Method increaseByValue

src/Basescape/PurchaseState.cpp:470–531

* Increases the quantity of the selected item to buy by "change". * @param change How much we want to add. */

 * @param change How much we want to add.
 */
void PurchaseState::increaseByValue(int change)
{
	if (0 >= change) return;
	if (_total + getPrice() > _game->getSavedGame()->getFunds())
	{
		_timerInc->stop();
		_game->pushState(new ErrorMessageState(_game, "STR_NOT_ENOUGH_MONEY", _palette, Palette::blockOffset(15)+1, "BACK13.SCR", 0));
	}
	else if (_sel <= 2 && _pQty + 1 > _base->getAvailableQuarters() - _base->getUsedQuarters())
	{
		_timerInc->stop();
		_game->pushState(new ErrorMessageState(_game, "STR_NOT_ENOUGH_LIVING_SPACE", _palette, Palette::blockOffset(15)+1, "BACK13.SCR", 0));
	}
	else if (_sel >= 3 && _sel < 3 + _crafts.size() && _cQty + 1 > _base->getAvailableHangars() - _base->getUsedHangars())
	{
		_timerInc->stop();
		_game->pushState(new ErrorMessageState(_game, "STR_NO_FREE_HANGARS_FOR_PURCHASE", _palette, Palette::blockOffset(15)+1, "BACK13.SCR", 0));
	}
	else if (_sel >= 3 + _crafts.size()
		&& _iQty + _game->getRuleset()->getItem(_items[_sel - 3 - _crafts.size()])->getSize() > _base->getAvailableStores() - _base->getUsedStores())
	{
		_timerInc->stop();
		_game->pushState(new ErrorMessageState(_game, "STR_NOT_ENOUGH_STORE_SPACE", _palette, Palette::blockOffset(15)+1, "BACK13.SCR", 0));
	}
	else
	{
		int maxByMoney = (_game->getSavedGame()->getFunds() - _total) / getPrice();
		change = std::min(maxByMoney, change);
		if (_sel <= 2)
		{
			// Personnel count
			int maxByQuarters = _base->getAvailableQuarters() - _base->getUsedQuarters() - _pQty;
			change = std::min(maxByQuarters, change);
			_pQty += change;
		}
		else if (_sel >= 3 && _sel < 3 + _crafts.size())
		{
			// Craft count
			int maxByHangars = _base->getAvailableHangars() - _base->getUsedHangars() - _cQty;
			change = std::min(maxByHangars, change);
			_cQty += change;
		}
		else
		{
			RuleItem *rule = _game->getRuleset()->getItem(_items[_sel - 3 - _crafts.size()]);

			// Item count
			double storesNeededPerItem = rule->getSize();
			double freeStores = _base->getAvailableStores() - _base->getUsedStores() - _iQty;
			double maxByStores = DBL_MAX;
			if (!AreSame(storesNeededPerItem, 0.0))
			{
				maxByStores = (freeStores + 0.05) / storesNeededPerItem;
			}
			change = std::min((int)maxByStores, change);
			_iQty += change * storesNeededPerItem;
		}
		_qtys[_sel] += change;