save current state

library/include/mobilisis/calculator_functions.h

@@ -3,6 +3,7 @@
 
 #include <iostream>
 #include <optional>
+#include <utility>
 
 #include "configuration.h"
 #include "calculate_price.h"
@@ -70,7 +71,8 @@ public:
 	/// <param name="start_datetime">Date/time of payment to be conducted in ISO8601 format (e.g. 2022-12-25T08:00:00Z)</param>
 	/// <param name="price"></param>
 	/// <returns>Returns duration in seconds (data type: double)</returns>
-    std::string GetDurationFromCost(Configuration* cfg, uint8_t vehicle_type, char const* start_datetime, double price,
+    std::pair<std::string, QDateTime>
+        GetDurationFromCost(Configuration* cfg, uint8_t vehicle_type, char const* start_datetime, double price,
                                     PermitType permitType, bool nextDay = false, bool prepaid = false);
 
 	/// <summary>