/**
* Change the kills amount of a char, and levels them up when necessary.
* @return int
*/
private function changeKills($amount)
{
$amount = (int) $amount;
GameLog::updateLevellingLog($this->id(), $amount);
if ($amount !== 0) {
// Ignore changes that amount to zero.
if ($amount > 0) {
// when adding kills, check if levelling occurs
$this->levelUp();
}
query("UPDATE players SET kills = kills + CASE WHEN kills + :amount1 < 0 THEN kills*(-1) ELSE :amount2 END WHERE player_id = :player_id", [':amount1' => [$amount, PDO::PARAM_INT], ':amount2' => [$amount, PDO::PARAM_INT], ':player_id' => $this->id()]);
}
return $this->vo->kills = query_item("SELECT kills FROM players WHERE player_id = :player_id", [':player_id' => [$this->id(), PDO::PARAM_INT]]);
}
