Added INVALID_START_DATE.

Added compute_duration_for_parking_ticket().

library/include/mobilisis/calculate_price.h

@@ -39,6 +39,7 @@ struct CALCULATE_LIBRARY_API CalcState {
         ERROR_LOADING_TARIFF,
         ERROR_PARSING_TARIFF,
         NEGATIVE_PARING_TIME,
+        INVALID_START_DATE,
         WRONG_PARAM_VALUES,
         ABOVE_MAX_PARKING_TIME,
         BELOW_MIN_PARKING_TIME,
@@ -88,6 +89,9 @@ struct CALCULATE_LIBRARY_API CalcState {
         case State::OVERPAID:
             s = "OVERPAID";
             break;
+        case State::INVALID_START_DATE:
+            s = "INVALID_START_DATE";
+            break;
         }
         return s + ":" + m_desc;
     }
@@ -101,10 +105,17 @@ CalcState CALCULATE_LIBRARY_API init_tariff(parking_tariff_t **tariff,
 void CALCULATE_LIBRARY_API free_tariff(parking_tariff_t *tariff);
 int CALCULATE_LIBRARY_API get_zone_nr();
 
-CalcState CALCULATE_LIBRARY_API compute_price_for_parking_ticket(parking_tariff_t *tariff,
+CalcState CALCULATE_LIBRARY_API compute_price_for_parking_ticket(
+                                            parking_tariff_t *tariff,
                                             time_t start_parking_time,
                                             time_t end_parking_time,
                                             struct price_t *price);
+
+CalcState CALCULATE_LIBRARY_API compute_duration_for_parking_ticket(
+                                            parking_tariff_t *tariff,
+                                            time_t start_parking_time,
+                                            double cost,
+                                            QString &duration);
 #ifdef __cplusplus
 } // extern "C"
 #endif