Function CmdSellRailWagon

src/train_cmd.cpp:1419–1491

* Sell a (single) train wagon/engine. * @param flags type of operation * @param t the train wagon to sell * @param sell_chain the selling mode * - sell_chain = false: only sell the single dragged wagon/engine (and any belonging rear-engines) * - sell_chain = true: sell the vehicle and all vehicles following it in the chain * if the wagon is dragged, don't delete t

 * @return the cost of this operation or an error
 */
CommandCost CmdSellRailWagon(DoCommandFlags flags, Vehicle *t, bool sell_chain, bool backup_order, ClientID user)
{
	Train *v = Train::From(t)->GetFirstEnginePart();
	Train *first = v->First();

	if (v->IsRearDualheaded()) return CommandCost(STR_ERROR_REAR_ENGINE_FOLLOW_FRONT);

	/* First make a backup of the order of the train. That way we can do
	 * whatever we want with the order and later on easily revert. */
	TrainList original;
	MakeTrainBackup(original, first);

	/* We need to keep track of the new head and the head of what we're going to sell. */
	Train *new_head = first;
	Train *sell_head = nullptr;

	/* Split the train in the wanted way. */
	ArrangeTrains(&sell_head, nullptr, &new_head, v, sell_chain);

	/* We don't need to validate the second train; it's going to be sold. */
	CommandCost ret = ValidateTrains(nullptr, nullptr, first, new_head, !flags.Test(DoCommandFlag::AutoReplace));
	if (ret.Failed()) {
		/* Restore the train we had. */
		RestoreTrainBackup(original);
		return ret;
	}

	if (first->orders == nullptr && !OrderList::CanAllocateItem()) {
		/* Restore the train we had. */
		RestoreTrainBackup(original);
		return CommandCost(STR_ERROR_NO_MORE_SPACE_FOR_ORDERS);
	}

	CommandCost cost(EXPENSES_NEW_VEHICLES);
	for (Train *part = sell_head; part != nullptr; part = part->Next()) cost.AddCost(-part->value);

	/* do it? */
	if (flags.Test(DoCommandFlag::Execute)) {
		/* First normalise the sub types of the chain. */
		NormaliseSubtypes(new_head);

		if (v == first && !sell_chain && new_head != nullptr && new_head->IsFrontEngine()) {
			if (v->IsEngine()) {
				/* We are selling the front engine. In this case we want to
				 * 'give' the order, unit number and such to the new head. */
				new_head->orders = first->orders;
				new_head->AddToShared(first);
				DeleteVehicleOrders(first);

				/* Copy other important data from the front engine */
				new_head->CopyVehicleConfigAndStatistics(first);
			}
			GroupStatistics::CountVehicle(new_head, 1); // after copying over the profit, if required
		} else if (v->IsPrimaryVehicle() && backup_order) {
			OrderBackup::Backup(v, user);
		}

		/* We need to update the information about the train. */