feat(翻译): 添加自动检测语种功能

实现文本翻译时的自动语种检测功能，当用户选择"自动检测"时，会先调用火山引擎API进行语种识别
在翻译服务中添加detectTextLanguage方法，支持频率控制和结果缓存
修改语言选择UI，在源语言列表中添加"自动检测"选项

lib/data/services/volcano_translation_service.dart

@@ -1,32 +1,42 @@
 import 'dart:convert';
-import 'dart:math';
 import 'dart:typed_data';
-import '../../data/models/appconfig.dart';
-import 'package:get_storage/get_storage.dart';
+
 import 'package:http/http.dart' as http;
 import 'package:crypto/crypto.dart';
 import 'package:flutter_dotenv/flutter_dotenv.dart';
 import 'package:get/get.dart';
+
+import '../../data/models/appconfig.dart';
 import '../../core/utils/logger.dart';
 import 'language_manager.dart';
 import '../../modules/picture_translation/models/picture_translation_models.dart';
 
 //// 火山引擎机器翻译服务
+/// 提供文本翻译功能
+/// 提供图片翻译功能
+/// 提供文本语种检测功能
 class VolcanoTranslationService extends GetxService {
   // API 配置
   late String _baseUrl;
   final String _endpoint = '/'; // 修改为根路径
-  late String _accessKey;
-  late String _secretKey;
-  late String _region;
-  late String _service;
+  late final String _accessKey;
+  late final String _secretKey;
+  late final String _region;
+  late final String _service;
 
   // 初始化标志
   bool _isInitialized = false;
 
   // 语言管理器
   final LanguageManager _languageManager = Get.find<LanguageManager>();
-  // final GetStorage _storage = GetStorage();
+
+  // 文本语种检测频率控制与缓存
+  DateTime? _lastDetectTime; // 上次检测时间
+  String? _lastDetectTextKey; // 上次检测的文本键
+  final Duration _detectMinInterval =
+      const Duration(milliseconds: 800); // 最小检测间隔，避免过频请求
+  final Map<String, String> _detectCache = {}; // 文本键 -> 检测到的短代码 缓存
+
   // 构造函数
   VolcanoTranslationService();
   @override
@@ -46,25 +56,13 @@ class VolcanoTranslationService extends GetxService {
       return true;
     }
     try {
-      // 优先使用后端 AppConfig，其次回退到 .env
-      final bool appConfigReady = AppConfig.isInitialized();
-
-      final accessKeyFromConfig = appConfigReady
-          ? AppConfig.env('VOLCANO_TRANSLATION_ACCESS_KEY')
-          : null;
-      final secretKeyFromConfig = appConfigReady
-          ? AppConfig.env('VOLCANO_TRANSLATION_SECRET_KEY')
-          : null;
-      final regionFromConfig =
-          appConfigReady ? AppConfig.env('VOLCANO_TRANSLATION_REGION') : null;
-
-      _accessKey = accessKeyFromConfig ??
+      _accessKey = AppConfig.env('VOLCANO_TRANSLATION_ACCESS_KEY') ??
           dotenv.env['VOLCANO_TRANSLATION_ACCESS_KEY'] ??
           '';
-      _secretKey = secretKeyFromConfig ??
+      _secretKey = AppConfig.env('VOLCANO_TRANSLATION_SECRET_KEY') ??
           dotenv.env['VOLCANO_TRANSLATION_SECRET_KEY'] ??
           '';
-      _region = regionFromConfig ??
+      _region = AppConfig.env('VOLCANO_TRANSLATION_REGION') ??
           dotenv.env['VOLCANO_TRANSLATION_REGION'] ??
           'cn-north-1';
 
@@ -288,6 +286,136 @@ class VolcanoTranslationService extends GetxService {
     }
   }
 
+  /// 文本语种检测
+  /// 返回值为 ASR 代码（例如 `zh-CN` / `en-US`），若检测失败返回 null。
+  /// 频率控制：同一文本键在最小间隔内复用缓存结果，降低请求频率。
+  Future<String?> detectTextLanguage({
+    required String text,
+  }) async {
+    if (!_isInitialized) {
+      Logger.error('语种检测服务未初始化');
+      return null;
+    }
+
+    try {
+      // 构建文本键用于频率控制与缓存：去除首尾空格并截取前 256 字符
+      final normalized = text.trim();
+      if (normalized.isEmpty) {
+        return null;
+      }
+      final textKey =
+          normalized.length > 256 ? normalized.substring(0, 256) : normalized;
+
+      // 命中缓存直接返回，避免重复请求
+      final cachedShortCode = _detectCache[textKey];
+      if (cachedShortCode != null && cachedShortCode.isNotEmpty) {
+        final cachedAsr =
+            _languageManager.getAsrCodeByShortCode(cachedShortCode);
+        if (cachedAsr != null && cachedAsr.isNotEmpty) {
+          return cachedAsr;
+        }
+      }
+
+      // 频率控制：同一文本键在最小时间间隔内直接复用上次结果或跳过
+      final now = DateTime.now();
+      if (_lastDetectTime != null && _lastDetectTextKey == textKey) {
+        final delta = now.difference(_lastDetectTime!);
+        if (delta < _detectMinInterval) {
+          Logger.info('语种检测过于频繁，已短路本次请求');
+          return null;
+        }
+      }
+      _lastDetectTime = now;
+      _lastDetectTextKey = textKey;
+
+      // 构建请求体
+      final requestBody = {
+        'TextList': [normalized],
+      };
+
+      // 查询参数（官方文档：Action=LangDetect, Version=2020-06-01）
+      final queryParams = {
+        'Action': 'LangDetect',
+        'Version': '2020-06-01',
+        'Region': _region,
+        'Service': _service,
+      };
+
+      // 生成签名与头部
+      final headers = _generateSignature('POST', requestBody, queryParams);
+
+      // 拼接请求 URL
+      final queryString = Uri(queryParameters: queryParams).query;
+      final url = '$_baseUrl/?$queryString';
+
+      // 发送请求，增加网络超时保护
+      final response = await http
+          .post(
+            Uri.parse(url),
+            headers: headers,
+            body: json.encode(requestBody),
+          )
+          .timeout(const Duration(seconds: 8));
+
+      if (response.statusCode == 200) {
+        final responseData = json.decode(response.body);
+
+        // 有效性校验：必须存在 DetectedLanguageList 且包含 Language/Confidence
+        if (responseData is! Map ||
+            responseData['DetectedLanguageList'] is! List ||
+            (responseData['DetectedLanguageList'] as List).isEmpty) {
+          Logger.error('语种检测响应无有效结果: ${response.body}');
+          return null;
+        }
+
+        // 选择置信度最高的结果
+        String? bestShortCode;
+        double bestConfidence = -1;
+        for (final item in (responseData['DetectedLanguageList'] as List)) {
+          if (item is Map) {
+            final lang = item['Language']?.toString();
+            final conf = (item['Confidence'] is num)
+                ? (item['Confidence'] as num).toDouble()
+                : null;
+            if (lang != null && lang.isNotEmpty && conf != null) {
+              if (conf > bestConfidence) {
+                bestConfidence = conf;
+                bestShortCode = lang;
+              }
+            }
+          }
+        }
+
+        // 置信度阈值校验：过低则视为失败
+        if (bestShortCode == null || bestConfidence < 0.6) {
+          Logger.info('语种检测置信度不足: code=$bestShortCode, conf=$bestConfidence');
+          return null;
+        }
+
+        // 映射为 ASR 代码
+        final asrCode = _languageManager.getAsrCodeByShortCode(bestShortCode);
+        if (asrCode == null || asrCode.isEmpty) {
+          Logger.error('语种检测返回短代码无法映射为ASR: $bestShortCode');
+          return null;
+        }
+
+        // 写入缓存（短代码缓存，便于后续复用）
+        _detectCache[textKey] = bestShortCode;
+
+        Logger.info(
+            'lxm---语种检测成功: $bestShortCode (conf=$bestConfidence) -> $asrCode');
+        return asrCode;
+      }
+
+      Logger.error(
+          '语种检测HTTP错误: status=${response.statusCode}, body=${response.body}');
+      return null;
+    } catch (e) {
+      Logger.error('语种检测请求异常: $e');
+      return null;
+    }
+  }
+
   /// 图片翻译（整图识别+回贴翻译）
   Future<ImageTranslationResult?> translateImage({
     required Uint8List imageBytes,
@@ -345,7 +473,8 @@ class VolcanoTranslationService extends GetxService {
             responseData['ResponseMetadata'] is Map &&
             (responseData['ResponseMetadata']['Error'] != null)) {
           final err = responseData['ResponseMetadata']['Error'];
-          Logger.error('图片翻译错误: code=${err['Code']}, message=${err['Message']}');
+          Logger.error(
+              '图片翻译错误: code=${err['Code']}, message=${err['Message']}');
           return null;
         }
 

lib/modules/text_translation/controllers/text_translation_controller.dart

@@ -129,10 +129,14 @@ class TextTranslationController extends GetxController {
     if (language != sourceLanguageChineseName.value) {
       sourceLanguageChineseName.value = language;
 
-      // 同时更新语言代码
-      final asrCode = _languageManager.getAsrCodeByChineseName(language);
-      if (asrCode != null) {
-        sourceLanguageCode.value = asrCode;
+      // 同时更新语言代码；当选择“自动检测”时，将源语言代码置空，后续翻译流程会进行语种检测
+      if (language == '自动检测') {
+        sourceLanguageCode.value = '';
+      } else {
+        final asrCode = _languageManager.getAsrCodeByChineseName(language);
+        if (asrCode != null) {
+          sourceLanguageCode.value = asrCode;
+        }
       }
 
       _saveLanguageSettings();
@@ -242,7 +246,28 @@ class TextTranslationController extends GetxController {
 
       Logger.info('调用翻译服务...');
 
-      // 调用翻译服务，直接使用维护的语言代码
+      // 若选择了“自动检测”，先进行语种检测
+      if (sourceLanguageChineseName.value == '自动检测' ||
+          sourceLanguageCode.value.isEmpty) {
+        Logger.info('源语言为自动检测，开始语种检测…');
+        final detectedAsrCode =
+            await _translationService.detectTextLanguage(text: text);
+        if (detectedAsrCode == null || detectedAsrCode.isEmpty) {
+          Logger.error('语种检测失败');
+          Get.snackbar(
+            '错误', // 翻译键代表的中文文本内容
+            '语种检测失败，请手动选择源语言或稍后重试', // 翻译键代表的中文文本内容
+            snackPosition: SnackPosition.TOP,
+            backgroundColor: Colors.red.withOpacity(0.9),
+            colorText: Colors.white,
+          );
+          return;
+        }
+        sourceLanguageCode.value = detectedAsrCode;
+        Logger.info('语种检测结果: $detectedAsrCode');
+      }
+
+      // 调用翻译服务，使用检测或手动选择的源语言代码
       final result = await _translationService.translateText(
         text: text,
         sourceLanguageCode: sourceLanguageCode.value,
@@ -328,9 +353,15 @@ class TextTranslationController extends GetxController {
             const Divider(height: 1),
             Expanded(
               child: ListView.builder(
-                itemCount: supportedLanguages.length,
+                itemCount: (isSourceLanguage
+                        ? (supportedLanguages.length + 1)
+                        : supportedLanguages.length),
                 itemBuilder: (context, index) {
-                  final language = supportedLanguages[index];
+                  final language = isSourceLanguage
+                      ? (index == 0
+                          ? '自动检测'
+                          : supportedLanguages[index - 1])
+                      : supportedLanguages[index];
                   final isSelected = isSourceLanguage
                       ? language == sourceLanguageChineseName.value
                       : language == targetLanguageChineseName.value;