part of '../lesson_flow.dart';

class _IndependentStep extends StatefulWidget {
  const _IndependentStep({
    required this.state,
    required this.lessonId,
    required this.segmentId,
    required this.keepRecording,
    required this.activity,
    required this.controller,
    required this.showHelp,
    required this.canContinue,
    required this.onChanged,
    required this.onNeedHelp,
    required this.onLookup,
    required this.onContinue,
    required this.onLater,
  });
  final AppState state;
  final String lessonId;
  final LessonActivity activity;
  final String segmentId;
  final bool keepRecording;
  final TextEditingController controller;
  final bool showHelp;
  final bool canContinue;
  final VoidCallback onChanged;
  final VoidCallback onNeedHelp;
  final VoidCallback onLookup;
  final void Function(
    bool spoken,
    String? recordingPath,
    bool aiCorrected,
    bool verified,
  )
  onContinue;
  final VoidCallback onLater;

  @override
  State<_IndependentStep> createState() => _IndependentStepState();
}

class _IndependentStepState extends State<_IndependentStep>
    with VoiceAnswerMixin<_IndependentStep> {
  bool usedVoice = false;
  bool transcriptEdited = false;
  String lastTranscript = '';
  String? validationError;
  bool checkingWithAi = false;
  WritingAiFeedback? aiCheck;
  String? aiCheckError;

  /// A shown AI correction is help, so finishing afterwards is assisted.
  bool aiCorrected = false;

  @override
  AppState get voiceState => widget.state;

  @override
  void dispose() {
    disposeVoiceAnswer(keepRecording: widget.keepRecording);
    super.dispose();
  }

  Future<void> _submit() async {
    if (!widget.canContinue || checkingWithAi) return;
    final shortfall = independentShortfall(
      widget.segmentId,
      widget.controller.text,
    );
    if (shortfall != null) {
      setState(() => validationError = shortfall);
      return;
    }
    if (widget.state.aiProvider == AiProviderType.mock) {
      _finish(verified: false);
      return;
    }
    await _checkWithAi();
    if (!mounted) return;
    if (aiCheck?.verdict == 'accepted') _finish(verified: true);
  }

  void _finish({required bool verified}) {
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text(
          verified ? '通过：用上了本段要练的表达，AI 也没发现拼写或语法问题。' : '练习已保存；答案未经核验，不计入独立掌握。',
        ),
      ),
    );
    widget.onContinue(
      usedVoice && !transcriptEdited,
      widget.keepRecording ? recordingPath : null,
      aiCorrected,
      verified,
    );
  }

  void _clearChecks() {
    validationError = null;
    aiCheck = null;
    aiCheckError = null;
  }

  Future<void> _checkWithAi() async {
    final answer = widget.controller.text.trim();
    setState(() {
      checkingWithAi = true;
      aiCheck = null;
      aiCheckError = null;
    });
    final feedback = await AiService.instance.capabilities.evaluation
        .evaluateAnswer(
          provider: widget.state.aiProvider,
          endpoint: widget.state.aiEndpoint,
          model: widget.state.aiModel,
          answerId: widget.segmentId,
          target: widget.activity.independentHelp,
          taskPrompt: widget.activity.independentPrompt,
          answer: answer,
          level: lessonLevel(widget.lessonId),
        );
    // The learner may have kept typing while the request ran.
    if (!mounted || widget.controller.text.trim() != answer) {
      if (mounted) setState(() => checkingWithAi = false);
      return;
    }
    setState(() {
      checkingWithAi = false;
      aiCheck = feedback;
      aiCheckError = feedback == null
          ? '暂时无法核验答案。可重试，或仅保存练习继续。'
          : feedback.verdict == 'uncertain'
          ? 'AI 无法确定答案是否正确。可重试，或仅保存练习继续。'
          : null;
      if (feedback?.verdict == 'rewrite') {
        aiCorrected = true;
      }
    });
  }

  Future<void> _toggleMic() async {
    if (aiVoiceRecording) {
      await finishVoiceInput(
        onTranscript: (text) {
          widget.controller.text = text;
          usedVoice = true;
          lastTranscript = text;
          transcriptEdited = false;
          _clearChecks();
        },
        afterTranscribe: widget.onChanged,
      );
      return;
    }

    if (listening) {
      await VoiceService.instance.stopListening();
      if (mounted) setState(() => listening = false);
      return;
    }

    final ready = await VoiceService.instance.startListening(
      (text, _) {
        if (!mounted) return;
        setState(() {
          widget.controller.text = text;
          usedVoice = true;
          lastTranscript = text;
          transcriptEdited = false;
          _clearChecks();
        });
        widget.onChanged();
      },
      onStatus: (status) {
        if (mounted && (status == 'notListening' || status == 'done')) {
          setState(() => listening = false);
        }
      },
      onError: (err) {
        if (mounted) {
          setState(() => listening = false);
        }
      },
    );

    if (!ready) {
      final recordStarted = await startVoiceInput();
      if (recordStarted && mounted) {
        showVoiceMessage('已启动麦克风录音，说完后再次点击，AI 将自动转写为英文。');
      }
      return;
    }

    if (mounted) setState(() => listening = ready);
  }

  @override
  Widget build(BuildContext context) => _LessonScaffold(
    step: 6,
    child: SpacedColumn(
      children: [
        const Eyebrow('试着自己写 / 说一次 · 约 1 分钟'),
        Text('现在不看句框。', style: Theme.of(context).textTheme.headlineMedium),
        Text(widget.activity.independentPrompt),
        if (widget.state.aiProvider == AiProviderType.mock)
          SectionCard(
            tint: AppColors.warm,
            child: const Text('尚未配置 AI 服务。本次可继续练习，但开放回答不会计入独立掌握。'),
          ),
        if (widget.showHelp)
          SectionCard(
            tint: AppColors.warm,
            child: Text(
              '帮助：${widget.activity.independentHelp}',
              style: TextStyle(color: AppColors.warmInk),
            ),
          ),
        TextField(
          controller: widget.controller,
          onChanged: (value) {
            if (usedVoice && value != lastTranscript) transcriptEdited = true;
            setState(_clearChecks);
            widget.onChanged();
          },
          minLines: 2,
          maxLines: 4,
          decoration: InputDecoration(
            hintText: '输入完整英文句子',
            filled: true,
            fillColor: AppColors.surface,
            prefixIcon: IconButton(
              tooltip: listening ? '停止录音' : '语音输入',
              icon: Icon(
                listening ? Icons.stop_circle_outlined : Icons.mic_none,
              ),
              onPressed: _toggleMic,
            ),
            border: OutlineInputBorder(),
          ),
        ),
        SectionCard(
          tint: AppColors.surfaceMuted,
          child: SpacedColumn(
            spacing: 8,
            children: [
              Text(
                widget.keepRecording
                    ? '可录下这次尝试并保存在本机；不会发送给 AI。'
                    : '可录下这次尝试并回听；离开本页后会自动删除。',
              ),
              RecordingControls(
                recording: recording,
                playing: playingRecording,
                hasRecording: recordingPath != null,
                onToggleRecording: toggleRecording,
                onPlay: playRecording,
                onDelete: deleteRecording,
              ),
            ],
          ),
        ),
        if (usedVoice)
          SectionCard(
            tint: transcriptEdited ? AppColors.warm : AppColors.softGreen,
            child: Text(
              transcriptEdited
                  ? '你修改了设备转写：这次会按文字练习保存，不计口语练习。'
                  : '这是设备转写。未修改并确认后，会保留为本次语音练习记录。',
              style: TextStyle(
                color: transcriptEdited ? AppColors.warmInk : AppColors.green,
              ),
            ),
          ),
        if (aiCheck != null)
          SectionCard(
            tint: aiCheck!.verdict == 'accepted'
                ? AppColors.softGreen
                : AppColors.warm,
            child: SpacedColumn(
              spacing: 6,
              children: [
                Text('AI 检查：${aiCheck!.feedback}'),
                for (final note in aiCheck!.missing) Text('· $note'),
                if (aiCheck!.suggestion != null)
                  Text('参考改正：${aiCheck!.suggestion}'),
                Text(
                  aiCheck!.verdict == 'accepted'
                      ? '本地目标与 AI 检查均通过。'
                      : aiCheck!.verdict == 'rewrite'
                      ? '修改后再次提交；看过改正，本次会记为辅助练习。'
                      : '答案尚未核验，可重试或仅保存练习。',
                  style: TextStyle(fontSize: 12, color: AppColors.muted),
                ),
              ],
            ),
          ),
        if (aiCheckError != null)
          SectionCard(
            tint: AppColors.warm,
            child: Text(
              aiCheckError!,
              style: TextStyle(color: AppColors.warmInk),
            ),
          ),
        if (validationError != null)
          SectionCard(
            tint: AppColors.warm,
            child: Text(
              validationError!,
              style: TextStyle(color: AppColors.warmInk),
            ),
          ),
        if (!widget.showHelp)
          Wrap(
            spacing: 8,
            children: [
              TextButton(
                onPressed: widget.onNeedHelp,
                child: const Text('需要帮助'),
              ),
              TextButton(
                onPressed: widget.onLookup,
                child: const Text('查词或短语'),
              ),
            ],
          )
        else
          TextButton(onPressed: widget.onLookup, child: const Text('查词或短语')),
        PrimaryButton(
          label: checkingWithAi ? '正在自动检查…' : '提交独立尝试',
          onPressed: widget.canContinue && !checkingWithAi ? _submit : null,
        ),
        if (aiCheckError != null)
          TextButton(
            onPressed: () => _finish(verified: false),
            child: const Text('未核验，保存练习并继续'),
          ),
        TextButton(onPressed: widget.onLater, child: const Text('稍后继续')),
      ],
    ),
  );
}