enum JlptLevel implements Comparable<JlptLevel> {
  none,
  n1,
  n2,
  n3,
  n4,
  n5;

  factory JlptLevel.fromString(String? level) {
    switch (level?.toUpperCase()) {
      case 'N1':
        return JlptLevel.n1;
      case 'N2':
        return JlptLevel.n2;
      case 'N3':
        return JlptLevel.n3;
      case 'N4':
        return JlptLevel.n4;
      case 'N5':
        return JlptLevel.n5;
      default:
        return JlptLevel.none;
    }
  }

  String? toNullableString() {
    switch (this) {
      case JlptLevel.n1:
        return 'N1';
      case JlptLevel.n2:
        return 'N2';
      case JlptLevel.n3:
        return 'N3';
      case JlptLevel.n4:
        return 'N4';
      case JlptLevel.n5:
        return 'N5';
      case JlptLevel.none:
        return null;
    }
  }

  int? get asInt =>
      this == JlptLevel.none ? null : JlptLevel.values.indexOf(this);

  @override
  String toString() => toNullableString() ?? 'N/A';

  Object? toJson() => toNullableString();

  factory JlptLevel.fromJson(Object? json) =>
      JlptLevel.fromString(json as String?);

  @override
  int compareTo(JlptLevel other) => index - other.index;
}