🚧 Core improvements

Core/Extensions/UserExtension.cs

@@ -0,0 +1,21 @@
+using System.Text;
+using Telegram.Bot.Types;
+
+namespace Kruzya.TelegramBot.Core.Extensions
+{
+    public static class UserExtension
+    {
+        public static string ToHtml(this User user)
+        {
+            var text = new StringBuilder();
+            text.Append("<a href=\"tg://user?id={member.Id}\">");
+            if (!string.IsNullOrWhiteSpace(user.Username))
+                text.Append(user.Username);
+            else
+                text.Append($"{user.FirstName} {user.LastName}".Trim().HtmlEncode());
+            text.Append("</a>");
+
+            return text.ToString();
+        }
+    }
+}