getUserName method Null safety

String? getUserName(
  1. String email

Retrieves the user name based on the specified email address. Returns null in case usernameType is UsernameType.realname or UsernameType.unknown.


String? getUserName(String email) {
  switch (usernameType) {
    case UsernameType.emailAddress:
      return email;
    case UsernameType.emailLocalPart:
      var lastAtIndex = email.lastIndexOf('@');
      if (lastAtIndex == -1) {
        return email;
      return email.substring(lastAtIndex + 1);
    case UsernameType.realname:
    case UsernameType.unknown:
      return null;