English/kouyu_english/lib/widgets/voice_answer.dart

import 'package:flutter/material.dart';

import '../core/ai_service.dart';
import '../core/app_state.dart';
import '../core/voice_service.dart';

/// Microphone handling shared by pages where the learner speaks an answer.
///
/// Two independent flows use the microphone:
/// * voice input records an answer and transcribes it into text
///   ([aiVoiceRecording], [listening], [transcribing]);
/// * the playback recorder keeps an attempt to listen back to
///   ([recording], [playingRecording], [recordingPath]).
mixin VoiceAnswerMixin<T extends StatefulWidget> on State<T> {
  static const noSpeechMessage = '未识别到清晰语音，请再试一次或直接输入文字。';
  static const micUnavailableMessage = '无法访问麦克风，请检查手机录音权限。';

  /// Supplies the AI configuration used for transcription.
  AppState get voiceState;

  /// The microphone is recording an answer to transcribe. A page that also
  /// uses device speech recognition sets [listening] alone for that.
  bool aiVoiceRecording = false;
  bool listening = false;
  bool transcribing = false;
  bool recording = false;
  bool playingRecording = false;
  String? recordingPath;

  void showVoiceMessage(String message) {
    ScaffoldMessenger.of(
      context,
    ).showSnackBar(SnackBar(content: Text(message)));
  }

  /// Starts recording an answer for transcription and reports whether the
  /// microphone started.
  Future<bool> startVoiceInput({
    String unavailableMessage = micUnavailableMessage,
  }) async {
    final started = await VoiceService.instance.startRecording();
    if (!mounted) return started;
    if (started) {
      setState(() {
        aiVoiceRecording = true;
        listening = true;
      });
    } else {
      showVoiceMessage(unavailableMessage);
    }
    return started;
  }

  /// Stops the answer recording and transcribes it.
  ///
  /// [onTranscript] runs inside `setState` with the trimmed, non-empty text.
  /// [afterTranscribe] runs once transcription has finished, whether or not
  /// anything was recognized. With [keepAudio] the answer audio also becomes
  /// the playback [recordingPath]; otherwise it is deleted once transcribed.
  Future<void> finishVoiceInput({
    required void Function(String text) onTranscript,
    VoidCallback? afterTranscribe,
    bool keepAudio = true,
    String noSpeech = noSpeechMessage,
  }) async {
    final path = await VoiceService.instance.stopRecording();
    if (!mounted) {
      if (!keepAudio) await VoiceService.instance.deleteRecording(path);
      return;
    }
    setState(() {
      aiVoiceRecording = false;
      listening = false;
      transcribing = path != null;
      if (keepAudio) recordingPath = path;
    });
    if (path == null) return;
    final config = voiceState.aiConfig;
    final transcribed = await AiService.instance.transcribeAudio(
      filePath: path,
      provider: config.provider,
      endpoint: config.endpoint,
      model: config.model,
    );
    // Without [keepAudio] the audio only served transcription.
    if (!keepAudio) await VoiceService.instance.deleteRecording(path);
    if (!mounted) return;
    final text = transcribed?.trim() ?? '';
    setState(() {
      transcribing = false;
      if (text.isNotEmpty) onTranscript(text);
    });
    afterTranscribe?.call();
    if (text.isEmpty) showVoiceMessage(noSpeech);
  }

  /// Starts a playback recording, replacing the previous one, or stops it.
  Future<void> toggleRecording() async {
    if (recording) {
      final path = await VoiceService.instance.stopRecording();
      if (mounted) {
        setState(() {
          recording = false;
          recordingPath = path;
        });
      }
      return;
    }
    await VoiceService.instance.deleteRecording(recordingPath);
    final ready = await VoiceService.instance.startRecording();
    if (!mounted) return;
    setState(() {
      recording = ready;
      if (ready) recordingPath = null;
    });
    if (!ready) showVoiceMessage('无法使用麦克风录音；请检查系统权限。');
  }

  Future<void> playRecording() async {
    final path = recordingPath;
    if (path == null) return;
    setState(() => playingRecording = true);
    await VoiceService.instance.playRecording(
      path,
      onComplete: () {
        if (mounted) setState(() => playingRecording = false);
      },
    );
  }

  Future<void> deleteRecording() async {
    await VoiceService.instance.stopRecordingPlayback();
    await VoiceService.instance.deleteRecording(recordingPath);
    if (mounted) {
      setState(() {
        recordingPath = null;
        playingRecording = false;
      });
    }
  }

  /// Releases the microphone and player; call from `dispose`. Unless
  /// [keepRecording], the recorded attempt is deleted.
  void disposeVoiceAnswer({required bool keepRecording}) {
    final voice = VoiceService.instance;
    voice.stopRecordingPlayback();
    if (listening && !aiVoiceRecording) voice.stopListening();
    if (aiVoiceRecording || recording) {
      voice.stopRecording().then((path) {
        if (!keepRecording) voice.deleteRecording(path);
      });
    }
    if (!keepRecording) voice.deleteRecording(recordingPath);
  }
}

/// Record / play back / delete buttons for [VoiceAnswerMixin]'s playback
/// recorder.
class RecordingControls extends StatelessWidget {
  const RecordingControls({
    super.key,
    required this.recording,
    required this.playing,
    required this.hasRecording,
    required this.onToggleRecording,
    required this.onPlay,
    required this.onDelete,
  });

  final bool recording;
  final bool playing;
  final bool hasRecording;

  /// Null disables the record button.
  final VoidCallback? onToggleRecording;
  final VoidCallback onPlay;
  final VoidCallback onDelete;

  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        Expanded(
          child: OutlinedButton.icon(
            onPressed: onToggleRecording,
            icon: Icon(
              recording
                  ? Icons.stop_circle_outlined
                  : Icons.fiber_manual_record,
            ),
            label: Text(recording ? '停止录音' : '录音回听'),
          ),
        ),
        if (hasRecording) ...[
          const SizedBox(width: 8),
          IconButton(
            tooltip: playing ? '正在播放' : '回听录音',
            onPressed: playing ? null : onPlay,
            icon: const Icon(Icons.play_arrow),
          ),
          IconButton(
            tooltip: '删除录音',
            onPressed: onDelete,
            icon: const Icon(Icons.delete_outline),
          ),
        ],
      ],
    );
  }
}