gui-cs.Terminal.Gui/UnitTests/Drawing/ColorTests.ParsingAndFormatting.cs

#nullable enable
using System.Buffers.Binary;
using System.Globalization;

namespace Terminal.Gui.DrawingTests;

public partial class ColorTests {
	[Fact]
	public void Color_ToString_WithNamedColor ()
	{
		// Arrange
		var color = new Color (0, 55, 218); // Blue

		// Act
		var colorString = color.ToString ();

		// Assert
		Assert.Equal ("Blue", colorString);
	}

	[Fact]
	public void Color_ToString_WithRGBColor ()
	{
		// Arrange
		var color = new Color (1, 64, 32); // Custom RGB color

		// Act
		var colorString = color.ToString ();

		// Assert
		Assert.Equal ("#014020", colorString);
	}

	[Theory]
	[CombinatorialData]
	public void Parse_And_ToString_RoundTrip_For_Known_FormatStrings ([CombinatorialValues (null, "", "g", "G", "d", "D")] string formatString, [CombinatorialValues (0, 64, 255)] byte r, [CombinatorialValues (0, 64, 255)] byte g, [CombinatorialValues (0, 64, 255)] byte b)
	{
		Color constructedColor = new (r, g, b, 255);

		// Pre-conditions for the rest of the test to be valid
		Assert.Equal (r, constructedColor.R);
		Assert.Equal (g, constructedColor.G);
		Assert.Equal (b, constructedColor.B);
		Assert.Equal (255, constructedColor.A);

		//Get the ToString result with the specified format string
		string formattedColorString = constructedColor.ToString (formatString);

		// Now parse that string
		Color parsedColor = Color.Parse (formattedColorString);

		// They should have identical underlying values
		Assert.Equal (constructedColor.Argb, parsedColor.Argb);
	}

	[Theory]
	[CombinatorialData]
	public void ToString_WithInvariantCultureAndNullString_IsSameAsParameterless ([CombinatorialValues (0, 64, 128, 255)] byte r, [CombinatorialValues (0, 64, 128, 255)] byte g, [CombinatorialValues (0, 64, 128, 255)] byte b)
	{
		string expected = $"#{r:X2}{g:X2}{b:X2}";
		Color testColor = new (r, g, b);

		string testStringWithExplicitInvariantCulture = testColor.ToString (null, CultureInfo.InvariantCulture);
		Assert.Equal (expected, testStringWithExplicitInvariantCulture);


		string parameterlessToStringValue = testColor.ToString ();
		Assert.Equal (parameterlessToStringValue, testStringWithExplicitInvariantCulture);
	}

	[Theory]
	[MemberData (nameof (ColorTestsTheoryDataGenerators.TryParse_string_Returns_False_For_Invalid_Inputs), MemberType = typeof (ColorTestsTheoryDataGenerators))]
	public void TryParse_string_Returns_False_For_Invalid_Inputs (string input)
	{
		bool tryParseStatus = Color.TryParse (input, out Color? color);
		Assert.False (tryParseStatus);
		Assert.Null (color);
	}

	[Theory]
	[MemberData (nameof (ColorTestsTheoryDataGenerators.TryParse_string_Returns_True_For_Valid_Inputs), MemberType = typeof (ColorTestsTheoryDataGenerators))]
	public void TryParse_string_Returns_True_For_Valid_Inputs (string input, int expectedColorArgb)
	{
		bool tryParseStatus = Color.TryParse (input, out Color? color);
		Assert.True (tryParseStatus);
		Assert.NotNull (color);
		Assert.IsType<Color> (color);
		Assert.Equal (expectedColorArgb, color.Value.Rgba);
	}
}
public static partial class ColorTestsTheoryDataGenerators {
	public static TheoryData<string?> TryParse_string_Returns_False_For_Invalid_Inputs ()
	{
		TheoryData<string?> values = [
			null
		];
		for ( char i = char.MinValue; i < 255; i++ ) {
			if ( !char.IsAsciiDigit (i) ) {
				values.Add ($"rgb({i},{i},{i})");
				values.Add ($"rgba({i},{i},{i})");
			}
			if ( !char.IsAsciiHexDigit (i) ) {
				values.Add ($"#{i}{i}{i}{i}{i}{i}");
				values.Add ($"#{i}{i}{i}{i}{i}{i}{i}{i}");
			}
		}
		//Also throw in a couple of just badly formatted strings
		values.Add ("rgbaa(1,2,3,4))");
		values.Add ("#rgb(1,FF,3,4)");
		values.Add ("rgb(1,FF,3,4");
		values.Add ("rgb(1,2,3,4.5))");
		return values;
	}
	public static TheoryData<string?, int> TryParse_string_Returns_True_For_Valid_Inputs ()
	{
		TheoryData<string?, int> values = [];
		for ( byte i = 16; i < 224; i += 32 ) {
			// Using this so the span only has to be written one way.
			int expectedRgb = BinaryPrimitives.ReadInt32LittleEndian ([(byte)(i + 16), i, (byte)(i - 16), 255]);
			int expectedRgba = BinaryPrimitives.ReadInt32LittleEndian ([(byte)(i + 16), i, (byte)(i - 16), i]);
			values.Add ($"rgb({i - 16:D},{i:D},{i + 16:D})", expectedRgb);
			values.Add ($"rgb({i - 16:D},{i:D},{i + 16:D},{i:D})", expectedRgba);
			values.Add ($"rgb({i - 16:D},{i:D},{i + 16:D})", expectedRgb);
			values.Add ($"rgba({i - 16:D},{i:D},{i + 16:D},{i:D})", expectedRgba);
			values.Add ($"#{i - 16:X2}{i:X2}{i + 16:X2}", expectedRgb);
			values.Add ($"#{i:X2}{i - 16:X2}{i:X2}{i + 16:X2}", expectedRgba);
		}
		for ( byte i = 1; i < 0xE; i++ ) {
			values.Add ($"#{i - 1:X0}{i:X0}{i + 1:X0}", BinaryPrimitives.ReadInt32LittleEndian (
			[
				// Have to stick the least significant 4 bits in the most significant 4 bits to duplicate the hex values
				// Breaking this out just so it's easier to see.
				(byte)(i + 1 | i + 1 << 4),
				(byte)(i | i << 4),
				(byte)(i - 1 | i - 1 << 4),
				255
			]));
			values.Add ($"#{i:X0}{i - 1:X0}{i:X0}{i + 1:X0}", BinaryPrimitives.ReadInt32LittleEndian (
			[
				(byte)(i + 1 | i + 1 << 4),
				(byte)(i | i << 4),
				(byte)(i - 1 | i - 1 << 4),
				(byte)(i | i << 4)
			]));
		}
		return values;
	}
}