get_minimal_parking_price(): compute this price dynamically according to settings

in the tariff-file. Introduced for Fuchs (500) for Valser Alm (Location: Fane)

library/src/calculate_price.cpp

@@ -94,6 +94,40 @@ int CALCULATE_LIBRARY_API get_minimal_parkingprice(Configuration *cfg,
     int minPrice = -1;
     paymentOptionIndex = cfg->getPaymentOptionIndex(permitType);
 
+    int payment_method_id = cfg->getPaymentOptions(paymentOptionIndex).pop_payment_method_id;
+
+    if (payment_method_id == PaymentMethod::Degressive) {
+        // Degressive: new for Fuchs Technik (500), ValserAlm (Fane):
+        // the minimal price has to be calculated, in cannot be hard coded into
+        // the tariff file.
+        // The working times have a reference into the payment rates. Two special
+        // entries (with the numbers 1000/1001) point to the respective prices.
+        switch(permitType) {
+            default: {
+                // find the correct work time range
+                int weekDay = start.date().dayOfWeek();
+                std::optional<QVector<ATBWeekDaysWorktime>> const &wd = cfg->getAllWeekDayWorkTimes();
+                if (wd.has_value()) {
+                    QVector<ATBWeekDaysWorktime> const &vec = wd.value();
+                    for (int i = 0; i < vec.size(); ++i) {
+                        ATBWeekDaysWorktime const &wt = vec[i];
+                        if (wt.pwd_period_day_in_week_id == weekDay) {
+                            if (start.time() >= QTime::fromString(QString::fromStdString(wt.pwd_time_from), Qt::ISODate)
+                             && start.time() <= QTime::fromString(QString::fromStdString(wt.pwd_time_to), Qt::ISODate)) {
+                                // found worktime range
+                                int pop_id = wt.pwd_pop_id; // 1000 or 1001
+                                for (auto[itr, rangeEnd] = cfg->PaymentRate.equal_range(pop_id); itr != rangeEnd; ++itr) {
+                                    i = vec.size(); // to leave outer loop
+                                    minPrice = itr->second.pra_price; // this is now the minimal price
+                                    break;
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    } else {
         switch(permitType) {
         case PERMIT_TYPE::SHORT_TERM_PARKING: { // e.g. szeged (customer_281)
             minPrice = cfg->getPaymentOptions(paymentOptionIndex).pop_min_price;
@@ -110,6 +144,7 @@ int CALCULATE_LIBRARY_API get_minimal_parkingprice(Configuration *cfg,
         default:
             minPrice = cfg->getPaymentOptions(paymentOptionIndex).pop_min_price;
         }
+    }
 
     return minPrice;
 }