import 'package:flutter_test/flutter_test.dart';
import 'package:kouyu_english/core/courses/courses.dart';
import 'package:kouyu_english/core/courses/course_repository.dart';

List<SeedLesson> get loadedLessons =>
    allLessons.where((lesson) => lesson.level != 'A0').toList();
List<DialogueScene> get loadedScenes =>
    allScenes.where((scene) => !scene.id.startsWith('a0-')).toList();

void main() {
  TestWidgetsFlutterBinding.ensureInitialized();

  setUp(() => CourseRepository.instance.resetForTest());
  tearDown(() => CourseRepository.instance.resetForTest());

  test('loads every unit and adapts it into the runtime registries', () async {
    await CourseRepository.instance.load();
    final units = CourseRepository.instance.units;

    // The course map lists 10 A0 + 21 A1 + 15 A2 + 14 B1 units.
    expect(units.length, 60);
    expect(units.where((u) => u.level == 'A0').length, 10);
    expect(units.where((u) => u.level == 'A1').length, 21);
    expect(units.where((u) => u.level == 'A2').length, 15);
    expect(units.where((u) => u.level == 'B1').length, 14);

    // Unit ids are unique.
    expect(units.map((u) => u.id).toSet().length, units.length);

    // Adapted lessons are appended after A0 with continuous numbering.
    expect(loadedLessons.length, 50);
    expect(loadedLessons.first.number, a0SeedLessons.length + 1);
    expect(loadedLessons.last.number, a0SeedLessons.length + 50);
    expect(allLessons.length, a0SeedLessons.length + 50);

    for (final lesson in loadedLessons) {
      expect(
        lesson.segments,
        isNotEmpty,
        reason: '${lesson.id} has no segments',
      );
      expect(lesson.targetItemIds, isNotEmpty);
      expect(lesson.vocabulary, isNotEmpty);
      // Every adapted lesson resolves through the shared accessors.
      expect(lessonById(lesson.id).id, lesson.id);
      for (final segment in lesson.segments) {
        expect(findLessonSegment(segment.id)?.id, segment.id);
        final activity = activityBySegmentId(segment.id);
        expect(
          activity.listening.isNotEmpty || activity.reading.isNotEmpty,
          isTrue,
          reason: '${segment.id} has empty listening and reading',
        );
      }
    }
  });

  test(
    'core items register their labels, mastery flag and match rules',
    () async {
      await CourseRepository.instance.load();
      final unit = CourseRepository.instance.unitById('A1-U01')!;
      expect(unit.coreItems, isNotEmpty);
      for (final item in unit.coreItems) {
        expect(isCoreItem(item.id), isTrue);
        expect(coreItemLabel(item.id), item.zh);
        expect(coreItemEnglish(item.id), item.en);
        expect(coreItemMatch[item.id], item.match);
        expect(coreReviewTemplates[item.id], isNotNull);
      }
    },
  );

  test('each unit main scene becomes a free-practice scene', () async {
    await CourseRepository.instance.load();
    final expected = CourseRepository.instance.units
        .where((u) => u.level != 'A0' && u.mainScene != null)
        .length;
    expect(loadedScenes.length, expected);
    for (final scene in loadedScenes) {
      expect(scene.unlockAfterLessonId, isNotNull);
      expect(scene.script.prompts, isNotEmpty);
      // The scene is reachable through the shared accessor.
      expect(sceneById(scene.id).id, scene.id);
    }
  });

  test('listening/reading materials parse with answerable questions', () async {
    await CourseRepository.instance.load();
    final withMaterials = CourseRepository.instance.units
        .where((u) => u.materials.isNotEmpty)
        .toList();
    expect(withMaterials, isNotEmpty);
    for (final unit in withMaterials) {
      for (final material in unit.materials) {
        expect(material.text, isNotEmpty);
        for (final question in material.questions) {
          expect(question.options, isNotEmpty);
          // The first option is the correct answer by contract.
          expect(question.answer, question.options.first);
        }
      }
    }
  });

  test('load is idempotent', () async {
    await CourseRepository.instance.load();
    final count = loadedLessons.length;
    await CourseRepository.instance.load();
    expect(loadedLessons.length, count);
    expect(CourseRepository.instance.units.length, 60);
  });

  test('AI word list covers only the recent units, in English', () async {
    await CourseRepository.instance.load();
    final b1 = loadedLessons.last;
    final words = taughtLanguageUpTo(b1.id);
    final window = loadedLessons.sublist(
      loadedLessons.length - taughtLanguageUnitWindow,
    );
    final expected = <String>{
      for (final lesson in window)
        for (final id in lesson.targetItemIds) coreItemEnglish(id),
    };
    expect(words, expected.toList());
    expect(words.any((w) => RegExp(r'[\u4e00-\u9fff]').hasMatch(w)), isFalse);
    // The first A1 unit does not pull in A0.
    final firstA1 = taughtLanguageUpTo(loadedLessons.first.id);
    expect(firstA1.any(a0CoreItems.values.contains), isFalse);
    expect(lessonLevel(b1.id), 'B1');
  });
}