/// <summary>
/// Find and hold the best available seats for a customer
/// </summary>
/// <param name="numSeats">count of seats to find and hold</param>
/// <param name="customerEmail">unique identifier for the customer</param>
/// <returns>a SeatHold object identifying the specific seats and related information</returns>
public SeatHold findAndHoldSeats(int numSeats, string customerEmail)
{
SeatHold ret = null;
DateTime dateTimeExpiration = DateTime.UtcNow.AddSeconds(-kSecondsHoldTimeout);
using (var dbContext = new TicketSystemDbContext())
using (var transaction = dbContext.Database.BeginTransaction())
{
var seats =
(from seat in dbContext.Seats
where
seat.SeatClaimId == null ||
(
seat.SeatClaim.TimeStampReserved == null
&&
seat.SeatClaim.TimeStampHeld != null
&&
seat.SeatClaim.TimeStampHeld < dateTimeExpiration
)
orderby seat.Rank descending
select seat)
.Take(numSeats)
.ToList();
SeatClaim seatClaim = null;
if (seats.Any())
{
// cleanup seats so the existing invalid claim is removed
seats.ForEach(seat => seat.SeatClaimId = null);
// create new claim, in a 'hold' state as indicated by TimeStampHeld
seatClaim = new SeatClaim
{
Email = customerEmail,
TimeStampHeld = DateTime.UtcNow,
TimeStampReserved = null,
Seats = seats,
HoldId = GenerateUniqueHoldId()
};
}
dbContext.SeatClaims.Add(seatClaim);
seats.ForEach(seat =>
{
seat.SeatClaim = seatClaim;
});
dbContext.SaveChanges();
transaction.Commit();
ret = new SeatHold(numSeats, seatClaim, HoldTimeout);
}
return(ret);
}
public SeatHold(int countRequested, SeatClaim seatClaim, TimeSpan holdTimeout)
{
SeatLocations = seatClaim.Seats
.Select(seat => new SeatLocation {
Row = seat.SeatRow, SeatNum = seat.SeatNum
})
.ToList();
CountHeld = SeatLocations.Count;
CountRequested = countRequested;
HoldId = seatClaim.HoldId;
HoldTimeout = holdTimeout;
}
