* This is the vehicle-type independent part of the CmdRefitXXX functions.

 * @param v            The vehicle to refit.

 * @param only_this    Whether to only refit this vehicle, or to check the rest of them.

 * @param num_vehicles Number of vehicles to refit (not counting articulated parts). Zero means the whole chain.

 * @param new_cid      Cargotype to refit to

 * @param new_subtype  Cargo subtype to refit to. 0xFF means to try keeping the same subtype according to GetBestFittingSubType().

 * @param flags        Command flags

 * @param auto_refit   Refitting is done as automatic refitting outside a depot.

 * @return Refit cost.

 */

static CommandCost RefitVehicle(Vehicle *v, bool only_this, uint8 num_vehicles, CargoID new_cid, byte new_subtype, DoCommandFlag flags, bool auto_refit)

{

	CommandCost cost(v->GetExpenseType(false));

	uint total_capacity = 0;

	uint total_mail_capacity = 0;

	num_vehicles = num_vehicles == 0 ? UINT8_MAX : num_vehicles;

	VehicleSet vehicles_to_refit;

	if (!only_this) {

		GetVehicleSet(vehicles_to_refit, v, num_vehicles);

		/* In this case, we need to check the whole chain. */

		v = v->First();

	}

	v->InvalidateNewGRFCacheOfChain();

	byte actual_subtype = new_subtype;

	for (; v != NULL; v = (only_this ? NULL : v->Next())) {

		/* Reset actual_subtype for every new vehicle */

		if (!v->IsArticulatedPart()) actual_subtype = new_subtype;

		if (v->type == VEH_TRAIN && std::find(vehicles_to_refit.begin(), vehicles_to_refit.end(), v->index) == vehicles_to_refit.end() && !only_this) continue;

		const Engine *e = v->GetEngine();

		if (!e->CanCarryCargo()) continue;

		/* If the vehicle is not refittable, or does not allow automatic refitting,

		 * count its capacity nevertheless if the cargo matches */

		bool refittable = HasBit(e->info.refit_mask, new_cid) && (!auto_refit || HasBit(e->info.misc_flags, EF_AUTO_REFIT));

		if (!refittable && v->cargo_type != new_cid) continue;

		/* Determine best fitting subtype if requested */

		if (actual_subtype == 0xFF) {

			actual_subtype = GetBestFittingSubType(v, v, new_cid);

		}

		/* Back up the vehicle's cargo type */

		CargoID temp_cid = v->cargo_type;