Add user management features.

server/api/user.go

@@ -277,6 +277,26 @@ func handleGetUserInfo(c fiber.Ctx) error {
 	})
 }
 
+func handleChangeUsername(c fiber.Ctx) error {
+	uid, ok := c.Locals("uid").(uint)
+	if !ok {
+		return model.NewUnAuthorizedError("Unauthorized")
+	}
+	newUsername := c.FormValue("username")
+	if newUsername == "" {
+		return model.NewRequestError("Username is required")
+	}
+	user, err := service.ChangeUsername(uid, newUsername)
+	if err != nil {
+		return err
+	}
+	return c.Status(fiber.StatusOK).JSON(model.Response[model.UserView]{
+		Success: true,
+		Data:    user,
+		Message: "Username changed successfully",
+	})
+}
+
 func AddUserRoutes(r fiber.Router) {
 	u := r.Group("user")
 	u.Post("/register", handleUserRegister)
@@ -290,4 +310,5 @@ func AddUserRoutes(r fiber.Router) {
 	u.Get("/search", handleSearchUsers)
 	u.Post("/delete", handleDeleteUser)
 	u.Get("/info", handleGetUserInfo)
+	u.Post("/username", handleChangeUsername)
 }

server/service/user.go

@@ -264,3 +264,18 @@ func GetUserByUsername(username string) (model.UserView, error) {
 	}
 	return user.ToView(), nil
 }
+
+func ChangeUsername(uid uint, newUsername string) (model.UserView, error) {
+	if len(newUsername) < 3 || len(newUsername) > 20 {
+		return model.UserView{}, model.NewRequestError("Username must be between 3 and 20 characters")
+	}
+	user, err := dao.GetUserByID(uid)
+	if err != nil {
+		return model.UserView{}, err
+	}
+	user.Username = newUsername
+	if err := dao.UpdateUser(user); err != nil {
+		return model.UserView{}, err
+	}
+	return user.ToView(), nil
+}