Fix #10117: Decrement object burst limit after build check

[openttd-github.git] / src / road_cmd.cpp

/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file road_cmd.cpp Commands related to road tiles. */

#include "stdafx.h"
#include "road.h"
#include "road_internal.h"
#include "viewport_func.h"
#include "command_func.h"
#include "pathfinder/yapf/yapf_cache.h"
#include "depot_base.h"
#include "newgrf.h"
#include "autoslope.h"
#include "tunnelbridge_map.h"
#include "strings_func.h"
#include "vehicle_func.h"
#include "sound_func.h"
#include "tunnelbridge.h"
#include "cheat_type.h"
#include "effectvehicle_func.h"
#include "effectvehicle_base.h"
#include "elrail_func.h"
#include "roadveh.h"
#include "town.h"
#include "company_base.h"
#include "core/random_func.hpp"
#include "newgrf_debug.h"
#include "newgrf_railtype.h"
#include "newgrf_roadtype.h"
#include "date_func.h"
#include "genworld.h"
#include "company_gui.h"
#include "road_func.h"
#include "road_cmd.h"
#include "landscape_cmd.h"
#include "rail_cmd.h"

#include "table/strings.h"
#include "table/roadtypes.h"

#include "safeguards.h"

/** Helper type for lists/vectors of road vehicles */
typedef std::vector<RoadVehicle *> RoadVehicleList;

RoadTypeInfo _roadtypes[ROADTYPE_END];
std::vector<RoadType> _sorted_roadtypes;
RoadTypes _roadtypes_hidden_mask;

/**
 * Bitmap of road/tram types.
 * Bit if set if a roadtype is tram.
 */
RoadTypes _roadtypes_type;

/**
 * Reset all road type information to its default values.
 */
void ResetRoadTypes()
{
        static_assert(lengthof(_original_roadtypes) <= lengthof(_roadtypes));

        uint i = 0;
        for (; i < lengthof(_original_roadtypes); i++) _roadtypes[i] = _original_roadtypes[i];

        static const RoadTypeInfo empty_roadtype = {
                { 0, 0, 0, 0, 0, 0 },
                { 0, 0, 0, 0, 0, 0 },
                { 0, 0, 0, 0, 0, 0, 0, 0, 0, {}, {}, 0, {}, {} },
                ROADTYPES_NONE, ROTFB_NONE, 0, 0, 0, 0,
                RoadTypeLabelList(), 0, 0, ROADTYPES_NONE, ROADTYPES_NONE, 0,
                {}, {} };
        for (; i < lengthof(_roadtypes);          i++) _roadtypes[i] = empty_roadtype;

        _roadtypes_hidden_mask = ROADTYPES_NONE;
        _roadtypes_type        = ROADTYPES_TRAM;
}

void ResolveRoadTypeGUISprites(RoadTypeInfo *rti)
{
        SpriteID cursors_base = GetCustomRoadSprite(rti, INVALID_TILE, ROTSG_CURSORS);
        if (cursors_base != 0) {
                rti->gui_sprites.build_y_road = cursors_base +  0;
                rti->gui_sprites.build_x_road = cursors_base +  1;
                rti->gui_sprites.auto_road    = cursors_base +  2;
                rti->gui_sprites.build_depot  = cursors_base +  3;
                rti->gui_sprites.build_tunnel = cursors_base +  4;
                rti->gui_sprites.convert_road = cursors_base +  5;
                rti->cursor.road_swne         = cursors_base +  6;
                rti->cursor.road_nwse         = cursors_base +  7;
                rti->cursor.autoroad          = cursors_base +  8;
                rti->cursor.depot             = cursors_base +  9;
                rti->cursor.tunnel            = cursors_base + 10;
                rti->cursor.convert_road      = cursors_base + 11;
        }
}

/**
 * Compare roadtypes based on their sorting order.
 * @param first  The roadtype to compare to.
 * @param second The roadtype to compare.
 * @return True iff the first should be sorted before the second.
 */
static bool CompareRoadTypes(const RoadType &first, const RoadType &second)
{
        if (RoadTypeIsRoad(first) == RoadTypeIsRoad(second)) {
                return GetRoadTypeInfo(first)->sorting_order < GetRoadTypeInfo(second)->sorting_order;
        }
        return RoadTypeIsTram(first) < RoadTypeIsTram(second);
}

/**
 * Resolve sprites of custom road types
 */
void InitRoadTypes()
{
        for (RoadType rt = ROADTYPE_BEGIN; rt != ROADTYPE_END; rt++) {
                RoadTypeInfo *rti = &_roadtypes[rt];
                ResolveRoadTypeGUISprites(rti);
                if (HasBit(rti->flags, ROTF_HIDDEN)) SetBit(_roadtypes_hidden_mask, rt);
        }

        _sorted_roadtypes.clear();
        for (RoadType rt = ROADTYPE_BEGIN; rt != ROADTYPE_END; rt++) {
                if (_roadtypes[rt].label != 0 && !HasBit(_roadtypes_hidden_mask, rt)) {
                        _sorted_roadtypes.push_back(rt);
                }
        }
        std::sort(_sorted_roadtypes.begin(), _sorted_roadtypes.end(), CompareRoadTypes);
}

/**
 * Allocate a new road type label
 */
RoadType AllocateRoadType(RoadTypeLabel label, RoadTramType rtt)
{
        for (RoadType rt = ROADTYPE_BEGIN; rt != ROADTYPE_END; rt++) {
                RoadTypeInfo *rti = &_roadtypes[rt];

                if (rti->label == 0) {
                        /* Set up new road type */
                        *rti = _original_roadtypes[(rtt == RTT_TRAM) ? ROADTYPE_TRAM : ROADTYPE_ROAD];
                        rti->label = label;
                        rti->alternate_labels.clear();
                        rti->flags = ROTFB_NONE;
                        rti->introduction_date = INVALID_DATE;

                        /* Make us compatible with ourself. */
                        rti->powered_roadtypes = (RoadTypes)(1ULL << rt);

                        /* We also introduce ourself. */
                        rti->introduces_roadtypes = (RoadTypes)(1ULL << rt);

                        /* Default sort order; order of allocation, but with some
                         * offsets so it's easier for NewGRF to pick a spot without
                         * changing the order of other (original) road types.
                         * The << is so you can place other roadtypes in between the
                         * other roadtypes, the 7 is to be able to place something
                         * before the first (default) road type. */
                        rti->sorting_order = rt << 2 | 7;

                        /* Set bitmap of road/tram types */
                        if (rtt == RTT_TRAM) {
                                SetBit(_roadtypes_type, rt);
                        } else {
                                ClrBit(_roadtypes_type, rt);
                        }

                        return rt;
                }
        }

        return INVALID_ROADTYPE;
}

/**
 * Verify whether a road vehicle is available.
 * @return \c true if at least one road vehicle is available, \c false if not
 */
bool RoadVehiclesAreBuilt()
{
        return !RoadVehicle::Iterate().empty();
}

/**
 * Update road infrastructure counts for a company.
 * @param rt Road type to update count of.
 * @param o Owner of road piece.
 * @param count Number of road pieces to adjust.
 */
void UpdateCompanyRoadInfrastructure(RoadType rt, Owner o, int count)
{
        if (rt == INVALID_ROADTYPE) return;

        Company *c = Company::GetIfValid(o);
        if (c == nullptr) return;

        c->infrastructure.road[rt] += count;
        DirtyCompanyInfrastructureWindows(c->index);
}

/** Invalid RoadBits on slopes.  */
static const RoadBits _invalid_tileh_slopes_road[2][15] = {
        /* The inverse of the mixable RoadBits on a leveled slope */
        {
                ROAD_NONE,         // SLOPE_FLAT
                ROAD_NE | ROAD_SE, // SLOPE_W
                ROAD_NE | ROAD_NW, // SLOPE_S

                ROAD_NE,           // SLOPE_SW
                ROAD_NW | ROAD_SW, // SLOPE_E
                ROAD_NONE,         // SLOPE_EW

                ROAD_NW,           // SLOPE_SE
                ROAD_NONE,         // SLOPE_WSE
                ROAD_SE | ROAD_SW, // SLOPE_N

                ROAD_SE,           // SLOPE_NW
                ROAD_NONE,         // SLOPE_NS
                ROAD_NONE,         // SLOPE_ENW

                ROAD_SW,           // SLOPE_NE
                ROAD_NONE,         // SLOPE_SEN
                ROAD_NONE          // SLOPE_NWS
        },
        /* The inverse of the allowed straight roads on a slope
         * (with and without a foundation). */
        {
                ROAD_NONE, // SLOPE_FLAT
                ROAD_NONE, // SLOPE_W    Foundation
                ROAD_NONE, // SLOPE_S    Foundation

                ROAD_Y,    // SLOPE_SW
                ROAD_NONE, // SLOPE_E    Foundation
                ROAD_ALL,  // SLOPE_EW

                ROAD_X,    // SLOPE_SE
                ROAD_ALL,  // SLOPE_WSE
                ROAD_NONE, // SLOPE_N    Foundation

                ROAD_X,    // SLOPE_NW
                ROAD_ALL,  // SLOPE_NS
                ROAD_ALL,  // SLOPE_ENW

                ROAD_Y,    // SLOPE_NE
                ROAD_ALL,  // SLOPE_SEN
                ROAD_ALL   // SLOPE_NW
        }
};

static Foundation GetRoadFoundation(Slope tileh, RoadBits bits);

/**
 * 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, DoCommandFlag 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, ROAD_REMOVE);
        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(TILE_ADDXY(tile, -1,  0), rtt) & ROAD_SW)) n |= ROAD_NE;
        if ((present & ROAD_SE) && (GetAnyRoadBits(TILE_ADDXY(tile,  0,  1), rtt) & ROAD_NW)) n |= ROAD_SE;
        if ((present & ROAD_SW) && (GetAnyRoadBits(TILE_ADDXY(tile,  1,  0), rtt) & ROAD_NE)) n |= ROAD_SW;
        if ((present & ROAD_NW) && (GetAnyRoadBits(TILE_ADDXY(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) {
                        SetDParam(0, t->index);
                        return_cmd_error(STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS);
                }
                rating_decrease = RATING_ROAD_DOWN_STEP_INNER;
        }
        ChangeTownRating(t, rating_decrease, RATING_ROAD_MINIMUM, flags);

        return CommandCost();
}


/**
 * Delete a piece of road.
 * @param tile tile where to remove road from
 * @param flags operation to perform
 * @param pieces roadbits to remove
 * @param rt roadtype to remove
 * @param crossing_check should we check if there is a tram track when we are removing road from crossing?
 * @param town_check should we check if the town allows removal?
 */
static CommandCost RemoveRoad(TileIndex tile, DoCommandFlag flags, RoadBits pieces, RoadTramType rtt, bool crossing_check, bool town_check = true)
{
        assert(pieces != ROAD_NONE);

        RoadType existing_rt = MayHaveRoad(tile) ? GetRoadType(tile, rtt) : INVALID_ROADTYPE;
        /* The tile doesn't have the given road type */
        if (existing_rt == INVALID_ROADTYPE) return_cmd_error((rtt == RTT_TRAM) ? STR_ERROR_THERE_IS_NO_TRAMWAY : STR_ERROR_THERE_IS_NO_ROAD);

        switch (GetTileType(tile)) {
                case MP_ROAD: {
                        CommandCost ret = EnsureNoVehicleOnGround(tile);
                        if (ret.Failed()) return ret;
                        break;
                }

                case MP_STATION: {
                        if (!IsDriveThroughStopTile(tile)) return CMD_ERROR;

                        CommandCost ret = EnsureNoVehicleOnGround(tile);
                        if (ret.Failed()) return ret;
                        break;
                }

                case MP_TUNNELBRIDGE: {
                        if (GetTunnelBridgeTransportType(tile) != TRANSPORT_ROAD) return CMD_ERROR;
                        CommandCost ret = TunnelBridgeIsFree(tile, GetOtherTunnelBridgeEnd(tile));
                        if (ret.Failed()) return ret;
                        break;
                }

                default:
                        return CMD_ERROR;
        }

        CommandCost ret = CheckAllowRemoveRoad(tile, pieces, GetRoadOwner(tile, rtt), rtt, flags, town_check);
        if (ret.Failed()) return ret;

        if (!IsTileType(tile, MP_ROAD)) {
                /* If it's the last roadtype, just clear the whole tile */
                if (GetRoadType(tile, OtherRoadTramType(rtt)) == INVALID_ROADTYPE) return Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile);

                CommandCost cost(EXPENSES_CONSTRUCTION);
                if (IsTileType(tile, MP_TUNNELBRIDGE)) {
                        /* Removing any roadbit in the bridge axis removes the roadtype (that's the behaviour remove-long-roads needs) */
                        if ((AxisToRoadBits(DiagDirToAxis(GetTunnelBridgeDirection(tile))) & pieces) == ROAD_NONE) return_cmd_error((rtt == RTT_TRAM) ? STR_ERROR_THERE_IS_NO_TRAMWAY : STR_ERROR_THERE_IS_NO_ROAD);

                        TileIndex other_end = GetOtherTunnelBridgeEnd(tile);
                        /* Pay for *every* tile of the bridge or tunnel */
                        uint len = GetTunnelBridgeLength(other_end, tile) + 2;
                        cost.AddCost(len * 2 * RoadClearCost(existing_rt));
                        if (flags & DC_EXEC) {
                                /* A full diagonal road tile has two road bits. */
                                UpdateCompanyRoadInfrastructure(existing_rt, GetRoadOwner(tile, rtt), -(int)(len * 2 * TUNNELBRIDGE_TRACKBIT_FACTOR));

                                SetRoadType(other_end, rtt, INVALID_ROADTYPE);
                                SetRoadType(tile,      rtt, INVALID_ROADTYPE);

                                /* If the owner of the bridge sells all its road, also move the ownership
                                 * to the owner of the other roadtype, unless the bridge owner is a town. */
                                Owner other_owner = GetRoadOwner(tile, OtherRoadTramType(rtt));
                                if (!IsTileOwner(tile, other_owner) && !IsTileOwner(tile, OWNER_TOWN)) {
                                        SetTileOwner(tile, other_owner);
                                        SetTileOwner(other_end, other_owner);
                                }

                                /* Mark tiles dirty that have been repaved */
                                if (IsBridge(tile)) {
                                        MarkBridgeDirty(tile);
                                } else {
                                        MarkTileDirtyByTile(tile);
                                        MarkTileDirtyByTile(other_end);
                                }
                        }
                } else {
                        assert(IsDriveThroughStopTile(tile));
                        cost.AddCost(RoadClearCost(existing_rt) * 2);
                        if (flags & DC_EXEC) {
                                /* A full diagonal road tile has two road bits. */
                                UpdateCompanyRoadInfrastructure(existing_rt, GetRoadOwner(tile, rtt), -2);
                                SetRoadType(tile, rtt, INVALID_ROADTYPE);
                                MarkTileDirtyByTile(tile);
                        }
                }
                return cost;
        }

        switch (GetRoadTileType(tile)) {
                case ROAD_TILE_NORMAL: {
                        Slope tileh = GetTileSlope(tile);

                        /* Steep slopes behave the same as slopes with one corner raised. */
                        if (IsSteepSlope(tileh)) {
                                tileh = SlopeWithOneCornerRaised(GetHighestSlopeCorner(tileh));
                        }

                        RoadBits present = GetRoadBits(tile, rtt);
                        const RoadBits other = GetRoadBits(tile, OtherRoadTramType(rtt));
                        const Foundation f = GetRoadFoundation(tileh, present);

                        if (HasRoadWorks(tile) && _current_company != OWNER_WATER) return_cmd_error(STR_ERROR_ROAD_WORKS_IN_PROGRESS);

                        /* Autocomplete to a straight road
                         * @li if the bits of the other roadtypes result in another foundation
                         * @li if build on slopes is disabled */
                        if ((IsStraightRoad(other) && (other & _invalid_tileh_slopes_road[0][tileh & SLOPE_ELEVATED]) != ROAD_NONE) ||
                                        (tileh != SLOPE_FLAT && !_settings_game.construction.build_on_slopes)) {
                                pieces |= MirrorRoadBits(pieces);
                        }

                        /* limit the bits to delete to the existing bits. */
                        pieces &= present;
                        if (pieces == ROAD_NONE) return_cmd_error((rtt == RTT_TRAM) ? STR_ERROR_THERE_IS_NO_TRAMWAY : STR_ERROR_THERE_IS_NO_ROAD);

                        /* Now set present what it will be after the remove */
                        present ^= pieces;

                        /* Check for invalid RoadBit combinations on slopes */
                        if (tileh != SLOPE_FLAT && present != ROAD_NONE &&
                                        (present & _invalid_tileh_slopes_road[0][tileh & SLOPE_ELEVATED]) == present) {
                                return CMD_ERROR;
                        }

                        if (flags & DC_EXEC) {
                                if (HasRoadWorks(tile)) {
                                        /* flooding tile with road works, don't forget to remove the effect vehicle too */
                                        assert(_current_company == OWNER_WATER);
                                        for (EffectVehicle *v : EffectVehicle::Iterate()) {
                                                if (TileVirtXY(v->x_pos, v->y_pos) == tile) {
                                                        delete v;
                                                }
                                        }
                                }

                                UpdateCompanyRoadInfrastructure(existing_rt, GetRoadOwner(tile, rtt), -(int)CountBits(pieces));

                                if (present == ROAD_NONE) {
                                        /* No other road type, just clear tile. */
                                        if (GetRoadType(tile, OtherRoadTramType(rtt)) == INVALID_ROADTYPE) {
                                                /* Includes MarkTileDirtyByTile() */
                                                DoClearSquare(tile);
                                        } else {
                                                if (rtt == RTT_ROAD && IsRoadOwner(tile, rtt, OWNER_TOWN)) {
                                                        /* Update nearest-town index */
                                                        const Town *town = CalcClosestTownFromTile(tile);
                                                        SetTownIndex(tile, town == nullptr ? INVALID_TOWN : town->index);
                                                }
                                                SetRoadBits(tile, ROAD_NONE, rtt);
                                                SetRoadType(tile, rtt, INVALID_ROADTYPE);
                                                MarkTileDirtyByTile(tile);
                                        }
                                } else {
                                        /* When bits are removed, you *always* end up with something that
                                         * is not a complete straight road tile. However, trams do not have
                                         * onewayness, so they cannot remove it either. */
                                        if (rtt == RTT_ROAD) SetDisallowedRoadDirections(tile, DRD_NONE);
                                        SetRoadBits(tile, present, rtt);
                                        MarkTileDirtyByTile(tile);
                                }
                        }

                        CommandCost cost(EXPENSES_CONSTRUCTION, CountBits(pieces) * RoadClearCost(existing_rt));
                        /* If we build a foundation we have to pay for it. */
                        if (f == FOUNDATION_NONE && GetRoadFoundation(tileh, present) != FOUNDATION_NONE) cost.AddCost(_price[PR_BUILD_FOUNDATION]);

                        return cost;
                }

                case ROAD_TILE_CROSSING: {
                        if (pieces & ComplementRoadBits(GetCrossingRoadBits(tile))) {
                                return CMD_ERROR;
                        }

                        if (flags & DC_EXEC) {
                                /* A full diagonal road tile has two road bits. */
                                UpdateCompanyRoadInfrastructure(existing_rt, GetRoadOwner(tile, rtt), -2);

                                Track railtrack = GetCrossingRailTrack(tile);
                                if (GetRoadType(tile, OtherRoadTramType(rtt)) == INVALID_ROADTYPE) {
                                        TrackBits tracks = GetCrossingRailBits(tile);
                                        bool reserved = HasCrossingReservation(tile);
                                        MakeRailNormal(tile, GetTileOwner(tile), tracks, GetRailType(tile));
                                        if (reserved) SetTrackReservation(tile, tracks);

                                        /* Update rail count for level crossings. The plain track should still be accounted
                                         * for, so only subtract the difference to the level crossing cost. */
                                        Company *c = Company::GetIfValid(GetTileOwner(tile));
                                        if (c != nullptr) {
                                                c->infrastructure.rail[GetRailType(tile)] -= LEVELCROSSING_TRACKBIT_FACTOR - 1;
                                                DirtyCompanyInfrastructureWindows(c->index);
                                        }
                                } else {
                                        SetRoadType(tile, rtt, INVALID_ROADTYPE);
                                }
                                MarkTileDirtyByTile(tile);
                                YapfNotifyTrackLayoutChange(tile, railtrack);
                        }
                        return CommandCost(EXPENSES_CONSTRUCTION, RoadClearCost(existing_rt) * 2);
                }

                default:
                case ROAD_TILE_DEPOT:
                        return CMD_ERROR;
        }
}


/**
 * Calculate the costs for roads on slopes
 *  Aside modify the RoadBits to fit on the slopes
 *
 * @note The RoadBits are modified too!
 * @param tileh The current slope
 * @param pieces The RoadBits we want to add
 * @param existing The existent RoadBits of the current type
 * @param other The other existent RoadBits
 * @return The costs for these RoadBits on this slope
 */
static CommandCost CheckRoadSlope(Slope tileh, RoadBits *pieces, RoadBits existing, RoadBits other)
{
        /* Remove already build pieces */
        CLRBITS(*pieces, existing);

        /* If we can't build anything stop here */
        if (*pieces == ROAD_NONE) return CMD_ERROR;

        /* All RoadBit combos are valid on flat land */
        if (tileh == SLOPE_FLAT) return CommandCost();

        /* Steep slopes behave the same as slopes with one corner raised. */
        if (IsSteepSlope(tileh)) {
                tileh = SlopeWithOneCornerRaised(GetHighestSlopeCorner(tileh));
        }

        /* Save the merge of all bits of the current type */
        RoadBits type_bits = existing | *pieces;

        /* Roads on slopes */
        if (_settings_game.construction.build_on_slopes && (_invalid_tileh_slopes_road[0][tileh] & (other | type_bits)) == ROAD_NONE) {

                /* If we add leveling we've got to pay for it */
                if ((other | existing) == ROAD_NONE) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);

                return CommandCost();
        }

        /* Autocomplete uphill roads */
        *pieces |= MirrorRoadBits(*pieces);
        type_bits = existing | *pieces;

        /* Uphill roads */
        if (IsStraightRoad(type_bits) && (other == type_bits || other == ROAD_NONE) &&
                        (_invalid_tileh_slopes_road[1][tileh] & (other | type_bits)) == ROAD_NONE) {

                /* Slopes with foundation ? */
                if (IsSlopeWithOneCornerRaised(tileh)) {

                        /* Prevent build on slopes if it isn't allowed */
                        if (_settings_game.construction.build_on_slopes) {

                                /* If we add foundation we've got to pay for it */
                                if ((other | existing) == ROAD_NONE) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);

                                return CommandCost();
                        }
                } else {
                        if (HasExactlyOneBit(existing) && GetRoadFoundation(tileh, existing) == FOUNDATION_NONE) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
                        return CommandCost();
                }
        }
        return CMD_ERROR;
}

/**
 * Build a piece of road.
 * @param flags operation to perform
 * @param tile tile where to build road
 * @param pieces road pieces to build (RoadBits)
 * @param rt road type
 * @param toggle_drd disallowed directions to toggle
 * @param town_id the town that is building the road (0 if not applicable)
 * @return the cost of this operation or an error
 */
CommandCost CmdBuildRoad(DoCommandFlag flags, TileIndex tile, RoadBits pieces, RoadType rt, DisallowedRoadDirections toggle_drd, TownID town_id)
{
        CompanyID company = _current_company;
        CommandCost cost(EXPENSES_CONSTRUCTION);

        RoadBits existing = ROAD_NONE;
        RoadBits other_bits = ROAD_NONE;

        /* Road pieces are max 4 bitset values (NE, NW, SE, SW) and town can only be non-zero
         * if a non-company is building the road */
        if ((Company::IsValidID(company) && town_id != 0) || (company == OWNER_TOWN && !Town::IsValidID(town_id)) || (company == OWNER_DEITY && town_id != 0)) return CMD_ERROR;
        if (company != OWNER_TOWN) {
                const Town *town = CalcClosestTownFromTile(tile);
                town_id = (town != nullptr) ? town->index : INVALID_TOWN;

                if (company == OWNER_DEITY) {
                        company = OWNER_TOWN;

                        /* If we are not within a town, we are not owned by the town */
                        if (town == nullptr || DistanceSquare(tile, town->xy) > town->cache.squared_town_zone_radius[HZB_TOWN_EDGE]) {
                                company = OWNER_NONE;
                        }
                }
        }

        /* do not allow building 'zero' road bits, code wouldn't handle it */
        if (pieces == ROAD_NONE || !IsValidRoadBits(pieces) || !IsValidDisallowedRoadDirections(toggle_drd)) return CMD_ERROR;
        if (!ValParamRoadType(rt)) return CMD_ERROR;

        Slope tileh = GetTileSlope(tile);
        RoadTramType rtt = GetRoadTramType(rt);

        bool need_to_clear = false;
        switch (GetTileType(tile)) {
                case MP_ROAD:
                        switch (GetRoadTileType(tile)) {
                                case ROAD_TILE_NORMAL: {
                                        if (HasRoadWorks(tile)) return_cmd_error(STR_ERROR_ROAD_WORKS_IN_PROGRESS);

                                        other_bits = GetRoadBits(tile, OtherRoadTramType(rtt));
                                        if (!HasTileRoadType(tile, rtt)) break;

                                        existing = GetRoadBits(tile, rtt);
                                        bool crossing = !IsStraightRoad(existing | pieces);
                                        if (rtt == RTT_ROAD && (GetDisallowedRoadDirections(tile) != DRD_NONE || toggle_drd != DRD_NONE) && crossing) {
                                                /* Junctions cannot be one-way */
                                                return_cmd_error(STR_ERROR_ONEWAY_ROADS_CAN_T_HAVE_JUNCTION);
                                        }
                                        if ((existing & pieces) == pieces) {
                                                /* We only want to set the (dis)allowed road directions */
                                                if (toggle_drd != DRD_NONE && rtt == RTT_ROAD) {
                                                        if (crossing) return_cmd_error(STR_ERROR_ONEWAY_ROADS_CAN_T_HAVE_JUNCTION);

                                                        Owner owner = GetRoadOwner(tile, rtt);
                                                        if (owner != OWNER_NONE) {
                                                                CommandCost ret = CheckOwnership(owner, tile);
                                                                if (ret.Failed()) return ret;
                                                        }

                                                        DisallowedRoadDirections dis_existing = GetDisallowedRoadDirections(tile);
                                                        DisallowedRoadDirections dis_new      = dis_existing ^ toggle_drd;

                                                        /* We allow removing disallowed directions to break up
                                                         * deadlocks, but adding them can break articulated
                                                         * vehicles. As such, only when less is disallowed,
                                                         * i.e. bits are removed, we skip the vehicle check. */
                                                        if (CountBits(dis_existing) <= CountBits(dis_new)) {
                                                                CommandCost ret = EnsureNoVehicleOnGround(tile);
                                                                if (ret.Failed()) return ret;
                                                        }

                                                        /* Ignore half built tiles */
                                                        if ((flags & DC_EXEC) && IsStraightRoad(existing)) {
                                                                SetDisallowedRoadDirections(tile, dis_new);
                                                                MarkTileDirtyByTile(tile);
                                                        }
                                                        return CommandCost();
                                                }
                                                return_cmd_error(STR_ERROR_ALREADY_BUILT);
                                        }
                                        /* Disallow breaking end-of-line of someone else
                                         * so trams can still reverse on this tile. */
                                        if (rtt == RTT_TRAM && HasExactlyOneBit(existing)) {
                                                Owner owner = GetRoadOwner(tile, rtt);
                                                if (Company::IsValidID(owner)) {
                                                        CommandCost ret = CheckOwnership(owner);
                                                        if (ret.Failed()) return ret;
                                                }
                                        }
                                        break;
                                }

                                case ROAD_TILE_CROSSING:
                                        if (RoadNoLevelCrossing(rt)) {
                                                return_cmd_error(STR_ERROR_CROSSING_DISALLOWED_ROAD);
                                        }

                                        other_bits = GetCrossingRoadBits(tile);
                                        if (pieces & ComplementRoadBits(other_bits)) goto do_clear;
                                        pieces = other_bits; // we need to pay for both roadbits

                                        if (HasTileRoadType(tile, rtt)) return_cmd_error(STR_ERROR_ALREADY_BUILT);
                                        break;

                                case ROAD_TILE_DEPOT:
                                        if ((GetAnyRoadBits(tile, rtt) & pieces) == pieces) return_cmd_error(STR_ERROR_ALREADY_BUILT);
                                        goto do_clear;

                                default: NOT_REACHED();
                        }
                        break;

                case MP_RAILWAY: {
                        if (IsSteepSlope(tileh)) {
                                return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
                        }

                        /* Level crossings may only be built on these slopes */
                        if (!HasBit(VALID_LEVEL_CROSSING_SLOPES, tileh)) {
                                return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
                        }

                        if (GetRailTileType(tile) != RAIL_TILE_NORMAL) goto do_clear;

                        if (RoadNoLevelCrossing(rt)) {
                                return_cmd_error(STR_ERROR_CROSSING_DISALLOWED_ROAD);
                        }

                        if (RailNoLevelCrossings(GetRailType(tile))) {
                                return_cmd_error(STR_ERROR_CROSSING_DISALLOWED_RAIL);
                        }

                        Axis roaddir;
                        switch (GetTrackBits(tile)) {
                                case TRACK_BIT_X:
                                        if (pieces & ROAD_X) goto do_clear;
                                        roaddir = AXIS_Y;
                                        break;

                                case TRACK_BIT_Y:
                                        if (pieces & ROAD_Y) goto do_clear;
                                        roaddir = AXIS_X;
                                        break;

                                default: goto do_clear;
                        }

                        CommandCost ret = EnsureNoVehicleOnGround(tile);
                        if (ret.Failed()) return ret;

                        if (flags & DC_EXEC) {
                                Track railtrack = AxisToTrack(OtherAxis(roaddir));
                                YapfNotifyTrackLayoutChange(tile, railtrack);
                                /* Update company infrastructure counts. A level crossing has two road bits. */
                                UpdateCompanyRoadInfrastructure(rt, company, 2);

                                /* Update rail count for level crossings. The plain track is already
                                 * counted, so only add the difference to the level crossing cost. */
                                Company *c = Company::GetIfValid(GetTileOwner(tile));
                                if (c != nullptr) {
                                        c->infrastructure.rail[GetRailType(tile)] += LEVELCROSSING_TRACKBIT_FACTOR - 1;
                                        DirtyCompanyInfrastructureWindows(c->index);
                                }

                                /* Always add road to the roadtypes (can't draw without it) */
                                bool reserved = HasBit(GetRailReservationTrackBits(tile), railtrack);
                                MakeRoadCrossing(tile, company, company, GetTileOwner(tile), roaddir, GetRailType(tile), rtt == RTT_ROAD ? rt : INVALID_ROADTYPE, (rtt == RTT_TRAM) ? rt : INVALID_ROADTYPE, town_id);
                                SetCrossingReservation(tile, reserved);
                                UpdateLevelCrossing(tile, false);
                                MarkTileDirtyByTile(tile);
                        }
                        return CommandCost(EXPENSES_CONSTRUCTION, 2 * RoadBuildCost(rt));
                }

                case MP_STATION: {
                        if ((GetAnyRoadBits(tile, rtt) & pieces) == pieces) return_cmd_error(STR_ERROR_ALREADY_BUILT);
                        if (!IsDriveThroughStopTile(tile)) goto do_clear;

                        RoadBits curbits = AxisToRoadBits(DiagDirToAxis(GetRoadStopDir(tile)));
                        if (pieces & ~curbits) goto do_clear;
                        pieces = curbits; // we need to pay for both roadbits

                        if (HasTileRoadType(tile, rtt)) return_cmd_error(STR_ERROR_ALREADY_BUILT);
                        break;
                }

                case MP_TUNNELBRIDGE: {
                        if (GetTunnelBridgeTransportType(tile) != TRANSPORT_ROAD) goto do_clear;
                        /* Only allow building the outern roadbit, so building long roads stops at existing bridges */
                        if (MirrorRoadBits(DiagDirToRoadBits(GetTunnelBridgeDirection(tile))) != pieces) goto do_clear;
                        if (HasTileRoadType(tile, rtt)) return_cmd_error(STR_ERROR_ALREADY_BUILT);
                        /* Don't allow adding roadtype to the bridge/tunnel when vehicles are already driving on it */
                        CommandCost ret = TunnelBridgeIsFree(tile, GetOtherTunnelBridgeEnd(tile));
                        if (ret.Failed()) return ret;
                        break;
                }

                default: {
do_clear:;
                        need_to_clear = true;
                        break;
                }
        }

        if (need_to_clear) {
                CommandCost ret = Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile);
                if (ret.Failed()) return ret;
                cost.AddCost(ret);
        }

        if (other_bits != pieces) {
                /* Check the foundation/slopes when adding road/tram bits */
                CommandCost ret = CheckRoadSlope(tileh, &pieces, existing, other_bits);
                /* Return an error if we need to build a foundation (ret != 0) but the
                 * current setting is turned off */
                if (ret.Failed() || (ret.GetCost() != 0 && !_settings_game.construction.build_on_slopes)) {
                        return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
                }
                cost.AddCost(ret);
        }

        if (!need_to_clear) {
                if (IsTileType(tile, MP_ROAD)) {
                        /* Don't put the pieces that already exist */
                        pieces &= ComplementRoadBits(existing);

                        /* Check if new road bits will have the same foundation as other existing road types */
                        if (IsNormalRoad(tile)) {
                                Slope slope = GetTileSlope(tile);
                                Foundation found_new = GetRoadFoundation(slope, pieces | existing);

                                RoadBits bits = GetRoadBits(tile, OtherRoadTramType(rtt));
                                /* do not check if there are not road bits of given type */
                                if (bits != ROAD_NONE && GetRoadFoundation(slope, bits) != found_new) {
                                        return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
                                }
                        }
                }

                CommandCost ret = EnsureNoVehicleOnGround(tile);
                if (ret.Failed()) return ret;

                if (IsNormalRoadTile(tile)) {
                        /* If the road types don't match, try to convert only if vehicles of
                         * the new road type are not powered on the present road type and vehicles of
                         * the present road type are powered on the new road type. */
                        RoadType existing_rt = GetRoadType(tile, rtt);
                        if (existing_rt != INVALID_ROADTYPE && existing_rt != rt) {
                                if (HasPowerOnRoad(rt, existing_rt)) {
                                        rt = existing_rt;
                                } else if (HasPowerOnRoad(existing_rt, rt)) {
                                        CommandCost ret = Command<CMD_CONVERT_ROAD>::Do(flags, tile, tile, rt);
                                        if (ret.Failed()) return ret;
                                        cost.AddCost(ret);
                                } else {
                                        return CMD_ERROR;
                                }
                        }
                }
        }

        uint num_pieces = (!need_to_clear && IsTileType(tile, MP_TUNNELBRIDGE)) ?
                        /* There are 2 pieces on *every* tile of the bridge or tunnel */
                        2 * (GetTunnelBridgeLength(GetOtherTunnelBridgeEnd(tile), tile) + 2) :
                        /* Count pieces */
                        CountBits(pieces);

        cost.AddCost(num_pieces * RoadBuildCost(rt));

        if (flags & DC_EXEC) {
                switch (GetTileType(tile)) {
                        case MP_ROAD: {
                                RoadTileType rttype = GetRoadTileType(tile);
                                if (existing == ROAD_NONE || rttype == ROAD_TILE_CROSSING) {
                                        SetRoadType(tile, rtt, rt);
                                        SetRoadOwner(tile, rtt, company);
                                        if (rtt == RTT_ROAD) SetTownIndex(tile, town_id);
                                }
                                if (rttype != ROAD_TILE_CROSSING) SetRoadBits(tile, existing | pieces, rtt);
                                break;
                        }

                        case MP_TUNNELBRIDGE: {
                                TileIndex other_end = GetOtherTunnelBridgeEnd(tile);

                                SetRoadType(other_end, rtt, rt);
                                SetRoadType(tile, rtt, rt);
                                SetRoadOwner(other_end, rtt, company);
                                SetRoadOwner(tile, rtt, company);

                                /* Mark tiles dirty that have been repaved */
                                if (IsBridge(tile)) {
                                        MarkBridgeDirty(tile);
                                } else {
                                        MarkTileDirtyByTile(other_end);
                                        MarkTileDirtyByTile(tile);
                                }
                                break;
                        }

                        case MP_STATION: {
                                assert(IsDriveThroughStopTile(tile));
                                SetRoadType(tile, rtt, rt);
                                SetRoadOwner(tile, rtt, company);
                                break;
                        }

                        default:
                                MakeRoadNormal(tile, pieces, (rtt == RTT_ROAD) ? rt : INVALID_ROADTYPE, (rtt == RTT_TRAM) ? rt : INVALID_ROADTYPE, town_id, company, company);
                                break;
                }

                /* Update company infrastructure count. */
                if (IsTileType(tile, MP_TUNNELBRIDGE)) num_pieces *= TUNNELBRIDGE_TRACKBIT_FACTOR;
                UpdateCompanyRoadInfrastructure(rt, GetRoadOwner(tile, rtt), num_pieces);

                if (rtt == RTT_ROAD && IsNormalRoadTile(tile)) {
                        existing |= pieces;
                        SetDisallowedRoadDirections(tile, IsStraightRoad(existing) ?
                                        GetDisallowedRoadDirections(tile) ^ toggle_drd : DRD_NONE);
                }

                MarkTileDirtyByTile(tile);
        }
        return cost;
}

/**
 * Checks whether a road or tram connection can be found when building a new road or tram.
 * @param tile Tile at which the road being built will end.
 * @param rt Roadtype of the road being built.
 * @param dir Direction that the road is following.
 * @return True if the next tile at dir direction is suitable for being connected directly by a second roadbit at the end of the road being built.
 */
static bool CanConnectToRoad(TileIndex tile, RoadType rt, DiagDirection dir)
{
        tile += TileOffsByDiagDir(dir);
        if (!IsValidTile(tile) || !MayHaveRoad(tile)) return false;

        RoadTramType rtt = GetRoadTramType(rt);
        RoadType existing = GetRoadType(tile, rtt);
        if (existing == INVALID_ROADTYPE) return false;
        if (!HasPowerOnRoad(existing, rt) && !HasPowerOnRoad(rt, existing)) return false;

        RoadBits bits = GetAnyRoadBits(tile, rtt, false);
        return (bits & DiagDirToRoadBits(ReverseDiagDir(dir))) != 0;
}

/**
 * Build a long piece of road.
 * @param flags operation to perform
 * @param end_tile end tile of drag
 * @param start_tile start tile of drag
 * @param rt road type
 * @param axis direction
 * @param drd set road direction
 * @param start_half start tile starts in the 2nd half of tile (p2 & 1). Only used if \c is_ai is set or if we are building a single tile
 * @param end_half end tile starts in the 2nd half of tile (p2 & 2). Only used if \c is_ai is set or if we are building a single tile
 * @param is_ai defines two different behaviors for this command:
 *      - false = Build up to an obstacle. Do not build the first and last roadbits unless they can be connected to something, or if we are building a single tile
 *      - true = Fail if an obstacle is found. Always take into account start_half and end_half. This behavior is used for scripts
 * @return the cost of this operation or an error
 */
CommandCost CmdBuildLongRoad(DoCommandFlag flags, TileIndex end_tile, TileIndex start_tile, RoadType rt, Axis axis, DisallowedRoadDirections drd, bool start_half, bool end_half, bool is_ai)
{
        if (start_tile >= MapSize()) return CMD_ERROR;

        if (!ValParamRoadType(rt) || !IsValidAxis(axis) || !IsValidDisallowedRoadDirections(drd)) return CMD_ERROR;

        /* Only drag in X or Y direction dictated by the direction variable */
        if (axis == AXIS_X && TileY(start_tile) != TileY(end_tile)) return CMD_ERROR; // x-axis
        if (axis == AXIS_Y && TileX(start_tile) != TileX(end_tile)) return CMD_ERROR; // y-axis

        DiagDirection dir = AxisToDiagDir(axis);

        /* Swap direction, also the half-tile drag vars. */
        if (start_tile > end_tile || (start_tile == end_tile && start_half)) {
                dir = ReverseDiagDir(dir);
                start_half = !start_half;
                end_half = !end_half;
                if (drd == DRD_NORTHBOUND || drd == DRD_SOUTHBOUND) drd ^= DRD_BOTH;
        }

        /* On the X-axis, we have to swap the initial bits, so they
         * will be interpreted correctly in the GTTS. Furthermore
         * when you just 'click' on one tile to build them. */
        if ((drd == DRD_NORTHBOUND || drd == DRD_SOUTHBOUND) && (axis == AXIS_Y) == (start_tile == end_tile && start_half == end_half)) drd ^= DRD_BOTH;

        CommandCost cost(EXPENSES_CONSTRUCTION);
        CommandCost last_error = CMD_ERROR;
        TileIndex tile = start_tile;
        bool had_bridge = false;
        bool had_tunnel = false;
        bool had_success = false;

        /* Start tile is the first tile clicked by the user. */
        for (;;) {
                RoadBits bits = AxisToRoadBits(axis);

                /* Determine which road parts should be built. */
                if (!is_ai && start_tile != end_tile) {
                        /* Only build the first and last roadbit if they can connect to something. */
                        if (tile == end_tile && !CanConnectToRoad(tile, rt, dir)) {
                                bits = DiagDirToRoadBits(ReverseDiagDir(dir));
                        } else if (tile == start_tile && !CanConnectToRoad(tile, rt, ReverseDiagDir(dir))) {
                                bits = DiagDirToRoadBits(dir);
                        }
                } else {
                        /* Road parts only have to be built at the start tile or at the end tile. */
                        if (tile == end_tile && !end_half) bits &= DiagDirToRoadBits(ReverseDiagDir(dir));
                        if (tile == start_tile && start_half) bits &= DiagDirToRoadBits(dir);
                }

                CommandCost ret = Command<CMD_BUILD_ROAD>::Do(flags, tile, bits, rt, drd, 0);
                if (ret.Failed()) {
                        last_error = ret;
                        if (last_error.GetErrorMessage() != STR_ERROR_ALREADY_BUILT) {
                                if (is_ai) return last_error;
                                break;
                        }
                } else {
                        had_success = true;
                        /* Only pay for the upgrade on one side of the bridges and tunnels */
                        if (IsTileType(tile, MP_TUNNELBRIDGE)) {
                                if (IsBridge(tile)) {
                                        if (!had_bridge || GetTunnelBridgeDirection(tile) == dir) {
                                                cost.AddCost(ret);
                                        }
                                        had_bridge = true;
                                } else { // IsTunnel(tile)
                                        if (!had_tunnel || GetTunnelBridgeDirection(tile) == dir) {
                                                cost.AddCost(ret);
                                        }
                                        had_tunnel = true;
                                }
                        } else {
                                cost.AddCost(ret);
                        }
                }

                if (tile == end_tile) break;

                tile += TileOffsByDiagDir(dir);
        }

        return had_success ? cost : last_error;
}

/**
 * Remove a long piece of road.
 * @param flags operation to perform
 * @param end_tile end tile of drag
 * @param start_tile start tile of drag
 * @param rt road type
 * @param axis direction
 * @param start_half start tile starts in the 2nd half of tile
 * @param end_half end tile starts in the 2nd half of tile (p2 & 2)
 * @return the cost of this operation or an error
 */
std::tuple<CommandCost, Money> CmdRemoveLongRoad(DoCommandFlag flags, TileIndex end_tile, TileIndex start_tile, RoadType rt, Axis axis, bool start_half, bool end_half)
{
        CommandCost cost(EXPENSES_CONSTRUCTION);

        if (start_tile >= MapSize()) return { CMD_ERROR, 0 };
        if (!ValParamRoadType(rt) || !IsValidAxis(axis)) return { CMD_ERROR, 0 };

        /* Only drag in X or Y direction dictated by the direction variable */
        if (axis == AXIS_X && TileY(start_tile) != TileY(end_tile)) return { CMD_ERROR, 0 }; // x-axis
        if (axis == AXIS_Y && TileX(start_tile) != TileX(end_tile)) return { CMD_ERROR, 0 }; // y-axis

        /* Swap start and ending tile, also the half-tile drag vars. */
        if (start_tile > end_tile || (start_tile == end_tile && start_half)) {
                std::swap(start_tile, end_tile);
                std::swap(start_half, end_half);
        }

        Money money_available = GetAvailableMoneyForCommand();
        Money money_spent = 0;
        TileIndex tile = start_tile;
        CommandCost last_error = CMD_ERROR;
        bool had_success = false;
        /* Start tile is the small number. */
        for (;;) {
                RoadBits bits = AxisToRoadBits(axis);

                if (tile == end_tile && !end_half) bits &= ROAD_NW | ROAD_NE;
                if (tile == start_tile && start_half) bits &= ROAD_SE | ROAD_SW;

                /* try to remove the halves. */
                if (bits != 0) {
                        RoadTramType rtt = GetRoadTramType(rt);
                        CommandCost ret = RemoveRoad(tile, flags & ~DC_EXEC, bits, rtt, true);
                        if (ret.Succeeded()) {
                                if (flags & DC_EXEC) {
                                        money_spent += ret.GetCost();
                                        if (money_spent > 0 && money_spent > money_available) {
                                                return { cost, std::get<0>(Command<CMD_REMOVE_LONG_ROAD>::Do(flags & ~DC_EXEC, end_tile, start_tile, rt, axis, start_half, end_half)).GetCost() };
                                        }
                                        RemoveRoad(tile, flags, bits, rtt, true, false);
                                }
                                cost.AddCost(ret);
                                had_success = true;
                        } else {
                                /* Some errors are more equal than others. */
                                switch (last_error.GetErrorMessage()) {
                                        case STR_ERROR_OWNED_BY:
                                        case STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS:
                                                break;
                                        default:
                                                last_error = ret;
                                }
                        }
                }

                if (tile == end_tile) break;

                tile += (axis == AXIS_Y) ? TileDiffXY(0, 1) : TileDiffXY(1, 0);
        }

        return { had_success ? cost : last_error, 0 };
}

/**
 * Build a road depot.
 * @param tile tile where to build the depot
 * @param flags operation to perform
 * @param rt road type
 * @param dir entrance direction
 * @return the cost of this operation or an error
 *
 * @todo When checking for the tile slope,
 * distinguish between "Flat land required" and "land sloped in wrong direction"
 */
CommandCost CmdBuildRoadDepot(DoCommandFlag flags, TileIndex tile, RoadType rt, DiagDirection dir)
{
        if (!ValParamRoadType(rt) || !IsValidDiagDirection(dir)) return CMD_ERROR;

        CommandCost cost(EXPENSES_CONSTRUCTION);

        Slope tileh = GetTileSlope(tile);
        if (tileh != SLOPE_FLAT) {
                if (!_settings_game.construction.build_on_slopes || !CanBuildDepotByTileh(dir, tileh)) {
                        return_cmd_error(STR_ERROR_FLAT_LAND_REQUIRED);
                }
                cost.AddCost(_price[PR_BUILD_FOUNDATION]);
        }

        cost.AddCost(Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile));
        if (cost.Failed()) return cost;

        if (IsBridgeAbove(tile)) return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);

        if (!Depot::CanAllocateItem()) return CMD_ERROR;

        if (flags & DC_EXEC) {
                Depot *dep = new Depot(tile);
                dep->build_date = _date;

                /* A road depot has two road bits. */
                UpdateCompanyRoadInfrastructure(rt, _current_company, ROAD_DEPOT_TRACKBIT_FACTOR);

                MakeRoadDepot(tile, _current_company, dep->index, dir, rt);
                MarkTileDirtyByTile(tile);
                MakeDefaultName(dep);
        }
        cost.AddCost(_price[PR_BUILD_DEPOT_ROAD]);
        return cost;
}

static CommandCost RemoveRoadDepot(TileIndex tile, DoCommandFlag flags)
{
        if (_current_company != OWNER_WATER) {
                CommandCost ret = CheckTileOwnership(tile);
                if (ret.Failed()) return ret;
        }

        CommandCost ret = EnsureNoVehicleOnGround(tile);
        if (ret.Failed()) return ret;

        if (flags & DC_EXEC) {
                Company *c = Company::GetIfValid(GetTileOwner(tile));
                if (c != nullptr) {
                        /* A road depot has two road bits. */
                        RoadType rt = GetRoadTypeRoad(tile);
                        if (rt == INVALID_ROADTYPE) rt = GetRoadTypeTram(tile);
                        c->infrastructure.road[rt] -= ROAD_DEPOT_TRACKBIT_FACTOR;
                        DirtyCompanyInfrastructureWindows(c->index);
                }

                delete Depot::GetByTile(tile);
                DoClearSquare(tile);
        }

        return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_CLEAR_DEPOT_ROAD]);
}

static CommandCost ClearTile_Road(TileIndex tile, DoCommandFlag flags)
{
        switch (GetRoadTileType(tile)) {
                case ROAD_TILE_NORMAL: {
                        RoadBits b = GetAllRoadBits(tile);

                        /* Clear the road if only one piece is on the tile OR we are not using the DC_AUTO flag */
                        if ((HasExactlyOneBit(b) && GetRoadBits(tile, RTT_TRAM) == ROAD_NONE) || !(flags & DC_AUTO)) {
                                CommandCost ret(EXPENSES_CONSTRUCTION);
                                for (RoadTramType rtt : _roadtramtypes) {
                                        if (!MayHaveRoad(tile) || GetRoadType(tile, rtt) == INVALID_ROADTYPE) continue;

                                        CommandCost tmp_ret = RemoveRoad(tile, flags, GetRoadBits(tile, rtt), rtt, true);
                                        if (tmp_ret.Failed()) return tmp_ret;
                                        ret.AddCost(tmp_ret);
                                }
                                return ret;
                        }
                        return_cmd_error(STR_ERROR_MUST_REMOVE_ROAD_FIRST);
                }

                case ROAD_TILE_CROSSING: {
                        CommandCost ret(EXPENSES_CONSTRUCTION);

                        if (flags & DC_AUTO) return_cmd_error(STR_ERROR_MUST_REMOVE_ROAD_FIRST);

                        /* Must iterate over the roadtypes in a reverse manner because
                         * tram tracks must be removed before the road bits. */
                        for (RoadTramType rtt : { RTT_TRAM, RTT_ROAD }) {
                                if (!MayHaveRoad(tile) || GetRoadType(tile, rtt) == INVALID_ROADTYPE) continue;

                                CommandCost tmp_ret = RemoveRoad(tile, flags, GetCrossingRoadBits(tile), rtt, false);
                                if (tmp_ret.Failed()) return tmp_ret;
                                ret.AddCost(tmp_ret);
                        }

                        if (flags & DC_EXEC) {
                                Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile);
                        }
                        return ret;
                }

                default:
                case ROAD_TILE_DEPOT:
                        if (flags & DC_AUTO) {
                                return_cmd_error(STR_ERROR_BUILDING_MUST_BE_DEMOLISHED);
                        }
                        return RemoveRoadDepot(tile, flags);
        }
}


struct DrawRoadTileStruct {
        uint16 image;
        byte subcoord_x;
        byte subcoord_y;
};

#include "table/road_land.h"

/**
 * Get the foundationtype of a RoadBits Slope combination
 *
 * @param tileh The Slope part
 * @param bits The RoadBits part
 * @return The resulting Foundation
 */
static Foundation GetRoadFoundation(Slope tileh, RoadBits bits)
{
        /* Flat land and land without a road doesn't require a foundation */
        if (tileh == SLOPE_FLAT || bits == ROAD_NONE) return FOUNDATION_NONE;

        /* Steep slopes behave the same as slopes with one corner raised. */
        if (IsSteepSlope(tileh)) {
                tileh = SlopeWithOneCornerRaised(GetHighestSlopeCorner(tileh));
        }

        /* Leveled RoadBits on a slope */
        if ((_invalid_tileh_slopes_road[0][tileh] & bits) == ROAD_NONE) return FOUNDATION_LEVELED;

        /* Straight roads without foundation on a slope */
        if (!IsSlopeWithOneCornerRaised(tileh) &&
                        (_invalid_tileh_slopes_road[1][tileh] & bits) == ROAD_NONE)
                return FOUNDATION_NONE;

        /* Roads on steep Slopes or on Slopes with one corner raised */
        return (bits == ROAD_X ? FOUNDATION_INCLINED_X : FOUNDATION_INCLINED_Y);
}

const byte _road_sloped_sprites[14] = {
        0,  0,  2,  0,
        0,  1,  0,  0,
        3,  0,  0,  0,
        0,  0
};

/**
 * Get the sprite offset within a spritegroup.
 * @param slope Slope
 * @param bits Roadbits
 * @return Offset for the sprite within the spritegroup.
 */
static uint GetRoadSpriteOffset(Slope slope, RoadBits bits)
{
        if (slope != SLOPE_FLAT) {
                switch (slope) {
                        case SLOPE_NE: return 11;
                        case SLOPE_SE: return 12;
                        case SLOPE_SW: return 13;
                        case SLOPE_NW: return 14;
                        default: NOT_REACHED();
                }
        } else {
                static const uint offsets[] = {
                        0, 18, 17, 7,
                        16, 0, 10, 5,
                        15, 8, 1, 4,
                        9, 3, 6, 2
                };
                return offsets[bits];
        }
}

/**
 * Should the road be drawn as a unpaved snow/desert road?
 * By default, roads are always drawn as unpaved if they are on desert or
 * above the snow line, but NewGRFs can override this for desert.
 *
 * @param tile The tile the road is on
 * @param roadside What sort of road this is
 * @return True if snow/desert road sprites should be used.
 */
static bool DrawRoadAsSnowDesert(TileIndex tile, Roadside roadside)
{
        return (IsOnSnow(tile) &&
                        !(_settings_game.game_creation.landscape == LT_TROPIC && HasGrfMiscBit(GMB_DESERT_PAVED_ROADS) &&
                                roadside != ROADSIDE_BARREN && roadside != ROADSIDE_GRASS && roadside != ROADSIDE_GRASS_ROAD_WORKS));
}

/**
 * Draws the catenary for the RoadType of the given tile
 * @param ti information about the tile (slopes, height etc)
 * @param rt road type to draw catenary for
 * @param rb the roadbits for the tram
 */
void DrawRoadTypeCatenary(const TileInfo *ti, RoadType rt, RoadBits rb)
{
        /* Don't draw the catenary under a low bridge */
        if (IsBridgeAbove(ti->tile) && !IsTransparencySet(TO_CATENARY)) {
                int height = GetBridgeHeight(GetNorthernBridgeEnd(ti->tile));

                if (height <= GetTileMaxZ(ti->tile) + 1) return;
        }

        if (CountBits(rb) > 2) {
                /* On junctions we check whether neighbouring tiles also have catenary, and possibly
                 * do not draw catenary towards those neighbours, which do not have catenary. */
                RoadBits rb_new = ROAD_NONE;
                for (DiagDirection dir = DIAGDIR_BEGIN; dir < DIAGDIR_END; dir++) {
                        if (rb & DiagDirToRoadBits(dir)) {
                                TileIndex neighbour = TileAddByDiagDir(ti->tile, dir);
                                if (MayHaveRoad(neighbour)) {
                                        RoadType rt_road = GetRoadTypeRoad(neighbour);
                                        RoadType rt_tram = GetRoadTypeTram(neighbour);

                                        if ((rt_road != INVALID_ROADTYPE && HasRoadCatenary(rt_road)) ||
                                                        (rt_tram != INVALID_ROADTYPE && HasRoadCatenary(rt_tram))) {
                                                rb_new |= DiagDirToRoadBits(dir);
                                        }
                                }
                        }
                }
                if (CountBits(rb_new) >= 2) rb = rb_new;
        }

        const RoadTypeInfo* rti = GetRoadTypeInfo(rt);
        SpriteID front = GetCustomRoadSprite(rti, ti->tile, ROTSG_CATENARY_FRONT);
        SpriteID back = GetCustomRoadSprite(rti, ti->tile, ROTSG_CATENARY_BACK);

        if (front != 0 || back != 0) {
                if (front != 0) front += GetRoadSpriteOffset(ti->tileh, rb);
                if (back != 0) back += GetRoadSpriteOffset(ti->tileh, rb);
        } else if (ti->tileh != SLOPE_FLAT) {
                back  = SPR_TRAMWAY_BACK_WIRES_SLOPED  + _road_sloped_sprites[ti->tileh - 1];
                front = SPR_TRAMWAY_FRONT_WIRES_SLOPED + _road_sloped_sprites[ti->tileh - 1];
        } else {
                back  = SPR_TRAMWAY_BASE + _road_backpole_sprites_1[rb];
                front = SPR_TRAMWAY_BASE + _road_frontwire_sprites_1[rb];
        }

        /* Catenary uses 1st company colour to help identify owner.
         * For tiles with OWNER_TOWN or OWNER_NONE, recolour CC to grey as a neutral colour. */
        Owner owner = GetRoadOwner(ti->tile, GetRoadTramType(rt));
        PaletteID pal = (owner == OWNER_NONE || owner == OWNER_TOWN ? GENERAL_SPRITE_COLOUR(COLOUR_GREY) : COMPANY_SPRITE_COLOUR(owner));
        int z_wires = (ti->tileh == SLOPE_FLAT ? 0 : TILE_HEIGHT) + BB_HEIGHT_UNDER_BRIDGE;
        if (back != 0) {
                /* The "back" sprite contains the west, north and east pillars.
                 * We cut the sprite at 3/8 of the west/east edges to create 3 sprites.
                 * 3/8 is chosen so that sprites can somewhat graphically extend into the tile. */
                static const int INF = 1000; ///< big number compared to sprite size
                static const SubSprite west  = { -INF, -INF, -12, INF };
                static const SubSprite north = {  -12, -INF,  12, INF };
                static const SubSprite east  = {   12, -INF, INF, INF };
                AddSortableSpriteToDraw(back, pal, ti->x, ti->y, 16,  1, z_wires, ti->z, IsTransparencySet(TO_CATENARY), 15,  0, GetSlopePixelZInCorner(ti->tileh, CORNER_W), &west);
                AddSortableSpriteToDraw(back, pal, ti->x, ti->y,  1,  1, z_wires, ti->z, IsTransparencySet(TO_CATENARY),  0,  0, GetSlopePixelZInCorner(ti->tileh, CORNER_N), &north);
                AddSortableSpriteToDraw(back, pal, ti->x, ti->y,  1, 16, z_wires, ti->z, IsTransparencySet(TO_CATENARY),  0, 15, GetSlopePixelZInCorner(ti->tileh, CORNER_E), &east);
        }
        if (front != 0) {
                /* Draw the "front" sprite (containing south pillar and wires) at a Z height that is both above the vehicles and above the "back" pillars. */
                AddSortableSpriteToDraw(front, pal, ti->x, ti->y, 16, 16, z_wires + 1, ti->z, IsTransparencySet(TO_CATENARY), 0, 0, z_wires);
        }
}

/**
 * Draws the catenary for the given tile
 * @param ti information about the tile (slopes, height etc)
 */
void DrawRoadCatenary(const TileInfo *ti)
{
        RoadBits road = ROAD_NONE;
        RoadBits tram = ROAD_NONE;

        if (IsTileType(ti->tile, MP_ROAD)) {
                if (IsNormalRoad(ti->tile)) {
                        road = GetRoadBits(ti->tile, RTT_ROAD);
                        tram = GetRoadBits(ti->tile, RTT_TRAM);
                } else if (IsLevelCrossing(ti->tile)) {
                        tram = road = (GetCrossingRailAxis(ti->tile) == AXIS_Y ? ROAD_X : ROAD_Y);
                }
        } else if (IsTileType(ti->tile, MP_STATION)) {
                if (IsRoadStop(ti->tile)) {
                        if (IsDriveThroughStopTile(ti->tile)) {
                                Axis axis = GetRoadStopDir(ti->tile) == DIAGDIR_NE ? AXIS_X : AXIS_Y;
                                tram = road = (axis == AXIS_X ? ROAD_X : ROAD_Y);
                        } else {
                                tram = road = DiagDirToRoadBits(GetRoadStopDir(ti->tile));
                        }
                }
        } else {
                // No road here, no catenary to draw
                return;
        }

        RoadType rt = GetRoadTypeRoad(ti->tile);
        if (rt != INVALID_ROADTYPE && HasRoadCatenaryDrawn(rt)) {
                DrawRoadTypeCatenary(ti, rt, road);
        }

        rt = GetRoadTypeTram(ti->tile);
        if (rt != INVALID_ROADTYPE && HasRoadCatenaryDrawn(rt)) {
                DrawRoadTypeCatenary(ti, rt, tram);
        }
}

/**
 * Draws details on/around the road
 * @param img the sprite to draw
 * @param ti  the tile to draw on
 * @param dx  the offset from the top of the BB of the tile
 * @param dy  the offset from the top of the BB of the tile
 * @param h   the height of the sprite to draw
 * @param transparent  whether the sprite should be transparent (used for roadside trees)
 */
static void DrawRoadDetail(SpriteID img, const TileInfo *ti, int dx, int dy, int h, bool transparent)
{
        int x = ti->x | dx;
        int y = ti->y | dy;
        int z = ti->z;
        if (ti->tileh != SLOPE_FLAT) z = GetSlopePixelZ(x, y);
        AddSortableSpriteToDraw(img, PAL_NONE, x, y, 2, 2, h, z, transparent);
}

/**
 * Draw road underlay and overlay sprites.
 * @param ti TileInfo
 * @param road_rti Road road type information
 * @param tram_rti Tram road type information
 * @param road_offset Road sprite offset (based on road bits)
 * @param tram_offset Tram sprite offset (based on road bits)
 */
void DrawRoadOverlays(const TileInfo *ti, PaletteID pal, const RoadTypeInfo *road_rti, const RoadTypeInfo *tram_rti, uint road_offset, uint tram_offset)
{
        /* Road underlay takes precedence over tram */
        if (road_rti != nullptr) {
                if (road_rti->UsesOverlay()) {
                        SpriteID ground = GetCustomRoadSprite(road_rti, ti->tile, ROTSG_GROUND);
                        DrawGroundSprite(ground + road_offset, pal);
                }
        } else {
                if (tram_rti->UsesOverlay()) {
                        SpriteID ground = GetCustomRoadSprite(tram_rti, ti->tile, ROTSG_GROUND);
                        DrawGroundSprite(ground + tram_offset, pal);
                } else {
                        DrawGroundSprite(SPR_TRAMWAY_TRAM + tram_offset, pal);
                }
        }

        /* Draw road overlay */
        if (road_rti != nullptr) {
                if (road_rti->UsesOverlay()) {
                        SpriteID ground = GetCustomRoadSprite(road_rti, ti->tile, ROTSG_OVERLAY);
                        if (ground != 0) DrawGroundSprite(ground + road_offset, pal);
                }
        }

        /* Draw tram overlay */
        if (tram_rti != nullptr) {
                if (tram_rti->UsesOverlay()) {
                        SpriteID ground = GetCustomRoadSprite(tram_rti, ti->tile, ROTSG_OVERLAY);
                        if (ground != 0) DrawGroundSprite(ground + tram_offset, pal);
                } else if (road_rti != nullptr) {
                        DrawGroundSprite(SPR_TRAMWAY_OVERLAY + tram_offset, pal);
                }
        }
}

/**
 * Get ground sprite to draw for a road tile.
 * @param ti TileInof
 * @param roadside Road side type
 * @param rti Road type info
 * @param offset Road sprite offset
 * @param[out] pal Palette to draw.
 */
static SpriteID GetRoadGroundSprite(const TileInfo *ti, Roadside roadside, const RoadTypeInfo *rti, uint offset, PaletteID *pal)
{
        /* Draw bare ground sprite if no road or road uses overlay system. */
        if (rti == nullptr || rti->UsesOverlay()) {
                if (DrawRoadAsSnowDesert(ti->tile, roadside)) {
                        return SPR_FLAT_SNOW_DESERT_TILE + SlopeToSpriteOffset(ti->tileh);
                }

                switch (roadside) {
                        case ROADSIDE_BARREN:           *pal = PALETTE_TO_BARE_LAND;
                                                        return SPR_FLAT_GRASS_TILE + SlopeToSpriteOffset(ti->tileh);
                        case ROADSIDE_GRASS:
                        case ROADSIDE_GRASS_ROAD_WORKS: return SPR_FLAT_GRASS_TILE + SlopeToSpriteOffset(ti->tileh);
                        default:                        break; // Paved
                }
        }

        /* Draw original road base sprite */
        SpriteID image = SPR_ROAD_Y + offset;
        if (DrawRoadAsSnowDesert(ti->tile, roadside)) {
                image += 19;
        } else {
                switch (roadside) {
                        case ROADSIDE_BARREN:           *pal = PALETTE_TO_BARE_LAND; break;
                        case ROADSIDE_GRASS:            break;
                        case ROADSIDE_GRASS_ROAD_WORKS: break;
                        default:                        image -= 19; break; // Paved
                }
        }

        return image;
}

/**
 * Draw ground sprite and road pieces
 * @param ti TileInfo
 */
static void DrawRoadBits(TileInfo *ti)
{
        RoadBits road = GetRoadBits(ti->tile, RTT_ROAD);
        RoadBits tram = GetRoadBits(ti->tile, RTT_TRAM);

        RoadType road_rt = GetRoadTypeRoad(ti->tile);
        RoadType tram_rt = GetRoadTypeTram(ti->tile);
        const RoadTypeInfo *road_rti = road_rt == INVALID_ROADTYPE ? nullptr : GetRoadTypeInfo(road_rt);
        const RoadTypeInfo *tram_rti = tram_rt == INVALID_ROADTYPE ? nullptr : GetRoadTypeInfo(tram_rt);

        if (ti->tileh != SLOPE_FLAT) {
                DrawFoundation(ti, GetRoadFoundation(ti->tileh, road | tram));
                /* DrawFoundation() modifies ti. */
        }

        /* Determine sprite offsets */
        uint road_offset = GetRoadSpriteOffset(ti->tileh, road);
        uint tram_offset = GetRoadSpriteOffset(ti->tileh, tram);

        /* Draw baseset underlay */
        Roadside roadside = GetRoadside(ti->tile);

        PaletteID pal = PAL_NONE;
        SpriteID image = GetRoadGroundSprite(ti, roadside, road_rti, road == ROAD_NONE ? tram_offset : road_offset, &pal);
        DrawGroundSprite(image, pal);

        DrawRoadOverlays(ti, pal, road_rti, tram_rti, road_offset, tram_offset);

        /* Draw one way */
        if (road_rti != nullptr) {
                DisallowedRoadDirections drd = GetDisallowedRoadDirections(ti->tile);
                if (drd != DRD_NONE) {
                        DrawGroundSpriteAt(SPR_ONEWAY_BASE + drd - 1 + ((road == ROAD_X) ? 0 : 3), PAL_NONE, 8, 8, GetPartialPixelZ(8, 8, ti->tileh));
                }
        }

        if (HasRoadWorks(ti->tile)) {
                /* Road works */
                DrawGroundSprite((road | tram) & ROAD_X ? SPR_EXCAVATION_X : SPR_EXCAVATION_Y, PAL_NONE);
                return;
        }

        /* Draw road, tram catenary */
        DrawRoadCatenary(ti);

        /* Return if full detail is disabled, or we are zoomed fully out. */
        if (!HasBit(_display_opt, DO_FULL_DETAIL) || _cur_dpi->zoom > ZOOM_LVL_DETAIL) return;

        /* Do not draw details (street lights, trees) under low bridge */
        if (IsBridgeAbove(ti->tile) && (roadside == ROADSIDE_TREES || roadside == ROADSIDE_STREET_LIGHTS)) {
                int height = GetBridgeHeight(GetNorthernBridgeEnd(ti->tile));
                int minz = GetTileMaxZ(ti->tile) + 2;

                if (roadside == ROADSIDE_TREES) minz++;

                if (height < minz) return;
        }

        /* If there are no road bits, return, as there is nothing left to do */
        if (HasAtMostOneBit(road)) return;

        if (roadside == ROADSIDE_TREES && IsInvisibilitySet(TO_TREES)) return;
        bool is_transparent = roadside == ROADSIDE_TREES && IsTransparencySet(TO_TREES);

        /* Draw extra details. */
        for (const DrawRoadTileStruct *drts = _road_display_table[roadside][road | tram]; drts->image != 0; drts++) {
                DrawRoadDetail(drts->image, ti, drts->subcoord_x, drts->subcoord_y, 0x10, is_transparent);
        }
}

/** Tile callback function for rendering a road tile to the screen */
static void DrawTile_Road(TileInfo *ti)
{
        switch (GetRoadTileType(ti->tile)) {
                case ROAD_TILE_NORMAL:
                        DrawRoadBits(ti);
                        break;

                case ROAD_TILE_CROSSING: {
                        if (ti->tileh != SLOPE_FLAT) DrawFoundation(ti, FOUNDATION_LEVELED);

                        Axis axis = GetCrossingRailAxis(ti->tile);

                        const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(ti->tile));

                        RoadType road_rt = GetRoadTypeRoad(ti->tile);
                        RoadType tram_rt = GetRoadTypeTram(ti->tile);
                        const RoadTypeInfo *road_rti = road_rt == INVALID_ROADTYPE ? nullptr : GetRoadTypeInfo(road_rt);
                        const RoadTypeInfo *tram_rti = tram_rt == INVALID_ROADTYPE ? nullptr : GetRoadTypeInfo(tram_rt);

                        PaletteID pal = PAL_NONE;

                        /* Draw base ground */
                        if (rti->UsesOverlay()) {
                                SpriteID image = SPR_ROAD_Y + axis;

                                Roadside roadside = GetRoadside(ti->tile);
                                if (DrawRoadAsSnowDesert(ti->tile, roadside)) {
                                        image += 19;
                                } else {
                                        switch (roadside) {
                                                case ROADSIDE_BARREN: pal = PALETTE_TO_BARE_LAND; break;
                                                case ROADSIDE_GRASS:  break;
                                                default:              image -= 19; break; // Paved
                                        }
                                }

                                DrawGroundSprite(image, pal);
                        } else {
                                SpriteID image = rti->base_sprites.crossing + axis;
                                if (IsCrossingBarred(ti->tile)) image += 2;

                                Roadside roadside = GetRoadside(ti->tile);
                                if (DrawRoadAsSnowDesert(ti->tile, roadside)) {
                                        image += 8;
                                } else {
                                        switch (roadside) {
                                                case ROADSIDE_BARREN: pal = PALETTE_TO_BARE_LAND; break;
                                                case ROADSIDE_GRASS:  break;
                                                default:              image += 4; break; // Paved
                                        }
                                }

                                DrawGroundSprite(image, pal);
                        }

                        DrawRoadOverlays(ti, pal, road_rti, tram_rti, axis, axis);

                        /* Draw rail/PBS overlay */
                        bool draw_pbs = _game_mode != GM_MENU && _settings_client.gui.show_track_reservation && HasCrossingReservation(ti->tile);
                        if (rti->UsesOverlay()) {
                                PaletteID pal = draw_pbs ? PALETTE_CRASH : PAL_NONE;
                                SpriteID rail = GetCustomRailSprite(rti, ti->tile, RTSG_CROSSING) + axis;
                                DrawGroundSprite(rail, pal);

                                DrawRailTileSeq(ti, &_crossing_layout, TO_CATENARY, rail, 0, PAL_NONE);
                        } else if (draw_pbs || tram_rti != nullptr || road_rti->UsesOverlay()) {
                                /* Add another rail overlay, unless there is only the base road sprite. */
                                PaletteID pal = draw_pbs ? PALETTE_CRASH : PAL_NONE;
                                SpriteID rail = GetCrossingRoadAxis(ti->tile) == AXIS_Y ? GetRailTypeInfo(GetRailType(ti->tile))->base_sprites.single_x : GetRailTypeInfo(GetRailType(ti->tile))->base_sprites.single_y;
                                DrawGroundSprite(rail, pal);
                        }

                        /* Draw road, tram catenary */
                        DrawRoadCatenary(ti);

                        /* Draw rail catenary */
                        if (HasRailCatenaryDrawn(GetRailType(ti->tile))) DrawRailCatenary(ti);

                        break;
                }

                default:
                case ROAD_TILE_DEPOT: {
                        if (ti->tileh != SLOPE_FLAT) DrawFoundation(ti, FOUNDATION_LEVELED);

                        PaletteID palette = COMPANY_SPRITE_COLOUR(GetTileOwner(ti->tile));

                        RoadType road_rt = GetRoadTypeRoad(ti->tile);
                        RoadType tram_rt = GetRoadTypeTram(ti->tile);
                        const RoadTypeInfo *rti = GetRoadTypeInfo(road_rt == INVALID_ROADTYPE ? tram_rt : road_rt);

                        int relocation = GetCustomRoadSprite(rti, ti->tile, ROTSG_DEPOT);
                        bool default_gfx = relocation == 0;
                        if (default_gfx) {
                                if (HasBit(rti->flags, ROTF_CATENARY)) {
                                        if (_loaded_newgrf_features.tram == TRAMWAY_REPLACE_DEPOT_WITH_TRACK && road_rt == INVALID_ROADTYPE && !rti->UsesOverlay()) {
                                                /* Sprites with track only work for default tram */
                                                relocation = SPR_TRAMWAY_DEPOT_WITH_TRACK - SPR_ROAD_DEPOT;
                                                default_gfx = false;
                                        } else {
                                                /* Sprites without track are always better, if provided */
                                                relocation = SPR_TRAMWAY_DEPOT_NO_TRACK - SPR_ROAD_DEPOT;
                                        }
                                }
                        } else {
                                relocation -= SPR_ROAD_DEPOT;
                        }

                        DiagDirection dir = GetRoadDepotDirection(ti->tile);
                        const DrawTileSprites *dts = &_road_depot[dir];
                        DrawGroundSprite(dts->ground.sprite, PAL_NONE);

                        if (default_gfx) {
                                uint offset = GetRoadSpriteOffset(SLOPE_FLAT, DiagDirToRoadBits(dir));
                                if (rti->UsesOverlay()) {
                                        SpriteID ground = GetCustomRoadSprite(rti, ti->tile, ROTSG_OVERLAY);
                                        if (ground != 0) DrawGroundSprite(ground + offset, PAL_NONE);
                                } else if (road_rt == INVALID_ROADTYPE) {
                                        DrawGroundSprite(SPR_TRAMWAY_OVERLAY + offset, PAL_NONE);
                                }
                        }

                        DrawRailTileSeq(ti, dts, TO_BUILDINGS, relocation, 0, palette);
                        break;
                }
        }
        DrawBridgeMiddle(ti);
}

/**
 * Draw the road depot sprite.
 * @param x   The x offset to draw at.
 * @param y   The y offset to draw at.
 * @param dir The direction the depot must be facing.
 * @param rt  The road type of the depot to draw.
 */
void DrawRoadDepotSprite(int x, int y, DiagDirection dir, RoadType rt)
{
        PaletteID palette = COMPANY_SPRITE_COLOUR(_local_company);

        const RoadTypeInfo* rti = GetRoadTypeInfo(rt);
        int relocation = GetCustomRoadSprite(rti, INVALID_TILE, ROTSG_DEPOT);
        bool default_gfx = relocation == 0;
        if (default_gfx) {
                if (HasBit(rti->flags, ROTF_CATENARY)) {
                        if (_loaded_newgrf_features.tram == TRAMWAY_REPLACE_DEPOT_WITH_TRACK && RoadTypeIsTram(rt) && !rti->UsesOverlay()) {
                                /* Sprites with track only work for default tram */
                                relocation = SPR_TRAMWAY_DEPOT_WITH_TRACK - SPR_ROAD_DEPOT;
                                default_gfx = false;
                        } else {
                                /* Sprites without track are always better, if provided */
                                relocation = SPR_TRAMWAY_DEPOT_NO_TRACK - SPR_ROAD_DEPOT;
                        }
                }
        } else {
                relocation -= SPR_ROAD_DEPOT;
        }

        const DrawTileSprites *dts = &_road_depot[dir];
        DrawSprite(dts->ground.sprite, PAL_NONE, x, y);

        if (default_gfx) {
                uint offset = GetRoadSpriteOffset(SLOPE_FLAT, DiagDirToRoadBits(dir));
                if (rti->UsesOverlay()) {
                        SpriteID ground = GetCustomRoadSprite(rti, INVALID_TILE, ROTSG_OVERLAY);
                        if (ground != 0) DrawSprite(ground + offset, PAL_NONE, x, y);
                } else if (RoadTypeIsTram(rt)) {
                        DrawSprite(SPR_TRAMWAY_OVERLAY + offset, PAL_NONE, x, y);
                }
        }

        DrawRailTileSeqInGUI(x, y, dts, relocation, 0, palette);
}

/**
 * Updates cached nearest town for all road tiles
 * @param invalidate are we just invalidating cached data?
 * @pre invalidate == true implies _generating_world == true
 */
void UpdateNearestTownForRoadTiles(bool invalidate)
{
        assert(!invalidate || _generating_world);

        for (TileIndex t = 0; t < MapSize(); t++) {
                if (IsTileType(t, MP_ROAD) && !IsRoadDepot(t) && !HasTownOwnedRoad(t)) {
                        TownID tid = INVALID_TOWN;
                        if (!invalidate) {
                                const Town *town = CalcClosestTownFromTile(t);
                                if (town != nullptr) tid = town->index;
                        }
                        SetTownIndex(t, tid);
                }
        }
}

static int GetSlopePixelZ_Road(TileIndex tile, uint x, uint y)
{

        if (IsNormalRoad(tile)) {
                int z;
                Slope tileh = GetTilePixelSlope(tile, &z);
                if (tileh == SLOPE_FLAT) return z;

                Foundation f = GetRoadFoundation(tileh, GetAllRoadBits(tile));
                z += ApplyPixelFoundationToSlope(f, &tileh);
                return z + GetPartialPixelZ(x & 0xF, y & 0xF, tileh);
        } else {
                return GetTileMaxPixelZ(tile);
        }
}

static Foundation GetFoundation_Road(TileIndex tile, Slope tileh)
{
        if (IsNormalRoad(tile)) {
                return GetRoadFoundation(tileh, GetAllRoadBits(tile));
        } else {
                return FlatteningFoundation(tileh);
        }
}

static const Roadside _town_road_types[][2] = {
        { ROADSIDE_GRASS,         ROADSIDE_GRASS },
        { ROADSIDE_PAVED,         ROADSIDE_PAVED },
        { ROADSIDE_PAVED,         ROADSIDE_PAVED },
        { ROADSIDE_TREES,         ROADSIDE_TREES },
        { ROADSIDE_STREET_LIGHTS, ROADSIDE_PAVED }
};

static const Roadside _town_road_types_2[][2] = {
        { ROADSIDE_GRASS,         ROADSIDE_GRASS },
        { ROADSIDE_PAVED,         ROADSIDE_PAVED },
        { ROADSIDE_STREET_LIGHTS, ROADSIDE_PAVED },
        { ROADSIDE_STREET_LIGHTS, ROADSIDE_PAVED },
        { ROADSIDE_STREET_LIGHTS, ROADSIDE_PAVED }
};


static void TileLoop_Road(TileIndex tile)
{
        switch (_settings_game.game_creation.landscape) {
                case LT_ARCTIC:
                        if (IsOnSnow(tile) != (GetTileZ(tile) > GetSnowLine())) {
                                ToggleSnow(tile);
                                MarkTileDirtyByTile(tile);
                        }
                        break;

                case LT_TROPIC:
                        if (GetTropicZone(tile) == TROPICZONE_DESERT && !IsOnDesert(tile)) {
                                ToggleDesert(tile);
                                MarkTileDirtyByTile(tile);
                        }
                        break;
        }

        if (IsRoadDepot(tile)) return;

        const Town *t = ClosestTownFromTile(tile, UINT_MAX);
        if (!HasRoadWorks(tile)) {
                HouseZonesBits grp = HZB_TOWN_EDGE;

                if (t != nullptr) {
                        grp = GetTownRadiusGroup(t, tile);

                        /* Show an animation to indicate road work */
                        if (t->road_build_months != 0 &&
                                        (DistanceManhattan(t->xy, tile) < 8 || grp != HZB_TOWN_EDGE) &&
                                        IsNormalRoad(tile) && !HasAtMostOneBit(GetAllRoadBits(tile))) {
                                if (GetFoundationSlope(tile) == SLOPE_FLAT && EnsureNoVehicleOnGround(tile).Succeeded() && Chance16(1, 40)) {
                                        StartRoadWorks(tile);

                                        if (_settings_client.sound.ambient) SndPlayTileFx(SND_21_ROAD_WORKS, tile);
                                        CreateEffectVehicleAbove(
                                                TileX(tile) * TILE_SIZE + 7,
                                                TileY(tile) * TILE_SIZE + 7,
                                                0,
                                                EV_BULLDOZER);
                                        MarkTileDirtyByTile(tile);
                                        return;
                                }
                        }
                }

                {
                        /* Adjust road ground type depending on 'grp' (grp is the distance to the center) */
                        const Roadside *new_rs = (_settings_game.game_creation.landscape == LT_TOYLAND) ? _town_road_types_2[grp] : _town_road_types[grp];
                        Roadside cur_rs = GetRoadside(tile);

                        /* We have our desired type, do nothing */
                        if (cur_rs == new_rs[0]) return;

                        /* We have the pre-type of the desired type, switch to the desired type */
                        if (cur_rs == new_rs[1]) {
                                cur_rs = new_rs[0];
                        /* We have barren land, install the pre-type */
                        } else if (cur_rs == ROADSIDE_BARREN) {
                                cur_rs = new_rs[1];
                        /* We're totally off limits, remove any installation and make barren land */
                        } else {
                                cur_rs = ROADSIDE_BARREN;
                        }
                        SetRoadside(tile, cur_rs);
                        MarkTileDirtyByTile(tile);
                }
        } else if (IncreaseRoadWorksCounter(tile)) {
                TerminateRoadWorks(tile);

                if (_settings_game.economy.mod_road_rebuild) {
                        /* Generate a nicer town surface */
                        const RoadBits old_rb = GetAnyRoadBits(tile, RTT_ROAD);
                        const RoadBits new_rb = CleanUpRoadBits(tile, old_rb);

                        if (old_rb != new_rb) {
                                RemoveRoad(tile, DC_EXEC | DC_AUTO | DC_NO_WATER, (old_rb ^ new_rb), RTT_ROAD, true);

                                /* If new_rb is 0, there are now no road pieces left and the tile is no longer a road tile */
                                if (new_rb == 0) {
                                        MarkTileDirtyByTile(tile);
                                        return;
                                }
                        }
                }

                /* Possibly change road type */
                if (GetRoadOwner(tile, RTT_ROAD) == OWNER_TOWN) {
                        RoadType rt = GetTownRoadType(t);
                        if (rt != GetRoadTypeRoad(tile)) {
                                SetRoadType(tile, RTT_ROAD, rt);
                        }
                }

                MarkTileDirtyByTile(tile);
        }
}

static bool ClickTile_Road(TileIndex tile)
{
        if (!IsRoadDepot(tile)) return false;

        ShowDepotWindow(tile, VEH_ROAD);
        return true;
}

/* Converts RoadBits to TrackBits */
static const TrackBits _road_trackbits[16] = {
        TRACK_BIT_NONE,                                  // ROAD_NONE
        TRACK_BIT_NONE,                                  // ROAD_NW
        TRACK_BIT_NONE,                                  // ROAD_SW
        TRACK_BIT_LEFT,                                  // ROAD_W
        TRACK_BIT_NONE,                                  // ROAD_SE
        TRACK_BIT_Y,                                     // ROAD_Y
        TRACK_BIT_LOWER,                                 // ROAD_S
        TRACK_BIT_LEFT | TRACK_BIT_LOWER | TRACK_BIT_Y,  // ROAD_Y | ROAD_SW
        TRACK_BIT_NONE,                                  // ROAD_NE
        TRACK_BIT_UPPER,                                 // ROAD_N
        TRACK_BIT_X,                                     // ROAD_X
        TRACK_BIT_LEFT | TRACK_BIT_UPPER | TRACK_BIT_X,  // ROAD_X | ROAD_NW
        TRACK_BIT_RIGHT,                                 // ROAD_E
        TRACK_BIT_RIGHT | TRACK_BIT_UPPER | TRACK_BIT_Y, // ROAD_Y | ROAD_NE
        TRACK_BIT_RIGHT | TRACK_BIT_LOWER | TRACK_BIT_X, // ROAD_X | ROAD_SE
        TRACK_BIT_ALL,                                   // ROAD_ALL
};

static TrackStatus GetTileTrackStatus_Road(TileIndex tile, TransportType mode, uint sub_mode, DiagDirection side)
{
        TrackdirBits trackdirbits = TRACKDIR_BIT_NONE;
        TrackdirBits red_signals = TRACKDIR_BIT_NONE; // crossing barred
        switch (mode) {
                case TRANSPORT_RAIL:
                        if (IsLevelCrossing(tile)) trackdirbits = TrackBitsToTrackdirBits(GetCrossingRailBits(tile));
                        break;

                case TRANSPORT_ROAD: {
                        RoadTramType rtt = (RoadTramType)sub_mode;
                        if (!HasTileRoadType(tile, rtt)) break;
                        switch (GetRoadTileType(tile)) {
                                case ROAD_TILE_NORMAL: {
                                        const uint drd_to_multiplier[DRD_END] = { 0x101, 0x100, 0x1, 0x0 };
                                        RoadBits bits = GetRoadBits(tile, rtt);

                                        /* no roadbit at this side of tile, return 0 */
                                        if (side != INVALID_DIAGDIR && (DiagDirToRoadBits(side) & bits) == 0) break;

                                        uint multiplier = drd_to_multiplier[(rtt == RTT_TRAM) ? DRD_NONE : GetDisallowedRoadDirections(tile)];
                                        if (!HasRoadWorks(tile)) trackdirbits = (TrackdirBits)(_road_trackbits[bits] * multiplier);
                                        break;
                                }

                                case ROAD_TILE_CROSSING: {
                                        Axis axis = GetCrossingRoadAxis(tile);

                                        if (side != INVALID_DIAGDIR && axis != DiagDirToAxis(side)) break;

                                        trackdirbits = TrackBitsToTrackdirBits(AxisToTrackBits(axis));
                                        if (IsCrossingBarred(tile)) red_signals = trackdirbits;
                                        break;
                                }

                                default:
                                case ROAD_TILE_DEPOT: {
                                        DiagDirection dir = GetRoadDepotDirection(tile);

                                        if (side != INVALID_DIAGDIR && side != dir) break;

                                        trackdirbits = TrackBitsToTrackdirBits(DiagDirToDiagTrackBits(dir));
                                        break;
                                }
                        }
                        break;
                }

                default: break;
        }
        return CombineTrackStatus(trackdirbits, red_signals);
}

static const StringID _road_tile_strings[] = {
        STR_LAI_ROAD_DESCRIPTION_ROAD,
        STR_LAI_ROAD_DESCRIPTION_ROAD,
        STR_LAI_ROAD_DESCRIPTION_ROAD,
        STR_LAI_ROAD_DESCRIPTION_ROAD_WITH_STREETLIGHTS,
        STR_LAI_ROAD_DESCRIPTION_ROAD,
        STR_LAI_ROAD_DESCRIPTION_TREE_LINED_ROAD,
        STR_LAI_ROAD_DESCRIPTION_ROAD,
        STR_LAI_ROAD_DESCRIPTION_ROAD,
};

static void GetTileDesc_Road(TileIndex tile, TileDesc *td)
{
        Owner rail_owner = INVALID_OWNER;
        Owner road_owner = INVALID_OWNER;
        Owner tram_owner = INVALID_OWNER;

        RoadType road_rt = GetRoadTypeRoad(tile);
        RoadType tram_rt = GetRoadTypeTram(tile);
        if (road_rt != INVALID_ROADTYPE) {
                const RoadTypeInfo *rti = GetRoadTypeInfo(road_rt);
                td->roadtype = rti->strings.name;
                td->road_speed = rti->max_speed / 2;
                road_owner = GetRoadOwner(tile, RTT_ROAD);
        }
        if (tram_rt != INVALID_ROADTYPE) {
                const RoadTypeInfo *rti = GetRoadTypeInfo(tram_rt);
                td->tramtype = rti->strings.name;
                td->tram_speed = rti->max_speed / 2;
                tram_owner = GetRoadOwner(tile, RTT_TRAM);
        }

        switch (GetRoadTileType(tile)) {
                case ROAD_TILE_CROSSING: {
                        td->str = STR_LAI_ROAD_DESCRIPTION_ROAD_RAIL_LEVEL_CROSSING;
                        rail_owner = GetTileOwner(tile);

                        const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(tile));
                        td->railtype = rti->strings.name;
                        td->rail_speed = rti->max_speed;

                        break;
                }

                case ROAD_TILE_DEPOT:
                        td->str = STR_LAI_ROAD_DESCRIPTION_ROAD_VEHICLE_DEPOT;
                        td->build_date = Depot::GetByTile(tile)->build_date;
                        break;

                default: {
                        td->str = (road_rt != INVALID_ROADTYPE ? _road_tile_strings[GetRoadside(tile)] : STR_LAI_ROAD_DESCRIPTION_TRAMWAY);
                        break;
                }
        }

        /* Now we have to discover, if the tile has only one owner or many:
         *   - Find a first_owner of the tile. (Currently road or tram must be present, but this will break when the third type becomes available)
         *   - Compare the found owner with the other owners, and test if they differ.
         * Note: If road exists it will be the first_owner.
         */
        Owner first_owner = (road_owner == INVALID_OWNER ? tram_owner : road_owner);
        bool mixed_owners = (tram_owner != INVALID_OWNER && tram_owner != first_owner) || (rail_owner != INVALID_OWNER && rail_owner != first_owner);

        if (mixed_owners) {
                /* Multiple owners */
                td->owner_type[0] = (rail_owner == INVALID_OWNER ? STR_NULL : STR_LAND_AREA_INFORMATION_RAIL_OWNER);
                td->owner[0] = rail_owner;
                td->owner_type[1] = (road_owner == INVALID_OWNER ? STR_NULL : STR_LAND_AREA_INFORMATION_ROAD_OWNER);
                td->owner[1] = road_owner;
                td->owner_type[2] = (tram_owner == INVALID_OWNER ? STR_NULL : STR_LAND_AREA_INFORMATION_TRAM_OWNER);
                td->owner[2] = tram_owner;
        } else {
                /* One to rule them all */
                td->owner[0] = first_owner;
        }
}

/**
 * Given the direction the road depot is pointing, this is the direction the
 * vehicle should be travelling in in order to enter the depot.
 */
static const byte _roadveh_enter_depot_dir[4] = {
        TRACKDIR_X_SW, TRACKDIR_Y_NW, TRACKDIR_X_NE, TRACKDIR_Y_SE
};

static VehicleEnterTileStatus VehicleEnter_Road(Vehicle *v, TileIndex tile, int x, int y)
{
        switch (GetRoadTileType(tile)) {
                case ROAD_TILE_DEPOT: {
                        if (v->type != VEH_ROAD) break;

                        RoadVehicle *rv = RoadVehicle::From(v);
                        if (rv->frame == RVC_DEPOT_STOP_FRAME &&
                                        _roadveh_enter_depot_dir[GetRoadDepotDirection(tile)] == rv->state) {
                                rv->state = RVSB_IN_DEPOT;
                                rv->vehstatus |= VS_HIDDEN;
                                rv->direction = ReverseDir(rv->direction);
                                if (rv->Next() == nullptr) VehicleEnterDepot(rv->First());
                                rv->tile = tile;

                                InvalidateWindowData(WC_VEHICLE_DEPOT, rv->tile);
                                return VETSB_ENTERED_WORMHOLE;
                        }
                        break;
                }

                default: break;
        }
        return VETSB_CONTINUE;
}


static void ChangeTileOwner_Road(TileIndex tile, Owner old_owner, Owner new_owner)
{
        if (IsRoadDepot(tile)) {
                if (GetTileOwner(tile) == old_owner) {
                        if (new_owner == INVALID_OWNER) {
                                Command<CMD_LANDSCAPE_CLEAR>::Do(DC_EXEC | DC_BANKRUPT, tile);
                        } else {
                                /* A road depot has two road bits. No need to dirty windows here, we'll redraw the whole screen anyway. */
                                RoadType rt = GetRoadTypeRoad(tile);
                                if (rt == INVALID_ROADTYPE) rt = GetRoadTypeTram(tile);
                                Company::Get(old_owner)->infrastructure.road[rt] -= 2;
                                Company::Get(new_owner)->infrastructure.road[rt] += 2;

                                SetTileOwner(tile, new_owner);
                                for (RoadTramType rtt : _roadtramtypes) {
                                        if (GetRoadOwner(tile, rtt) == old_owner) {
                                                SetRoadOwner(tile, rtt, new_owner);
                                        }
                                }
                        }
                }
                return;
        }

        for (RoadTramType rtt : _roadtramtypes) {
                /* Update all roadtypes, no matter if they are present */
                if (GetRoadOwner(tile, rtt) == old_owner) {
                        RoadType rt = GetRoadType(tile, rtt);
                        if (rt != INVALID_ROADTYPE) {
                                /* A level crossing has two road bits. No need to dirty windows here, we'll redraw the whole screen anyway. */
                                uint num_bits = IsLevelCrossing(tile) ? 2 : CountBits(GetRoadBits(tile, rtt));
                                Company::Get(old_owner)->infrastructure.road[rt] -= num_bits;
                                if (new_owner != INVALID_OWNER) Company::Get(new_owner)->infrastructure.road[rt] += num_bits;
                        }

                        SetRoadOwner(tile, rtt, new_owner == INVALID_OWNER ? OWNER_NONE : new_owner);
                }
        }

        if (IsLevelCrossing(tile)) {
                if (GetTileOwner(tile) == old_owner) {
                        if (new_owner == INVALID_OWNER) {
                                Command<CMD_REMOVE_SINGLE_RAIL>::Do(DC_EXEC | DC_BANKRUPT, tile, GetCrossingRailTrack(tile));
                        } else {
                                /* Update infrastructure counts. No need to dirty windows here, we'll redraw the whole screen anyway. */
                                Company::Get(old_owner)->infrastructure.rail[GetRailType(tile)] -= LEVELCROSSING_TRACKBIT_FACTOR;
                                Company::Get(new_owner)->infrastructure.rail[GetRailType(tile)] += LEVELCROSSING_TRACKBIT_FACTOR;

                                SetTileOwner(tile, new_owner);
                        }
                }
        }
}

static CommandCost TerraformTile_Road(TileIndex tile, DoCommandFlag flags, int z_new, Slope tileh_new)
{
        if (_settings_game.construction.build_on_slopes && AutoslopeEnabled()) {
                switch (GetRoadTileType(tile)) {
                        case ROAD_TILE_CROSSING:
                                if (!IsSteepSlope(tileh_new) && (GetTileMaxZ(tile) == z_new + GetSlopeMaxZ(tileh_new)) && HasBit(VALID_LEVEL_CROSSING_SLOPES, tileh_new)) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
                                break;

                        case ROAD_TILE_DEPOT:
                                if (AutoslopeCheckForEntranceEdge(tile, z_new, tileh_new, GetRoadDepotDirection(tile))) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
                                break;

                        case ROAD_TILE_NORMAL: {
                                RoadBits bits = GetAllRoadBits(tile);
                                RoadBits bits_copy = bits;
                                /* Check if the slope-road_bits combination is valid at all, i.e. it is safe to call GetRoadFoundation(). */
                                if (CheckRoadSlope(tileh_new, &bits_copy, ROAD_NONE, ROAD_NONE).Succeeded()) {
                                        /* CheckRoadSlope() sometimes changes the road_bits, if it does not agree with them. */
                                        if (bits == bits_copy) {
                                                int z_old;
                                                Slope tileh_old = GetTileSlope(tile, &z_old);

                                                /* Get the slope on top of the foundation */
                                                z_old += ApplyFoundationToSlope(GetRoadFoundation(tileh_old, bits), &tileh_old);
                                                z_new += ApplyFoundationToSlope(GetRoadFoundation(tileh_new, bits), &tileh_new);

                                                /* The surface slope must not be changed */
                                                if ((z_old == z_new) && (tileh_old == tileh_new)) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
                                        }
                                }
                                break;
                        }

                        default: NOT_REACHED();
                }
        }

        return Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile);
}

/** Update power of road vehicle under which is the roadtype being converted */
static Vehicle *UpdateRoadVehPowerProc(Vehicle *v, void *data)
{
        if (v->type != VEH_ROAD) return nullptr;

        RoadVehicleList *affected_rvs = static_cast<RoadVehicleList*>(data);
        include(*affected_rvs, RoadVehicle::From(v)->First());

        return nullptr;
}

/**
 * Checks the tile and returns whether the current player is allowed to convert the roadtype to another roadtype without taking ownership
 * @param owner the tile owner.
 * @param rtt Road/tram type.
 * @return whether the road is convertible
 */
static bool CanConvertUnownedRoadType(Owner owner, RoadTramType rtt)
{
        return (owner == OWNER_NONE || (owner == OWNER_TOWN && rtt == RTT_ROAD));
}

/**
 * Convert the ownership of the RoadType of the tile if applicable
 * @param tile the tile of which convert ownership
 * @param num_pieces the count of the roadbits to assign to the new owner
 * @param owner the current owner of the RoadType
 * @param from_type the old road type
 * @param to_type the new road type
 */
static void ConvertRoadTypeOwner(TileIndex tile, uint num_pieces, Owner owner, RoadType from_type, RoadType to_type)
{
        // Scenario editor, maybe? Don't touch the owners when converting roadtypes...
        if (_current_company >= MAX_COMPANIES) return;

        // We can't get a company from invalid owners but we can get ownership of roads without an owner
        if (owner >= MAX_COMPANIES && owner != OWNER_NONE) return;

        Company *c;

        switch (owner) {
        case OWNER_NONE:
                SetRoadOwner(tile, GetRoadTramType(to_type), (Owner)_current_company);
                UpdateCompanyRoadInfrastructure(to_type, _current_company, num_pieces);
                break;

        default:
                c = Company::Get(owner);
                c->infrastructure.road[from_type] -= num_pieces;
                c->infrastructure.road[to_type] += num_pieces;
                DirtyCompanyInfrastructureWindows(c->index);
                break;
        }
}

/**
 * Convert one road subtype to another.
 * Not meant to convert from road to tram.
 *
 * @param flags operation to perform
 * @param tile end tile of road conversion drag
 * @param area_start start tile of drag
 * @param to_type new roadtype to convert to.
 * @return the cost of this operation or an error
 */
CommandCost CmdConvertRoad(DoCommandFlag flags, TileIndex tile, TileIndex area_start, RoadType to_type)
{
        TileIndex area_end = tile;

        if (!ValParamRoadType(to_type)) return CMD_ERROR;
        if (area_start >= MapSize()) return CMD_ERROR;

        RoadVehicleList affected_rvs;
        RoadTramType rtt = GetRoadTramType(to_type);

        CommandCost cost(EXPENSES_CONSTRUCTION);
        CommandCost error = CommandCost((rtt == RTT_TRAM) ? STR_ERROR_NO_SUITABLE_TRAMWAY : STR_ERROR_NO_SUITABLE_ROAD); // by default, there is no road to convert.
        bool found_convertible_road = false; // whether we actually did convert any road/tram (see bug #7633)

        TileIterator *iter = new OrthogonalTileIterator(area_start, area_end);
        for (; (tile = *iter) != INVALID_TILE; ++(*iter)) {
                /* Is road present on tile? */
                if (!MayHaveRoad(tile)) continue;

                /* Converting to the same subtype? */
                RoadType from_type = GetRoadType(tile, rtt);
                if (from_type == INVALID_ROADTYPE || from_type == to_type) continue;

                /* Check if there is any infrastructure on tile */
                TileType tt = GetTileType(tile);
                switch (tt) {
                        case MP_STATION:
                                if (!IsRoadStop(tile)) continue;
                                break;
                        case MP_ROAD:
                                if (IsLevelCrossing(tile) && RoadNoLevelCrossing(to_type)) {
                                        error.MakeError(STR_ERROR_CROSSING_DISALLOWED_ROAD);
                                        continue;
                                }
                                break;
                        case MP_TUNNELBRIDGE:
                                if (GetTunnelBridgeTransportType(tile) != TRANSPORT_ROAD) continue;
                                break;
                        default: continue;
                }

                /* Trying to convert other's road */
                Owner owner = GetRoadOwner(tile, rtt);
                if (!CanConvertUnownedRoadType(owner, rtt)) {
                        CommandCost ret = CheckOwnership(owner, tile);
                        if (ret.Failed()) {
                                error = ret;
                                continue;
                        }
                }

                /* Base the ability to replace town roads and bridges on the town's
                 * acceptance of destructive actions. */
                if (owner == OWNER_TOWN) {
                        Town *t = ClosestTownFromTile(tile, _settings_game.economy.dist_local_authority);
                        CommandCost ret = CheckforTownRating(DC_NONE, t, tt == MP_TUNNELBRIDGE ? TUNNELBRIDGE_REMOVE : ROAD_REMOVE);
                        if (ret.Failed()) {
                                error = ret;
                                continue;
                        }
                }

                /* Vehicle on the tile when not converting normal <-> powered
                 * Tunnels and bridges have special check later */
                if (tt != MP_TUNNELBRIDGE) {
                        if (!HasPowerOnRoad(from_type, to_type)) {
                                CommandCost ret = EnsureNoVehicleOnGround(tile);
                                if (ret.Failed()) {
                                        error = ret;
                                        continue;
                                }

                                if (rtt == RTT_ROAD && owner == OWNER_TOWN) {
                                        error.MakeError(STR_ERROR_OWNED_BY);
                                        GetNameOfOwner(OWNER_TOWN, tile);
                                        continue;
                                }
                        }

                        uint num_pieces = CountBits(GetAnyRoadBits(tile, rtt));
                        if (tt == MP_STATION && IsStandardRoadStopTile(tile)) {
                                num_pieces *= ROAD_STOP_TRACKBIT_FACTOR;
                        } else if (tt == MP_ROAD && IsRoadDepot(tile)) {
                                num_pieces *= ROAD_DEPOT_TRACKBIT_FACTOR;
                        }

                        found_convertible_road = true;
                        cost.AddCost(num_pieces * RoadConvertCost(from_type, to_type));

                        if (flags & DC_EXEC) { // we can safely convert, too
                                /* Call ConvertRoadTypeOwner() to update the company infrastructure counters. */
                                if (owner == _current_company) {
                                        ConvertRoadTypeOwner(tile, num_pieces, owner, from_type, to_type);
                                }

                                /* Perform the conversion */
                                SetRoadType(tile, rtt, to_type);
                                MarkTileDirtyByTile(tile);

                                /* update power of train on this tile */
                                FindVehicleOnPos(tile, &affected_rvs, &UpdateRoadVehPowerProc);

                                if (IsRoadDepotTile(tile)) {
                                        /* Update build vehicle window related to this depot */
                                        InvalidateWindowData(WC_VEHICLE_DEPOT, tile);
                                        InvalidateWindowData(WC_BUILD_VEHICLE, tile);
                                }
                        }
                } else {
                        TileIndex endtile = GetOtherTunnelBridgeEnd(tile);

                        /* If both ends of tunnel/bridge are in the range, do not try to convert twice -
                         * it would cause assert because of different test and exec runs */
                        if (endtile < tile) {
                                if (OrthogonalTileArea(area_start, area_end).Contains(endtile)) continue;
                        }

                        /* When not converting rail <-> el. rail, any vehicle cannot be in tunnel/bridge */
                        if (!HasPowerOnRoad(from_type, to_type)) {
                                CommandCost ret = TunnelBridgeIsFree(tile, endtile);
                                if (ret.Failed()) {
                                        error = ret;
                                        continue;
                                }

                                if (rtt == RTT_ROAD && owner == OWNER_TOWN) {
                                        error.MakeError(STR_ERROR_OWNED_BY);
                                        GetNameOfOwner(OWNER_TOWN, tile);
                                        continue;
                                }
                        }

                        /* There are 2 pieces on *every* tile of the bridge or tunnel */
                        uint num_pieces = (GetTunnelBridgeLength(tile, endtile) + 2) * 2;
                        found_convertible_road = true;
                        cost.AddCost(num_pieces * RoadConvertCost(from_type, to_type));

                        if (flags & DC_EXEC) {
                                /* Update the company infrastructure counters. */
                                if (owner == _current_company) {
                                        /* Each piece should be counted TUNNELBRIDGE_TRACKBIT_FACTOR times
                                         * for the infrastructure counters (cause of #8297). */
                                        ConvertRoadTypeOwner(tile, num_pieces * TUNNELBRIDGE_TRACKBIT_FACTOR, owner, from_type, to_type);
                                        SetTunnelBridgeOwner(tile, endtile, _current_company);
                                }

                                /* Perform the conversion */
                                SetRoadType(tile,    rtt, to_type);
                                SetRoadType(endtile, rtt, to_type);

                                FindVehicleOnPos(tile, &affected_rvs, &UpdateRoadVehPowerProc);
                                FindVehicleOnPos(endtile, &affected_rvs, &UpdateRoadVehPowerProc);

                                if (IsBridge(tile)) {
                                        MarkBridgeDirty(tile);
                                } else {
                                        MarkTileDirtyByTile(tile);
                                        MarkTileDirtyByTile(endtile);
                                }
                        }
                }
        }

        if (flags & DC_EXEC) {
                /* Roadtype changed, update roadvehicles as when entering different track */
                for (RoadVehicle *v : affected_rvs) {
                        v->CargoChanged();
                }
        }

        delete iter;
        return found_convertible_road ? cost : error;
}


/** Tile callback functions for road tiles */
extern const TileTypeProcs _tile_type_road_procs = {
        DrawTile_Road,           // draw_tile_proc
        GetSlopePixelZ_Road,     // get_slope_z_proc
        ClearTile_Road,          // clear_tile_proc
        nullptr,                    // add_accepted_cargo_proc
        GetTileDesc_Road,        // get_tile_desc_proc
        GetTileTrackStatus_Road, // get_tile_track_status_proc
        ClickTile_Road,          // click_tile_proc
        nullptr,                    // animate_tile_proc
        TileLoop_Road,           // tile_loop_proc
        ChangeTileOwner_Road,    // change_tile_owner_proc
        nullptr,                    // add_produced_cargo_proc
        VehicleEnter_Road,       // vehicle_enter_tile_proc
        GetFoundation_Road,      // get_foundation_proc
        TerraformTile_Road,      // terraform_tile_proc
};