feat: Ajout d'un service de synthèse vocale hybride et intégration de Google Cloud TTS

em2rp/lib/services/cloud_text_to_speech_service.dart

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+import 'package:web/web.dart' as web;
+import 'package:em2rp/config/api_config.dart';
+import 'package:em2rp/utils/debug_log.dart';
+import 'package:firebase_auth/firebase_auth.dart';
+import 'dart:convert';
+import 'package:http/http.dart' as http;
+
+/// Service de Text-to-Speech utilisant Google Cloud TTS via Cloud Function
+/// Avec système de cache pour optimiser les performances et réduire les coûts
+class CloudTextToSpeechService {
+  static final Map<String, String> _audioCache = {};
+  static final Map<String, web.HTMLAudioElement> _audioPlayers = {};
+
+  /// Générer l'audio TTS via Cloud Function
+  /// Retourne l'URL de l'audio (mise en cache automatiquement côté serveur)
+  static Future<String?> generateAudio(String text) async {
+    try {
+      // Vérifier le cache local d'abord
+      if (_audioCache.containsKey(text)) {
+        DebugLog.info('[CloudTTS] ✓ Local cache HIT: "${text.substring(0, 30)}..."');
+        return _audioCache[text];
+      }
+
+      DebugLog.info('[CloudTTS] Generating audio for: "$text"');
+
+      // Récupérer le token d'authentification
+      final user = FirebaseAuth.instance.currentUser;
+      if (user == null) {
+        DebugLog.error('[CloudTTS] User not authenticated');
+        return null;
+      }
+
+      final token = await user.getIdToken();
+      if (token == null) {
+        DebugLog.error('[CloudTTS] Failed to get auth token');
+        return null;
+      }
+
+      // Préparer la requête
+      final url = '${ApiConfig.baseUrl}/generateTTSV2';
+      final headers = {
+        'Authorization': 'Bearer $token',
+        'Content-Type': 'application/json',
+      };
+
+      final body = json.encode({
+        'data': {
+          'text': text,
+          'voiceConfig': {
+            'languageCode': 'fr-FR',
+            'name': 'fr-FR-Standard-B', // Voix masculine gratuite
+            'ssmlGender': 'MALE',
+          },
+        },
+      });
+
+      DebugLog.info('[CloudTTS] Calling Cloud Function...');
+      final startTime = DateTime.now();
+
+      // Appeler la Cloud Function
+      final response = await http.post(
+        Uri.parse(url),
+        headers: headers,
+        body: body,
+      );
+
+      final duration = DateTime.now().difference(startTime).inMilliseconds;
+
+      if (response.statusCode == 200) {
+        final data = json.decode(response.body);
+        final audioUrl = data['audioUrl'] as String?;
+        final cached = data['cached'] as bool? ?? false;
+
+      if (audioUrl != null) {
+        // Mettre en cache localement
+        _audioCache[text] = audioUrl;
+
+        DebugLog.info('[CloudTTS] ✓ Audio generated - cached: $cached, duration: ${duration}ms');
+
+        return audioUrl;
+      }
+      }
+
+      DebugLog.error('[CloudTTS] Failed to generate audio', {
+        'status': response.statusCode,
+        'body': response.body,
+      });
+
+      return null;
+    } catch (e) {
+      DebugLog.error('[CloudTTS] Exception:', e);
+      return null;
+    }
+  }
+
+  /// Lire un audio depuis une URL
+  static void playAudio(String audioUrl) {
+    try {
+      DebugLog.info('[CloudTTS] Playing audio...');
+
+      // Créer ou réutiliser un HTMLAudioElement
+      final player = _audioPlayers[audioUrl] ?? web.HTMLAudioElement();
+      if (!_audioPlayers.containsKey(audioUrl)) {
+        player.src = audioUrl;
+        _audioPlayers[audioUrl] = player;
+      }
+
+      // Configurer le volume
+      player.volume = 1.0;
+
+      // Écouter les événements
+      player.onEnded.listen((_) {
+        DebugLog.info('[CloudTTS] ✓ Playback finished');
+      });
+
+      player.onError.listen((event) {
+        DebugLog.error('[CloudTTS] ✗ Playback error:', event);
+      });
+
+      // Lire l'audio (pas de await avec package:web)
+      player.play();
+
+      DebugLog.info('[CloudTTS] ✓ Playback started');
+    } catch (e) {
+      DebugLog.error('[CloudTTS] Error playing audio:', e);
+      rethrow;
+    }
+  }
+
+  /// Générer et lire l'audio en une seule opération
+  static Future<void> speak(String text) async {
+    try {
+      final audioUrl = await generateAudio(text);
+
+      if (audioUrl != null) {
+        playAudio(audioUrl);
+      } else {
+        DebugLog.error('[CloudTTS] Failed to generate audio for speech');
+      }
+    } catch (e) {
+      DebugLog.error('[CloudTTS] Error in speak:', e);
+      rethrow;
+    }
+  }
+
+  /// Arrêter tous les audios en cours
+  static void stopAll() {
+    for (final player in _audioPlayers.values) {
+      try {
+        player.pause();
+        player.currentTime = 0;
+      } catch (e) {
+        // Ignorer les erreurs de pause
+      }
+    }
+    DebugLog.info('[CloudTTS] All players stopped');
+  }
+
+  /// Nettoyer le cache
+  static void clearCache() {
+    _audioCache.clear();
+    _audioPlayers.clear();
+    DebugLog.info('[CloudTTS] Cache cleared');
+  }
+
+  /// Pré-charger des audios fréquemment utilisés
+  static Future<void> preloadCommonPhrases() async {
+    final phrases = [
+      'Équipement scanné',
+      'Flight case',
+      'Conteneur',
+      'Validé',
+      'Erreur',
+    ];
+
+    DebugLog.info('[CloudTTS] Preloading ${phrases.length} common phrases...');
+
+    for (final phrase in phrases) {
+      try {
+        await generateAudio(phrase);
+      } catch (e) {
+        DebugLog.warning('[CloudTTS] Failed to preload: $phrase - $e');
+      }
+    }
+
+    DebugLog.info('[CloudTTS] ✓ Preload complete');
+  }
+}
+