import 'school_identity.dart';

/// School-specific term numbers, independent of teaching-week dates.
class SchoolTerm {
  SchoolTerm(this.id, {this.school = SupportedSchool.uestcGraduate}) {
    if (id < 1 || id > 9999 ||
        (school == SupportedSchool.uestcUndergraduate && (id < 3 || (id-3)%20 != 0))) {
      throw ArgumentError('学校学期编号无效');
    }
  }
  final int id;
  final SupportedSchool school;
  String get label {
    if (school == SupportedSchool.uestcUndergraduate) {
      final n = (id - 3) ~/ 20, year = 2013 + ((id - 3) ~/ 40);
      return '$year-${year+1}${n.isEven ? '第一学期' : '第二学期'}';
    }
    final year = 1990 + ((id - 1) ~/ 2);
    return '$year-${year + 1}年${id.isOdd ? '秋' : '春'}';
  }

  static List<SchoolTerm> get choices =>
      List.generate(73, (index) => SchoolTerm(73 - index));
  static List<SchoolTerm> undergraduateChoices(DateTime now, {SchoolTerm? saved}) {
    final maxN = (now.year + 1 - 2013)*2+1;
    final ids = {for(var n=0;n<=maxN;n++) 3+n*20,
      if(saved?.school == SupportedSchool.uestcUndergraduate) saved!.id}.toList()
        ..sort((a,b)=>b.compareTo(a));
    return ids.where((id)=>id<=9999).map((id)=>SchoolTerm(id,school:SupportedSchool.uestcUndergraduate)).toList();
  }
  void _graduateOnly() {
    if (school != SupportedSchool.uestcGraduate) throw StateError('本科查询不能使用研究生链接');
  }
  Uri get timetableUri {
    _graduateOnly();
    return Uri.https('yjsjy.uestc.edu.cn', '/pyxx/pygl/xskbcx/index/$id');
  }
  Uri get examUri {
    _graduateOnly();
    return Uri.https('yjsjy.uestc.edu.cn', '/pyxx/pygl/kskcxx/index', {'xq': '$id'});
  }
  Map<String, dynamic> toJson() => {'id': id, 'schoolId': school.id};
  factory SchoolTerm.fromJson(Map<String, dynamic> json) {
    if (json['id'] is! int) throw const FormatException('学校学期无效');
    try {
      return SchoolTerm(json['id'] as int, school: json['schoolId'] == null
          ? SupportedSchool.uestcGraduate : SupportedSchool.fromId(json['schoolId'] as String));
    } catch (_) { throw const FormatException('学校学期无效'); }
  }
  @override
  bool operator ==(Object other) => other is SchoolTerm && other.id == id && other.school == school;
  @override
  int get hashCode => Object.hash(id, school);
}