var q = from dt in _definitionsDataContext.DefinedTicket
                    where dt.SalesPeriodStart <= currentDate
                        && (dt.SalesPeriodEndNullable == null || dt.SalesPeriodEnd > currentDate)
                        && dt.IsSoldInTerminal
                        && (dt.AvailableInTrain == legacyAllTrainsFlag || (

                        (
                            EnumUtil.HasFlag(dt.AvailableInTrain, (int)Classificators.TicketAvailableInTrainTypes.RegularTrains) &&
                            train.TrainType == (int)Classificators.TrainType.Regular
                        )

                        ||

                        (
                            EnumUtil.HasFlag(dt.AvailableInTrain, (int)Classificators.TicketAvailableInTrainTypes.SpecialTrains) &&
                            train.TrainType == (int)Classificators.TrainType.Special
                        )

                        ||

                        (
                            EnumUtil.HasFlag(dt.AvailableInTrain, (int)Classificators.TicketAvailableInTrainTypes.ExpressTrains) &&
                            train.TrainType == (int)Classificators.TrainType.Express
                        )))
                        && (ticketTypes == null || ticketTypes.Contains(dt.TicketType))
                        && (isTrainBased == null || dt.IsTrainBased == isTrainBased)
                        && (train.FirstClassSeatsNullable.HasValue && train.FirstClassSeatsNullable.Value > 0 || !dt.IsSoldInFirstClassTrainsOnly)
                    select dt;