import 'package:flutter_test/flutter_test.dart';
import 'package:timezone/data/latest.dart' as tzdata;
import 'package:hepan_everyday/domain/schedule_engine.dart';

Course course({
  String id = 'math',
  int day = 3,
  int first = 1,
  int last = 1,
  Set<int> weeks = const {1},
}) => Course(
  id: id,
  name: '矩阵论',
  teacher: '示例教师',
  room: '示例教室',
  weekday: day,
  startPeriod: first,
  endPeriod: last,
  weeks: weeks,
  source: CourseSource.file,
);

void main() {
  setUpAll(tzdata.initializeTimeZones);
  final term = Semester(startDate: DateTime(2026, 9, 9), totalWeeks: 5);
  test(
    'all eleven lessons produce the specified Shanghai start and end times',
    () {
      const starts = [
        510,
        560,
        620,
        670,
        870,
        920,
        980,
        1030,
        1170,
        1220,
        1270,
      ];
      const ends = [555, 605, 665, 715, 915, 965, 1025, 1075, 1215, 1265, 1315];
      for (var p = 1; p <= 11; p++) {
        final result = ScheduleEngine.occurrences([
          course(first: p, last: p),
        ], term);
        expect(result, hasLength(1));
        expect(
          result.single.start.hour * 60 + result.single.start.minute,
          starts[p - 1],
        );
        expect(
          result.single.end.hour * 60 + result.single.end.minute,
          ends[p - 1],
        );
      }
    },
  );
  test('term beginning Wednesday suppresses earlier Monday', () {
    expect(
      ScheduleEngine.occurrences([
        course(day: 1, weeks: {1, 2}),
      ], term).map((e) => e.start.day).toList(),
      [14],
    );
    expect(ScheduleEngine.weekNumber(term, DateTime(2026, 9, 9)), 1);
    expect(ScheduleEngine.weekNumber(term, DateTime(2026, 9, 14)), 2);
    expect(ScheduleEngine.weekNumber(term, DateTime(2026, 10, 12)), isNull);
  });
  test('odd and nonconsecutive weeks create only matching dates', () {
    expect(
      ScheduleEngine.occurrences([
        course(weeks: {1, 3, 5}),
      ], term).map((e) => '${e.start.month}/${e.start.day}').toList(),
      ['9/9', '9/23', '10/7'],
    );
  });
  test('Sunday and consecutive periods use one correct occurrence', () {
    final events = ScheduleEngine.occurrences([
      course(day: 7, first: 2, last: 3),
    ], term);
    expect(events, hasLength(1));
    expect(events.single.start.day, 13);
    expect(events.single.start.hour, 9);
    expect(events.single.start.minute, 20);
    expect(events.single.end.hour, 11);
    expect(events.single.end.minute, 5);
  });
  test(
    'school lesson time has a fixed UTC instant regardless of device zone',
    () {
      final events = ScheduleEngine.occurrences([course()], term);
      expect(events, hasLength(1));
      expect(events.single.start.toUtc(), DateTime.utc(2026, 9, 9, 0, 30));
    },
  );
  test('overlap keeps simultaneous courses but excludes adjacent courses', () {
    final events = ScheduleEngine.occurrences([
      course(id: 'a', first: 1, last: 2),
      course(id: 'b', first: 2, last: 3),
      course(id: 'c', first: 4, last: 4),
    ], term);
    expect(events, hasLength(3));
    expect(ScheduleEngine.overlaps(events[0], events[1]), isTrue);
    expect(ScheduleEngine.overlaps(events[1], events[2]), isFalse);
  });
  test('invalid lesson, weekday and week values are rejected', () {
    expect(() => course(first: 0), throwsArgumentError);
    expect(() => course(last: 12), throwsArgumentError);
    expect(() => course(day: 8), throwsArgumentError);
    expect(() => course(weeks: {0}), throwsArgumentError);
    expect(
      () => Semester(startDate: DateTime(2026), totalWeeks: 31),
      throwsArgumentError,
    );
  });
}