feat: initial 6-character HID rework

PluralKit.Core/Database/Utils/HidUtils.cs

@@ -0,0 +1,35 @@
+using System.Linq;
+using System.Text.RegularExpressions;
+
+namespace PluralKit.Core;
+
+public static class HidUtils
+{
+    private static readonly Regex _hidRegex = new(@"^[a-zA-Z]{5,6}$");
+
+    public static string? ParseHid(string input)
+    {
+        input = input.ToLower().Replace("-", null);
+        if (!_hidRegex.IsMatch(input))
+            return null;
+
+        return input;
+    }
+
+    public static bool TryParseHid(this string input, out string hid)
+    {
+        hid = ParseHid(input);
+        return hid != null;
+    }
+
+    public static string HidTransform(string input, bool split = false)
+    {
+        if (split && input.Length > 5)
+        {
+            var len = (int)Math.Floor(input.Length / 2.0);
+            input = string.Concat(input.AsSpan(0, len), "-", input.AsSpan(len));
+        }
+
+        return input;
+    }
+}