Function CheckAllowRemoveRoad

src/road_cmd.cpp:252–303

* Is it allowed to remove the given road bits from the given tile? * @param tile the tile to remove the road from * @param remove the roadbits that are going to be removed * @param owner the actual owner of the roadbits of the tile * @param rt the road type to remove the bits from * @param flags command flags * @param town_check Shall the town rating checked/affected

 * @return A succeeded command when it is allowed to remove the road bits, a failed command otherwise.
 */
CommandCost CheckAllowRemoveRoad(TileIndex tile, RoadBits remove, Owner owner, RoadTramType rtt, DoCommandFlags flags, bool town_check)
{
	if (_game_mode == GM_EDITOR || remove == ROAD_NONE) return CommandCost();

	/* Water can always flood and towns can always remove "normal" road pieces.
	 * Towns are not be allowed to remove non "normal" road pieces, like tram
	 * tracks as that would result in trams that cannot turn. */
	if (_current_company == OWNER_WATER ||
			(rtt == RTT_ROAD && !Company::IsValidID(_current_company))) return CommandCost();

	/* Only do the special processing if the road is owned
	 * by a town */
	if (owner != OWNER_TOWN) {
		if (owner == OWNER_NONE) return CommandCost();
		CommandCost ret = CheckOwnership(owner);
		return ret;
	}

	if (!town_check) return CommandCost();

	if (_cheats.magic_bulldozer.value) return CommandCost();

	Town *t = ClosestTownFromTile(tile, UINT_MAX);
	if (t == nullptr) return CommandCost();

	/* check if you're allowed to remove the street owned by a town
	 * removal allowance depends on difficulty setting */
	CommandCost ret = CheckforTownRating(flags, t, TownRatingCheckType::RoadRemove);
	if (ret.Failed()) return ret;

	/* Get a bitmask of which neighbouring roads has a tile */
	RoadBits n = ROAD_NONE;
	RoadBits present = GetAnyRoadBits(tile, rtt);
	if ((present & ROAD_NE) && (GetAnyRoadBits(TileAddXY(tile, -1,  0), rtt) & ROAD_SW)) n |= ROAD_NE;
	if ((present & ROAD_SE) && (GetAnyRoadBits(TileAddXY(tile,  0,  1), rtt) & ROAD_NW)) n |= ROAD_SE;
	if ((present & ROAD_SW) && (GetAnyRoadBits(TileAddXY(tile,  1,  0), rtt) & ROAD_NE)) n |= ROAD_SW;
	if ((present & ROAD_NW) && (GetAnyRoadBits(TileAddXY(tile,  0, -1), rtt) & ROAD_SE)) n |= ROAD_NW;

	int rating_decrease = RATING_ROAD_DOWN_STEP_EDGE;
	/* If 0 or 1 bits are set in n, or if no bits that match the bits to remove,
	 * then allow it */
	if (KillFirstBit(n) != ROAD_NONE && (n & remove) != ROAD_NONE) {
		/* you can remove all kind of roads with extra dynamite */
		if (!_settings_game.construction.extra_dynamite) {
			return CommandCostWithParam(STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS, t->index);
		}
		rating_decrease = RATING_ROAD_DOWN_STEP_INNER;
	}
	ChangeTownRating(t, rating_decrease, RATING_ROAD_MINIMUM, flags);

	return CommandCost();
}


/**