/// <summary>Part of a shuffle process.</summary>
/// <param name="group">The group being shuffled.</param>
/// <param name="card">An array containing the CardIdentity ids to shuffle.</param>
public void Shuffle(Group group, int[] card)
{
// Array to hold the new aliases (sent to CreateAlias)
ulong[] aliases = new ulong[card.Length];
// Intialize the group shuffle
group.filledShuffleSlots = 0;
group.hasReceivedFirstShuffledMessage = false;
group.myShufflePos = new short[card.Length];
// Check if we received enough cards
if (Player.Count <= 1)
return;
if (card.Length < group.Count / (Player.Count - 1))
Program.Trace.TraceEvent(TraceEventType.Warning, EventIds.Event, "[Shuffle] Too few cards received.");
// Do the shuffling
Random rnd = new Random();
for (int i = card.Length - 1; i >= 0; i--)
{
int r = rnd.Next(i);
int tc = card[r];
card[r] = card[i];
// Create a new alias, if the card is not face up
CardIdentity ci = CardIdentity.Find(tc);
if (group.FindByCardIdentity(ci) != null)
{
card[i] = tc; aliases[i] = ulong.MaxValue;
ci.visible = true;
}
else
{
ci = new CardIdentity(Program.Game.GenerateCardId());
ci.mySecret = ci.alias = true;
ci.key = ((ulong)Crypto.PositiveRandom()) << 32 | (uint)tc;
card[i] = ci.id; aliases[i] = Crypto.ModExp(ci.key);
ci.visible = false;
}
// Give a random position to the card
// TODO: I don't think this shuffling algorithm generates all possibilities equiprobably
group.myShufflePos[i] = (short)Crypto.Random(group.Count);
}
// Send the results
Program.Client.Rpc.CreateAlias(card, aliases);
Program.Client.Rpc.Shuffled(group, card, group.myShufflePos);
}
