import 'package:flutter/material.dart';

import '../../core/app_state.dart';
import '../../core/app_theme.dart';
import '../../core/models.dart';
import '../../core/courses/courses.dart';
import '../../core/voice_service.dart';
import '../../widgets/app_widgets.dart';
import '../../widgets/voice_answer.dart';

class WelcomePage extends StatefulWidget {
  const WelcomePage({super.key, required this.state, required this.onContinue});

  final AppState state;
  final VoidCallback onContinue;

  @override
  State<WelcomePage> createState() => _WelcomePageState();
}

class _WelcomePageState extends State<WelcomePage> {
  late int selectedMinutes;

  @override
  void initState() {
    super.initState();
    selectedMinutes = widget.state.dailyMinutes;
  }

  @override
  Widget build(BuildContext context) {
    return AppPage(
      child: SpacedColumn(
        spacing: 20,
        children: [
          Row(
            children: [
              ClipRRect(
                borderRadius: BorderRadius.circular(12),
                child: Image.asset(
                  'assets/branding/logo_512.png',
                  width: 44,
                  height: 44,
                ),
              ),
              const SizedBox(width: 12),
              Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    '芽说英语',
                    style: TextStyle(
                      fontSize: 18,
                      fontWeight: FontWeight.bold,
                      color: AppColors.ink,
                    ),
                  ),
                  Text(
                    'SpeakSprout',
                    style: TextStyle(
                      fontSize: 12,
                      color: AppColors.green,
                      fontWeight: FontWeight.w600,
                    ),
                  ),
                ],
              ),
            ],
          ),
          const Eyebrow('欢迎'),
          Text(
            '每天 20 分钟，\n说出能用的英语。',
            style: Theme.of(context).textTheme.headlineMedium,
          ),
          const Text('从真实生活场景开始，先做到听得懂、说得清。'),
          _ChoiceGroup<int>(
            title: '每天学习多久？',
            value: selectedMinutes,
            options: const {10: '10 分钟', 20: '20 分钟', 30: '30 分钟'},
            onChanged: (value) => setState(() => selectedMinutes = value),
          ),
          PrimaryButton(
            label: '继续',
            onPressed: () {
              widget.state.setDailyMinutes(selectedMinutes);
              widget.onContinue();
            },
          ),
        ],
      ),
    );
  }
}

class PlacementPage extends StatefulWidget {
  const PlacementPage({
    super.key,
    required this.state,
    required this.onStart,
    this.onBack,
  });

  final AppState state;
  final VoidCallback onStart;
  final VoidCallback? onBack;

  @override
  State<PlacementPage> createState() => _PlacementPageState();
}

enum _PlacementPhase { selfReport, listen, readAloud, answer, result }

class _PlacementPageState extends State<PlacementPage>
    with VoiceAnswerMixin<PlacementPage> {
  static const _listeningText = 'Hello. My name is Mia. Nice to meet you.';
  static const _listeningOptions = [
    '你好，我叫 Mia，很高兴认识你。',
    '你好，我来自 Mia，今天很开心。',
    '再见，Mia，明天见。',
  ];
  static const _readAloudText = 'Hello. My name is ...';

  late PlacementLevel selected;
  var phase = _PlacementPhase.selfReport;
  int listeningChoice = -1;
  final answerController = TextEditingController();

  @override
  AppState get voiceState => widget.state;

  @override
  void initState() {
    super.initState();
    selected = widget.state.placement;
  }

  @override
  void dispose() {
    VoiceService.instance.stopSpeaking();
    disposeVoiceAnswer(keepRecording: false);
    answerController.dispose();
    super.dispose();
  }

  bool get _understoodGreeting => listeningChoice == 0;

  bool get _answeredName =>
      coreItemUsedIn('A0-P01', answerController.text.trim());

  /// Placement only picks an A0 starting point until A1 content is frozen, and
  /// it never marks a lesson as passed.
  String get _suggestedLessonId =>
      _understoodGreeting && _answeredName ? 'a0-02' : 'a0-01';

  String get _reason => _understoodGreeting && _answeredName
      ? '你已经能听懂问候，也能说出自己的名字，可以从拼写名字开始。'
      : _understoodGreeting
      ? '你能听懂问候，先把自我介绍说完整会更稳。'
      : '先从问候和介绍名字开始，打好第一句的基础。';

  void _back() {
    VoiceService.instance.stopSpeaking();
    switch (phase) {
      case _PlacementPhase.selfReport:
        widget.onBack?.call();
      case _PlacementPhase.listen:
        setState(() => phase = _PlacementPhase.selfReport);
      case _PlacementPhase.readAloud:
        setState(() => phase = _PlacementPhase.listen);
      case _PlacementPhase.answer:
        setState(() => phase = _PlacementPhase.readAloud);
      case _PlacementPhase.result:
        setState(() => phase = _PlacementPhase.answer);
    }
  }

  void _startFrom(String lessonId) {
    widget.state.setPlacementStartLesson(lessonId);
    widget.onStart();
  }

  Future<void> _toggleVoiceAnswer() async {
    if (aiVoiceRecording) {
      await finishVoiceInput(
        keepAudio: false,
        onTranscript: (text) => answerController.text = text,
      );
      return;
    }
    await startVoiceInput();
  }

  @override
  Widget build(BuildContext context) {
    final showBack =
        widget.onBack != null || phase != _PlacementPhase.selfReport;
    return AppPage(
      appBar: showBack
          ? AppBar(
              leading: IconButton(
                icon: const Icon(Icons.arrow_back),
                tooltip: "返回",
                onPressed: _back,
              ),
              title: const Text("基础定位"),
            )
          : null,
      child: switch (phase) {
        _PlacementPhase.selfReport => _selfReport(context),
        _PlacementPhase.listen => _listen(context),
        _PlacementPhase.readAloud => _readAloud(context),
        _PlacementPhase.answer => _answer(context),
        _PlacementPhase.result => _result(context),
      },
    );
  }

  Widget _selfReport(BuildContext context) {
    const labels = {
      PlacementLevel.beginner: ('完全零基础', '从你好、自我介绍开始'),
      PlacementLevel.someBasics: ('能说一点', '认识常见单词或短句'),
      PlacementLevel.simpleConversation: ('能简单对话', '想说得更自然、更有信心'),
    };
    return SpacedColumn(
      spacing: 14,
      children: [
        const Eyebrow('第一步 · 约 3 分钟'),
        Text('从哪里开始？', style: Theme.of(context).textTheme.headlineMedium),
        const Text('选择最接近的状态，之后随时能调整。'),
        for (final option in PlacementLevel.values)
          _PlacementChoice(
            option: option,
            labels: labels[option]!,
            isSelected: selected == option,
            onTap: () => setState(() => selected = option),
          ),
        PrimaryButton(
          label: '开始 3 分钟定位',
          onPressed: () {
            widget.state.setPlacement(selected);
            setState(() => phase = _PlacementPhase.listen);
          },
        ),
        Center(
          child: TextButton(
            onPressed: () => _startFrom('a0-01'),
            child: const Text('直接从第一课开始'),
          ),
        ),
      ],
    );
  }

  Widget _listen(BuildContext context) => SpacedColumn(
    spacing: 14,
    children: [
      const Eyebrow('定位 · 1 / 3'),
      Text('听一听，选出意思。', style: Theme.of(context).textTheme.headlineMedium),
      SecondaryButton(
        label: '播放句子',
        onPressed: () => VoiceService.instance.speak(_listeningText),
      ),
      for (var index = 0; index < _listeningOptions.length; index++)
        SectionCard(
          tint: listeningChoice == index ? AppColors.softGreen : null,
          onTap: () => setState(() => listeningChoice = index),
          child: Row(
            children: [
              Icon(
                listeningChoice == index
                    ? Icons.radio_button_checked
                    : Icons.radio_button_off,
                color: listeningChoice == index
                    ? AppColors.green
                    : AppColors.muted,
              ),
              const SizedBox(width: 10),
              Expanded(child: Text(_listeningOptions[index])),
            ],
          ),
        ),
      PrimaryButton(
        label: '下一题',
        onPressed: listeningChoice < 0
            ? null
            : () => setState(() => phase = _PlacementPhase.readAloud),
      ),
      Center(
        child: TextButton(
          onPressed: () => setState(() {
            listeningChoice = -1;
            phase = _PlacementPhase.readAloud;
          }),
          child: const Text('听不懂，下一题'),
        ),
      ),
    ],
  );

  Widget _readAloud(BuildContext context) => SpacedColumn(
    spacing: 14,
    children: [
      const Eyebrow('定位 · 2 / 3'),
      Text('跟着读一句。', style: Theme.of(context).textTheme.headlineMedium),
      const Text(
        _readAloudText,
        textAlign: TextAlign.center,
        style: TextStyle(fontSize: 26, fontWeight: FontWeight.w600),
      ),
      SecondaryButton(
        label: '播放示范音',
        onPressed: () => VoiceService.instance.speak(_readAloudText),
      ),
      SectionCard(
        tint: AppColors.surfaceMuted,
        child: Text('这一题只是开口热身，不录音、不打分，可以跳过。'),
      ),
      PrimaryButton(
        label: '我读完了',
        onPressed: () => setState(() => phase = _PlacementPhase.answer),
      ),
      Center(
        child: TextButton(
          onPressed: () => setState(() => phase = _PlacementPhase.answer),
          child: const Text('现在不方便开口，跳过'),
        ),
      ),
    ],
  );

  Widget _answer(BuildContext context) => SpacedColumn(
    spacing: 14,
    children: [
      const Eyebrow('定位 · 3 / 3'),
      Text('回答这个问题。', style: Theme.of(context).textTheme.headlineMedium),
      SectionCard(
        tint: AppColors.surfaceMuted,
        child: Row(
          children: [
            const Expanded(
              child: Text(
                'What is your name?',
                style: TextStyle(fontSize: 20, fontWeight: FontWeight.w600),
              ),
            ),
            IconButton(
              tooltip: '播放问题',
              icon: const Icon(Icons.volume_up_outlined),
              onPressed: () =>
                  VoiceService.instance.speak('What is your name?'),
            ),
          ],
        ),
      ),
      TextField(
        controller: answerController,
        decoration: const InputDecoration(hintText: '用英语输入你的回答'),
        onChanged: (_) => setState(() {}),
      ),
      SecondaryButton(
        label: transcribing ? '正在识别…' : (aiVoiceRecording ? '说完了，识别' : '用语音回答'),
        onPressed: transcribing ? null : _toggleVoiceAnswer,
      ),
      PrimaryButton(
        label: '查看建议',
        onPressed: aiVoiceRecording || transcribing
            ? null
            : () => setState(() => phase = _PlacementPhase.result),
      ),
      Center(
        child: TextButton(
          onPressed: () => setState(() {
            answerController.clear();
            phase = _PlacementPhase.result;
          }),
          child: const Text('还不会说，查看建议'),
        ),
      ),
    ],
  );

  Widget _result(BuildContext context) {
    final lesson = lessonById(_suggestedLessonId);
    return SpacedColumn(
      spacing: 14,
      children: [
        const Eyebrow('定位结果'),
        Text(
          '建议从 A0 第 ${lesson.number} 课开始',
          style: Theme.of(context).textTheme.headlineMedium,
        ),
        SectionCard(
          tint: AppColors.softGreen,
          child: SpacedColumn(
            spacing: 6,
            children: [
              Text(
                '第 ${lesson.number} 课 · ${lesson.title}',
                style: const TextStyle(fontWeight: FontWeight.w600),
              ),
              Text(_reason),
            ],
          ),
        ),
        const Text('前面的课程随时可以回去学，定位不会跳过任何复习。'),
        PrimaryButton(
          label: '开始今天学习',
          onPressed: () => _startFrom(_suggestedLessonId),
        ),
        if (_suggestedLessonId != 'a0-01')
          Center(
            child: TextButton(
              onPressed: () => _startFrom('a0-01'),
              child: const Text('从更简单内容开始'),
            ),
          ),
      ],
    );
  }
}

class _PlacementChoice extends StatelessWidget {
  const _PlacementChoice({
    required this.option,
    required this.labels,
    required this.isSelected,
    required this.onTap,
  });

  final PlacementLevel option;
  final (String, String) labels;
  final bool isSelected;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) => SectionCard(
    tint: isSelected ? AppColors.softGreen : null,
    onTap: onTap,
    child: Row(
      children: [
        Icon(
          isSelected ? Icons.radio_button_checked : Icons.radio_button_off,
          color: isSelected ? AppColors.green : AppColors.muted,
        ),
        const SizedBox(width: 10),
        Expanded(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                labels.$1,
                style: const TextStyle(fontWeight: FontWeight.w600),
              ),
              const SizedBox(height: 3),
              Text(labels.$2, style: Theme.of(context).textTheme.bodyMedium),
            ],
          ),
        ),
      ],
    ),
  );
}

class _ChoiceGroup<T> extends StatelessWidget {
  const _ChoiceGroup({
    required this.title,
    required this.value,
    required this.options,
    required this.onChanged,
  });

  final String title;
  final T value;
  final Map<T, String> options;
  final ValueChanged<T> onChanged;

  @override
  Widget build(BuildContext context) {
    return SectionCard(
      child: SpacedColumn(
        spacing: 10,
        children: [
          Text(title, style: const TextStyle(fontWeight: FontWeight.w600)),
          Wrap(
            spacing: 8,
            runSpacing: 8,
            children: options.entries
                .map(
                  (entry) => ChoiceChip(
                    label: Text(entry.value),
                    selected: value == entry.key,
                    selectedColor: AppColors.softGreen,
                    onSelected: (_) => onChanged(entry.key),
                  ),
                )
                .toList(),
          ),
        ],
      ),
    );
  }
}