/**
* Get the date of delivery of one contract.
*
* @return the integer of date of delivery
* @param contract: the contract that need to get delivery date.
*/
public int getDeliveryDate(Contract contract) {
World world = WorldManager.getInstance().getWorld();
int currentDay = world.getTimeManager().getDays();
int startDay = currentContracts.get(contract);
int interval = contract.getInterval();
return (startDay + interval) - currentDay;
}
