/*!
* \brief Draw a winning number for the lottery.
*
* The draw number is ensured to not have bee drawn before in this lottery,
* and to have been sold for a ticket.
*
* \return null if no lottery numbers have been sold, or all tickets have won;
* otherwise the ticket with the winning number is returned.
*/
public Ticket DrawWinningNumber()
{
// If there are no sold tickets, don't draw a number.
if (Tickets.Count < 1)
{
return(null);
}
// If every sold ticket has won, don't draw a number.
if (WinningLotteryNumbers.Count == Tickets.Count)
{
return(null);
}
// Pick a winning number, checking that it's not still availibe
// (i.e. a ticket has this number) and it's not already been picked.
var winningNumber = Rng.Next(LotteryNumberMin, LotteryNumberMax + 1);
while (LotteryNumbers[winningNumber] != InvalidLotteryNumber || WinningLotteryNumbers.Contains(winningNumber))
{
winningNumber = Rng.Next(LotteryNumberMin, LotteryNumberMax + 1);
}
// Store winning number and return the winning ticket.
WinningLotteryNumbers.Add(winningNumber);
return(Tickets.Find(T => T.LotteryNumber == winningNumber));
}
/*!
* \brief Remove a ticket from the lottery.
*
* If the ticket has not been sold no action will be made.
* Otherwise, the ticket's number will be added to the availible numbers again,
* and if it was a winning number it will be removed from the list of winners as well.
*/
public void RemoveTicket(Ticket ticket)
{
var target = Tickets.Find(T => T.LotteryNumber == ticket.LotteryNumber);
if (target == null)
{
return;
}
// Remove the number from winners (if there) and add it to the availible numbers again,
// before removing it from the list of sold tickets.
WinningLotteryNumbers.Remove(target.LotteryNumber);
++NumLotteryNumbersLeft;
LotteryNumbers[target.LotteryNumber] = target.LotteryNumber;
Tickets.Remove(target);
}
/*!
* \brief Export the lottery session to a given file.
* \param exportFile String stream denoting target export file.
*/
public void ExportToFile(Stream exportFile)
{
var xmlRoot = new XElement(XmlTagNames.Root,
new XElement(XmlTagNames.MaxLotteryNumber, LotteryNumberMax),
new XElement(XmlTagNames.Tickets, new XAttribute(XmlTagNames.TicketsPriceAttribute, TicketPrice),
Tickets.Select(t => new XElement(XmlTagNames.Ticket,
// Only lottery number is mandatory. Owner and comment are only included if not empty.
new XElement(XmlTagNames.TicketLotteryNumber, t.LotteryNumber),
(string.IsNullOrEmpty(t.Owner) ? null : new XElement(XmlTagNames.TicketOwner, t.Owner)),
(string.IsNullOrEmpty(t.Comment) ? null : new XElement(XmlTagNames.TicketComment, t.Comment))
))
),
// Winners are optional. If none have been drawn, don't empty tag.
(WinningLotteryNumbers.Any() ? new XElement("Winners",
WinningLotteryNumbers.Select(w => new XElement("Winner", new XAttribute("LotteryNumber", w))))
: null)
);
xmlRoot.Save(exportFile);
}
/*!
* \brief Remove a winning lottery number, if it's in the collection.
*
* NOTE that this DOES NOT delete the ticket with the winning number,
* it simply removes the winning association.
*/
public void RemoveWinningTicket(int winningLotteryNumber)
{
WinningLotteryNumbers.Remove(winningLotteryNumber);
}
