feat: initial official i18n support for backend

common/i18n/i18n.go

@@ -0,0 +1,72 @@
+package i18n
+
+import (
+	"embed"
+	"encoding/json"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+)
+
+//go:embed locales/*.json
+var localesFS embed.FS
+
+var (
+	translations = make(map[string]map[string]string)
+	defaultLang  = "en"
+	ContextKey   = "i18n"
+)
+
+// Init loads all translation files from embedded filesystem
+func Init() error {
+	entries, err := localesFS.ReadDir("locales")
+	if err != nil {
+		return err
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".json") {
+			continue
+		}
+
+		langCode := strings.TrimSuffix(entry.Name(), ".json")
+		content, err := localesFS.ReadFile("locales/" + entry.Name())
+		if err != nil {
+			return err
+		}
+
+		var translation map[string]string
+		if err := json.Unmarshal(content, &translation); err != nil {
+			return err
+		}
+		translations[langCode] = translation
+	}
+
+	return nil
+}
+
+func GetLang(c *gin.Context) string {
+	rawLang, ok := c.Get(ContextKey)
+	if !ok {
+		return defaultLang
+	}
+	lang, _ := rawLang.(string)
+	if lang != "" {
+		return lang
+	}
+	return defaultLang
+}
+
+func Translate(c *gin.Context, message string) string {
+	lang := GetLang(c)
+	return translateHelper(lang, message)
+}
+
+func translateHelper(lang, message string) string {
+	if trans, ok := translations[lang]; ok {
+		if translated, exists := trans[message]; exists {
+			return translated
+		}
+	}
+	return message
+}