#include "calculate_price.h"
#include "configuration.h"
#include "calculator_functions.h"
#include "payment_option.h"
#include "utilities.h"
#include "tariff_global_defines.h"
#include "period_year.h"

#include <QFile>
#include <QFileInfo>
#include <QDateTime>
#include <QDebug>
#include <QList>

QString const CalcState::SUCCESS = "SUCCESS";
QString const CalcState::ERROR_PARSING_ZONE_NR = "ERROR_PARSING_ZONE_NR";
QString const CalcState::ERROR_LOADING_TARIFF = "ERROR_LOADING_TARIFF";
QString const CalcState::ERROR_PARSING_TARIFF = "ERROR_PARSING_TARIFF";
QString const CalcState::NEGATIVE_PARKING_TIME = "NEGATIVE_PARKING_TIME";
QString const CalcState::INVALID_START_DATE = "INVALID_START_DATE";
QString const CalcState::WRONG_PARAM_VALUES = "WRONG_PARAM_VALUES";
QString const CalcState::WRONG_ISO_TIME_FORMAT = "WRONG_ISO_TIME_FORMAT";
QString const CalcState::ABOVE_MAX_PARKING_TIME = "ABOVE_MAX_PARKING_TIME";
QString const CalcState::BELOW_MIN_PARKING_TIME = "BELOW_MIN_PARKING_TIME";
QString const CalcState::BELOW_MIN_PARKING_PRICE = "BELOW_MIN_PARKING_PRICE";
QString const CalcState::ABOVE_MAX_PARKING_PRICE = "ABOVE_MAX_PARKING_PRICE";
QString const CalcState::OVERPAID = "OVERPAID";
QString const CalcState::OUTSIDE_ALLOWED_PARKING_TIME = "OUTSIDE_ALLOWED_PARKING_TIME";

QList<int> CALCULATE_LIBRARY_API get_time_steps(Configuration *cfg) {
    return Calculator::GetInstance().GetTimeSteps(cfg);
}

int CALCULATE_LIBRARY_API get_minimal_parkingtime(Configuration const *cfg,
                                                  PERMIT_TYPE permitType,
                                                  int paymentOptionIndex) {
    int minTime = 0;

    paymentOptionIndex = cfg->getPaymentOptionIndex(permitType);

    qCritical() << __func__ << __LINE__ << "paymentOptionIndex" << paymentOptionIndex;
    qCritical() << __func__ << __LINE__ << "permit" << PermitType(permitType).toString();

    switch(permitType) {
    case PERMIT_TYPE::SHORT_TERM_PARKING: { // e.g. szeged (customer_281)
        qCritical() << __LINE__ << Calculator::GetInstance().GetTimeSteps((Configuration *)cfg, paymentOptionIndex);
        minTime = cfg->getPaymentOptions(paymentOptionIndex).pop_min_time;
        qCritical() << __func__ << __LINE__ << minTime;
    } break;
    case PERMIT_TYPE::DAY_TICKET_ADULT: {
    } break;
    case PERMIT_TYPE::DAY_TICKET_TEEN: {
    } break;
    case PERMIT_TYPE::DAY_TICKET_CHILD: {
    } break;
    default:
        // for each new sell-procedure, recomute the timesteps. implicitly, set
        // the minimal parking time.
        Calculator::GetInstance().ResetTimeSteps(paymentOptionIndex);
        qCritical() << __LINE__ << Calculator::GetInstance().GetTimeSteps((Configuration *)cfg, paymentOptionIndex);
        minTime = qRound(cfg->getPaymentOptions(paymentOptionIndex).pop_min_time);
    }

    qCritical() << "minTime" << minTime;
    return minTime;
}

int CALCULATE_LIBRARY_API get_maximal_parkingtime(Configuration const *cfg,
                                                  PERMIT_TYPE permitType,
                                                  int paymentOptionIndex) {

    paymentOptionIndex = cfg->getPaymentOptionIndex(permitType);
    int maxTime = 0;

    switch(permitType) {
    case PERMIT_TYPE::SHORT_TERM_PARKING: { // e.g. szeged (customer_281)
        maxTime = cfg->getPaymentOptions(paymentOptionIndex).pop_max_time;
    } break;
    case PERMIT_TYPE::DAY_TICKET_ADULT: {
    } break;
    case PERMIT_TYPE::DAY_TICKET_TEEN: {
    } break;
    case PERMIT_TYPE::DAY_TICKET_CHILD: {
    } break;
    default: ;
        maxTime = cfg->getPaymentOptions(paymentOptionIndex).pop_max_time;
    }

    return maxTime;
}

int CALCULATE_LIBRARY_API get_minimal_parkingprice(Configuration *cfg,
                                                   PERMIT_TYPE permitType,
                                                   int paymentOptionIndex,
                                                   QDateTime const &start) {
    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;
        } break;
        case PERMIT_TYPE::DAY_TICKET_ADULT: {
        } break;
        case PERMIT_TYPE::DAY_TICKET_TEEN: {
        } break;
        case PERMIT_TYPE::DAY_TICKET_CHILD: {
        } break;
        case PERMIT_TYPE::DAY_TICKET: {
            minPrice = compute_product_price(cfg, permitType, start);
        } break;
        default:
            minPrice = cfg->getPaymentOptions(paymentOptionIndex).pop_min_price;
        }
    }

    return minPrice;
}

int CALCULATE_LIBRARY_API compute_product_price(Configuration const *cfg,
                                                PERMIT_TYPE permitType,
                                                QDateTime const &start,
                                                QDateTime *productStart,
                                                QDateTime *productEnd) {

    switch(permitType) {
    case PERMIT_TYPE::SHORT_TERM_PARKING: { // e.g. szeged (customer_281)
    } break;
    case PERMIT_TYPE::DAY_TICKET_CHILD:
        // [[fallthrough]];
    case PERMIT_TYPE::DAY_TICKET_TEEN:
        // [[fallthrough]];
    case PERMIT_TYPE::FOOD_STAMP:
        // [[fallthrough]];
    case PERMIT_TYPE::DAY_TICKET_ADULT: {
        std::optional<QVector<ATBTariffProduct>> products = cfg->getTariffProductForProductId(permitType);
        if (products) {
            QVector<ATBTariffProduct> product = products.value();
            if (product.size() > 0) {
                ATBTariffProduct const &p = product[0];
                return p.m_tariff_product_price;
#if 0
                // in case we do not have prepaid-option
                QTime const &currentTime = QDateTime::currentDateTime().time();

                if (p.m_tariff_product_start <= currentTime && currentTime <= p.m_tariff_product_end) {
                    return p.m_tariff_product_price;
                } else {
                    qCritical() << "(" << __func__ << ":" << __LINE__ << ")"
                                << "ERROR currentTime"
                                << currentTime.toString(Qt::ISODate)
                                << "INVALID ("
                                << p.m_tariff_product_start.toString(Qt::ISODate)
                                << p.m_tariff_product_end.toString(Qt::ISODate) << ")";
                }
#endif
            }
        }
    } break;
    case PERMIT_TYPE::INVALID:
        // [[fallthrough]];
    case PERMIT_TYPE::DAY_TICKET: {
        std::optional<QVector<ATBTariffProduct>> products = cfg->getTariffProductForProductId(permitType);
        if (products) {
            QVector<ATBTariffProduct> product = products.value();
            int product_price = 0;

            if (productStart && productEnd) {
                *productStart = start;
                *productEnd = start;
                if (product.size() > 0) {
                    productStart->setTime(product[0].getTimeStart());
                    productEnd->setTime(product[0].getTimeEnd());
                }
            }

            for (QVector<ATBTariffProduct>::size_type i=0; i<product.size(); ++i) {
                ATBTariffProduct const &p = product[i];
                QTime const &startTime = p.getTimeStart();
                QTime const &endTime = p.getTimeEnd();

                // qCritical() << __LINE__ << startTime.toString(Qt::ISODate);
                // qCritical() << __LINE__ << endTime.toString(Qt::ISODate);
                // qCritical() << __LINE__ << start.toString(Qt::ISODate);

                if (start.time() >= startTime && start.time() < endTime) {
                    product_price = p.getProductPrice();
                    if (productStart && productEnd) {
                        productStart->setTime(startTime);
                        productEnd->setTime(endTime);
                    }
                }
            }

            return product_price;
        } else {
            // SZEGED
            int const pop_daily_card_price = cfg->getPaymentOptions().pop_daily_card_price;

            qDebug() << QString("(%1:%2) no products defined in tariff-file").arg(__func__).arg(__LINE__);
            qDebug() << QString("(%1:%2) pop_daily_card_price=%3").arg(__func__).arg(__LINE__).arg(pop_daily_card_price);

            // static const PaymentMethod paymentMethodId = Utilities::getPaymentMethodId(cfg);
            // return Utilities::getDailyTicketCardPrice(cfg, paymentMethodId);

            return pop_daily_card_price;
        }
    } break;
    case PERMIT_TYPE::TWENTY_FOUR_HOURS_TICKET: {
        std::optional<QVector<ATBTariffProduct>> products = cfg->getTariffProductForProductId(permitType);
        if (products) {
            int product_price = 0;
            QVector<ATBTariffProduct> product = products.value();

            if (product.size() > 0) {
                if (productStart && productEnd) {
                    int pop_min_time = get_minimal_parkingtime(cfg, PERMIT_TYPE::TWENTY_FOUR_HOURS_TICKET); // in minutes
                    int pop_max_time = get_maximal_parkingtime(cfg, PERMIT_TYPE::TWENTY_FOUR_HOURS_TICKET); // in minutes
                    if (pop_max_time >= pop_min_time) {
                        *productStart = start;
                        *productEnd = start.addSecs(pop_max_time*60);
                        product_price = product[0].getProductPrice();
                    }
                }
            }

            return product_price;
        }

    } break;
    case PERMIT_TYPE::SHORT_TERM_PARKING_PKW: {
        PermitType p(permitType);
        std::optional<ATBPaymentOption> const paymentOption = cfg->getPaymentOptionForKey(p.get());
        if (paymentOption.has_value()) {
            ATBPaymentOption option = paymentOption.value();
            int const pop_daily_card_price = option.pop_daily_card_price;
            qCritical() << "SHORT_TERM_PARKING_PKW: daily ticket price" << pop_daily_card_price;
            return pop_daily_card_price;
        }
    } break;
    case PERMIT_TYPE::SHORT_TERM_PARKING_BUS: {
        qCritical() << "TODO: SHORT_TERM_PARKING_BUS";
    } break;
    case PERMIT_TYPE::SHORT_TERM_PARKING_CAMPER: {
        qCritical() << "TODO: SHORT_TERM_PARKING_CAMPER";
    } break;
    case PERMIT_TYPE::DAY_TICKET_PKW: {
        PermitType p(permitType);
        std::optional<ATBPaymentOption> const paymentOption = cfg->getPaymentOptionForKey(p.get());
        if (paymentOption.has_value()) {
            ATBPaymentOption option = paymentOption.value();
            int const pop_daily_card_price = option.pop_daily_card_price;
            qCritical() << "DAY_TICKET_PKW: daily ticket price" << pop_daily_card_price;
            return pop_daily_card_price;
        }
    } break;
    case PERMIT_TYPE::DAY_TICKET_BUS: {
        PermitType p(permitType);
        std::optional<ATBPaymentOption> const paymentOption = cfg->getPaymentOptionForKey(p.get());
        if (paymentOption.has_value()) {
            ATBPaymentOption option = paymentOption.value();
            int const pop_daily_card_price = option.pop_daily_card_price;
            qCritical() << "DAY_TICKET_BUS: daily ticket price" << pop_daily_card_price;
            return pop_daily_card_price;
        }
    } break;
    case PERMIT_TYPE::DAY_TICKET_CAMPER: {
        PermitType p(permitType);
        std::optional<ATBPaymentOption> const paymentOption = cfg->getPaymentOptionForKey(p.get());
        if (paymentOption.has_value()) {
            ATBPaymentOption option = paymentOption.value();
            int const pop_daily_card_price = option.pop_daily_card_price;
            qCritical() << "DAY_TICKET_CAMPER: daily ticket price" << pop_daily_card_price;
            return pop_daily_card_price;
        }
    } break;
    default:
      break;
    }

    return 0;
}

int CALCULATE_LIBRARY_API get_maximal_parkingprice(Configuration *cfg,
                                                   PERMIT_TYPE permitType,
                                                   int paymentOptionIndex) {
    int maxPrice = -1;
    static const PaymentMethod paymentMethodId = Utilities::getPaymentMethodId(cfg);

    paymentOptionIndex = cfg->getPaymentOptionIndex(permitType);

    switch(permitType) {
    case PERMIT_TYPE::SHORT_TERM_PARKING: { // e.g. szeged (customer_281)
        if (paymentMethodId == PaymentMethod::Progressive || paymentMethodId == PaymentMethod::Steps) {
            maxPrice = Utilities::getMaximalParkingPrice(cfg, paymentMethodId);
        } else { // PaymentMethod::Linear -> e.g. szeged
            int const key = cfg->getPaymentOptions(paymentOptionIndex).pop_id;
            int const maxTime = cfg->getPaymentOptions(paymentOptionIndex).pop_max_time; // maxTime is given in minutes
            std::optional<QVector<ATBPaymentRate>> const &pv = cfg->getPaymentRateForKey(key);
            if (pv) {
                QVector<ATBPaymentRate> const &paymentRate = pv.value();
                if (paymentRate.size() > 0) {
                    int const price = paymentRate.last().pra_price; // price is given per hour
                    maxPrice = qRound((maxTime * price) / 60.0f);
                }
            }
        }
    } break;
    case PERMIT_TYPE::DAY_TICKET_ADULT:
        break;
    case PERMIT_TYPE::DAY_TICKET_TEEN:
        break;
    case PERMIT_TYPE::DAY_TICKET_CHILD:
        break;
    case PERMIT_TYPE::DAY_TICKET_BUS:
        break;
    case PERMIT_TYPE::DAY_TICKET_CAMPER:
        break;
    case PERMIT_TYPE::DAY_TICKET_PKW:
        break;
    case PERMIT_TYPE::SHORT_TERM_PARKING_BUS: {
        std::optional<ATBPaymentOption> po = cfg->getPaymentOptionForKey(permitType);
        if (po.has_value()) {
            ATBPaymentOption option = po.value();
            return option.pop_max_price;
        }
    } break;
    case PERMIT_TYPE::SHORT_TERM_PARKING_PKW: {
        std::optional<ATBPaymentOption> po = cfg->getPaymentOptionForKey(permitType);
        if (po.has_value()) {
            ATBPaymentOption option = po.value();
            return option.pop_max_price;
        }
    } break;
    case PERMIT_TYPE::SHORT_TERM_PARKING_CAMPER:
        break;
    default: ;
    }

    return maxPrice;
}

int CALCULATE_LIBRARY_API get_zone_nr(int zone)
{
    if(zone > -1) return zone;
    else
    {
        QFile zone("/etc/zone_nr");
        if (zone.exists()) {
            QFileInfo finfo(zone);
            if (finfo.size() <= 4) { // decimal 000\n
                if (zone.open(QIODevice::ReadOnly | QIODevice::Text)) {
                    QTextStream in(&zone);
                    return in.readLine(100).toInt();
                }
            }
        }
        return -1;
    }
}

CalcState CALCULATE_LIBRARY_API init_tariff(parking_tariff_t **tariff, char const *config_file) {
    *tariff = new Configuration();

    CalcState calcState;
#if __linux__

    int const zone = get_zone_nr();

    // DEBUG
    qCritical() << "init_tariff:";
    qCritical() << "      ... zone = " << zone;

    if (zone <= 0) {
        delete *tariff;
        *tariff = nullptr;
        return calcState.set(CalcState::State::ERROR_PARSING_ZONE_NR);
    }

    QString confFile(config_file);
    if (!confFile.endsWith(QChar('/'))) {
        confFile += "/";
    }

    char buffer[32];
    memset(buffer, 0x00, sizeof(buffer));
    snprintf(buffer, sizeof(buffer)-1, "tariff%02d.json", zone);
    confFile += buffer;
#else // windows
    QString confFile(config_file);
#endif

    // DEBUG
    qCritical() << "      ... confFile = " << confFile;

    QFile fname(confFile);
    if (fname.exists() &&
            fname.open(QIODevice::ReadOnly | QIODevice::Text)) {
        // DEBUG
        qCritical() << "      ... confFile is open";

        QString json = fname.readAll();
        if (! (*tariff)->ParseJson(*tariff, json.toStdString().c_str())) {
            delete *tariff;
            *tariff = nullptr;
            qCritical() << "      ... error parsing tariff";
            return calcState.set(CalcState::State::ERROR_PARSING_TARIFF);
        }
    } else {
        delete *tariff;
        *tariff = nullptr;
            qCritical() << "      ... error loading tariff";
        return calcState.set(CalcState::State::ERROR_LOADING_TARIFF);
    }

    qCritical() << "init_tariff: Parsing tariff config (" << confFile << ")";

    return calcState;
}

void CALCULATE_LIBRARY_API free_tariff(parking_tariff_t *tariff) {
    if (tariff != nullptr) {
        delete tariff;
    }
}

//
// UpDown 1 -> up; 0 -> down
int CALCULATE_LIBRARY_API compute_next_timestep(parking_tariff_t *tariff, int currentTimeMinutes,
                                                int UpDown, PermitType const &permitType)
{

    qCritical() << __LINE__ << "compute_next_timestep()     currentTimeMinutes: " << currentTimeMinutes;
    qCritical() << __LINE__ << "compute_next_timestep() up/down (1=up, 0=down): " << UpDown;

    // FIXME
    //std::optional<ATBPaymentOption> paymentOption = tariff->getPaymentOptionForKey(permitType.get());
    //if (!paymentOption.has_value()) {
    //    qCritical() << "   compute_next_timestep() ERROR";
    //    return currentTimeMinutes;
    //}

    int const paymentOptionIndex = tariff->getPaymentOptionIndex(permitType);
    int const &pop_plus_steps = tariff->getPaymentOptions(paymentOptionIndex).pop_plus_steps;
    int const &pop_minus_steps = tariff->getPaymentOptions(paymentOptionIndex).pop_minus_steps;

    qCritical() << __LINE__ << "compute_next_timestep()   payment option index: " << paymentOptionIndex;
    qCritical() << __LINE__ << "compute_next_timestep()             plus steps: " << pop_plus_steps;
    qCritical() << __LINE__ << "compute_next_timestep()            minus steps: " << pop_minus_steps;

    Configuration const *cfg = tariff;

    // compute payment method id (e.g. Linear=3, Steps=4)
    PaymentMethod const paymentMethodId = Utilities::getPaymentMethodId(cfg);
    switch (paymentMethodId) {
    case PaymentMethod::Progressive:
        qCritical() << __LINE__ << "compute_next_timestep() paymentMethodId: Progressive";
        break;
    case PaymentMethod::Degressive:
        qCritical() << __LINE__ << "compute_next_timestep() paymentMethodId: Degressive";
        break;
    case PaymentMethod::Linear:
        qCritical() << __LINE__ << "compute_next_timestep() paymentMethodId: Linear";
        break;
    case PaymentMethod::Steps:
        qCritical() << __LINE__ << "compute_next_timestep() paymentMethodId: Steps";
        break;
    case PaymentMethod::Undefined:
        qCritical() << __LINE__ << "compute_next_timestep() paymentMethodId: Undefined";
        break;
    }

    // use tariff with structure as for instance Schnau, Koenigsee:
    // without given YearPeriod, SpecialDays and SpecialDaysWorktime
    if ((paymentMethodId == PaymentMethod::Steps) ||
        // progressive tariff: e.g. Neuhauser, Kirchdorf (743)
        (paymentMethodId == PaymentMethod::Progressive) ||
        // degressive tariff: e.g. Fuchs Technik (500)
        (paymentMethodId == PaymentMethod::Degressive))
    {
        QList<int> &stepList = Calculator::GetInstance().GetTimeSteps(tariff, paymentOptionIndex);

        int const size = stepList.size();
        if (size == 0) {
            qCritical() << "compute_next_timestep() *ERROR empty step-list*";
            return  currentTimeMinutes;
        }

        qCritical() << __LINE__ << "compute_next_timestep()      first time step:" << stepList[0];
        qCritical() << __LINE__ << "compute_next_timestep()            timeSteps:" << stepList;
        qCritical() << __LINE__ << "compute_next_timestep() currentTimeInMinutes:" << currentTimeMinutes;

        // consider time shift: the step-list might have been computed at a
        // slightly different time point

        int currentStepIndex = stepList.indexOf(currentTimeMinutes);
        if (currentStepIndex == -1) {
            unsigned minimalDistance = ~0;
            int j = -1;
            for (int i = 0; i < stepList.size(); ++i) {
                unsigned distance = std::abs(stepList[i] - currentTimeMinutes);
                if (distance < minimalDistance) {
                    minimalDistance = distance;
                    j = i;
                }
            }
            // max. tolerance set to 3 minutes
            unsigned const tolerance = std::min(minimalDistance, (unsigned)(3));
            if (j != -1) {
                stepList[j] = currentTimeMinutes;
            }
        }

#if 0
        int maxStep = -1;
        if (size >= 2) {
            maxStep = stepList[1] - stepList[0];
        }
        // max. tolerance set to 5 minutes
        int const tolerance = (maxStep == -1) ? 5 : std::min(maxStep, 5);
        for (int i=0; i < stepList.size(); ++i) {
            if (std::abs(stepList[i] - currentTimeMinutes) <= tolerance) {
                qCritical().noquote()
                    << __LINE__ << QString("compute_next_timestep() correction stepList[%1]=%2 -> %3:")
                                    .arg(i).arg(stepList[0]).arg(currentTimeMinutes);
                stepList[i] = currentTimeMinutes;
                qCritical() << __LINE__ << "compute_next_timestep()        NEW timeSteps:" << stepList;
            }
        }

        int currentStepIndex = stepList.indexOf(currentTimeMinutes);
#endif

        currentStepIndex = stepList.indexOf(currentTimeMinutes);
        qCritical() << __LINE__ << "compute_next_timestep() currentStepIndex (" << currentStepIndex << ")";

        if (currentStepIndex == -1) {
            qCritical() << __LINE__ << "compute_next_timestep() *NO STEP* for currentTimeMinutes (" << currentTimeMinutes << ")";
            return  currentTimeMinutes;
        }

        if (UpDown == 1) { // UP
            if (stepList[currentStepIndex] == stepList.last()) {
                qCritical() << __LINE__ << "compute_next_timestep() *NO NEXT STEP* for currentTimeMinutes (" << currentTimeMinutes << ")";
                return  currentTimeMinutes;
            }
            else {
                int const rest = currentStepIndex % pop_plus_steps;

                if (rest) {
                    currentStepIndex -= rest;
                }

                qCritical() << __LINE__ << "compute_next_timestep() currentStepIndex (" << currentStepIndex << ")";

                int const nextStepIndex = currentStepIndex + pop_plus_steps;

                qCritical() << __LINE__ << "compute_next_timestep()       next step index:" << nextStepIndex;
                if (nextStepIndex >= 0 && nextStepIndex < stepList.size()) {
                    qCritical() << __LINE__ << "compute_next_timestep() return next time step:" << stepList[nextStepIndex];
                    return stepList[nextStepIndex];
                }
            }
        }
        if (UpDown == 0) { // DOWN
            if (stepList[currentStepIndex] == stepList.first()) {
                qCritical() << __LINE__ << "compute_next_timestep() *NO PREVIOUS STEP* for currentTimeMinutes (" << currentTimeMinutes << ")";
                return  currentTimeMinutes;
            }
            else {
                int const nextStepIndex = currentStepIndex - pop_minus_steps;
                qCritical() << __LINE__ << "compute_next_timestep()       next step index:" << nextStepIndex;
                if (nextStepIndex >= 0 && nextStepIndex < stepList.size()) {
                    qCritical() << __LINE__ << "compute_next_timestep() return next time step:" << stepList[nextStepIndex];
                    return stepList[nextStepIndex];
                }
            }
        }
    } else
    if (paymentMethodId == PaymentMethod::Linear) {

        // currentTimeMinutes is the number of minutes actually used. This
        // value is an offset from the start time and cannot be used as a
        // QDateTime.

        qCritical() << "compute_next_timestep() up/down (1=up, 0=down):" << UpDown;

        // get minimal and maximal parking times
        int const minParkingTime = Utilities::getMinimalParkingTime(cfg, paymentMethodId);
        int const maxParkingTime = Utilities::getMaximalParkingTime(cfg, paymentMethodId);

        qCritical() << "        compute_next_timestep() maxParkingTime:" << maxParkingTime;
        qCritical() << "        compute_next_timestep() minParkingTime:" << minParkingTime;

        // use the first (i.e. main duration step contained in the tariff json-file)
        int firstDurationStep = Utilities::getFirstDurationStep(cfg, paymentMethodId);
        firstDurationStep = ((UpDown == 1) ? firstDurationStep : -firstDurationStep);

        qCritical() << "     compute_next_timestep() firstDurationStep:" << firstDurationStep;

        int const nextTimeStep = currentTimeMinutes + firstDurationStep;

        if (nextTimeStep >= minParkingTime && nextTimeStep <= maxParkingTime) {
            qCritical() << "          compute_next_timestep() nextTimeStep:" << nextTimeStep;
            return nextTimeStep;
        }
    }

    qCritical() << "compute_next_timestep() *CAN NOT COMPUTE* for currentTimeMinutes (" << currentTimeMinutes << ")";
    return  currentTimeMinutes;
}

// this is currently not used
CalcState CALCULATE_LIBRARY_API compute_price_for_parking_ticket(
        parking_tariff_t *tariff,
        time_t start_parking_time,  // in minutes
        time_t end_parking_time,    // netto time in minutes
        struct price_t *price,
        PermitType permitType) {    // permitType maps to product

    CalcState calcState;

    int const paymentOptionIndex = tariff->getPaymentOptionIndex(permitType.get());

    double minMin = tariff->PaymentOption.find(tariff->getPaymentOptions(paymentOptionIndex).pop_payment_method_id)->second.pop_min_time;
    double maxMin = tariff->PaymentOption.find(tariff->getPaymentOptions(paymentOptionIndex).pop_payment_method_id)->second.pop_max_time;

    if (minMin < 0 || maxMin < 0 || maxMin < minMin) {
        calcState.setDesc(QString("minMin=%1, maxMin=%2").arg(minMin).arg(maxMin));
        return calcState.set(CalcState::State::WRONG_PARAM_VALUES);
    }

    int const duration = end_parking_time - start_parking_time;
    if (duration < 0) {
        calcState.setDesc(QString("end=%1, start=%2")
                          .arg(end_parking_time, start_parking_time));
        return calcState.set(CalcState::State::NEGATIVE_PARKING_TIME);
    }
    if (duration > maxMin) {
        calcState.setDesc(QString("duration=%1, maxMin=%2").arg(duration).arg(maxMin));
        return calcState.set(CalcState::State::ABOVE_MAX_PARKING_TIME);
    }
    if (duration < minMin) {
        calcState.setDesc(QString("duration=%1, minMin=%2").arg(duration).arg(minMin));
        return calcState.set(CalcState::State::BELOW_MIN_PARKING_TIME);
    }
    if (duration == 0) {
        return calcState.set(CalcState::State::SUCCESS);
    }

    QDate const d(1970, 1, 1);
    QTime const t(0, 0, 0);
    QDateTime start(d, t, Qt::UTC);
    start = start.toLocalTime().addSecs(start_parking_time * 60);
    QDateTime end(start);
    if (start.isValid()) {
        double cost = Calculator::GetInstance().GetCostFromDuration(
                    tariff,
                    tariff->getPaymentOptions(paymentOptionIndex).pop_payment_method_id,
                    start,
                    end,
                    duration, false, true);
        double minCost = tariff->PaymentOption.find(tariff->getPaymentOptions(paymentOptionIndex).pop_payment_method_id)->second.pop_min_price;
        if (cost < minCost) {
            calcState.setDesc(QString("line=%1 minCost=%2, cost=%3").arg(__LINE__).arg(minCost).arg(cost));
            return calcState.set(CalcState::State::BELOW_MIN_PARKING_PRICE);
        }
        price->units = cost;
        price->netto = cost;
    } else {
        return calcState.set(CalcState::State::INVALID_START_DATE);
    }

    return calcState.set(CalcState::State::SUCCESS);
}

CalcState CALCULATE_LIBRARY_API compute_price_for_parking_ticket(
        parking_tariff_t *tariff,
        QDateTime &start_parking_time_,
        int netto_parking_time,
        QDateTime &end_parking_time,
        struct price_t *price,
        PermitType permitType,
        bool prepaid)
{
    CalcState calcState;

    QDateTime start_parking_time(start_parking_time_);

    int paymentOptionIndex = tariff->getPaymentOptionIndex(permitType);

    double minMin = tariff->getPaymentOptions(paymentOptionIndex).pop_min_time;
    double maxMin = tariff->getPaymentOptions(paymentOptionIndex).pop_max_time;

    // DEBUG
    qCritical() << "compute_price_for_parking_ticket() " << endl
                << "          paymentOptionIndex: " << paymentOptionIndex << endl
                << "          start_parking_time: " << start_parking_time << endl
                << "          netto_parking_time: " << netto_parking_time << endl
                << "               start + netto: " << start_parking_time.addSecs(netto_parking_time * 60) << endl
                << "                      minMin: " << minMin << endl
                << "                      maxMin: " << maxMin
                << "                     prepaid: " << prepaid
                << "                  permitType: " << permitType.toString();

    if (netto_parking_time < 0) {
        calcState.setDesc(QString("end=%1, start=%2")
                          .arg(end_parking_time.toString(Qt::ISODate),
                               start_parking_time.toString(Qt::ISODate)));
        return calcState.set(CalcState::State::NEGATIVE_PARKING_TIME);
    }
    if (netto_parking_time > maxMin) {
        calcState.setDesc(QString("duration=%1, maxMin=%2").arg(netto_parking_time).arg(maxMin));
        return calcState.set(CalcState::State::ABOVE_MAX_PARKING_TIME);
    }
    if (netto_parking_time < minMin) {
        calcState.setDesc(QString("duration=%1, minMin=%2").arg(netto_parking_time).arg(minMin));
        return calcState.set(CalcState::State::BELOW_MIN_PARKING_TIME);
    }
    if (netto_parking_time == 0) {
        return calcState.set(CalcState::State::SUCCESS);
    }

    double cost = -1;
    if (start_parking_time.isValid()) {
        if (tariff->getPaymentOptions(paymentOptionIndex).pop_payment_method_id == PaymentMethod::Steps ||
            tariff->getPaymentOptions(paymentOptionIndex).pop_payment_method_id == PaymentMethod::Degressive) {
            // hier muesste man unterscheiden: uebertrag oder nicht?
            calcState = Calculator::GetInstance().isParkingAllowed(tariff, start_parking_time,
                                                                   netto_parking_time, paymentOptionIndex);
            if (calcState.getStatus() == CalcState::State::OUTSIDE_ALLOWED_PARKING_TIME) {
                qCritical() << "(" << __func__ << ":" << __LINE__ << ")"
                            << calcState.toString();
                return calcState;
            }

            QList<int> tlist = Calculator::GetInstance().GetTimeSteps(tariff);
            Q_UNUSED(tlist);

            // compute cost (price)
            cost = Calculator::GetInstance().GetCostFromDuration(tariff, start_parking_time, netto_parking_time, paymentOptionIndex);

            int weekDay = start_parking_time.date().dayOfWeek();
            int pop_carry_over_option_id = tariff->getPaymentOptions(paymentOptionIndex).pop_carry_over_option_id;
            qCritical() << __func__ << __LINE__ << "configured carry-over-id" << pop_carry_over_option_id;

            std::optional<ATBPeriodYear> yperiod = Utilities::GetYearPeriodActive(tariff, start_parking_time);
            if (yperiod.has_value()) {
                ATBPeriodYear const &period = yperiod.value();
                pop_carry_over_option_id = period.pye_id;
                qCritical() << __func__ << __LINE__ << "re-computed carry-over-id" << pop_carry_over_option_id;
            }

            QTime const carryOverStart = tariff->TariffCarryOverOptions.find(pop_carry_over_option_id)->second.carryover[weekDay].static_start;
            int const carryOverDuration = tariff->TariffCarryOverOptions.find(pop_carry_over_option_id)->second.carryover[weekDay].duration;

            qCritical() << __func__ << __LINE__ << "carryOverStart" << carryOverStart.toString(Qt::ISODate);
            qCritical() << __func__ << __LINE__ << "carryOverDuration" << carryOverDuration;

            // handle prepaid option
            QDateTime effectiveStartTime(start_parking_time);
            int const prepaid_option_id = tariff->getPaymentOptions(paymentOptionIndex).pop_prepaid_option_id;
            std::optional<ATBPrepaid> prepaidOption = tariff->getPrepaidType(prepaid_option_id);
            if (prepaidOption.has_value()) {
                ATBPrepaid const &p = prepaidOption.value();
                if (p.never) {
                    qCritical() << __func__ << __LINE__ << "prepaid: no";
                } else {
                    if (start_parking_time.time() < p.static_end) {     // static_end: e.g. 08:00:00
                        effectiveStartTime.setTime(p.static_end);
                    } else
                    if (start_parking_time.time() > p.static_start) {   // static_start: e.g. 22:00:00
                        effectiveStartTime.setTime(p.static_start);
                    }
                }
            }

            // handle carry over
            int minutesUntilCarryOver = effectiveStartTime.time().secsTo(carryOverStart) / 60;
            if (netto_parking_time > minutesUntilCarryOver) {
                int const rest = netto_parking_time - minutesUntilCarryOver;
                QDateTime s(effectiveStartTime);
                s = s.addSecs(minutesUntilCarryOver * 60);
                s = s.addSecs(carryOverDuration * 60);
                end_parking_time = s.addSecs(rest * 60);
            } else {
                end_parking_time = effectiveStartTime.addSecs(netto_parking_time*60);
            }

        } else {
            cost = Calculator::GetInstance().GetCostFromDuration(
                        tariff,
                        tariff->getPaymentOptions().pop_payment_method_id,
                        start_parking_time,         // starting time
                        end_parking_time,           // return value: end time
                        netto_parking_time,         // minutes, netto
                        false, prepaid);
        }
        // qCritical() << __func__ << __LINE__;
        double minCost = tariff->getPaymentOptions(paymentOptionIndex).pop_min_price;
        if (cost < minCost) {
            calcState.setDesc(QString("line=%1 minCost=%2, cost=%3").arg(__LINE__).arg(minCost).arg(cost));
            return calcState.set(CalcState::State::BELOW_MIN_PARKING_PRICE);
        }

        // DEBUG
        //qCritical() << __LINE__ << "            end_parking_time: " << end_parking_time;
        //qCritical() << __LINE__ << "  -> calculated cost (netto): " << cost;

        price->brutto = price->vat = price->vat_percentage = 0;
        price->units = cost;
        price->netto = cost;

    } else {
        return calcState.set(CalcState::State::INVALID_START_DATE);
    }

    if (end_parking_time.time().hour() == 0 && end_parking_time.time().minute() == 0) {
        end_parking_time = end_parking_time.addDays(-1);
        end_parking_time.setTime(QTime(23, 59, 0));
    }
    qCritical() << __func__ << __LINE__ << "end_parking_time" << end_parking_time.toString(Qt::ISODate);

    return calcState.set(CalcState::State::SUCCESS);
}

CalcState CALCULATE_LIBRARY_API compute_duration_for_parking_ticket(
        parking_tariff_t *tariff,
        time_t start_parking_time,
        double price,
        QString &duration,
        PermitType permitType) {
    CalcState calcState;
    QDate const d(1970, 1, 1);
    QTime const t(0, 0, 0);
    QDateTime start(d, t, Qt::UTC);
    start = start.toLocalTime().addSecs(start_parking_time * 60);
    if (start.isValid()) {
        QString cs = start.toString(Qt::ISODate);

        bool prepaid = true;
        int paymentOptionIndex = tariff->getPaymentOptionIndex(permitType);
        int prepaid_option_id = tariff->getPaymentOptions(paymentOptionIndex).pop_prepaid_option_id;
        if (prepaid_option_id == 2) { // see tariff03.json for 502: 2 means no prepaid-option
            prepaid = false;
        }
        bool const nextDay = false;

        // DEBUG
        qCritical() << "compute_duration_for_parking_ticket(1): ";
        qCritical() << " payment option index: " << paymentOptionIndex;
        qCritical() << "              prepaid: " << prepaid;
        qCritical() << "           start (cs): " << cs;
        qCritical() << "                price: " << price;

        duration = Calculator::GetInstance().GetDurationFromCost(tariff,
                                                  tariff->getPaymentOptions(paymentOptionIndex).pop_payment_method_id,
                                                  cs.toLocal8Bit().constData(),
                                                  price, permitType, nextDay, prepaid).c_str();
        QDateTime d = QDateTime::fromString(duration, Qt::ISODate);
        if (!d.isValid()) {
            calcState.setDesc(QString("ticketEndTime=%1").arg(duration));
            return calcState.set(CalcState::State::WRONG_ISO_TIME_FORMAT);
        }
    } else {
        return calcState.set(CalcState::State::INVALID_START_DATE);
    }

    return calcState.set(CalcState::State::SUCCESS);
}

CalcState CALCULATE_LIBRARY_API compute_duration_for_parking_ticket(
        parking_tariff_t *tariff,
        QDateTime const &start_parking_time,
        double price,
        QDateTime &ticketEndTime,
        PermitType permitType)
{
    CalcState calcState;

    bool prepaid = true;
    int paymentOptionIndex = tariff->getPaymentOptionIndex(permitType);
    int prepaid_option_id = tariff->getPaymentOptions(paymentOptionIndex).pop_prepaid_option_id;
    if (prepaid_option_id == 2) {
        prepaid = false;
    }
    bool const nextDay = false;

    // DEBUG
    if (DBG_LEVEL >= DBG_DEBUG) {
        qCritical() << "compute_duration_for_parking_ticket(2): ";
        qCritical() << " payment option index: " << paymentOptionIndex;
        qCritical() << "              prepaid: " << prepaid;
        qCritical() << "                price: " << price;
    }

    if (start_parking_time.isValid()) {

        // handle prepaid option
        QDateTime effectiveStartTime(start_parking_time);
        int const prepaid_option_id = tariff->getPaymentOptions(paymentOptionIndex).pop_prepaid_option_id;
        std::optional<ATBPrepaid> prepaidOption = tariff->getPrepaidType(prepaid_option_id);
        if (prepaidOption.has_value()) {
            ATBPrepaid const &p = prepaidOption.value();
            if (p.never) {
                qCritical() << __func__ << __LINE__ << "prepaid: no";
            } else {
                if (start_parking_time.time() < p.static_end) {     // static_end: e.g. 08:00:00
                    effectiveStartTime.setTime(p.static_end);
                } else
                if (start_parking_time.time() > p.static_start) {   // static_start: e.g. 22:00:00
                    effectiveStartTime.setTime(p.static_start);
                }
            }
        }

        QString cs = start_parking_time.toString(Qt::ISODate);
        QString endTime = Calculator::GetInstance().GetDurationFromCost(
                    tariff,
                    tariff->getPaymentOptions().pop_payment_method_id,
                    cs.toLocal8Bit().constData(),
                    price, permitType, nextDay, prepaid).c_str();

        if (endTime == CalcState::SUCCESS) {
            calcState.setDesc(QString("SUCCESS"));
            calcState.setStatus(endTime);
        } else
        if (endTime == CalcState::ERROR_PARSING_ZONE_NR) {
            calcState.setStatus(endTime);
            return calcState;
        } else
        if (endTime == CalcState::ERROR_LOADING_TARIFF) {
            calcState.setStatus(endTime);
            return calcState;
        } else
        if (endTime == CalcState::ERROR_PARSING_TARIFF) {
            calcState.setStatus(endTime);
            return calcState;
        } else
        if (endTime == CalcState::NEGATIVE_PARKING_TIME) {
            calcState.setStatus(endTime);
            return calcState;
        } else
        if (endTime == CalcState::INVALID_START_DATE) {
            calcState.setStatus(endTime);
            return calcState;
        } else
        if (endTime == CalcState::WRONG_PARAM_VALUES) {
            calcState.setStatus(endTime);
            return calcState;
        } else
        if (endTime == CalcState::WRONG_ISO_TIME_FORMAT) {
            calcState.setStatus(endTime);
            return calcState;
        } else
        if (endTime == CalcState::ABOVE_MAX_PARKING_TIME) {
            calcState.setStatus(endTime);
            return calcState;
        } else
        if (endTime == CalcState::BELOW_MIN_PARKING_TIME) {
            calcState.setStatus(endTime);
            return calcState;
        } else
        if (endTime == CalcState::BELOW_MIN_PARKING_PRICE) {
            calcState.setStatus(endTime);
            return calcState;
        } else
        if (endTime == CalcState::ABOVE_MAX_PARKING_PRICE) {
            calcState.setDesc(CalcState::ABOVE_MAX_PARKING_PRICE);
            calcState.setStatus(CalcState::ABOVE_MAX_PARKING_PRICE);
            return calcState;
        } else
        if (endTime == CalcState::OVERPAID) {
            calcState.setDesc(CalcState::OVERPAID);
            calcState.setStatus(CalcState::OVERPAID);
            return calcState;
        } else
        if (endTime == CalcState::OUTSIDE_ALLOWED_PARKING_TIME) {
            calcState.setStatus(endTime);
            return calcState;
        } else {
            ticketEndTime = QDateTime::fromString(endTime,Qt::ISODate);

            if (!ticketEndTime.isValid()) {
                calcState.setDesc(QString("ticketEndTime=%1").arg(endTime));
                return calcState.set(CalcState::State::WRONG_ISO_TIME_FORMAT);
            }

            if (ticketEndTime.time().hour() == 0 && ticketEndTime.time().minute() == 0) {
                ticketEndTime = ticketEndTime.addDays(-1);
                ticketEndTime.setTime(QTime(23, 59, 0));
            }

            // DEBUG
            qCritical() << "compute_duration_for_parking_ticket(): ";
            qCritical() << "                 endTime: " << endTime;
            qCritical() << "           ticketEndTime: " << ticketEndTime;
        }
    } else {
        return calcState.set(CalcState::State::INVALID_START_DATE);
    }

    return calcState.set(CalcState::State::SUCCESS);
}

CalcState CALCULATE_LIBRARY_API compute_duration_for_daily_ticket(parking_tariff_t *tariff,
                                                                  QDateTime const &start_parking_time,
                                                                  QDateTime &ticketEndTime,
                                                                  PermitType PermitType)
{
    CalcState calcState;
    if (start_parking_time.isValid()) {

        ticketEndTime = Calculator::GetInstance().GetDailyTicketDuration(tariff,
                                                            start_parking_time,
                                                            tariff->getPaymentOptions().pop_payment_method_id,
                                                            false);    // carry over

        // DEBUG
        qCritical() << "compute_duration_for_daily_ticket(): ";
        qCritical() << "           ticketEndTime: " << ticketEndTime;

        if (!ticketEndTime.isValid()) {
            calcState.setDesc(QString("ticketEndTime=%1").arg(ticketEndTime.toString(Qt::ISODate)));
            return calcState.set(CalcState::State::WRONG_ISO_TIME_FORMAT);
        }

    } else {
        return calcState.set(CalcState::State::INVALID_START_DATE);
    }

    return calcState.set(CalcState::State::SUCCESS);
}


CalcState CALCULATE_LIBRARY_API compute_price_for_daily_ticket(
                                    parking_tariff_t *tariff,
                                    QDateTime const &startDatetime,
                                    QDateTime &endDatetime,
                                    PERMIT_TYPE permitType,
                                    struct price_t *price) {// return value
    CalcState calcState;


    if (startDatetime.isValid()) {
        if (std::optional<struct price_t> p =
            Calculator::GetInstance().GetDailyTicketPrice(tariff,
                                                          startDatetime,
                                                          endDatetime,
                                                          permitType)) {
           *price = p.value();
        }
    } else {
        return calcState.set(CalcState::State::INVALID_START_DATE);
    }
    return calcState.set(CalcState::State::SUCCESS);
}