Fixes diactritics regressions

src/Jellyfin.Extensions/StringExtensions.cs

@@ -1,4 +1,8 @@
 using System;
+using System.Diagnostics;
+using System.Globalization;
+using System.Text;
+using System.Text.RegularExpressions;
 
 namespace Jellyfin.Extensions
 {
@@ -7,6 +11,44 @@ namespace Jellyfin.Extensions
     /// </summary>
     public static class StringExtensions
     {
+        // Matches non-conforming unicode chars
+        // https://mnaoumov.wordpress.com/2014/06/14/stripping-invalid-characters-from-utf-16-strings/
+        private static readonly Regex _nonConformingUnicode = new Regex("([\ud800-\udbff](?![\udc00-\udfff]))|((?<![\ud800-\udbff])[\udc00-\udfff])|(\ufffd)");
+
+        /// <summary>
+        /// Removes the diacritics character from the strings.
+        /// </summary>
+        /// <param name="text">The string to act on.</param>
+        /// <returns>The string without diacritics character.</returns>
+        public static string RemoveDiacritics(this string text)
+        {
+            string withDiactritics = _nonConformingUnicode
+                .Replace(text, string.Empty)
+                .Normalize(NormalizationForm.FormD);
+
+            var withoutDiactritics = new StringBuilder();
+            foreach (char c in withDiactritics)
+            {
+                UnicodeCategory uc = CharUnicodeInfo.GetUnicodeCategory(c);
+                if (uc != UnicodeCategory.NonSpacingMark)
+                {
+                    withoutDiactritics.Append(c);
+                }
+            }
+
+            return withoutDiactritics.ToString().Normalize(NormalizationForm.FormC);
+        }
+
+        /// <summary>
+        /// Checks wether or not the specified string has diacritics in it.
+        /// </summary>
+        /// <param name="text">The string to check.</param>
+        /// <returns>True if the string has diacritics, false otherwise.</returns>
+        public static bool HasDiacritics(this string text)
+        {
+            return !string.Equals(text, text.RemoveDiacritics(), StringComparison.Ordinal);
+        }
+
         /// <summary>
         /// Counts the number of occurrences of [needle] in the string.
         /// </summary>