import 'package:flutter/material.dart';
import 'dart:math';
import 'package:flutter_tts/flutter_tts.dart';
import '../models/custom_kanji_item.dart';
import '../widgets/options_grid.dart';
import '../widgets/kanji_card.dart';

enum CustomQuizMode { japaneseToEnglish, englishToJapanese, listeningComprehension }

class CustomQuizScreen extends StatefulWidget {
  final List<CustomKanjiItem> deck;
  final CustomQuizMode quizMode;
  final Function(CustomKanjiItem) onCardReviewed;
  final bool useKanji;
  final bool isActive;

  const CustomQuizScreen({
    super.key,
    required this.deck,
    required this.quizMode,
    required this.onCardReviewed,
    required this.useKanji,
    required this.isActive,
  });

  @override
  State<CustomQuizScreen> createState() => CustomQuizScreenState();
}

class CustomQuizScreenState extends State<CustomQuizScreen>
    with TickerProviderStateMixin {
  int _currentIndex = 0;
  List<CustomKanjiItem> _shuffledDeck = [];
  List<String> _options = [];
  bool _answered = false;
  bool? _correct;
  late FlutterTts _flutterTts;
  late AnimationController _shakeController;
  late Animation<double> _shakeAnimation;
  final List<String> _incorrectlyAnsweredItems = [];

  @override
  void initState() {
    super.initState();
    _shuffledDeck = widget.deck.toList()..shuffle();
    _initTts();
    if (_shuffledDeck.isNotEmpty) {
      _generateOptions();
    }

    _shakeController = AnimationController(
      duration: const Duration(milliseconds: 500),
      vsync: this,
    );
    _shakeAnimation = Tween<double>(begin: 0, end: 1).animate(
      CurvedAnimation(
        parent: _shakeController,
        curve: Curves.elasticIn,
      ),
    );
  }

  @override
  void didUpdateWidget(CustomQuizScreen oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (widget.deck != oldWidget.deck && !widget.isActive) {
      setState(() {
        _shuffledDeck = widget.deck.toList()..shuffle();
        _currentIndex = 0;
        _answered = false;
        _correct = null;
        if (_shuffledDeck.isNotEmpty) {
          _generateOptions();
        }
      });
    }
    if (widget.useKanji != oldWidget.useKanji) {
      setState(() {
        _generateOptions();
      });
    }
  }

  void playAudio() {
    if (widget.quizMode == CustomQuizMode.listeningComprehension && _currentIndex < _shuffledDeck.length) {
      _speak(_shuffledDeck[_currentIndex].characters);
    }
  }

  void _initTts() async {
    _flutterTts = FlutterTts();
    await _flutterTts.setLanguage("ja-JP");
  }

  @override
  void dispose() {
    _flutterTts.stop();
    _shakeController.dispose();
    super.dispose();
  }

  void _generateOptions() {
    final currentItem = _shuffledDeck[_currentIndex];
    if (widget.quizMode == CustomQuizMode.listeningComprehension || widget.quizMode == CustomQuizMode.japaneseToEnglish) {
      _options = [currentItem.meaning];
    } else {
      _options = [widget.useKanji && currentItem.kanji != null ? currentItem.kanji! : currentItem.characters];
    }
    final otherItems = widget.deck
        .where((item) => item.characters != currentItem.characters)
        .toList();
    otherItems.shuffle();
    for (var i = 0; i < min(3, otherItems.length); i++) {
      if (widget.quizMode == CustomQuizMode.listeningComprehension || widget.quizMode == CustomQuizMode.japaneseToEnglish) {
        _options.add(otherItems[i].meaning);
      } else {
        _options.add(widget.useKanji && otherItems[i].kanji != null ? otherItems[i].kanji! : otherItems[i].characters);
      }
    }
    _options.shuffle();
  }

  void _checkAnswer(String answer) async {
    final currentItem = _shuffledDeck[_currentIndex];
    final correctAnswer = (widget.quizMode == CustomQuizMode.englishToJapanese)
        ? (widget.useKanji && currentItem.kanji != null ? currentItem.kanji! : currentItem.characters)
        : currentItem.meaning;
    final isCorrect = answer == correctAnswer;

    if (currentItem.useInterval) {
      int currentSrsLevel;
      switch (widget.quizMode) {
        case CustomQuizMode.japaneseToEnglish:
          currentSrsLevel = currentItem.srsData.japaneseToEnglish;
          break;
        case CustomQuizMode.englishToJapanese:
          currentSrsLevel = currentItem.srsData.englishToJapanese;
          break;
        case CustomQuizMode.listeningComprehension:
          currentSrsLevel = currentItem.srsData.listeningComprehension;
          break;
      }

      if (isCorrect) {
        if (_incorrectlyAnsweredItems.contains(currentItem.characters)) {
          _incorrectlyAnsweredItems.remove(currentItem.characters);
        } else {
          currentSrsLevel++;
        }
        final interval = pow(2, currentSrsLevel).toInt();
        final newNextReview = DateTime.now().add(Duration(hours: interval));
        switch (widget.quizMode) {
          case CustomQuizMode.japaneseToEnglish:
            currentItem.srsData.japaneseToEnglishNextReview = newNextReview;
            break;
          case CustomQuizMode.englishToJapanese:
            currentItem.srsData.englishToJapaneseNextReview = newNextReview;
            break;
          case CustomQuizMode.listeningComprehension:
            currentItem.srsData.listeningComprehensionNextReview = newNextReview;
            break;
        }
      } else {
        if (!_incorrectlyAnsweredItems.contains(currentItem.characters)) {
          _incorrectlyAnsweredItems.add(currentItem.characters);
        }
        currentSrsLevel = max(0, currentSrsLevel - 1);
        final newNextReview = DateTime.now().add(const Duration(hours: 1));
        switch (widget.quizMode) {
          case CustomQuizMode.japaneseToEnglish:
            currentItem.srsData.japaneseToEnglishNextReview = newNextReview;
            break;
          case CustomQuizMode.englishToJapanese:
            currentItem.srsData.englishToJapaneseNextReview = newNextReview;
            break;
          case CustomQuizMode.listeningComprehension:
            currentItem.srsData.listeningComprehensionNextReview = newNextReview;
            break;
        }
      }

      switch (widget.quizMode) {
        case CustomQuizMode.japaneseToEnglish:
          currentItem.srsData.japaneseToEnglish = currentSrsLevel;
          break;
        case CustomQuizMode.englishToJapanese:
          currentItem.srsData.englishToJapanese = currentSrsLevel;
          break;
        case CustomQuizMode.listeningComprehension:
          currentItem.srsData.listeningComprehension = currentSrsLevel;
          break;
      }

      widget.onCardReviewed(currentItem);
    }

    // --- SnackBar Logic (new) ---
    final correctDisplay = (widget.quizMode == CustomQuizMode.englishToJapanese)
        ? (widget.useKanji && currentItem.kanji != null ? currentItem.kanji! : currentItem.characters)
        : currentItem.meaning;

    final snack = SnackBar(
      content: Text(
        isCorrect ? 'Correct!' : 'Wrong — correct: $correctDisplay',
        style: TextStyle(
          color: isCorrect ? Colors.greenAccent : Colors.redAccent,
          fontWeight: FontWeight.bold,
        ),
      ),
      backgroundColor: const Color(0xFF222222),
      duration: const Duration(milliseconds: 900),
    );
    if (mounted) {
      ScaffoldMessenger.of(context).showSnackBar(snack);
    }
    // --- End SnackBar Logic ---

    if (isCorrect) {
      if (widget.quizMode == CustomQuizMode.japaneseToEnglish) {
        await _speak(currentItem.characters);
      }
      await Future.delayed(const Duration(milliseconds: 500)); // Small delay after correct answer
    } else {
      _shakeController.forward(from: 0);
      await Future.delayed(const Duration(milliseconds: 900)); // Delay for shake animation
    }

    _nextQuestion();
  }

  void _nextQuestion() {
    setState(() {
      _currentIndex++;
      _answered = false;
      _correct = null;
      if (_currentIndex < _shuffledDeck.length) {
        _generateOptions();
        if (widget.quizMode == CustomQuizMode.listeningComprehension) {
          _speak(_shuffledDeck[_currentIndex].characters);
        }
      }
    });
  }

  Future<void> _speak(String text) async {
    await _flutterTts.speak(text);
  }

  void _onOptionSelected(String option) {
    if (!(_answered && _correct!)) {
      _checkAnswer(option);
    }
  }

  @override
  Widget build(BuildContext context) {
    if (_shuffledDeck.isEmpty || _currentIndex >= _shuffledDeck.length) {
      return const Center(
        child: Text('Review session complete!'),
      );
    }

    final currentItem = _shuffledDeck[_currentIndex];
    final question = (widget.quizMode == CustomQuizMode.englishToJapanese)
        ? currentItem.meaning
        : (widget.useKanji && currentItem.kanji != null ? currentItem.kanji! : currentItem.characters);

    Widget promptWidget;
    if (widget.quizMode == CustomQuizMode.listeningComprehension) {
      promptWidget = IconButton(
        icon: const Icon(Icons.volume_up, size: 64),
        onPressed: () => _speak(currentItem.characters),
      );
    } else {
      promptWidget = GestureDetector(
        onTap: () => _speak(question),
        child: Text(
          question,
          style: const TextStyle(fontSize: 48),
          textAlign: TextAlign.center,
        ),
      );
    }

    return Padding(
      padding: const EdgeInsets.all(16.0),
      child: Column(
        children: [
          const SizedBox(height: 18),
          Expanded(
            flex: 3,
            child: Center(
              child: ConstrainedBox(
                constraints: const BoxConstraints(
                  minWidth: 0,
                  maxWidth: 500,
                  minHeight: 150,
                ),
                child: KanjiCard(
                  characterWidget: promptWidget,
                  subtitle: '',
                ),
              ),
            ),
          ),
          const SizedBox(height: 12),
          SafeArea(
            top: false,
            child: Column(
              children: [
                AnimatedBuilder(
                  animation: _shakeAnimation,
                  builder: (context, child) {
                    return Transform.translate(
                      offset: Offset(_shakeAnimation.value * 10, 0),
                      child: child,
                    );
                  },
                  child: OptionsGrid(
                    options: _options,
                    onSelected: _onOptionSelected,
                    correctAnswers: [],
                    showResult: false,
                    isDisabled: false,
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}