/// <summary>
/// Gets ifnromation about the seat types.
/// </summary>
/// <remarks>
/// Because the seat type contains the number of available seats, and this information can change often, notice
/// how we manage the risks associated with displaying data that is very stale by adjusting caching duration
/// or not even caching at all if only a few seats remain.
/// For more information on the optimizations we did for V3
/// see <see cref="http://go.microsoft.com/fwlink/p/?LinkID=258557"> Journey chapter 7</see>.
/// </remarks>
public IList <SeatType> GetPublishedSeatTypes(Guid conferenceId)
{
var key = "ConferenceDao_PublishedSeatTypes_" + conferenceId;
var seatTypes = cache.Get(key) as IList <SeatType>;
if (seatTypes == null)
{
seatTypes = decoratedDao.GetPublishedSeatTypes(conferenceId);
if (seatTypes != null)
{
// determine how long to cache depending on criticality of using stale data.
TimeSpan timeToCache;
if (seatTypes.All(x => x.AvailableQuantity > 200 || x.AvailableQuantity <= 0))
{
timeToCache = TimeSpan.FromMinutes(5);
}
else if (seatTypes.Any(x => x.AvailableQuantity < 30 && x.AvailableQuantity > 0))
{
// there are just a few seats remaining. Do not cache.
timeToCache = TimeSpan.Zero;
}
else if (seatTypes.Any(x => x.AvailableQuantity < 100 && x.AvailableQuantity > 0))
{
timeToCache = TimeSpan.FromSeconds(20);
}
else
{
timeToCache = TimeSpan.FromMinutes(1);
}
if (timeToCache > TimeSpan.Zero)
{
cache.Set(key, seatTypes, new CacheItemPolicy {
AbsoluteExpiration = DateTimeOffset.UtcNow.Add(timeToCache)
});
}
}
}
return(seatTypes);
}
public OrderTotal CalculateTotal(Guid conferenceId, ICollection <SeatQuantity> seatItems)
{
var seatTypes = conferenceDao.GetPublishedSeatTypes(conferenceId);
var lineItems = new List <OrderLine>();
foreach (var item in seatItems)
{
var seatType = seatTypes.FirstOrDefault(x => x.Id == item.SeatType);
if (seatType == null)
{
throw new InvalidDataException(string.Format(CultureInfo.InvariantCulture, "Invalid seat type ID '{0}' for conference with ID '{1}'", item.SeatType, conferenceId));
}
lineItems.Add(new SeatOrderLine {
SeatType = item.SeatType, Quantity = item.Quantity, UnitPrice = seatType.Price, LineTotal = Math.Round(seatType.Price * item.Quantity, 2)
});
}
return(new OrderTotal {
Total = lineItems.Sum(x => x.LineTotal),
Lines = lineItems
});
}