public Booking AddBooking(Booking booking)
        {
            List<ITimeSlot> availableTimeSlots = GetAvailableTimeSlots(booking);
            if (!availableTimeSlots.Any())
            {
                throw new ArgumentException("This is no place for booking");
            }

            ITimeSlot firstTimeSlot = availableTimeSlots
                .FirstOrDefault(ts => ts.StartTime <= booking.DateTime.TimeOfDay
                                && ts.StartTime.Add(ts.Duration)  > booking.DateTime.TimeOfDay);

            if (firstTimeSlot != null)
            {
                int amount = firstTimeSlot.GetSlotsAmount(booking.GetDuration());
                for (int i = 0; i < amount; i++)
                {
                    TimeSlots.Find(ts => ts.Number == firstTimeSlot.Number + i).IsAvailable = false;
                }
                Bookings.Add(booking);
                return booking;
            }
            throw new ArgumentException("This is no place for booking");
        }
        public List<ITimeSlot> GetAvailableTimeSlots(Booking booking)
        {
            List<ITimeSlot> timeSlots = new List<ITimeSlot>();
            List<ITimeSlot> allAvailableTimeSlots = GetAllAvailableTimeSlots();
            TimeSpan bookingDuration = booking.GetDuration().Duration();

            if (allAvailableTimeSlots.Any())
            {
                int amount = allAvailableTimeSlots.First().GetSlotsAmount(bookingDuration);

                for (int i = 0; i <= allAvailableTimeSlots.Count - amount; i++)
                {
                    bool flag = true;
                    ITimeSlot timeSlot = allAvailableTimeSlots[i];

                    for (int j = 1; j < amount; j++)
                    {
                        if ( allAvailableTimeSlots[i+j].Number != timeSlot.Number + j)
                        {
                            flag = false;
                            break;
                        }
                    }

                    if (flag)
                    {
                        timeSlots.Add(timeSlot);
                    }
                }
            }
            return timeSlots;
        }
        public Booking RemoveBooking(Booking booking)
        {
            if (booking.DateTime <= DateTime.Now.AddDays(1))
            {
                throw new OperationCanceledException("Can not remove booking 24 hours before booking time");
            }
            Bookings.Remove(booking);
            ITimeSlot firstTimeSlot = TimeSlots
                .FirstOrDefault(ts=>ts.StartTime == booking.DateTime.TimeOfDay);
            if (firstTimeSlot !=null)
            {
                int amount = firstTimeSlot.GetSlotsAmount(booking.GetDuration());
                for (int i = 0; i < amount; i++)
                {
                    TimeSlots.Find(ts => ts.Number == firstTimeSlot.Number + i).IsAvailable = true;
                }
                return booking;
            }

            throw new Exception("Can not delete booking");
        }