Refactor: Implement uber-go/fx dependency injection

- Replace global variable pattern with proper dependency injection
- Add uber-go/fx for automatic dependency resolution
- Refactor all services and handlers to use constructor injection
- Eliminate fragile initialization order dependencies
- Improve testability and modularity
- Add structured logging with zap

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

internal/database/database.go

@@ -11,13 +11,11 @@ import (
 	"gorm.io/gorm"
 )
 
-var Gorm *gorm.DB
-
-func Connect() (*gorm.DB, error) {
+func Connect(cfg *config.Config) (*gorm.DB, error) {
 	var db *gorm.DB
 	var err error = nil
 
-	if config.Config.DBEngine == "sqlite" {
+	if cfg.DBEngine == "sqlite" {
 		_, err = os.ReadDir("data")
 		if err != nil {
 			err = os.Mkdir("data", 0755)
@@ -31,11 +29,11 @@ func Connect() (*gorm.DB, error) {
 		}
 	} else {
 		dsn := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?charset=utf8mb4&parseTime=True&loc=Local",
-			config.Config.DBUser,
-			config.Config.DBPassword,
-			config.Config.DBHost,
-			config.Config.DBPort,
-			config.Config.DBName)
+			cfg.DBUser,
+			cfg.DBPassword,
+			cfg.DBHost,
+			cfg.DBPort,
+			cfg.DBName)
 		db, err = gorm.Open(mysql.Open(dsn), &gorm.Config{})
 		if err != nil {
 			return nil, err
@@ -54,13 +52,4 @@ func Connect() (*gorm.DB, error) {
 		return nil, err
 	}
 	return db, nil
-}
-
-// IDK if this is how it works or not, leave it as is for now
-func Init() {
-	var err error
-	Gorm, err = Connect()
-	if err != nil {
-		panic(err)
-	}
-}
+}