/// The graduate system's term number, independent of teaching-week dates.
class SchoolTerm {
  SchoolTerm(this.id) {
    if (id < 1 || id > 9999) throw ArgumentError('学校学期编号无效');
  }
  final int id;
  String get label {
    final year = 1990 + ((id - 1) ~/ 2);
    return '$year-${year + 1}年${id.isOdd ? '秋' : '春'}';
  }

  static List<SchoolTerm> get choices =>
      List.generate(73, (index) => SchoolTerm(73 - index));
  Uri get timetableUri =>
      Uri.https('yjsjy.uestc.edu.cn', '/pyxx/pygl/xskbcx/index/$id');
  Uri get examUri =>
      Uri.https('yjsjy.uestc.edu.cn', '/pyxx/pygl/kskcxx/index', {'xq': '$id'});
  Map<String, dynamic> toJson() => {'id': id};
  factory SchoolTerm.fromJson(Map<String, dynamic> json) {
    if (json['id'] is! int) throw const FormatException('学校学期无效');
    return SchoolTerm(json['id'] as int);
  }
  @override
  bool operator ==(Object other) => other is SchoolTerm && other.id == id;
  @override
  int get hashCode => id.hashCode;
}