/**
* bid on an item
* only works with those listings that set an opening bid (even if that amount is zero).
* We use the proxy-bid system here, as used by ebay:
* @see http://en.wikipedia.org/wiki/Proxy_bid
* the winning bidder pays the price of the second-highest bid plus the step
*/
public function bid($id, $bid, array $data = NULL)
{
// normalize the data.
$data = new Store\KVP($data);
// create an internal transaction if no transaction has been passed in.
Transaction::start();
try {
// we assume the current user is always the bidder
$bidder = $this->user();
// if no bidder was passed into the constructor, blow up.
if (!Souk\Util::validatePositiveInteger($bidder)) {
throw new Exception('invalid bidder', $bidder);
}
// get a row lock on the listing.
$listing = $this->get($id, TRUE);
if (!$listing || !$listing->id) {
throw new Exception('not found', $id);
}
// need the current time to do some comparisons.
$ts = Souk\util::now();
// don't go anywhere if the bidding is already closed.
if ($listing->closed) {
throw new Exception('closed', $listing);
}
// can't let the seller bid on the listing.
if ($listing->seller == $bidder) {
throw new Exception('invalid bidder', $listing);
}
// step is set when it is a biddable item. if it isn't there, don't allow bidding.
if ($listing->step < 1) {
throw new Exception('buy only', $listing);
}
// has time expired on this listing?
if ($listing->expires <= $ts) {
throw new Exception('expired', $listing);
}
// make sure we bid enough to challenge the current bid level.
// if proxy bidding is enabled we still might not win the bid,
// but at least we pushed it up a bit.
if ($listing->bid + $listing->step > $bid) {
throw new Exception('too low', $listing);
}
// keep a pristine copy of the listing internally so other wrapper classes can compare
// afterward and see what changes were made.
// The Souk\stockpile adapter especially needs this so it can return escrowed bids
// to the previous bidder.
$listing->setPriorState($listing);
// if proxy bidding is enabled, this gets a little more complicated.
// proxy bidding is where you bid the max you are willing to pay, but only pay
// one step above the previous bidder's level.
// This is how ebay runs its auction site.
// this means when you bid, we track your max amount you are willing to spend, but only
// bid the minimum. When the next bid comes in, we automatically up your bid for you
// until you go over your max amount and someone else takes the lead.
// this approach makes the escrow system more efficient as well since it can excrow your
// maximum amount all at once, and then refund when you get outbid or refund the difference
// if you get it for a lower bid.
if ($data->enable_proxy) {
// looks like the previous bidder got outbid.
// track their maximum amount, and set the bid based on one step above the previous bid.
if ($bid >= $listing->proxybid + $listing->step) {
$listing->bid = $listing->proxybid + $listing->step;
$listing->proxybid = $bid;
$listing->bidder = $bidder;
$listing->bidcount = $listing->bidcount + 1;
// the other bidder is still the winner of the bid. our bid didn't go over their
// max bid amount. Bump up their bid amount to what we bid, and increment the
// bid count by 2, since we bid on it, and they bid back.
} else {
$listing->bid = $bid;
$listing->bidcount = $listing->bidcount + 2;
}
// in this case, not a proxy bid system, just a straight up english auction.
// don't worry about previous bidder. we know we bid more than the previous bidder,
// so pump up the bid to whatever we passed in.
} else {
$listing->bid = $bid;
$listing->bidder = $bidder;
$listing->bidcount = $listing->bidcount + 1;
}
$listing->touch = $ts;
$this->storage()->bid($listing);
Transaction::commit();
// done.
return $listing;
// something went wrong ...
} catch (Exception $e) {
// revert the transaction ...
// if it was created internally, remove it.
Transaction::rollback();
// toss the exception again.
throw $e;
}
}
/**
* what is the item id of the currency, in stockpile?
*/
protected function currencyId()
{
$id = $this->binder->currencyId();
if (!Util::validatePositiveInteger($id)) {
throw new Exception('invalid currency id', $id);
}
return $id;
}
