feat(user): add user type modification endpoint

- Implement new endpoint `/userMgr/modifyType` for updating user types
- Add database function DBUpdateUserType to handle type updates
- Include request validation and proper error handling
- Update API documentation with new endpoint details

userAct.go

@@ -24,6 +24,11 @@ type CreateUserRequest struct {
 	Type     string `json:"type"`
 }
 
+type ModifyUserRequest struct {
+	UserID int `json:"userID"`
+	Type   string `json:"newType"`
+}
+
 type RemoveUserRequest struct {
 	TargetUserID int `json:"targetUserID"`
 }
@@ -310,6 +315,48 @@ func CreateUserHandler(w http.ResponseWriter, r *http.Request) {
 	postLog.Info(fmt.Sprintf("[CreateUserHandler] User \"%s\" created successfully with ID: %d", req.Username, userID))
 }
 
+func ModifyUserTypeHandler (w http.ResponseWriter, r *http.Request) {
+	_, err := Auth(w, r, http.MethodPost, "superuser")
+	if err != nil {
+		SendErrorResponse(w, http.StatusUnauthorized, err.Error())
+		postLog.Warning(fmt.Sprintf("[ModifyUserHandler] Auth failed: %v", err))
+		return
+	}
+
+	body, err := io.ReadAll(r.Body)
+	if err != nil {
+		SendErrorResponse(w, http.StatusBadRequest, "Failed to read request body")
+		postLog.Warning(fmt.Sprintf("[ModifyUserHandler] Failed to read request body: %v", err))
+		return
+	}
+	defer r.Body.Close()
+
+	var req ModifyUserRequest
+
+	if err := json.Unmarshal(body, &req); err != nil {
+		SendErrorResponse(w, http.StatusBadRequest, "Invalid request format")
+		postLog.Warning(fmt.Sprintf("[ModifyUserHandler] Invalid request format: %v", err))
+		return
+	}
+	if req.UserID == 0 {
+		SendErrorResponse(w, http.StatusBadRequest, "UserID is required")
+		postLog.Warning("[ModifyUserHandler] ModifyUser failed: UserID is empty")
+		return
+	}
+	if req.Type != "admin" && req.Type != "visitor" && req.Type != "superuser" {
+		SendErrorResponse(w, http.StatusBadRequest, "Invalid type: must be 'admin' or 'visitor' or 'superuser'")
+		postLog.Warning(fmt.Sprintf("[ModifyUserHandler] ModifyUser failed: invalid type: %s", req.Type))
+		return
+	}
+	if err := DBUpdateUserType(req.UserID, req.Type); err != nil {
+		SendErrorResponse(w, http.StatusInternalServerError, err.Error())
+		postLog.Error(fmt.Sprintf("[ModifyUserHandler] Failed to update user type [%d]: %v", req.UserID, err))
+		return
+	}
+	SendSuccessResponse(w, "User type updated successfully", nil)
+	postLog.Info(fmt.Sprintf("[ModifyUserHandler] User [%d]%s type updated successfully to: %s", req.UserID, GetUsernameByID(req.UserID), req.Type))
+}
+
 func RemoveUserHandler(w http.ResponseWriter, r *http.Request) {
 	_, err := Auth(w, r, http.MethodPost, "superuser")
 	if err != nil {