gui-cs.Terminal.Gui/Terminal.Gui/Drawing/ColorExtensions.cs

using System.Collections.Frozen;

namespace Terminal.Gui;

internal static class ColorExtensions {

	static FrozenDictionary<Color, ColorName> colorToNameMap;

	static ColorExtensions ()
	{
		Dictionary<ColorName, AnsiColorCode> nameToCodeMap = new () {
			{ ColorName.Black, AnsiColorCode.BLACK },
			{ ColorName.Blue, AnsiColorCode.BLUE },
			{ ColorName.Green, AnsiColorCode.GREEN },
			{ ColorName.Cyan, AnsiColorCode.CYAN },
			{ ColorName.Red, AnsiColorCode.RED },
			{ ColorName.Magenta, AnsiColorCode.MAGENTA },
			{ ColorName.Yellow, AnsiColorCode.YELLOW },
			{ ColorName.Gray, AnsiColorCode.WHITE },
			{ ColorName.DarkGray, AnsiColorCode.BRIGHT_BLACK },
			{ ColorName.BrightBlue, AnsiColorCode.BRIGHT_BLUE },
			{ ColorName.BrightGreen, AnsiColorCode.BRIGHT_GREEN },
			{ ColorName.BrightCyan, AnsiColorCode.BRIGHT_CYAN },
			{ ColorName.BrightRed, AnsiColorCode.BRIGHT_RED },
			{ ColorName.BrightMagenta, AnsiColorCode.BRIGHT_MAGENTA },
			{ ColorName.BrightYellow, AnsiColorCode.BRIGHT_YELLOW },
			{ ColorName.White, AnsiColorCode.BRIGHT_WHITE }
		};
		ColorNameToAnsiColorMap = nameToCodeMap.ToFrozenDictionary ();

		ColorToNameMap = new Dictionary<Color, ColorName> {
			// using "Windows 10 Console/PowerShell 6" here: https://i.stack.imgur.com/9UVnC.png
			// See also: https://en.wikipedia.org/wiki/ANSI_escape_code
			{ new Color (12, 12, 12), ColorName.Black },
			{ new Color (0, 55, 218), ColorName.Blue },
			{ new Color (19, 161, 14), ColorName.Green },
			{ new Color (58, 150, 221), ColorName.Cyan },
			{ new Color (197, 15, 31), ColorName.Red },
			{ new Color (136, 23, 152), ColorName.Magenta },
			{ new Color (128, 64, 32), ColorName.Yellow },
			{ new Color (204, 204, 204), ColorName.Gray },
			{ new Color (118, 118, 118), ColorName.DarkGray },
			{ new Color (59, 120, 255), ColorName.BrightBlue },
			{ new Color (22, 198, 12), ColorName.BrightGreen },
			{ new Color (97, 214, 214), ColorName.BrightCyan },
			{ new Color (231, 72, 86), ColorName.BrightRed },
			{ new Color (180, 0, 158), ColorName.BrightMagenta },
			{ new Color (249, 241, 165), ColorName.BrightYellow },
			{ new Color (242, 242, 242), ColorName.White }
		}.ToFrozenDictionary ();
	}

	/// <summary>Defines the 16 legacy color names and their corresponding ANSI color codes.</summary>
	internal static FrozenDictionary<ColorName, AnsiColorCode> ColorNameToAnsiColorMap { get; }

	/// <summary>
	///   Gets or sets a <see cref="FrozenDictionary{TKey,TValue}" /> that maps legacy 16-color values to the corresponding
	///   <see cref="ColorName" />.
	/// </summary>
	/// <remarks>
	///   Setter should be called as infrequently as possible, as <see cref="FrozenDictionary{TKey,TValue}" /> is expensive to create.
	/// </remarks>
	internal static FrozenDictionary<Color, ColorName> ColorToNameMap {
		get => colorToNameMap;
		set {
			colorToNameMap = value;
			//Also be sure to set the reverse mapping
			ColorNameToColorMap = value.ToFrozenDictionary (static kvp => kvp.Value, static kvp => kvp.Key);
		}
	}

	/// <summary>Reverse mapping for <see cref="ColorToNameMap" />.</summary>
	internal static FrozenDictionary<ColorName, Color> ColorNameToColorMap { get; private set; }
}