import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:kouyu_english/core/app_state.dart';
import 'package:kouyu_english/core/models.dart';
import 'package:kouyu_english/core/courses/courses.dart';
import 'package:kouyu_english/core/courses/course_pack.dart';
import 'package:kouyu_english/core/courses/course_repository.dart';
import 'package:kouyu_english/features/lesson/lesson_flow.dart';

/// Widget smoke test for the JSON units' 听读材料 (listening/reading
/// comprehension) step: it must be reached only on the last segment of a unit
/// that has materials, render from the real loaded content, and let the learner
/// continue to writing once every question is answered.
void main() {
  TestWidgetsFlutterBinding.ensureInitialized();

  setUpAll(() async {
    await CourseRepository.instance.load();
  });

  tearDownAll(() => CourseRepository.instance.resetForTest());

  /// The first loaded unit whose materials contain at least one question.
  CoursePack unitWithQuestions() => CourseRepository.instance.units.firstWhere(
    (u) => u.materials.any((m) => m.questions.isNotEmpty),
  );

  AppState stateOn(String unitId, int segmentIndex) {
    final state = AppState();
    state.activeLessonId = unitId;
    state.activeSegmentIndexes[unitId] = segmentIndex;
    return state;
  }

  testWidgets(
    'material step is reached only on the last segment with materials',
    (tester) async {
      final unit = unitWithQuestions();
      final lesson = lessonById(unit.id);
      expect(
        lesson.segments.length,
        greaterThan(1),
        reason: 'need a multi-segment unit to prove the gate',
      );

      // Finishing reading on an earlier segment skips straight to writing.
      final early = stateOn(unit.id, 0);
      early.lessonStep = LessonStep.reading;
      early.completeReading();
      expect(early.lessonStep, LessonStep.writing);

      // Finishing reading on the final segment opens the comprehension step.
      final last = stateOn(unit.id, lesson.segments.length - 1);
      last.lessonStep = LessonStep.reading;
      last.completeReading();
      expect(last.lessonStep, LessonStep.material);
    },
  );

  testWidgets(
    'renders the unit materials and continues once every question is answered',
    (tester) async {
      final unit = unitWithQuestions();
      final lesson = lessonById(unit.id);
      final state = stateOn(unit.id, lesson.segments.length - 1);
      state.lessonStep = LessonStep.material;

      await tester.pumpWidget(
        MaterialApp(
          home: LessonFlow(
            state: state,
            onOpenDialogue: () {},
            onFinish: () {},
          ),
        ),
      );
      await tester.pumpAndSettle();

      // The step rendered from the real loaded content.
      expect(find.text('读一段真实的小材料，做完理解题。'), findsOneWidget);
      // Continue is gated until every question is answered.
      expect(find.text('答对所有理解题后继续'), findsOneWidget);
      expect(find.text('继续写一写'), findsNothing);

      // Answer every question by tapping its correct option (answer == the
      // parsed contract's first option; the widget shuffles their display order).
      for (final material in unit.materials) {
        for (final question in material.questions) {
          final option = find.text(question.answer).first;
          await tester.ensureVisible(option);
          await tester.pumpAndSettle();
          await tester.tap(option);
          await tester.pumpAndSettle();
        }
      }

      // Now the button is enabled and advances the lesson to writing.
      final go = find.text('继续写一写');
      expect(go, findsOneWidget);
      await tester.ensureVisible(go);
      await tester.tap(go);
      await tester.pumpAndSettle();

      expect(state.lessonStep, LessonStep.writing);
    },
  );
}