Add validation to RealmCreate

IdentityShroud.Core/Helpers/SlugHelper.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Globalization;
+using System.Security.Cryptography;
+using System.Text;
+using Microsoft.AspNetCore.WebUtilities;
+
+namespace IdentityShroud.Core.Helpers;
+
+public static class SlugHelper
+{
+    public static string GenerateSlug(string text, int maxLength = 40)
+    {
+        if (string.IsNullOrWhiteSpace(text))
+            return string.Empty;
+
+        // Normalize to decomposed form (separates accents from letters)
+        string normalized = text.Normalize(NormalizationForm.FormD);
+        
+        StringBuilder sb = new StringBuilder(normalized.Length);
+        bool lastWasHyphen = false;
+        
+        foreach (char c in normalized)
+        {
+            // Skip diacritics (accents)
+            if (CharUnicodeInfo.GetUnicodeCategory(c) == UnicodeCategory.NonSpacingMark)
+                continue;
+            
+            char lower = char.ToLowerInvariant(c);
+            
+            // Convert valid characters
+            if ((lower >= 'a' && lower <= 'z') || (lower >= '0' && lower <= '9'))
+            {
+                sb.Append(lower);
+                lastWasHyphen = false;
+            }
+            // Convert spaces, underscores, and other separators to hyphen
+            else if (char.IsWhiteSpace(c) || c == '_' || c == '-')
+            {
+                if (!lastWasHyphen && sb.Length > 0)
+                {
+                    sb.Append('-');
+                    lastWasHyphen = true;
+                }
+            }
+            // Skip all other characters
+        }
+        
+        // Trim trailing hyphen if any
+        if (sb.Length > 0 && sb[sb.Length - 1] == '-')
+            sb.Length--;
+        
+        string slug = sb.ToString();
+        
+        // Handle truncation with hash suffix for long strings
+        if (slug.Length > maxLength)
+        {
+            // Generate hash of original text
+            string hashSuffix = GenerateHashSuffix(text);
+            int contentLength = maxLength - hashSuffix.Length;
+            
+            // Truncate at word boundary if possible
+            int cutPoint = contentLength;
+            int lastHyphen = slug.LastIndexOf('-', contentLength - 1);
+            
+            if (lastHyphen > contentLength / 2)
+                cutPoint = lastHyphen;
+            
+            slug = slug.Substring(0, cutPoint).TrimEnd('-') + hashSuffix;
+        }
+        
+        return slug;
+    }
+    
+    private static string GenerateHashSuffix(string text)
+    {
+        using (var sha256 = SHA256.Create())
+        {
+            byte[] hash = sha256.ComputeHash(Encoding.UTF8.GetBytes(text));
+            
+            // Take first 4 bytes (will become ~5-6 base64url chars)
+            string base64Url = WebEncoders.Base64UrlEncode(hash, 0, 4);
+            return "-" + base64Url;
+        }
+    }
+}