[add] i18n support zh,en

api/app/i18n/service.py

@@ -0,0 +1,370 @@
+"""
+Translation service for i18n system.
+
+This module provides the core translation functionality including:
+- Translation lookup with fallback mechanism
+- Parameterized message support
+- Enum value translation
+- Memory caching for performance
+- Performance monitoring and metrics
+"""
+
+import logging
+from functools import lru_cache
+from typing import Any, Dict, Optional
+
+from app.i18n.loader import TranslationLoader
+from app.i18n.cache import TranslationCache
+from app.i18n.metrics import get_metrics, monitor_performance, track_missing_translation, track_translation_request
+from app.i18n.logger import get_translation_logger
+
+logger = logging.getLogger(__name__)
+
+
+class TranslationService:
+    """
+    Translation service that provides:
+    - Fast translation lookup with memory cache
+    - Parameterized message support ({param} syntax)
+    - Fallback mechanism (current locale → default locale → key)
+    - Enum value translation
+    - Deep merge of multi-directory translations
+    """
+
+    def __init__(self, locales_dirs: Optional[list] = None):
+        """
+        Initialize the translation service.
+
+        Args:
+            locales_dirs: List of directories containing translation files.
+                         If None, will auto-detect from settings.
+        """
+        from app.core.config import settings
+
+        self.loader = TranslationLoader(locales_dirs)
+        self.default_locale = settings.I18N_DEFAULT_LANGUAGE
+        self.fallback_locale = settings.I18N_FALLBACK_LANGUAGE
+        self.log_missing = settings.I18N_LOG_MISSING_TRANSLATIONS
+        self.enable_cache = settings.I18N_ENABLE_TRANSLATION_CACHE
+
+        # Initialize advanced cache with LRU
+        lru_cache_size = getattr(settings, 'I18N_LRU_CACHE_SIZE', 1000)
+        self.cache = TranslationCache(
+            max_lru_size=lru_cache_size,
+            enable_lazy_load=False  # Load all at startup for now
+        )
+
+        # Load all translations into cache
+        self._load_all_locales()
+
+        # Initialize metrics
+        self.metrics = get_metrics()
+        
+        # Initialize translation logger
+        self.translation_logger = get_translation_logger()
+
+        logger.info(
+            f"TranslationService initialized with default locale: {self.default_locale}, "
+            f"LRU cache size: {lru_cache_size}"
+        )
+
+    def _load_all_locales(self):
+        """Load all available locales into memory cache."""
+        available_locales = self.loader.get_available_locales()
+        logger.info(f"Loading translations for locales: {available_locales}")
+
+        for locale in available_locales:
+            locale_data = self.loader.load_locale(locale)
+            self.cache.set_locale_data(locale, locale_data)
+
+        logger.info(f"Loaded {len(available_locales)} locales into cache")
+
+    @monitor_performance("translate")
+    def translate(
+        self,
+        key: str,
+        locale: Optional[str] = None,
+        **params
+    ) -> str:
+        """
+        Translate a key to the target locale.
+
+        Supports:
+        - Dot-separated keys (e.g., "common.success.created")
+        - Parameterized messages (e.g., "Hello {name}")
+        - Fallback mechanism
+
+        Args:
+            key: Translation key (format: "namespace.key.subkey")
+            locale: Target locale (defaults to default locale)
+            **params: Parameters for parameterized messages
+
+        Returns:
+            Translated string, or the key itself if translation not found
+
+        Examples:
+            translate("common.success.created", "zh")
+            # => "创建成功"
+
+            translate("common.validation.required", "zh", field="名称")
+            # => "名称不能为空"
+        """
+        if locale is None:
+            locale = self.default_locale
+
+        # Parse key (namespace.key.subkey)
+        parts = key.split(".", 1)
+        if len(parts) < 2:
+            if self.log_missing:
+                logger.warning(f"Invalid translation key format: {key}")
+            return key
+
+        namespace = parts[0]
+        key_path = parts[1].split(".")
+
+        # Track request
+        track_translation_request(locale, namespace)
+
+        # Get translation from cache
+        translation = self.cache.get_translation(locale, namespace, key_path)
+
+        # Fallback to default locale if not found
+        if translation is None and locale != self.fallback_locale:
+            translation = self.cache.get_translation(
+                self.fallback_locale, namespace, key_path
+            )
+
+        # If still not found, return the key itself
+        if translation is None:
+            if self.log_missing:
+                logger.warning(
+                    f"Missing translation: {key} (locale: {locale})"
+                )
+                track_missing_translation(key, locale)
+                
+                # Log to translation logger with context
+                self.translation_logger.log_missing_translation(
+                    key=key,
+                    locale=locale,
+                    context={"namespace": namespace}
+                )
+            return key
+
+        # Apply parameters if provided
+        if params:
+            try:
+                translation = translation.format(**params)
+            except KeyError as e:
+                error_msg = f"Missing parameter in translation '{key}': {e}"
+                logger.error(error_msg)
+                self.translation_logger.log_translation_error(
+                    error_type="parameter_missing",
+                    message=error_msg,
+                    key=key,
+                    locale=locale,
+                    context={"params": list(params.keys())}
+                )
+            except Exception as e:
+                error_msg = f"Error formatting translation '{key}': {e}"
+                logger.error(error_msg)
+                self.translation_logger.log_translation_error(
+                    error_type="format_error",
+                    message=error_msg,
+                    key=key,
+                    locale=locale
+                )
+
+        return translation
+
+    def _get_translation(
+        self,
+        locale: str,
+        namespace: str,
+        key_path: list
+    ) -> Optional[str]:
+        """
+        Get translation from cache (deprecated, use cache.get_translation).
+
+        Args:
+            locale: Locale code
+            namespace: Translation namespace
+            key_path: List of nested keys
+
+        Returns:
+            Translation string or None if not found
+        """
+        return self.cache.get_translation(locale, namespace, key_path)
+
+    @monitor_performance("translate_enum")
+    def translate_enum(
+        self,
+        enum_type: str,
+        value: str,
+        locale: Optional[str] = None
+    ) -> str:
+        """
+        Translate an enum value.
+
+        Args:
+            enum_type: Enum type name (e.g., "workspace_role")
+            value: Enum value (e.g., "manager")
+            locale: Target locale
+
+        Returns:
+            Translated enum display name
+
+        Examples:
+            translate_enum("workspace_role", "manager", "zh")
+            # => "管理员"
+
+            translate_enum("invite_status", "pending", "en")
+            # => "Pending"
+        """
+        key = f"enums.{enum_type}.{value}"
+        return self.translate(key, locale)
+
+    def has_translation(self, key: str, locale: str) -> bool:
+        """
+        Check if a translation exists for the given key and locale.
+
+        Args:
+            key: Translation key
+            locale: Locale code
+
+        Returns:
+            True if translation exists, False otherwise
+        """
+        parts = key.split(".", 1)
+        if len(parts) < 2:
+            return False
+
+        namespace = parts[0]
+        key_path = parts[1].split(".")
+
+        translation = self.cache.get_translation(locale, namespace, key_path)
+        return translation is not None
+
+    def reload(self, locale: Optional[str] = None):
+        """
+        Reload translation files.
+
+        Args:
+            locale: Specific locale to reload. If None, reloads all locales.
+        """
+        logger.info(f"Reloading translations for locale: {locale or 'all'}")
+
+        if locale:
+            locale_data = self.loader.load_locale(locale)
+            self.cache.set_locale_data(locale, locale_data)
+            # Clear LRU cache for this locale
+            self.cache.clear_locale(locale)
+        else:
+            self._load_all_locales()
+            # Clear all LRU cache
+            self.cache.clear_lru()
+
+        logger.info("Translation reload completed")
+
+    def get_available_locales(self) -> list:
+        """
+        Get list of all available locales.
+
+        Returns:
+            List of locale codes
+        """
+        return self.cache.get_loaded_locales()
+    
+    def get_cache_stats(self) -> Dict[str, Any]:
+        """
+        Get cache statistics.
+        
+        Returns:
+            Dictionary with cache statistics
+        """
+        return self.cache.get_stats()
+    
+    def get_metrics_summary(self) -> Dict[str, Any]:
+        """
+        Get metrics summary.
+        
+        Returns:
+            Dictionary with metrics summary
+        """
+        return self.metrics.get_summary()
+    
+    def get_memory_usage(self) -> Dict[str, Any]:
+        """
+        Get memory usage information.
+        
+        Returns:
+            Dictionary with memory usage information
+        """
+        return self.cache.get_memory_usage()
+
+    def get_loaded_dirs(self) -> list:
+        """
+        Get list of loaded translation directories.
+
+        Returns:
+            List of directory paths
+        """
+        return self.loader.locales_dirs
+
+
+# Global singleton instance
+_translation_service: Optional[TranslationService] = None
+
+
+def get_translation_service() -> TranslationService:
+    """
+    Get the global translation service instance.
+
+    Returns:
+        TranslationService singleton
+    """
+    global _translation_service
+    if _translation_service is None:
+        _translation_service = TranslationService()
+    return _translation_service
+
+
+# Convenience functions for easy access
+def t(key: str, locale: Optional[str] = None, **params) -> str:
+    """
+    Translate a key (convenience function).
+
+    Args:
+        key: Translation key
+        locale: Target locale (optional, uses default if not provided)
+        **params: Parameters for parameterized messages
+
+    Returns:
+        Translated string
+
+    Examples:
+        t("common.success.created")
+        t("common.validation.required", field="名称")
+        t("workspace.member_count", count=5)
+    """
+    service = get_translation_service()
+    return service.translate(key, locale, **params)
+
+
+def t_enum(enum_type: str, value: str, locale: Optional[str] = None) -> str:
+    """
+    Translate an enum value (convenience function).
+
+    Args:
+        enum_type: Enum type name
+        value: Enum value
+        locale: Target locale
+
+    Returns:
+        Translated enum display name
+
+    Examples:
+        t_enum("workspace_role", "manager")
+        t_enum("invite_status", "pending", "en")
+    """
+    service = get_translation_service()
+    return service.translate_enum(enum_type, value, locale)