Obfuscate emails

main.dart

String safeEmail(String email) {
  final match = RegExp(r"(?<a>.?)(?<x>[^@]*)@(?<b>.)(?<y>.+?)(?<c>\..+)").firstMatch(email);
  
  if (match == null) {
    return email.replaceAll(RegExp(r"."), "*");
  }
  
  var sb = StringBuffer();
  
  sb.write(match.namedGroup("a"));
  sb.write(List.filled(match.namedGroup("x")?.length ?? 1, "*").join(""));  
  sb.write("@");
  sb.write(match.namedGroup("b"));
  sb.write(List.filled(match.namedGroup("y")?.length ?? 1, "*").join(""));  
  sb.write(match.namedGroup("c"));
  
  return sb.toString();
}

void main() {
  final List<String> emails = [
    "john.test@gmail.com",
    "test@gmail.com",
    "test@mail.ru",
    "testmail.ru",
  ];
  
  for (var email in emails) {
    print("${email} => ${safeEmail(email)}");
  }
}