Create a (Discord)Color using a string (#2979)

* Create a (Discord)Color using a string

* You made me learn bitwise operators and shifting I am angery now, also AI sucks at this shit

* xmldoc

* Apply suggestions from code review

---------

Co-authored-by: Mihail Gribkov <61027276+Misha-133@users.noreply.github.com>

src/Discord.Net.Core/Entities/Roles/Color.cs

@@ -200,6 +200,94 @@ namespace Discord
         public static implicit operator uint(Color color)
             => color.RawValue;
 
+        /// <summary>
+        ///     Converts the string representation of a color to a Color object.
+        /// </summary>
+        /// <param name="rawValue">String to be parsed to a color</param>
+        /// <param name="colorType">Color format of the string</param>
+        /// <returns>A Color object with a color value parsed from a string</returns>
+        /// <exception cref="ArgumentOutOfRangeException">The argument is not a number or of incorrect length</exception>
+        public static Color Parse(string rawValue, ColorType colorType = ColorType.CssHexColor)
+        {
+            if (TryParse(rawValue, out var color, colorType))
+                return color;
+
+            throw new ArgumentOutOfRangeException(nameof(rawValue), "Value must be a number of valid length - matching the specified ColorType");
+        }
+
+        /// <summary>
+        ///     Converts the string representation of a color to a Color object. The return value indicates whether the conversion succeeded.
+        /// </summary>
+        /// <param name="rawValue">String to be parsed to a color</param>
+        /// <param name="color">When this method returns true, contains a Color that represents the parsed string.</param>
+        /// <param name="colorType">Color format of the string</param>
+        /// <returns>true if the conversion succeeded; false otherwise.</returns>
+        public static bool TryParse(string rawValue, out Color color, ColorType colorType = ColorType.CssHexColor)
+        {
+            color = new Color();
+
+            if (string.IsNullOrWhiteSpace(rawValue))
+                return false;
+            
+            rawValue = rawValue.TrimStart('#');
+
+            if (rawValue.StartsWith("0x"))
+                rawValue = rawValue.Substring(2);
+
+            if (!uint.TryParse(rawValue, System.Globalization.NumberStyles.HexNumber, null, out var parsedValue))
+                return false;
+
+            uint r;
+            uint g;
+            uint b;
+            uint fullHex;
+
+            switch (rawValue.Length, colorType)
+            {
+                case (3, ColorType.CssHexColor):
+                    r = parsedValue >> 8;
+                    g = (parsedValue & 0xF0) >> 4;
+                    b = parsedValue & 0xF;
+
+                    r = (r << 4) | r;
+                    g = (g << 4) | g;
+                    b = (b << 4) | b;
+
+                    fullHex = (r << 16) | (g << 8) | b;
+
+                    break;
+                
+                case (4, ColorType.CssHexColor):
+                    r = (parsedValue & 0xF00) >> 8;
+                    g = (parsedValue & 0xF0) >> 4;
+                    b = parsedValue & 0xF;
+
+                    r = (r << 4) | r;
+                    g = (g << 4) | g;
+                    b = (b << 4) | b;
+
+                    fullHex = (r << 16) | (g << 8) | b;
+
+                    break;
+
+                case (6, ColorType.CssHexColor):
+                    color = new Color(parsedValue);
+                    return true;
+
+                case (8, ColorType.CssHexColor):
+                    parsedValue &= 0xFFFFFF;
+                    color = new Color(parsedValue);
+                    return true;
+
+                default:
+                    return false;
+            }
+
+            color = new Color(fullHex);
+            
+            return true;
+        }
+
         public override bool Equals(object obj)
             => obj is Color c && RawValue == c.RawValue;
 

src/Discord.Net.Core/Entities/Roles/ColorType.cs

@@ -0,0 +1,21 @@
+using System;
+
+namespace Discord;
+
+public enum ColorType
+{
+    /// <summary>
+    ///     Color in one of the following formats.
+    /// <para>
+    ///     #RGB        The three-value syntax
+    /// </para>
+    /// <para>
+    ///     #RGBA       The four-value syntax
+    /// </para>
+    /// <para>
+    ///     #RRGGBB     The six-value syntax
+    /// </para>
+    ///     #RRGGBBAA   The eight-value syntax
+    /// </summary>
+    CssHexColor = 0
+}

test/Discord.Net.Tests.Unit/ColorTests.cs

@@ -74,6 +74,26 @@ namespace Discord
             Assert.Throws<ArgumentOutOfRangeException>(() => new Color(2.0f, 2.0f, 2.0f));
         }
         [Fact]
+        public void Color_FromRgb_String_CssHexColor()
+        {
+            Assert.Equal(0xFF0000u, Color.Parse("#F00", ColorType.CssHexColor).RawValue);
+            Assert.Equal(0x22BB44u, Color.Parse("#2B4", ColorType.CssHexColor).RawValue);
+            Assert.Equal(0xAABBAAu, Color.Parse("FABA", ColorType.CssHexColor).RawValue);
+            Assert.Equal(0x00F672u, Color.Parse("00F672", ColorType.CssHexColor).RawValue);
+            Assert.Equal(0x257777u, Color.Parse("0xFF257777", ColorType.CssHexColor).RawValue);
+        }
+        [Fact]
+        public void Color_FromRgb_String_Invalid()
+        {
+            Assert.Throws<ArgumentOutOfRangeException>(() => Color.Parse(" ", ColorType.CssHexColor));
+            Assert.Throws<ArgumentOutOfRangeException>(() => Color.Parse(null, ColorType.CssHexColor));
+            Assert.Throws<ArgumentOutOfRangeException>(() => Color.Parse("#F"));
+            Assert.Throws<ArgumentOutOfRangeException>(() => Color.Parse("F0", ColorType.CssHexColor));
+            Assert.Throws<ArgumentOutOfRangeException>(() => Color.Parse("FF000"));
+            Assert.Throws<ArgumentOutOfRangeException>(() => Color.Parse("FF00000"));
+            Assert.Throws<ArgumentOutOfRangeException>(() => Color.Parse("FF0000000"));
+        }
+        [Fact]
         public void Color_Red()
         {
             Assert.Equal(0xAF, new Color(0xAF1390).R);