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/generated_content.dart';
import 'package:kouyu_english/core/models.dart';
import 'package:kouyu_english/features/dialogue/dialogue_flow.dart';
import 'package:kouyu_english/features/review/review_page.dart';
import 'package:kouyu_english/features/shell/learning_shell.dart';
import 'package:kouyu_english/main.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() {
  setUp(() {
    SharedPreferences.setMockInitialValues({});
  });

  testWidgets('Onboarding PlacementPage back button returns to WelcomePage', (
    tester,
  ) async {
    await tester.pumpWidget(const KouyuEnglishApp());
    await tester.pumpAndSettle();

    expect(find.text('每天 20 分钟，\n说出能用的英语。'), findsOneWidget);
    await tester.tap(find.text('继续'));
    await tester.pumpAndSettle();

    expect(find.text('从哪里开始？'), findsOneWidget);
    expect(find.byIcon(Icons.arrow_back), findsOneWidget);

    await tester.tap(find.byIcon(Icons.arrow_back));
    await tester.pumpAndSettle();

    expect(find.text('每天 20 分钟，\n说出能用的英语。'), findsOneWidget);
  });

  testWidgets('SettingsPage back button returns to ProgressPage', (
    tester,
  ) async {
    final state = AppState()..finishOnboarding();
    await tester.pumpWidget(
      MaterialApp(home: LearningShell(state: state)),
    );
    await tester.pumpAndSettle();

    // Navigate to "我的" (progress tab)
    await tester.tap(find.text('我的'));
    await tester.pumpAndSettle();

    final settingsButton = find.text('调整学习与 AI 设置');
    await tester.ensureVisible(settingsButton);
    await tester.pumpAndSettle();

    expect(settingsButton, findsOneWidget);
    await tester.tap(settingsButton);
    await tester.pumpAndSettle();

    // In SettingsPage
    expect(find.text('学习设置'), findsOneWidget);
    expect(find.byIcon(Icons.arrow_back), findsOneWidget);

    // Tap back button
    await tester.tap(find.byIcon(Icons.arrow_back));
    await tester.pumpAndSettle();

    expect(find.text('调整学习与 AI 设置'), findsOneWidget);
  });

  testWidgets('LessonFlow back button returns to tab', (tester) async {
    final state = AppState()..finishOnboarding();
    await tester.pumpWidget(
      MaterialApp(home: LearningShell(state: state)),
    );
    await tester.pumpAndSettle();

    expect(find.text('开始今天的学习'), findsOneWidget);
    await tester.tap(find.text('开始今天的学习'));
    await tester.pumpAndSettle();

    // In LessonFlow
    expect(find.byIcon(Icons.arrow_back), findsOneWidget);

    // Tap back button
    await tester.tap(find.byIcon(Icons.arrow_back));
    await tester.pumpAndSettle();

    expect(find.text('开始今天的学习'), findsOneWidget);
  });

  testWidgets('DialogueScenePage from Home has back button and returns to Home', (
    tester,
  ) async {
    final state = AppState()..finishOnboarding();
    await tester.pumpWidget(
      MaterialApp(home: LearningShell(state: state)),
    );
    await tester.pumpAndSettle();

    expect(find.text('开始情境对话'), findsOneWidget);
    await tester.tap(find.text('开始情境对话'));
    await tester.pumpAndSettle();

    // In DialogueScenePage as secondary route
    expect(find.text('AI 情境对话'), findsOneWidget);
    expect(find.byIcon(Icons.arrow_back), findsOneWidget);

    await tester.tap(find.byIcon(Icons.arrow_back));
    await tester.pumpAndSettle();

    expect(find.text('开始情境对话'), findsOneWidget);
  });

  testWidgets('DialogueSummaryPage has back button', (tester) async {
    var backCalled = false;
    await tester.pumpWidget(
      MaterialApp(
        home: DialogueSummaryPage(
          summary: const DialogueSummaryData(
            completedTasks: ['介绍姓名'],
            personalSentence: 'My name is Shen.',
            usedHelp: false,
          ),
          onHome: () {},
          onLesson: () {},
          onRetry: () {},
          onBack: () => backCalled = true,
        ),
      ),
    );
    await tester.pumpAndSettle();

    expect(find.text('对话完成'), findsNWidgets(2)); // AppBar title and Eyebrow
    expect(find.byIcon(Icons.arrow_back), findsOneWidget);

    await tester.tap(find.byIcon(Icons.arrow_back));
    await tester.pumpAndSettle();

    expect(backCalled, isTrue);
  });

  testWidgets('AdaptiveLessonPage has back button in all states', (tester) async {
    final state = AppState()..finishOnboarding();

    // 1. Empty state
    var finished = false;
    await tester.pumpWidget(
      MaterialApp(
        home: AdaptiveLessonPage(
          state: state,
          onFinished: () => finished = true,
        ),
      ),
    );
    await tester.pumpAndSettle();

    expect(find.text('AI 四技能补练'), findsNWidgets(2));
    expect(find.byIcon(Icons.arrow_back), findsOneWidget);
    await tester.tap(find.byIcon(Icons.arrow_back));
    expect(finished, isTrue);

    // 2. Active lesson state
    state.cacheApprovedAdaptiveLesson(
      const GeneratedLesson(
        lessonId: 'adapt-1',
        revision: 1,
        stageVersion: 'A0',
        abilityIds: ['greeting'],
        prerequisiteIds: [],
        targetItemIds: ['name'],
        receptiveChunks: ['My name is Mia.'],
        previewItemIds: ['name'],
        estimatedMinutes: 5,
        tasks: [
          GeneratedLessonTask(
            taskId: 't1',
            skill: 'listening',
            type: 'listen',
            prompt: '听并写出名字',
            stimulus: 'My name is Mia.',
            answer: 'Mia',
            targetItemIds: ['name'],
          ),
        ],
      ),
      auditor: 'test',
    );

    finished = false;
    await tester.pumpWidget(
      MaterialApp(
        home: AdaptiveLessonPage(
          state: state,
          onFinished: () => finished = true,
        ),
      ),
    );
    await tester.pumpAndSettle();

    expect(find.byIcon(Icons.arrow_back), findsOneWidget);
    await tester.tap(find.byIcon(Icons.arrow_back));
    expect(finished, isTrue);
  });

  testWidgets('AssessmentPreparationPage and AssessmentPage have back buttons', (
    tester,
  ) async {
    final state = AppState()..finishOnboarding();
    await tester.pumpWidget(
      MaterialApp(home: LearningShell(state: state)),
    );
    await tester.pumpAndSettle();

    // Navigate to "我的"
    await tester.tap(find.text('我的'));
    await tester.pumpAndSettle();

    // Open assessment pack A0-E1
    final packAButton = find.text('开始 A0-E1');
    await tester.ensureVisible(packAButton);
    await tester.pumpAndSettle();

    expect(packAButton, findsOneWidget);
    await tester.tap(packAButton);
    await tester.pumpAndSettle();

    // In AssessmentPreparationPage
    expect(find.text('评估准备'), findsOneWidget);
    expect(find.byIcon(Icons.arrow_back), findsOneWidget);

    // Start assessment
    await tester.tap(find.text('开始评估'));
    await tester.pumpAndSettle();

    // In AssessmentPage
    expect(find.byIcon(Icons.arrow_back), findsOneWidget);

    // Tap back button in AssessmentPage
    await tester.tap(find.byIcon(Icons.arrow_back));
    await tester.pumpAndSettle();

    // Returns to Progress tab
    expect(find.text('A0 四技能评估'), findsOneWidget);
  });
}