private bool ComputeReturn(CDatM1 m1Return, CDatM1 m1)
        {
            trace.Write(TraceLevel.Debug, "ComputeReturn");
            bool   fnResult                 = true;
            CDatM1 M1ComputeTime            = null;
            CDatM1 M1ReturnWithCompleteHist = null;

            try
            {
                bool     bM1Plus      = false;
                int      nMaxQuantity = 0;
                COPSDate dt;
                COPSDate dt2;
                bool     bWholeOperationWithChipCard;
                bool     bWholeOperationWithMobile;

                M1ReturnWithCompleteHist = new CDatM1(loggerManager);
                m1Return.SetInOperType(OperationDat.DEF_OPERTYPE_PARK);
                M1ReturnWithCompleteHist.Copy(m1Return);

                m1Return.SetInHistOnlyWithSamePaymentType(true);

                if (!tariffCalculator.GetM1(m1Return, bM1Plus, nMaxQuantity))
                {
                    throw new InvalidOperationException("Error computing M1");
                }

                if (!tariffCalculator.GetM1(M1ReturnWithCompleteHist, bM1Plus, nMaxQuantity))
                {
                    throw new InvalidOperationException("Error computing M1");
                }

                if ((!m1Return.GetOutHistPostPay()) && (!M1ReturnWithCompleteHist.GetOutHistPostPay()))
                {
                    dt = m1Return.GetOutOperDateRealIni();
                    m1.SetOutOperDateIni0(dt);
                    m1.SetOutOperDateIni(dt);

                    dt2 = m1Return.GetOutOperDateIni();
                    if (dt2.GetStatus() == COPSDateStatus.Valid)
                    {
                        m1.SetOutOperDateEnd(dt2);
                    }
                    else
                    {
                        m1.SetOutOperDateEnd(dt);
                    }

                    m1.SetOutAccumulateMoney(m1Return.GetOutRealAccumulateMoney());
                    m1.SetOutAccumulateTime(m1Return.GetOutRealAccumulateTime());

                    m1.SetInIntervalOffsetMoney(M1ReturnWithCompleteHist.GetOutRealAccumulateMoney() - m1Return.GetOutRealAccumulateMoney());
                    m1.SetInIntervalOffsetMinutes(M1ReturnWithCompleteHist.GetOutRealAccumulateTime() - m1Return.GetOutRealAccumulateTime());

                    bWholeOperationWithChipCard = m1Return.GetOutWholeOperationWithChipCard() == 1;
                    bWholeOperationWithMobile   = m1Return.GetOutWholeOperationWithMobile() == 1;

                    if (!tariffCalculator.GetM1(m1, bM1Plus, nMaxQuantity))
                    {
                        throw new InvalidOperationException("Error computing Return M1");
                    }

                    if (m1.GetOutResult() <= 0)
                    {
                        m1.SetOutResult(TariffCalculator.M1_NO_RETURN);
                    }
                    else if ((m1.GetInPaymentType() != OperationDat.DEF_OPERPAY_CHIPCARD) && (m1.GetInPaymentType() != OperationDat.DEF_OPERPAY_MOBILE))
                    {
                        m1.SetOutResult(TariffCalculator.M1_NO_RETURN);
                    }
                    else if (m1.GetOutRetImport() <= 0)
                    {
                        m1.SetOutResult(TariffCalculator.M1_NO_RETURN);
                    }

                    if (m1.GetOutResult() > 0)
                    {
                        string    strUnit;
                        COPSPlate strVehicleId;

                        M1ComputeTime = new CDatM1(loggerManager);
                        M1ComputeTime.SetInUnit(m1.GetInUnit());
                        strUnit = m1.GetInUnit().ToString();
                        M1ComputeTime.SetSrc(strUnit);
                        dt = m1.GetDate();
                        M1ComputeTime.SetDate(dt);

                        M1ComputeTime.SetInOperType(OperationDat.DEF_OPERTYPE_PARK);        // DEFINES en operdat.h
                        M1ComputeTime.SetInDate(dt);

                        M1ComputeTime.SetInArticleDef(m1.GetInArticleDef());
                        M1ComputeTime.SetInGroup(m1.GetInGroup());
                        strVehicleId = m1.GetInVehicleID();
                        M1ComputeTime.SetInVehicleID(strVehicleId);

                        dt = m1Return.GetOutOperDateRealIni();

                        M1ComputeTime.SetInDate(dt);
                        M1ComputeTime.SetOutOperDateIni0(dt);
                        M1ComputeTime.SetOutOperDateIni(dt);

                        M1ComputeTime.SetOutMaxImport(m1.GetOutAccumulateMoney());
                        M1ComputeTime.SetInIntervalOffsetMoney(M1ReturnWithCompleteHist.GetOutRealAccumulateMoney() - m1Return.GetOutRealAccumulateMoney());
                        M1ComputeTime.SetInIntervalOffsetMinutes(M1ReturnWithCompleteHist.GetOutRealAccumulateTime() - m1Return.GetOutRealAccumulateTime());

                        if (!tariffCalculator.GetM1(M1ComputeTime, bM1Plus, nMaxQuantity, false))
                        {
                            throw new InvalidOperationException("Error computing Compute Time M1");
                        }

                        if (M1ComputeTime.GetOutResult() <= 0)
                        {
                            m1.SetOutResult(TariffCalculator.M1_NO_RETURN);
                        }
                        else
                        {
                            dt = M1ComputeTime.GetOutOperDateEnd();
                            m1.SetOutOperDateEnd(dt);

                            // Total parking time
                            m1.SetOutEfMaxTime(M1ComputeTime.GetOutEfMaxTime());
                        }
                    }
                }
                else
                {
                    m1.SetOutResult(TariffCalculator.M1_NO_RETURN);
                }
            }
            catch (Exception error)
            {
                trace.Write(TraceLevel.Error, error.ToLogString());
                fnResult = false;
            }

            return(fnResult);
        }