MenuItems) {
			item.OnItemActivated += ItemActivatedHandler;
			item.RegisterKeyHandler ();
		}
	}

	/// <summary>
	/// Unregister key event handlers for each menu item
	/// </summary>
	private void UnregisterItemEventHandlers () {
		foreach (var item in MenuItems) {
			item.OnItemActivated -= ItemActivatedHandler;
			item.UnregisterKeyHandler ();
		}
	}

	/// <summary>
	/// Event handler to update menu interface when item reports itself as activated
	/// </summary>
	/// <param name="sender">Sender Menu Item firing the event</param>
	/// <param name="e">Event arguments</param>
	private void ItemActivatedHandler (object? sender, EventArgs e) {
		if (sender is null) return;

		activeMenuItem = (MenuItem) sender;
		DrawMenu ();
	}

	/// <summary>
	/// Draw the top menu with currently configured menu items
	/// </summary>
	private void DrawMenu () {
		NCurses.ClearWindow (innerWindow);

		var normalColor = ColorSchemes.TopMenuNormal ();
		var activeColor = ColorSchemes.TopMenuActive ();

		foreach (var item in MenuItems) {
			var itemIsActive = item == activeMenuItem;
			var itemString = " ";

			if (itemIsActive) {
				itemString = "[";
				NCurses.WindowAttributeOff (innerWindow, normalColor);
				NCurses.WindowAttributeOn (innerWindow, activeColor);
			}
			
			itemString += $"{item.Label}";

			if (item.Key is not null) {
				itemString += $" ({item.Key})";
			}

			if (itemIsActive) {
				NCurses.WindowAttributeOff (innerWindow, activeColor);
				NCurses.WindowAttributeOn (innerWindow, normalColor);
				itemString += "] ";
			} else {
				itemString += "  ";
			}

			NCurses.WindowAddString (innerWindow, itemString);
		}

		NCurses.Refresh ();
		NCurses.WindowRefresh (innerWindow);
	}

	public void Refresh () {
		DrawMenu ();
	}
}