/* Do not allow moving crashed vehicles inside the depot, it is likely to cause asserts later */

	if (src->vehstatus & VS_CRASHED) return CMD_ERROR;

	/* if nothing is selected as destination, try and find a matching vehicle to drag to. */

	Train *dst;

	if (dest_veh == INVALID_VEHICLE) {

		dst = (src->IsEngine() || (flags & DC_AUTOREPLACE)) ? nullptr : FindGoodVehiclePos(src);

	} else {

		dst = Train::GetIfValid(dest_veh);

		if (dst == nullptr) return CMD_ERROR;

		if (ret.Failed()) return ret;

		/* Do not allow appending to crashed vehicles, too */

		if (dst->vehstatus & VS_CRASHED) return CMD_ERROR;

	}

	/* if an articulated part is being handled, deal with its parent vehicle */

	src = src->GetFirstEnginePart();

	if (dst != nullptr) {

		dst = dst->GetFirstEnginePart();

	}

	 * original_src_head can't be nullptr; src is by definition != nullptr, so src_head can't be nullptr as

	 * src->GetFirst() always yields non-nullptr, so eventually original_src_head != nullptr as well. */

	bool original_src_head_front_engine = original_src_head->IsFrontEngine();

	bool original_dst_head_front_engine = original_dst_head != nullptr && original_dst_head->IsFrontEngine();

	/* (Re)arrange the trains in the wanted arrangement. */

	ArrangeTrains(&dst_head, dst, &src_head, src, move_chain);

	if ((flags & DC_AUTOREPLACE) == 0) {

		/* If the autoreplace flag is set we do not need to test for the validity

		 * because we are going to revert the train to its original state. As we

		 * assume the original state was correct autoreplace can skip this. */

		if (ret.Failed()) {

			/* Restore the train we had. */

			RestoreTrainBackup(original_src);

			RestoreTrainBackup(original_dst);

			return ret;

		}

	}

	/* do it? */

	if (flags & DC_EXEC) {

		/* Remove old heads from the statistics */

		if (original_src_head_front_engine) GroupStatistics::CountVehicle(original_src_head, -1);