From 1b55498b0048739978de4cbada46bd9a0cfd16a1 Mon Sep 17 00:00:00 2001
From: Nikolai Papin <nikolai@weirdcat.ru>
Date: Mon, 23 Jun 2025 14:18:25 +0300
Subject: [PATCH] refactor: a better DI-friendy logger implementation that
 doesn't suck

---
 backend/cmd/main.go               | 15 ++++++++++--
 backend/internal/logger/logger.go | 40 ++++++++++++++-----------------
 backend/internal/services/auth.go |  9 ++++---
 3 files changed, 35 insertions(+), 29 deletions(-)

diff --git a/backend/cmd/main.go b/backend/cmd/main.go
index b69e2e8..1fb5fb1 100644
--- a/backend/cmd/main.go
+++ b/backend/cmd/main.go
@@ -20,6 +20,7 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"go.uber.org/fx"
+	"go.uber.org/zap"
 
 	"easywish/config"
 	docs "easywish/docs"
@@ -42,6 +43,7 @@ func main() {
 	fx.New(	
 		fx.Provide(
 			logger.NewLogger,
+			logger.NewSyncLogger,
 			gin.Default,
 		),
 		database.Module,
@@ -49,7 +51,7 @@ func main() {
 		controllers.Module,
 		routes.Module,
 
-		fx.Invoke(func(lc fx.Lifecycle, router *gin.Engine) {
+		fx.Invoke(func(lc fx.Lifecycle, router *gin.Engine, syncLogger *logger.SyncLogger) {
 
 			// Swagger
 			docs.SwaggerInfo.Schemes = []string{"http"}
@@ -65,6 +67,7 @@ func main() {
 				OnStart: func(ctx context.Context) error {
 					go func() {
 						if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+							syncLogger.Fatal("Server failed", zap.Error(err))
 						}
 					}()
 					return nil
@@ -72,7 +75,15 @@ func main() {
 				OnStop: func(ctx context.Context) error {
 					shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 					defer cancel()
-					return server.Shutdown(shutdownCtx)
+
+					if err := server.Shutdown(shutdownCtx); err != nil {
+						syncLogger.Error("Server shutdown error", zap.Error(err))
+					}
+
+					if err := syncLogger.Close(); err != nil {
+						syncLogger.Error("Logger sync error", zap.Error(err))
+					}
+					return nil
 				},
 			})
 		}),
diff --git a/backend/internal/logger/logger.go b/backend/internal/logger/logger.go
index d2586bd..5bac938 100644
--- a/backend/internal/logger/logger.go
+++ b/backend/internal/logger/logger.go
@@ -8,40 +8,36 @@ import (
 	"go.uber.org/zap"
 )
 
-type Logger interface {
-	Get() *zap.Logger	
-	Sync() error
-}
-
-type loggerImpl struct {
-}
-
-func NewLogger() Logger {
-	return &loggerImpl{}
-}
-
 var (
-	logger *zap.Logger
-	once   sync.Once
+	instance *zap.Logger
+	once     sync.Once
 )
 
-func (l *loggerImpl) Get() *zap.Logger {
+func NewLogger() *zap.Logger {
 	once.Do(func() {
-		var err error
 		cfg := config.GetConfig()
+		var err error
 
 		if cfg.Environment == "production" {
-			logger, err = zap.NewProduction()
+			instance, err = zap.NewProduction()
 		} else {
-			logger, err = zap.NewDevelopment()
+			instance, err = zap.NewDevelopment()
 		}
 		if err != nil {
-			panic(err)
+			panic("failed to initialize logger: " + err.Error())
 		}
 	})
-	return logger
+	return instance
 }
 
-func (l *loggerImpl) Sync() error {
-	return logger.Sync()
+type SyncLogger struct {
+	*zap.Logger
+}
+
+func NewSyncLogger(logger *zap.Logger) *SyncLogger {
+	return &SyncLogger{logger}
+}
+
+func (s *SyncLogger) Close() error {
+	return s.Sync()
 }
diff --git a/backend/internal/services/auth.go b/backend/internal/services/auth.go
index b752d01..a91db04 100644
--- a/backend/internal/services/auth.go
+++ b/backend/internal/services/auth.go
@@ -3,7 +3,6 @@ package services
 import (
 	"easywish/internal/database"
 	errs "easywish/internal/errors"
-	"easywish/internal/logger"
 	"easywish/internal/models"
 	"easywish/internal/utils"
 
@@ -18,11 +17,11 @@ type AuthService interface {
 }
 
 type authServiceImpl struct {
-	log logger.Logger
+	log *zap.Logger
 	dbctx database.DbContext
 }
 
-func NewAuthService(_log logger.Logger, _dbctx database.DbContext) AuthService {
+func NewAuthService(_log *zap.Logger, _dbctx database.DbContext) AuthService {
 	return &authServiceImpl{log: _log, dbctx: _dbctx}
 }
 
@@ -33,10 +32,10 @@ func (a *authServiceImpl) RegistrationBegin(request models.RegistrationBeginRequ
 	user, err := db.TXQueries.CreateUser(db.CTX, request.Username) // TODO: validation
 
   if err != nil {
-		a.log.Get().Error("Failed to add user to database", zap.Error(err))
+		a.log.Error("Failed to add user to database", zap.Error(err))
 		return false, errs.ErrServerError
 	}
-	a.log.Get().Info("Registered a new user", zap.String("username", user.Username))
+	a.log.Info("Registered a new user", zap.String("username", user.Username))
 
 	helper.Commit()