// returns the last outstanding request; status in (processing, vending) and within a timeout interval
public static VendingRequest LastOutstandingRequest()
{
using (klick_vending_machineEntities context = new klick_vending_machineEntities())
{
int processingTimeoutSeconds = 30;
int vendingTimeoutSeconds = 60;
// request in status 'processing'
VendingRequest request = (
from r in context.VendingRequests
where r.Status == "processing" && SqlFunctions.DateDiff("second", r.RequestDate, DateTime.Now) < processingTimeoutSeconds
orderby r.RequestDate descending
select r).FirstOrDefault();
if (request != null)
{
return(request);
}
request = (
from r in context.VendingRequests
where r.Status == "vending" && SqlFunctions.DateDiff("second", r.VendStartDate, DateTime.Now) < vendingTimeoutSeconds
orderby r.VendStartDate descending
select r).FirstOrDefault();
return(request);
}
}
// Called when the user has pushed some coordinates
private static string RequestItem(string coordinateString)
{
// Get the last card scan
CardScan scan = CardScan.LastCardScan();
if (scan == null)
{
return MSG_ERROR_NO_CARD;
}
VendingRequest lastRequest = VendingRequest.LastOutstandingRequest();
string error = null;
string successMessage = MSG_VEND_ITEM;
int x = -1;
int y = -1;
string requestStatus = null;
using (klick_vending_machineEntities context = new klick_vending_machineEntities())
{
CardScanResult scanResult = scan.CardScanResult;
// create a new vending request
VendingRequest request = new VendingRequest()
{
CardScanResultID = scanResult.CardScanResultID,
Status = STATUS_PROCESSING,
RequestDate = DateTime.Now,
Coordinates = coordinateString
};
context.VendingRequests.Add(request);
context.SaveChanges();
try
{
// Error checking block
if (lastRequest != null)
{
// We found a vending request with that is either processing or vending within a timeout interval
// Cannot vend again at this point
error = MSG_ERROR_VENDING_IN_PROGRESS;
}
else if (scan.HasTimedOut)
{
// We've timed out
if (DateTime.Now.Subtract(scan.ScanDate).TotalMinutes > 5)
{
// Last scan was a while ago - just tell the user to scan first, so they don't get confused
error = MSG_ERROR_NO_CARD;
}
else
{
// Display timeout error message
error = MSG_ERROR_CARD_TIMEOUT;
}
}
else if (scanResult.Status != "valid")
{
// Invalid card!
error = MSG_ERROR_INVALID_CARD;
}
else if (scan.HasVended(request.VendingRequestID))
{
// We've already vended an item for this card scan. Sneaky!
error = MSG_ERROR_ALREADY_VENDED;
}
else if (coordinateString == "TIMEOUT")
{
// Timed out before anything was vended
string DefaultTimeoutPath = "smb_warning.wav";
PlaySound(GetConfigPath("timeout", DefaultTimeoutPath));
error = MSG_ERROR_CARD_TIMEOUT;
}
else if (!GetCoordinates(coordinateString, out x, out y))
{
// Unable to parse coordinates
error = MSG_ERROR_INVALID_COORDS;
}
else
{
requestStatus = GetItemStatusType(x, y);
if (requestStatus == null)
{
error = MSG_ERROR_INVALID_ITEM;
}
}
request.X = x;
request.Y = y;
}
catch (Exception e)
{
error = MSG_ERROR_SYSTEM_FAIL;
Error.CreateError(e);
}
if (error == null)
{
// TODO: consider what happens if the message to the Arduino fails?
request.Status = requestStatus;
request.VendStartDate = DateTime.Now;
// Adjust the success message if necessary
if (requestStatus == STATUS_TAKING_PHOTO)
{
successMessage = MSG_TAKING_PHOTO;
}
else if (requestStatus == STATUS_PLAYING_SOUND)
{
successMessage = MSG_PLAYING_SOUND;
}
}
else
{
request.Status = "failed";
request.ErrorMessage = error;
}
context.SaveChanges();
}
Logger.WriteLine("Returning! " + (error == null ? MSG_VEND_ITEM : error));
// Finally, success! Vend it. Or display the error instead if there is one.
return (error == null ? successMessage : error);
}