station_cmd.cpp

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/*
 * 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 <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */
 
#include "stdafx.h"
#include "core/flatset_type.hpp"
#include "aircraft.h"
#include "bridge_map.h"
#include "vehiclelist_func.h"
#include "viewport_func.h"
#include "viewport_kdtree.h"
#include "command_func.h"
#include "town.h"
#include "news_func.h"
#include "train.h"
#include "ship.h"
#include "roadveh.h"
#include "industry.h"
#include "newgrf_cargo.h"
#include "newgrf_debug.h"
#include "newgrf_station.h"
#include "newgrf_canal.h" /* For the buoy */
#include "pathfinder/yapf/yapf_cache.h"
#include "road_internal.h" /* For drawing catenary/checking road removal */
#include "autoslope.h"
#include "water.h"
#include "tilehighlight_func.h"
#include "strings_func.h"
#include "clear_func.h"
#include "timer/timer_game_calendar.h"
#include "vehicle_func.h"
#include "string_func.h"
#include "animated_tile_func.h"
#include "elrail_func.h"
#include "station_base.h"
#include "station_func.h"
#include "station_kdtree.h"
#include "roadstop_base.h"
#include "newgrf_railtype.h"
#include "newgrf_roadtype.h"
#include "waypoint_base.h"
#include "waypoint_func.h"
#include "pbs.h"
#include "debug.h"
#include "core/random_func.hpp"
#include "core/container_func.hpp"
#include "company_base.h"
#include "table/airporttile_ids.h"
#include "newgrf_airporttiles.h"
#include "order_backup.h"
#include "newgrf_house.h"
#include "company_gui.h"
#include "linkgraph/linkgraph_base.h"
#include "linkgraph/refresh.h"
#include "tunnelbridge_map.h"
#include "station_cmd.h"
#include "waypoint_cmd.h"
#include "landscape_cmd.h"
#include "rail_cmd.h"
#include "newgrf_roadstop.h"
#include "timer/timer.h"
#include "timer/timer_game_calendar.h"
#include "timer/timer_game_economy.h"
#include "timer/timer_game_tick.h"
#include "cheat_type.h"
#include "road_func.h"
#include "station_layout_type.h"
 
#include "widgets/station_widget.h"
#include "widgets/misc_widget.h"
 
#include "table/strings.h"
#include "table/station_land.h"
 
#include <bitset>
 
#include "safeguards.h"
 
/* static */ const FlowStat::SharesMap FlowStat::empty_sharesmap;
 
bool IsHangar(Tile t)
{
  assert(IsTileType(t, MP_STATION));
 
  /* If the tile isn't an airport there's no chance it's a hangar. */
  if (!IsAirport(t)) return false;
 
  const Station *st = Station::GetByTile(t);
  const AirportSpec *as = st->airport.GetSpec();
 
  for (const auto &depot : as->depots) {
    if (st->airport.GetRotatedTileFromOffset(depot.ti) == TileIndex(t)) return true;
  }
 
  return false;
}
 
template <class T, class F>
CommandCost GetStationAround(TileArea ta, StationID closest_station, CompanyID company, T **st, F filter)
{
  ta.Expand(1);
 
  /* check around to see if there are any stations there owned by the company */
  for (TileIndex tile_cur : ta) {
    if (IsTileType(tile_cur, MP_STATION)) {
      StationID t = GetStationIndex(tile_cur);
      if (!T::IsValidID(t) || T::Get(t)->owner != company || !filter(T::Get(t))) continue;
      if (closest_station == StationID::Invalid()) {
        closest_station = t;
      } else if (closest_station != t) {
        return CommandCost(STR_ERROR_ADJOINS_MORE_THAN_ONE_EXISTING);
      }
    }
  }
  *st = (closest_station == StationID::Invalid()) ? nullptr : T::Get(closest_station);
  return CommandCost();
}
 
typedef bool (*CMSAMatcher)(TileIndex tile);
 
static int CountMapSquareAround(TileIndex tile, CMSAMatcher cmp)
{
  int num = 0;
 
  for (int dx = -3; dx <= 3; dx++) {
    for (int dy = -3; dy <= 3; dy++) {
      TileIndex t = TileAddWrap(tile, dx, dy);
      if (t != INVALID_TILE && cmp(t)) num++;
    }
  }
 
  return num;
}
 
static bool CMSAMine(TileIndex tile)
{
  /* No industry */
  if (!IsTileType(tile, MP_INDUSTRY)) return false;
 
  const Industry *ind = Industry::GetByTile(tile);
 
  /* No extractive industry */
  if (!GetIndustrySpec(ind->type)->life_type.Test(IndustryLifeType::Extractive)) return false;
 
  for (const auto &p : ind->produced) {
    /* The industry extracts something non-liquid, i.e. no oil or plastic, so it is a mine.
     * Also the production of passengers and mail is ignored. */
    if (IsValidCargoType(p.cargo) &&
        !CargoSpec::Get(p.cargo)->classes.Any({CargoClass::Liquid, CargoClass::Passengers, CargoClass::Mail})) {
      return true;
    }
  }
 
  return false;
}
 
static bool CMSAWater(TileIndex tile)
{
  return IsTileType(tile, MP_WATER) && IsWater(tile);
}
 
static bool CMSATree(TileIndex tile)
{
  return IsTileType(tile, MP_TREES);
}
 
enum StationNaming : uint8_t {
  STATIONNAMING_RAIL,
  STATIONNAMING_ROAD,
  STATIONNAMING_AIRPORT,
  STATIONNAMING_OILRIG,
  STATIONNAMING_DOCK,
  STATIONNAMING_HELIPORT,
};
 
struct StationNameInformation {
  std::bitset<STR_SV_STNAME_FALLBACK - STR_SV_STNAME> used_names; 
  std::bitset<NUM_INDUSTRYTYPES> indtypes; 
 
  bool IsAvailable(StringID str) const
  {
    assert(IsInsideMM(str, STR_SV_STNAME, STR_SV_STNAME_FALLBACK));
    return !this->used_names.test(str - STR_SV_STNAME);
  }
 
  void SetUsed(StringID str)
  {
    assert(IsInsideMM(str, STR_SV_STNAME, STR_SV_STNAME_FALLBACK));
    this->used_names.set(str - STR_SV_STNAME);
  }
};
 
static StringID GenerateStationName(Station *st, TileIndex tile, StationNaming name_class)
{
  const Town *t = st->town;
 
  StationNameInformation sni{};
 
  for (const Station *s : Station::Iterate()) {
    if (s != st && s->town == t) {
      if (s->indtype != IT_INVALID) {
        sni.indtypes[s->indtype] = true;
        StringID name = GetIndustrySpec(s->indtype)->station_name;
        if (name != STR_UNDEFINED) {
          /* Filter for other industrytypes with the same name */
          for (IndustryType it = 0; it < NUM_INDUSTRYTYPES; it++) {
            const IndustrySpec *indsp = GetIndustrySpec(it);
            if (indsp->enabled && indsp->station_name == name) sni.indtypes[it] = true;
          }
        }
        continue;
      }
      if (IsInsideMM(s->string_id, STR_SV_STNAME, STR_SV_STNAME_FALLBACK)) {
        auto str = s->string_id;
        if (str == STR_SV_STNAME_FOREST) str = STR_SV_STNAME_WOODS;
        sni.SetUsed(str);
      }
    }
  }
 
  for (auto indtile : SpiralTileSequence(tile, 7)) {
    if (!IsTileType(indtile, MP_INDUSTRY)) continue;
 
    /* If the station name is undefined it means that it doesn't name a station */
    IndustryType indtype = GetIndustryType(indtile);
    const IndustrySpec *indsp = GetIndustrySpec(indtype);
    if (indsp->station_name == STR_UNDEFINED) continue;
 
    /* In all cases if an industry that provides a name is found two of
     * the standard names will be disabled. */
    sni.SetUsed(STR_SV_STNAME_OILFIELD);
    sni.SetUsed(STR_SV_STNAME_MINES);
    if (sni.indtypes[indtype]) continue;
 
    /* STR_NULL means it only disables oil rig/mines */
    if (indsp->station_name != STR_NULL) {
      st->indtype = indtype;
      return STR_SV_STNAME_FALLBACK;
    }
    break;
  }
 
  /* check default names
   * Oil rigs/mines name could be marked not free by looking for a near by industry. */
  switch (name_class) {
    case STATIONNAMING_AIRPORT:
      if (sni.IsAvailable(STR_SV_STNAME_AIRPORT)) return STR_SV_STNAME_AIRPORT;
      break;
    case STATIONNAMING_OILRIG:
      if (sni.IsAvailable(STR_SV_STNAME_OILFIELD)) return STR_SV_STNAME_OILFIELD;
      break;
    case STATIONNAMING_DOCK:
      if (sni.IsAvailable(STR_SV_STNAME_DOCKS)) return STR_SV_STNAME_DOCKS;
      break;
    case STATIONNAMING_HELIPORT:
      if (sni.IsAvailable(STR_SV_STNAME_HELIPORT)) return STR_SV_STNAME_HELIPORT;
      break;
    default:
      break;
  };
 
  /* check mine? */
  if (sni.IsAvailable(STR_SV_STNAME_MINES)) {
    if (CountMapSquareAround(tile, CMSAMine) >= 2) {
      return STR_SV_STNAME_MINES;
    }
  }
 
  /* check close enough to town to get central as name? */
  if (DistanceMax(tile, t->xy) < 8) {
    if (sni.IsAvailable(STR_SV_STNAME)) return STR_SV_STNAME;
    if (sni.IsAvailable(STR_SV_STNAME_CENTRAL)) return STR_SV_STNAME_CENTRAL;
  }
 
  /* Check lakeside */
  if (sni.IsAvailable(STR_SV_STNAME_LAKESIDE) &&
      DistanceFromEdge(tile) < 20 &&
      CountMapSquareAround(tile, CMSAWater) >= 5) {
    return STR_SV_STNAME_LAKESIDE;
  }
 
  /* Check woods */
  if (sni.IsAvailable(STR_SV_STNAME_WOODS) && (
        CountMapSquareAround(tile, CMSATree) >= 8 ||
        CountMapSquareAround(tile, IsTileForestIndustry) >= 2)
      ) {
    return _settings_game.game_creation.landscape == LandscapeType::Tropic ? STR_SV_STNAME_FOREST : STR_SV_STNAME_WOODS;
  }
 
  /* check elevation compared to town */
  int z = GetTileZ(tile);
  int z2 = GetTileZ(t->xy);
  if (z < z2) {
    if (sni.IsAvailable(STR_SV_STNAME_VALLEY)) return STR_SV_STNAME_VALLEY;
  } else if (z > z2) {
    if (sni.IsAvailable(STR_SV_STNAME_HEIGHTS)) return STR_SV_STNAME_HEIGHTS;
  }
 
  /* check direction compared to town */
  if (TileX(tile) < TileX(t->xy)) {
    sni.SetUsed(STR_SV_STNAME_SOUTH);
    sni.SetUsed(STR_SV_STNAME_WEST);
  } else {
    sni.SetUsed(STR_SV_STNAME_NORTH);
    sni.SetUsed(STR_SV_STNAME_EAST);
  }
  if (TileY(tile) < TileY(t->xy)) {
    sni.SetUsed(STR_SV_STNAME_SOUTH);
    sni.SetUsed(STR_SV_STNAME_EAST);
  } else {
    sni.SetUsed(STR_SV_STNAME_NORTH);
    sni.SetUsed(STR_SV_STNAME_WEST);
  }
 
  static const StringID fallback_names[] = {
    STR_SV_STNAME_NORTH,
    STR_SV_STNAME_SOUTH,
    STR_SV_STNAME_EAST,
    STR_SV_STNAME_WEST,
    STR_SV_STNAME_TRANSFER,
    STR_SV_STNAME_HALT,
    STR_SV_STNAME_EXCHANGE,
    STR_SV_STNAME_ANNEXE,
    STR_SV_STNAME_SIDINGS,
    STR_SV_STNAME_BRANCH,
    STR_SV_STNAME_UPPER,
    STR_SV_STNAME_LOWER,
  };
  for (auto str : fallback_names) {
    if (sni.IsAvailable(str)) return str;
  }
  return STR_SV_STNAME_FALLBACK;
}
 
static Station *GetClosestDeletedStation(TileIndex tile)
{
  uint threshold = 8;
 
  Station *best_station = nullptr;
  ForAllStationsRadius(tile, threshold, [&](Station *st) {
    if (!st->IsInUse() && st->owner == _current_company) {
      uint cur_dist = DistanceManhattan(tile, st->xy);
 
      if (cur_dist < threshold) {
        threshold = cur_dist;
        best_station = st;
      } else if (cur_dist == threshold && best_station != nullptr) {
        /* In case of a tie, lowest station ID wins */
        if (st->index < best_station->index) best_station = st;
      }
    }
  });
 
  return best_station;
}
 
 
TileArea Station::GetTileArea(StationType type) const
{
  switch (type) {
    case StationType::Rail: return this->train_station;
    case StationType::Airport: return this->airport;
    case StationType::Truck: return this->truck_station;
    case StationType::Bus: return this->bus_station;
    case StationType::Dock:
    case StationType::Oilrig: return this->docking_station;
    default: NOT_REACHED();
  }
}
 
void Station::UpdateVirtCoord()
{
  Point pt = RemapCoords2(TileX(this->xy) * TILE_SIZE, TileY(this->xy) * TILE_SIZE);
 
  pt.y -= 32 * ZOOM_BASE;
  if (this->facilities.Test(StationFacility::Airport) && this->airport.type == AT_OILRIG) pt.y -= 16 * ZOOM_BASE;
 
  if (this->sign.kdtree_valid) _viewport_sign_kdtree.Remove(ViewportSignKdtreeItem::MakeStation(this->index));
 
  this->sign.UpdatePosition(pt.x, pt.y, GetString(STR_VIEWPORT_STATION, this->index, this->facilities), GetString(STR_STATION_NAME, this->index, this->facilities));
 
  _viewport_sign_kdtree.Insert(ViewportSignKdtreeItem::MakeStation(this->index));
 
  SetWindowDirty(WC_STATION_VIEW, this->index);
}
 
void Station::MoveSign(TileIndex new_xy)
{
  if (this->xy == new_xy) return;
 
  _station_kdtree.Remove(this->index);
 
  this->BaseStation::MoveSign(new_xy);
 
  _station_kdtree.Insert(this->index);
}
 
void UpdateAllStationVirtCoords()
{
  for (BaseStation *st : BaseStation::Iterate()) {
    st->UpdateVirtCoord();
  }
}
 
void BaseStation::FillCachedName() const
{
  auto tmp_params = MakeParameters(this->index);
  this->cached_name = GetStringWithArgs(Waypoint::IsExpected(this) ? STR_WAYPOINT_NAME : STR_STATION_NAME, tmp_params);
}
 
void ClearAllStationCachedNames()
{
  for (BaseStation *st : BaseStation::Iterate()) {
    st->cached_name.clear();
  }
}
 
CargoTypes GetAcceptanceMask(const Station *st)
{
  CargoTypes mask = 0;
 
  for (auto it = std::begin(st->goods); it != std::end(st->goods); ++it) {
    if (it->status.Test(GoodsEntry::State::Acceptance)) SetBit(mask, std::distance(std::begin(st->goods), it));
  }
  return mask;
}
 
CargoTypes GetEmptyMask(const Station *st)
{
  CargoTypes mask = 0;
 
  for (auto it = std::begin(st->goods); it != std::end(st->goods); ++it) {
    if (it->TotalCount() == 0) SetBit(mask, std::distance(std::begin(st->goods), it));
  }
  return mask;
}
 
static void ShowRejectOrAcceptNews(const Station *st, CargoTypes cargoes, bool reject)
{
  StringID msg = reject ? STR_NEWS_STATION_NO_LONGER_ACCEPTS_CARGO_LIST : STR_NEWS_STATION_NOW_ACCEPTS_CARGO_LIST;
  AddNewsItem(GetEncodedString(msg, st->index, cargoes), NewsType::Acceptance, NewsStyle::Small, NewsFlag::InColour, st->index);
}
 
CargoArray GetProductionAroundTiles(TileIndex north_tile, int w, int h, int rad)
{
  CargoArray produced{};
  FlatSet<IndustryID> industries;
  TileArea ta = TileArea(north_tile, w, h).Expand(rad);
 
  /* Loop over all tiles to get the produced cargo of
   * everything except industries */
  for (TileIndex tile : ta) {
    if (IsTileType(tile, MP_INDUSTRY)) industries.insert(GetIndustryIndex(tile));
    AddProducedCargo(tile, produced);
  }
 
  /* Loop over the seen industries. They produce cargo for
   * anything that is within 'rad' of any one of their tiles.
   */
  for (IndustryID industry : industries) {
    const Industry *i = Industry::Get(industry);
    /* Skip industry with neutral station */
    if (i->neutral_station != nullptr && !_settings_game.station.serve_neutral_industries) continue;
 
    for (const auto &p : i->produced) {
      if (IsValidCargoType(p.cargo)) produced[p.cargo]++;
    }
  }
 
  return produced;
}
 
CargoArray GetAcceptanceAroundTiles(TileIndex center_tile, int w, int h, int rad, CargoTypes *always_accepted)
{
  CargoArray acceptance{};
  if (always_accepted != nullptr) *always_accepted = 0;
 
  TileArea ta = TileArea(center_tile, w, h).Expand(rad);
 
  for (TileIndex tile : ta) {
    /* Ignore industry if it has a neutral station. */
    if (!_settings_game.station.serve_neutral_industries && IsTileType(tile, MP_INDUSTRY) && Industry::GetByTile(tile)->neutral_station != nullptr) continue;
 
    AddAcceptedCargo(tile, acceptance, always_accepted);
  }
 
  return acceptance;
}
 
static CargoArray GetAcceptanceAroundStation(const Station *st, CargoTypes *always_accepted)
{
  CargoArray acceptance{};
  if (always_accepted != nullptr) *always_accepted = 0;
 
  BitmapTileIterator it(st->catchment_tiles);
  for (TileIndex tile = it; tile != INVALID_TILE; tile = ++it) {
    AddAcceptedCargo(tile, acceptance, always_accepted);
  }
 
  return acceptance;
}
 
void UpdateStationAcceptance(Station *st, bool show_msg)
{
  /* old accepted goods types */
  CargoTypes old_acc = GetAcceptanceMask(st);
 
  /* And retrieve the acceptance. */
  CargoArray acceptance{};
  if (!st->rect.IsEmpty()) {
    acceptance = GetAcceptanceAroundStation(st, &st->always_accepted);
  }
 
  /* Adjust in case our station only accepts fewer kinds of goods */
  for (CargoType cargo = 0; cargo < NUM_CARGO; ++cargo) {
    uint amt = acceptance[cargo];
 
    /* Make sure the station can accept the goods type. */
    bool is_passengers = IsCargoInClass(cargo, CargoClass::Passengers);
    if ((!is_passengers && !st->facilities.Any({StationFacility::Train, StationFacility::TruckStop, StationFacility::Airport, StationFacility::Dock})) ||
        (is_passengers && !st->facilities.Any({StationFacility::Train, StationFacility::BusStop, StationFacility::Airport, StationFacility::Dock}))) {
      amt = 0;
    }
 
    GoodsEntry &ge = st->goods[cargo];
    ge.status.Set(GoodsEntry::State::Acceptance, amt >= 8);
    if (LinkGraph::IsValidID(ge.link_graph)) {
      (*LinkGraph::Get(ge.link_graph))[ge.node].SetDemand(amt / 8);
    }
  }
 
  /* Only show a message in case the acceptance was actually changed. */
  CargoTypes new_acc = GetAcceptanceMask(st);
  if (old_acc == new_acc) return;
 
  /* show a message to report that the acceptance was changed? */
  if (show_msg && st->owner == _local_company && st->IsInUse()) {
    /* Combine old and new masks to get changes */
    CargoTypes accepts = new_acc & ~old_acc;
    CargoTypes rejects = ~new_acc & old_acc;
 
    /* Show news message if there are any changes */
    if (accepts != 0) ShowRejectOrAcceptNews(st, accepts, false);
    if (rejects != 0) ShowRejectOrAcceptNews(st, rejects, true);
  }
 
  /* redraw the station view since acceptance changed */
  SetWindowWidgetDirty(WC_STATION_VIEW, st->index, WID_SV_ACCEPT_RATING_LIST);
}
 
static void UpdateStationSignCoord(BaseStation *st)
{
  const StationRect *r = &st->rect;
 
  if (r->IsEmpty()) return; // no tiles belong to this station
 
  /* clamp sign coord to be inside the station rect */
  TileIndex new_xy = TileXY(ClampU(TileX(st->xy), r->left, r->right), ClampU(TileY(st->xy), r->top, r->bottom));
  st->MoveSign(new_xy);
 
  if (!Station::IsExpected(st)) return;
  Station *full_station = Station::From(st);
  for (const GoodsEntry &ge : full_station->goods) {
    LinkGraphID lg = ge.link_graph;
    if (!LinkGraph::IsValidID(lg)) continue;
    (*LinkGraph::Get(lg))[ge.node].UpdateLocation(st->xy);
  }
}
 
static CommandCost BuildStationPart(Station **st, DoCommandFlags flags, bool reuse, TileArea area, StationNaming name_class)
{
  /* Find a deleted station close to us */
  if (*st == nullptr && reuse) *st = GetClosestDeletedStation(area.tile);
 
  if (*st != nullptr) {
    if ((*st)->owner != _current_company) {
      return CommandCost(CMD_ERROR);
    }
 
    CommandCost ret = (*st)->rect.BeforeAddRect(area.tile, area.w, area.h, StationRect::ADD_TEST);
    if (ret.Failed()) return ret;
  } else {
    /* allocate and initialize new station */
    if (!Station::CanAllocateItem()) return CommandCost(STR_ERROR_TOO_MANY_STATIONS_LOADING);
 
    if (flags.Test(DoCommandFlag::Execute)) {
      *st = Station::Create(area.tile);
      _station_kdtree.Insert((*st)->index);
 
      (*st)->town = ClosestTownFromTile(area.tile, UINT_MAX);
      (*st)->string_id = GenerateStationName(*st, area.tile, name_class);
 
      if (Company::IsValidID(_current_company)) {
        (*st)->town->have_ratings.Set(_current_company);
      }
    }
  }
  return CommandCost();
}
 
static void DeleteStationIfEmpty(BaseStation *st)
{
  if (!st->IsInUse()) {
    st->delete_ctr = 0;
    InvalidateWindowData(WC_STATION_LIST, st->owner, 0);
  }
  /* station remains but it probably lost some parts - station sign should stay in the station boundaries */
  UpdateStationSignCoord(st);
}
 
void Station::AfterStationTileSetChange(bool adding, StationType type)
{
  this->UpdateVirtCoord();
  DirtyCompanyInfrastructureWindows(this->owner);
 
  if (adding) {
    this->RecomputeCatchment();
    MarkCatchmentTilesDirty();
    InvalidateWindowData(WC_STATION_LIST, this->owner, 0);
  } else {
    MarkCatchmentTilesDirty();
  }
 
  switch (type) {
    case StationType::Rail:
      SetWindowWidgetDirty(WC_STATION_VIEW, this->index, WID_SV_TRAINS);
      break;
    case StationType::Airport:
      break;
    case StationType::Truck:
    case StationType::Bus:
      SetWindowWidgetDirty(WC_STATION_VIEW, this->index, WID_SV_ROADVEHS);
      break;
    case StationType::Dock:
      SetWindowWidgetDirty(WC_STATION_VIEW, this->index, WID_SV_SHIPS);
      break;
    default: NOT_REACHED();
  }
 
  if (adding) {
    UpdateStationAcceptance(this, false);
    InvalidateWindowData(WC_SELECT_STATION, 0, 0);
  } else {
    DeleteStationIfEmpty(this);
    this->RecomputeCatchment();
  }
 
}
 
CommandCost ClearTile_Station(TileIndex tile, DoCommandFlags flags);
 
CommandCost CheckBuildableTile(TileIndex tile, DiagDirections invalid_dirs, int &allowed_z, bool allow_steep, bool check_bridge = true)
{
  if (check_bridge && IsBridgeAbove(tile)) {
    return CommandCost(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
  }
 
  CommandCost ret = EnsureNoVehicleOnGround(tile);
  if (ret.Failed()) return ret;
 
  auto [tileh, z] = GetTileSlopeZ(tile);
 
  /* Prohibit building if
   *   1) The tile is "steep" (i.e. stretches two height levels).
   *   2) The tile is non-flat and the build_on_slopes switch is disabled.
   */
  if ((!allow_steep && IsSteepSlope(tileh)) ||
      ((!_settings_game.construction.build_on_slopes) && tileh != SLOPE_FLAT)) {
    return CommandCost(STR_ERROR_FLAT_LAND_REQUIRED);
  }
 
  CommandCost cost(EXPENSES_CONSTRUCTION);
  int flat_z = z + GetSlopeMaxZ(tileh);
  if (tileh != SLOPE_FLAT) {
    /* Forbid building if the tile faces a slope in a invalid direction. */
    for (DiagDirection dir = DIAGDIR_BEGIN; dir != DIAGDIR_END; dir++) {
      if (invalid_dirs.Test(dir) && !CanBuildDepotByTileh(dir, tileh)) {
        return CommandCost(STR_ERROR_FLAT_LAND_REQUIRED);
      }
    }
    cost.AddCost(_price[PR_BUILD_FOUNDATION]);
  }
 
  /* The level of this tile must be equal to allowed_z. */
  if (allowed_z < 0) {
    /* First tile. */
    allowed_z = flat_z;
  } else if (allowed_z != flat_z) {
    return CommandCost(STR_ERROR_FLAT_LAND_REQUIRED);
  }
 
  return cost;
}
 
static CommandCost CheckFlatLandAirport(AirportTileTableIterator tile_iter, DoCommandFlags flags)
{
  CommandCost cost(EXPENSES_CONSTRUCTION);
  int allowed_z = -1;
 
  for (; tile_iter != INVALID_TILE; ++tile_iter) {
    CommandCost ret = CheckBuildableTile(tile_iter, {}, allowed_z, true);
    if (ret.Failed()) return ret;
    cost.AddCost(ret.GetCost());
 
    ret = Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile_iter);
    if (ret.Failed()) return ret;
    cost.AddCost(ret.GetCost());
  }
 
  return cost;
}
 
static StringID GetBridgeTooLowMessageForStationType(StationType type)
{
  static constexpr std::array<StringID, to_underlying(StationType::End)> too_low_msgs = {
    STR_ERROR_BRIDGE_TOO_LOW_FOR_STATION, // Rail
    INVALID_STRING_ID, // Airport
    STR_ERROR_BRIDGE_TOO_LOW_FOR_ROADSTOP, // Truck
    STR_ERROR_BRIDGE_TOO_LOW_FOR_ROADSTOP, // Bus
    INVALID_STRING_ID, // Oilrig
    STR_ERROR_BRIDGE_TOO_LOW_FOR_DOCK, // Dock
    STR_ERROR_BRIDGE_TOO_LOW_FOR_BUOY, // Buoy
    STR_ERROR_BRIDGE_TOO_LOW_FOR_RAIL_WAYPOINT, // RailWaypoint
    STR_ERROR_BRIDGE_TOO_LOW_FOR_ROAD_WAYPOINT, // RoadWaypoint
  };
  return too_low_msgs[to_underlying(type)];
};
 
static CommandCost IsStationBridgeAboveOk(TileIndex tile, std::span<const BridgeableTileInfo> bridgeable_info, StationType type, StationGfx layout, int bridge_height, StringID disallowed_msg = INVALID_STRING_ID)
{
  int height = layout < std::size(bridgeable_info) ? bridgeable_info[layout].height : 0;
 
  if (height == 0) {
    if (disallowed_msg != INVALID_STRING_ID) return CommandCost{disallowed_msg};
    /* Get normal error message associated with clearing the tile. */
    return Command<CMD_LANDSCAPE_CLEAR>::Do(DoCommandFlag::Auto, tile);
  }
  if (GetTileMaxZ(tile) + height > bridge_height) {
    int height_diff = (GetTileMaxZ(tile) + height - bridge_height) * TILE_HEIGHT_STEP;
    return CommandCostWithParam(GetBridgeTooLowMessageForStationType(type), height_diff);
  }
 
  return CommandCost{};
}
 
static std::span<const BridgeableTileInfo> GetStationBridgeableTileInfo(StationType type)
{
  return _station_bridgeable_info[to_underlying(type)];
}
 
CommandCost IsRailStationBridgeAboveOk(TileIndex tile, const StationSpec *spec, StationType type, StationGfx layout)
{
  if (!IsBridgeAbove(tile)) return CommandCost();
 
  TileIndex rampsouth = GetSouthernBridgeEnd(tile);
  auto bridgeable_info = spec == nullptr ? GetStationBridgeableTileInfo(type) : spec->bridgeable_info;
  return IsStationBridgeAboveOk(tile, bridgeable_info, type, layout, GetBridgeHeight(rampsouth), STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
}
 
CommandCost IsRoadStationBridgeAboveOk(TileIndex tile, const RoadStopSpec *spec, StationType type, StationGfx layout)
{
  if (!IsBridgeAbove(tile)) return CommandCost();
 
  TileIndex rampsouth = GetSouthernBridgeEnd(tile);
  auto bridgeable_info = spec == nullptr ? GetStationBridgeableTileInfo(type) : spec->bridgeable_info;
  return IsStationBridgeAboveOk(tile, bridgeable_info, type, layout, GetBridgeHeight(rampsouth), STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
}
 
static CommandCost IsDockBridgeAboveOk(TileIndex tile, StationGfx layout)
{
  if (!IsBridgeAbove(tile)) return CommandCost();
 
  TileIndex rampsouth = GetSouthernBridgeEnd(tile);
  auto bridgeable_info = GetStationBridgeableTileInfo(StationType::Dock);
  return IsStationBridgeAboveOk(tile, bridgeable_info, StationType::Dock, layout, GetBridgeHeight(rampsouth), STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
}
 
CommandCost IsBuoyBridgeAboveOk(TileIndex tile)
{
  if (!IsBridgeAbove(tile)) return CommandCost();
 
  TileIndex rampsouth = GetSouthernBridgeEnd(tile);
  auto bridgeable_info = GetStationBridgeableTileInfo(StationType::Buoy);
  return IsStationBridgeAboveOk(tile, bridgeable_info, StationType::Buoy, 0, GetBridgeHeight(rampsouth), STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
}
 
static CommandCost CheckFlatLandRailStation(TileIndex tile_cur, TileIndex north_tile, int &allowed_z, DoCommandFlags flags, Axis axis, StationID *station, RailType rt, std::vector<Train *> &affected_vehicles, StationClassID spec_class, uint16_t spec_index, uint8_t plat_len, uint8_t numtracks)
{
  CommandCost cost(EXPENSES_CONSTRUCTION);
  DiagDirections invalid_dirs = AxisToDiagDirs(axis);
 
  const StationSpec *statspec = StationClass::Get(spec_class)->GetSpec(spec_index);
  bool slope_cb = statspec != nullptr && statspec->callback_mask.Test(StationCallbackMask::SlopeCheck);
 
  CommandCost ret = CheckBuildableTile(tile_cur, invalid_dirs, allowed_z, false, false);
  if (ret.Failed()) return ret;
  cost.AddCost(ret.GetCost());
 
  if (slope_cb) {
    /* Do slope check if requested. */
    ret = PerformStationTileSlopeCheck(north_tile, tile_cur, statspec, axis, plat_len, numtracks);
    if (ret.Failed()) return ret;
  }
 
  /* if station is set, then we have special handling to allow building on top of already existing stations.
   * so station points to StationID::Invalid() if we can build on any station.
   * Or it points to a station if we're only allowed to build on exactly that station. */
  if (station != nullptr && IsTileType(tile_cur, MP_STATION)) {
    if (!IsRailStation(tile_cur)) {
      return ClearTile_Station(tile_cur, DoCommandFlag::Auto); // get error message
    } else {
      StationID st = GetStationIndex(tile_cur);
      if (*station == StationID::Invalid()) {
        *station = st;
      } else if (*station != st) {
        return CommandCost(STR_ERROR_ADJOINS_MORE_THAN_ONE_EXISTING);
      }
    }
  } else {
    /* If we are building a station with a valid railtype, we may be able to overbuild an existing rail tile. */
    if (rt != INVALID_RAILTYPE && IsPlainRailTile(tile_cur)) {
      /* Don't overbuild signals. */
      if (HasSignals(tile_cur)) return CommandCost(STR_ERROR_MUST_REMOVE_SIGNALS_FIRST);
 
      /* The current rail type must have power on the to-be-built type (e.g. convert normal rail to electrified rail). */
      if (HasPowerOnRail(GetRailType(tile_cur), rt)) {
        TrackBits tracks = GetTrackBits(tile_cur);
        Track track = RemoveFirstTrack(&tracks);
        Track expected_track = invalid_dirs.Test(DIAGDIR_NE) ? TRACK_X : TRACK_Y;
 
        /* The existing track must align with the desired station axis. */
        if (tracks == TRACK_BIT_NONE && track == expected_track) {
          /* Check for trains having a reservation for this tile. */
          if (HasBit(GetRailReservationTrackBits(tile_cur), track)) {
            Train *v = GetTrainForReservation(tile_cur, track);
            if (v != nullptr) {
              affected_vehicles.push_back(v);
            }
          }
          ret = Command<CMD_REMOVE_SINGLE_RAIL>::Do(flags, tile_cur, track);
          if (ret.Failed()) return ret;
          cost.AddCost(ret.GetCost());
          /* With DoCommandFlags{flags}.Reset(DoCommandFlag::Execute) CmdLandscapeClear would fail since the rail still exists */
          return cost;
        }
      }
    }
    ret = Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile_cur);
    if (ret.Failed()) return ret;
    cost.AddCost(ret.GetCost());
  }
 
  return cost;
}
 
static CommandCost CheckFlatLandRoadStop(TileIndex cur_tile, int &allowed_z, const RoadStopSpec *spec, DoCommandFlags flags, DiagDirections invalid_dirs, bool is_drive_through, StationType station_type, Axis axis, StationID *station, RoadType rt)
{
  CommandCost cost(EXPENSES_CONSTRUCTION);
 
  CommandCost ret = CheckBuildableTile(cur_tile, invalid_dirs, allowed_z, !is_drive_through, false);
  if (ret.Failed()) return ret;
  cost.AddCost(ret.GetCost());
 
  ret = IsRoadStationBridgeAboveOk(cur_tile, spec, station_type, is_drive_through ? GFX_TRUCK_BUS_DRIVETHROUGH_OFFSET + axis : FindFirstBit(invalid_dirs.base()));
  if (ret.Failed()) return ret;
 
  /* If station is set, then we have special handling to allow building on top of already existing stations.
   * Station points to StationID::Invalid() if we can build on any station.
   * Or it points to a station if we're only allowed to build on exactly that station. */
  if (station != nullptr && IsTileType(cur_tile, MP_STATION)) {
    if (!IsAnyRoadStop(cur_tile)) {
      return ClearTile_Station(cur_tile, DoCommandFlag::Auto); // Get error message.
    } else {
      if (station_type != GetStationType(cur_tile) ||
          is_drive_through != IsDriveThroughStopTile(cur_tile)) {
        return ClearTile_Station(cur_tile, DoCommandFlag::Auto); // Get error message.
      }
      /* Drive-through station in the wrong direction. */
      if (is_drive_through && IsDriveThroughStopTile(cur_tile) && GetDriveThroughStopAxis(cur_tile) != axis) {
        return CommandCost(STR_ERROR_DRIVE_THROUGH_DIRECTION);
      }
      StationID st = GetStationIndex(cur_tile);
      if (*station == StationID::Invalid()) {
        *station = st;
      } else if (*station != st) {
        return CommandCost(STR_ERROR_ADJOINS_MORE_THAN_ONE_EXISTING);
      }
    }
  } else {
    bool build_over_road = is_drive_through && IsNormalRoadTile(cur_tile);
    /* Road bits in the wrong direction. */
    RoadBits rb = IsNormalRoadTile(cur_tile) ? GetAllRoadBits(cur_tile) : ROAD_NONE;
    if (build_over_road && (rb & (axis == AXIS_X ? ROAD_Y : ROAD_X)) != 0) {
      /* Someone was pedantic and *NEEDED* three fracking different error messages. */
      switch (CountBits(rb)) {
        case 1:
          return CommandCost(STR_ERROR_DRIVE_THROUGH_DIRECTION);
 
        case 2:
          if (rb == ROAD_X || rb == ROAD_Y) return CommandCost(STR_ERROR_DRIVE_THROUGH_DIRECTION);
          return CommandCost(STR_ERROR_DRIVE_THROUGH_CORNER);
 
        default: // 3 or 4
          return CommandCost(STR_ERROR_DRIVE_THROUGH_JUNCTION);
      }
    }
 
    if (build_over_road) {
      /* There is a road, check if we can build road+tram stop over it. */
      RoadType road_rt = GetRoadType(cur_tile, RTT_ROAD);
      if (road_rt != INVALID_ROADTYPE) {
        Owner road_owner = GetRoadOwner(cur_tile, RTT_ROAD);
        if (road_owner == OWNER_TOWN) {
          if (!_settings_game.construction.road_stop_on_town_road) return CommandCost(STR_ERROR_DRIVE_THROUGH_ON_TOWN_ROAD);
        } else if (!_settings_game.construction.road_stop_on_competitor_road && road_owner != OWNER_NONE) {
          ret = CheckOwnership(road_owner);
          if (ret.Failed()) return ret;
        }
        uint num_pieces = CountBits(GetRoadBits(cur_tile, RTT_ROAD));
 
        if (rt != INVALID_ROADTYPE && RoadTypeIsRoad(rt) && !HasPowerOnRoad(rt, road_rt)) return CommandCost(STR_ERROR_NO_SUITABLE_ROAD);
 
        if (GetDisallowedRoadDirections(cur_tile) != DRD_NONE && road_owner != OWNER_TOWN) {
          ret = CheckOwnership(road_owner);
          if (ret.Failed()) return ret;
        }
 
        cost.AddCost(RoadBuildCost(road_rt) * (2 - num_pieces));
      } else if (rt != INVALID_ROADTYPE && RoadTypeIsRoad(rt)) {
        cost.AddCost(RoadBuildCost(rt) * 2);
      }
 
      /* There is a tram, check if we can build road+tram stop over it. */
      RoadType tram_rt = GetRoadType(cur_tile, RTT_TRAM);
      if (tram_rt != INVALID_ROADTYPE) {
        Owner tram_owner = GetRoadOwner(cur_tile, RTT_TRAM);
        if (Company::IsValidID(tram_owner) &&
            (!_settings_game.construction.road_stop_on_competitor_road ||
            /* Disallow breaking end-of-line of someone else
             * so trams can still reverse on this tile. */
              HasExactlyOneBit(GetRoadBits(cur_tile, RTT_TRAM)))) {
          ret = CheckOwnership(tram_owner);
          if (ret.Failed()) return ret;
        }
        uint num_pieces = CountBits(GetRoadBits(cur_tile, RTT_TRAM));
 
        if (rt != INVALID_ROADTYPE && RoadTypeIsTram(rt) && !HasPowerOnRoad(rt, tram_rt)) return CommandCost(STR_ERROR_NO_SUITABLE_ROAD);
 
        cost.AddCost(RoadBuildCost(tram_rt) * (2 - num_pieces));
      } else if (rt != INVALID_ROADTYPE && RoadTypeIsTram(rt)) {
        cost.AddCost(RoadBuildCost(rt) * 2);
      }
    } else if (rt == INVALID_ROADTYPE) {
      return CommandCost(STR_ERROR_THERE_IS_NO_ROAD);
    } else {
      ret = Command<CMD_LANDSCAPE_CLEAR>::Do(flags, cur_tile);
      if (ret.Failed()) return ret;
      cost.AddCost(ret.GetCost());
      cost.AddCost(RoadBuildCost(rt) * 2);
    }
  }
 
  return cost;
}
 
CommandCost CanExpandRailStation(const BaseStation *st, TileArea &new_ta)
{
  TileArea cur_ta = st->train_station;
 
  /* determine new size of train station region.. */
  int x = std::min(TileX(cur_ta.tile), TileX(new_ta.tile));
  int y = std::min(TileY(cur_ta.tile), TileY(new_ta.tile));
  new_ta.w = std::max(TileX(cur_ta.tile) + cur_ta.w, TileX(new_ta.tile) + new_ta.w) - x;
  new_ta.h = std::max(TileY(cur_ta.tile) + cur_ta.h, TileY(new_ta.tile) + new_ta.h) - y;
  new_ta.tile = TileXY(x, y);
 
  /* make sure the final size is not too big. */
  if (new_ta.w > _settings_game.station.station_spread || new_ta.h > _settings_game.station.station_spread) {
    return CommandCost(STR_ERROR_STATION_TOO_SPREAD_OUT);
  }
 
  return CommandCost();
}
 
RailStationTileLayout::RailStationTileLayout(const StationSpec *spec, uint8_t platforms, uint8_t length) : platforms(platforms), length(length)
{
  if (spec == nullptr) return;
 
  /* Look for a predefined layout for the required size. */
  auto found = spec->layouts.find(GetStationLayoutKey(platforms, length));
  if (found != std::end(spec->layouts)) this->layout = found->second;
}
 
StationGfx RailStationTileLayout::Iterator::operator*() const
{
  /* Use predefined layout if it exists. Mask bit zero which will indicate axis. */
  if (!stl.layout.empty()) return this->stl.layout[this->position] & ~1;
 
  if (this->stl.length == 1) {
    /* Special case for 1-long platforms, all bare platforms except one small building. */
    return this->position == ((this->stl.platforms - 1) / 2) ? 2 : 0;
  }
 
  if ((this->position < this->stl.length && (this->stl.platforms % 2 == 1))) {
    /* Number of tracks is odd, make the first platform bare with a small building. */
    return this->position == ((this->stl.length - 1) / 2) ? 2 : 0;
  }
 
  if (this->stl.length > 4 && ((this->position % this->stl.length) == 0 || (this->position % this->stl.length) == this->stl.length - 1)) {
    /* Station is longer than 4 tiles, place bare platforms at either end. */
    return 0;
  }
 
  /* None of the above so must be north or south part of larger station. */
  return (((this->position / this->stl.length) % 2) == (this->stl.platforms % 2)) ? 4 : 6;
}
 
template <class T, StringID error_message, class F>
CommandCost FindJoiningBaseStation(StationID existing_station, StationID station_to_join, bool adjacent, TileArea ta, T **st, F filter)
{
  assert(*st == nullptr);
  bool check_surrounding = true;
 
  if (existing_station != StationID::Invalid()) {
    if (adjacent && existing_station != station_to_join) {
      /* You can't build an adjacent station over the top of one that
       * already exists. */
      return CommandCost(error_message);
    } else {
      /* Extend the current station, and don't check whether it will
       * be near any other stations. */
      T *candidate = T::GetIfValid(existing_station);
      if (candidate != nullptr && filter(candidate)) *st = candidate;
      check_surrounding = (*st == nullptr);
    }
  } else {
    /* There's no station here. Don't check the tiles surrounding this
     * one if the company wanted to build an adjacent station. */
    if (adjacent) check_surrounding = false;
  }
 
  if (check_surrounding) {
    /* Make sure there is no more than one other station around us that is owned by us. */
    CommandCost ret = GetStationAround(ta, existing_station, _current_company, st, filter);
    if (ret.Failed()) return ret;
  }
 
  /* Distant join */
  if (*st == nullptr && station_to_join != StationID::Invalid()) *st = T::GetIfValid(station_to_join);
 
  return CommandCost();
}
 
static CommandCost FindJoiningStation(StationID existing_station, StationID station_to_join, bool adjacent, TileArea ta, Station **st)
{
  return FindJoiningBaseStation<Station, STR_ERROR_MUST_REMOVE_RAILWAY_STATION_FIRST>(existing_station, station_to_join, adjacent, ta, st, [](const Station *) -> bool { return true; });
}
 
CommandCost FindJoiningWaypoint(StationID existing_waypoint, StationID waypoint_to_join, bool adjacent, TileArea ta, Waypoint **wp, bool is_road)
{
  if (is_road) {
    return FindJoiningBaseStation<Waypoint, STR_ERROR_MUST_REMOVE_ROADWAYPOINT_FIRST>(existing_waypoint, waypoint_to_join, adjacent, ta, wp, [](const Waypoint *wp) -> bool { return HasBit(wp->waypoint_flags, WPF_ROAD); });
  } else {
    return FindJoiningBaseStation<Waypoint, STR_ERROR_MUST_REMOVE_RAILWAYPOINT_FIRST>(existing_waypoint, waypoint_to_join, adjacent, ta, wp, [](const Waypoint *wp) -> bool { return !HasBit(wp->waypoint_flags, WPF_ROAD); });
  }
}
 
static void FreeTrainReservation(Train *v)
{
  FreeTrainTrackReservation(v);
  if (IsRailStationTile(v->tile)) SetRailStationPlatformReservation(v->tile, TrackdirToExitdir(v->GetVehicleTrackdir()), false);
  v = v->Last();
  if (IsRailStationTile(v->tile)) SetRailStationPlatformReservation(v->tile, TrackdirToExitdir(ReverseTrackdir(v->GetVehicleTrackdir())), false);
}
 
static void RestoreTrainReservation(Train *v)
{
  if (IsRailStationTile(v->tile)) SetRailStationPlatformReservation(v->tile, TrackdirToExitdir(v->GetVehicleTrackdir()), true);
  TryPathReserve(v, true, true);
  v = v->Last();
  if (IsRailStationTile(v->tile)) SetRailStationPlatformReservation(v->tile, TrackdirToExitdir(ReverseTrackdir(v->GetVehicleTrackdir())), true);
}
 
static CommandCost CalculateRailStationCost(TileArea tile_area, DoCommandFlags flags, Axis axis, StationID *station, RailType rt, std::vector<Train *> &affected_vehicles, StationClassID spec_class, uint16_t spec_index, uint8_t plat_len, uint8_t numtracks)
{
  CommandCost cost(EXPENSES_CONSTRUCTION);
  bool length_price_ready = true;
  uint8_t tracknum = 0;
  int allowed_z = -1;
  for (TileIndex cur_tile : tile_area) {
    /* Clear the land below the station. */
    CommandCost ret = CheckFlatLandRailStation(cur_tile, tile_area.tile, allowed_z, flags, axis, station, rt, affected_vehicles, spec_class, spec_index, plat_len, numtracks);
    if (ret.Failed()) return ret;
 
    /* Only add _price[PR_BUILD_STATION_RAIL_LENGTH] once for each valid plat_len. */
    if (tracknum == numtracks) {
      length_price_ready = true;
      tracknum = 0;
    } else {
      tracknum++;
    }
 
    /* AddCost for new or rotated rail stations. */
    if (!IsRailStationTile(cur_tile) || (IsRailStationTile(cur_tile) && GetRailStationAxis(cur_tile) != axis)) {
      cost.AddCost(ret.GetCost());
      cost.AddCost(_price[PR_BUILD_STATION_RAIL]);
      cost.AddCost(RailBuildCost(rt));
 
      if (length_price_ready) {
        cost.AddCost(_price[PR_BUILD_STATION_RAIL_LENGTH]);
        length_price_ready = false;
      }
    }
  }
 
  return cost;
}
 
static StationSpec::TileFlags GetStationTileFlags(StationGfx gfx, const StationSpec *statspec)
{
  /* Default stations do not draw pylons under roofs (gfx >= 4) */
  if (statspec == nullptr || gfx >= statspec->tileflags.size()) return gfx < 4 ? StationSpec::TileFlag::Pylons : StationSpec::TileFlags{};
  return statspec->tileflags[gfx];
}
 
void SetRailStationTileFlags(TileIndex tile, const StationSpec *statspec)
{
  const auto flags = GetStationTileFlags(GetStationGfx(tile), statspec);
  SetStationTileBlocked(tile, flags.Test(StationSpec::TileFlag::Blocked));
  SetStationTileHavePylons(tile, flags.Test(StationSpec::TileFlag::Pylons));
  SetStationTileHaveWires(tile, !flags.Test(StationSpec::TileFlag::NoWires));
}
 
CommandCost CmdBuildRailStation(DoCommandFlags flags, TileIndex tile_org, RailType rt, Axis axis, uint8_t numtracks, uint8_t plat_len, StationClassID spec_class, uint16_t spec_index, StationID station_to_join, bool adjacent)
{
  /* Does the authority allow this? */
  CommandCost ret = CheckIfAuthorityAllowsNewStation(tile_org, flags);
  if (ret.Failed()) return ret;
 
  if (!ValParamRailType(rt) || !IsValidAxis(axis)) return CMD_ERROR;
 
  /* Check if the given station class is valid */
  if (static_cast<uint>(spec_class) >= StationClass::GetClassCount()) return CMD_ERROR;
  const StationClass *cls = StationClass::Get(spec_class);
  if (IsWaypointClass(*cls)) return CMD_ERROR;
  if (spec_index >= cls->GetSpecCount()) return CMD_ERROR;
  if (plat_len == 0 || numtracks == 0) return CMD_ERROR;
 
  int w_org, h_org;
  if (axis == AXIS_X) {
    w_org = plat_len;
    h_org = numtracks;
  } else {
    h_org = plat_len;
    w_org = numtracks;
  }
 
  /* Check if the first tile and the last tile are valid */
  if (!IsValidTile(tile_org) || TileAddWrap(tile_org, w_org - 1, h_org - 1) == INVALID_TILE) return CMD_ERROR;
 
  bool reuse = (station_to_join != NEW_STATION);
  if (!reuse) station_to_join = StationID::Invalid();
  bool distant_join = (station_to_join != StationID::Invalid());
 
  if (distant_join && (!_settings_game.station.distant_join_stations || !Station::IsValidID(station_to_join))) return CMD_ERROR;
 
  if (h_org > _settings_game.station.station_spread || w_org > _settings_game.station.station_spread) return CMD_ERROR;
 
  /* these values are those that will be stored in train_tile and station_platforms */
  TileArea new_location(tile_org, w_org, h_org);
 
  /* Make sure the area below consists of clear tiles. (OR tiles belonging to a certain rail station) */
  StationID est = StationID::Invalid();
  std::vector<Train *> affected_vehicles;
  /* Add construction and clearing expenses. */
  CommandCost cost = CalculateRailStationCost(new_location, flags, axis, &est, rt, affected_vehicles, spec_class, spec_index, plat_len, numtracks);
  if (cost.Failed()) return cost;
 
  Station *st = nullptr;
  ret = FindJoiningStation(est, station_to_join, adjacent, new_location, &st);
  if (ret.Failed()) return ret;
 
  ret = BuildStationPart(&st, flags, reuse, new_location, STATIONNAMING_RAIL);
  if (ret.Failed()) return ret;
 
  if (st != nullptr && st->train_station.tile != INVALID_TILE) {
    ret = CanExpandRailStation(st, new_location);
    if (ret.Failed()) return ret;
  }
 
  const StationSpec *statspec = StationClass::Get(spec_class)->GetSpec(spec_index);
  TileIndexDiff tile_delta = TileOffsByAxis(axis); // offset to go to the next platform tile
  TileIndexDiff track_delta = TileOffsByAxis(OtherAxis(axis)); // offset to go to the next track
 
  RailStationTileLayout stl{statspec, numtracks, plat_len};
  for (auto [i, it, tile_track] = std::make_tuple(0, stl.begin(), tile_org); i != numtracks; ++i, tile_track += track_delta) {
    for (auto [j, tile] = std::make_tuple(0, tile_track); j != plat_len; ++j, tile += tile_delta, ++it) {
      /* Don't check the layout if there's no bridge above anyway. */
      if (!IsBridgeAbove(tile)) continue;
 
      StationGfx gfx = *it + axis;
      if (statspec != nullptr) {
        uint32_t platinfo = GetPlatformInfo(AXIS_X, gfx, plat_len, numtracks, j, i, false);
        /* As the station is not yet completely finished, the station does not yet exist. */
        uint16_t callback = GetStationCallback(CBID_STATION_BUILD_TILE_LAYOUT, platinfo, 0, statspec, nullptr, INVALID_TILE);
        if (callback != CALLBACK_FAILED && callback <= UINT8_MAX) gfx = (callback & ~1) + axis;
      }
 
      ret = IsRailStationBridgeAboveOk(tile, statspec, StationType::Rail, gfx);
      if (ret.Failed()) return ret;
    }
  }
 
  /* Check if we can allocate a custom stationspec to this station */
  auto specindex = AllocateSpecToStation(statspec, st);
  if (!specindex.has_value()) return CommandCost(STR_ERROR_TOO_MANY_STATION_SPECS);
 
  if (statspec != nullptr) {
    /* Perform NewStation checks */
 
    /* Check if the station size is permitted */
    if (HasBit(statspec->disallowed_platforms, std::min(numtracks - 1, 7))) return CommandCost(STR_ERROR_STATION_DISALLOWED_NUMBER_TRACKS);
    if (HasBit(statspec->disallowed_lengths, std::min(plat_len - 1, 7))) return CommandCost(STR_ERROR_STATION_DISALLOWED_LENGTH);
 
    /* Check if the station is buildable */
    if (statspec->callback_mask.Test(StationCallbackMask::Avail)) {
      uint16_t cb_res = GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, nullptr, INVALID_TILE);
      if (cb_res != CALLBACK_FAILED && !Convert8bitBooleanCallback(statspec->grf_prop.grffile, CBID_STATION_AVAILABILITY, cb_res)) return CMD_ERROR;
    }
  }
 
  if (flags.Test(DoCommandFlag::Execute)) {
    st->train_station = new_location;
    st->AddFacility(StationFacility::Train, new_location.tile);
 
    st->rect.BeforeAddRect(tile_org, w_org, h_org, StationRect::ADD_TRY);
 
    if (specindex.has_value()) AssignSpecToStation(statspec, st, *specindex);
    if (statspec != nullptr) {
      /* Include this station spec's animation trigger bitmask
       * in the station's cached copy. */
      st->cached_anim_triggers.Set(statspec->animation.triggers);
    }
 
    Track track = AxisToTrack(axis);
    Company *c = Company::Get(st->owner);
    for (auto [i, it, tile_track] = std::make_tuple(0, stl.begin(), tile_org); i != numtracks; ++i, tile_track += track_delta) {
      for (auto [j, tile] = std::make_tuple(0, tile_track); j != plat_len; ++j, tile += tile_delta, ++it) {
        if (IsRailStationTile(tile) && HasStationReservation(tile)) {
          /* Check for trains having a reservation for this tile. */
          Train *v = GetTrainForReservation(tile, AxisToTrack(GetRailStationAxis(tile)));
          if (v != nullptr) {
            affected_vehicles.push_back(v);
            FreeTrainReservation(v);
          }
        }
 
        /* Railtype can change when overbuilding. */
        if (IsRailStationTile(tile)) {
          if (!IsStationTileBlocked(tile)) c->infrastructure.rail[GetRailType(tile)]--;
          c->infrastructure.station--;
        }
 
        /* Remove animation if overbuilding */
        DeleteAnimatedTile(tile);
        uint8_t old_specindex = HasStationTileRail(tile) ? GetCustomStationSpecIndex(tile) : 0;
 
        MakeRailStation(tile, st->owner, st->index, axis, *it, rt);
        /* Free the spec if we overbuild something */
        DeallocateSpecFromStation(st, old_specindex);
        if (statspec == nullptr) DeleteNewGRFInspectWindow(GSF_STATIONS, tile);
 
        SetCustomStationSpecIndex(tile, *specindex);
        SetStationTileRandomBits(tile, GB(Random(), 0, 4));
        SetAnimationFrame(tile, 0);
 
        if (statspec != nullptr) {
          /* Use a fixed axis for GetPlatformInfo as our platforms / numtracks are always the right way around */
          uint32_t platinfo = GetPlatformInfo(AXIS_X, GetStationGfx(tile), plat_len, numtracks, j, i, false);
 
          /* As the station is not yet completely finished, the station does not yet exist. */
          uint16_t callback = GetStationCallback(CBID_STATION_BUILD_TILE_LAYOUT, platinfo, 0, statspec, nullptr, tile);
          if (callback != CALLBACK_FAILED) {
            if (callback <= UINT8_MAX) {
              SetStationGfx(tile, (callback & ~1) + axis);
            } else {
              ErrorUnknownCallbackResult(statspec->grf_prop.grfid, CBID_STATION_BUILD_TILE_LAYOUT, callback);
            }
          }
 
          /* Trigger station animation -- after building? */
          TriggerStationAnimation(st, tile, StationAnimationTrigger::Built);
        }
 
        SetRailStationTileFlags(tile, statspec);
 
        if (!IsStationTileBlocked(tile)) c->infrastructure.rail[rt]++;
        c->infrastructure.station++;
      }
      AddTrackToSignalBuffer(tile_track, track, _current_company);
      YapfNotifyTrackLayoutChange(tile_track, track);
    }
 
    for (uint i = 0; i < affected_vehicles.size(); ++i) {
      /* Restore reservations of trains. */
      RestoreTrainReservation(affected_vehicles[i]);
    }
 
    /* Check whether we need to expand the reservation of trains already on the station. */
    TileArea update_reservation_area;
    if (axis == AXIS_X) {
      update_reservation_area = TileArea(tile_org, 1, numtracks);
    } else {
      update_reservation_area = TileArea(tile_org, numtracks, 1);
    }
 
    for (TileIndex tile : update_reservation_area) {
      /* Don't even try to make eye candy parts reserved. */
      if (IsStationTileBlocked(tile)) continue;
 
      DiagDirection dir = AxisToDiagDir(axis);
      TileIndexDiff tile_offset = TileOffsByDiagDir(dir);
      TileIndex platform_begin = tile;
      TileIndex platform_end = tile;
 
      /* We can only account for tiles that are reachable from this tile, so ignore primarily blocked tiles while finding the platform begin and end. */
      for (TileIndex next_tile = platform_begin - tile_offset; IsCompatibleTrainStationTile(next_tile, platform_begin); next_tile -= tile_offset) {
        platform_begin = next_tile;
      }
      for (TileIndex next_tile = platform_end + tile_offset; IsCompatibleTrainStationTile(next_tile, platform_end); next_tile += tile_offset) {
        platform_end = next_tile;
      }
 
      /* If there is at least on reservation on the platform, we reserve the whole platform. */
      bool reservation = false;
      for (TileIndex t = platform_begin; !reservation && t <= platform_end; t += tile_offset) {
        reservation = HasStationReservation(t);
      }
 
      if (reservation) {
        SetRailStationPlatformReservation(platform_begin, dir, true);
      }
    }
 
    st->MarkTilesDirty(false);
    st->AfterStationTileSetChange(true, StationType::Rail);
  }
 
  return cost;
}
 
static TileArea MakeStationAreaSmaller(BaseStation *st, TileArea ta, bool (*func)(BaseStation *, TileIndex))
{
restart:
 
  /* too small? */
  if (ta.w != 0 && ta.h != 0) {
    /* check the left side, x = constant, y changes */
    for (uint i = 0; !func(st, ta.tile + TileDiffXY(0, i));) {
      /* the left side is unused? */
      if (++i == ta.h) {
        ta.tile += TileDiffXY(1, 0);
        ta.w--;
        goto restart;
      }
    }
 
    /* check the right side, x = constant, y changes */
    for (uint i = 0; !func(st, ta.tile + TileDiffXY(ta.w - 1, i));) {
      /* the right side is unused? */
      if (++i == ta.h) {
        ta.w--;
        goto restart;
      }
    }
 
    /* check the upper side, y = constant, x changes */
    for (uint i = 0; !func(st, ta.tile + TileDiffXY(i, 0));) {
      /* the left side is unused? */
      if (++i == ta.w) {
        ta.tile += TileDiffXY(0, 1);
        ta.h--;
        goto restart;
      }
    }
 
    /* check the lower side, y = constant, x changes */
    for (uint i = 0; !func(st, ta.tile + TileDiffXY(i, ta.h - 1));) {
      /* the left side is unused? */
      if (++i == ta.w) {
        ta.h--;
        goto restart;
      }
    }
  } else {
    ta.Clear();
  }
 
  return ta;
}
 
static bool TileBelongsToRailStation(BaseStation *st, TileIndex tile)
{
  return st->TileBelongsToRailStation(tile);
}
 
static void MakeRailStationAreaSmaller(BaseStation *st)
{
  st->train_station = MakeStationAreaSmaller(st, st->train_station, TileBelongsToRailStation);
}
 
static bool TileBelongsToShipStation(BaseStation *st, TileIndex tile)
{
  return IsDockTile(tile) && GetStationIndex(tile) == st->index;
}
 
static void MakeShipStationAreaSmaller(Station *st)
{
  st->ship_station = MakeStationAreaSmaller(st, st->ship_station, TileBelongsToShipStation);
  UpdateStationDockingTiles(st);
}
 
static bool TileBelongsToRoadWaypointStation(BaseStation *st, TileIndex tile)
{
  return IsRoadWaypointTile(tile) && GetStationIndex(tile) == st->index;
}
 
void MakeRoadWaypointStationAreaSmaller(BaseStation *st, TileArea &road_waypoint_area)
{
  road_waypoint_area = MakeStationAreaSmaller(st, road_waypoint_area, TileBelongsToRoadWaypointStation);
}
 
template <class T>
CommandCost RemoveFromRailBaseStation(TileArea ta, std::vector<T *> &affected_stations, DoCommandFlags flags, Money removal_cost, bool keep_rail)
{
  /* Count of the number of tiles removed */
  int quantity = 0;
  CommandCost total_cost(EXPENSES_CONSTRUCTION);
  /* Accumulator for the errors seen during clearing. If no errors happen,
   * and the quantity is 0 there is no station. Otherwise it will be one
   * of the other error that got accumulated. */
  CommandCost error;
 
  /* Do the action for every tile into the area */
  for (TileIndex tile : ta) {
    /* Make sure the specified tile is a rail station */
    if (!HasStationTileRail(tile)) continue;
 
    /* If there is a vehicle on ground, do not allow to remove (flood) the tile */
    CommandCost ret = EnsureNoVehicleOnGround(tile);
    error.AddCost(std::move(ret));
    if (error.Failed()) continue;
 
    /* Check ownership of station */
    T *st = T::GetByTile(tile);
    if (st == nullptr) continue;
 
    if (_current_company != OWNER_WATER) {
      ret = CheckOwnership(st->owner);
      error.AddCost(std::move(ret));
      if (error.Failed()) continue;
    }
 
    /* If we reached here, the tile is valid so increase the quantity of tiles we will remove */
    quantity++;
 
    if (keep_rail || IsStationTileBlocked(tile)) {
      /* Don't refund the 'steel' of the track when we keep the
       *  rail, or when the tile didn't have any rail at all. */
      total_cost.AddCost(-_price[PR_CLEAR_RAIL]);
    }
 
    if (flags.Test(DoCommandFlag::Execute)) {
      /* read variables before the station tile is removed */
      uint specindex = GetCustomStationSpecIndex(tile);
      Track track = GetRailStationTrack(tile);
      Owner owner = GetTileOwner(tile);
      RailType rt = GetRailType(tile);
      Train *v = nullptr;
 
      if (HasStationReservation(tile)) {
        v = GetTrainForReservation(tile, track);
        if (v != nullptr) FreeTrainReservation(v);
      }
 
      bool build_rail = keep_rail && !IsStationTileBlocked(tile);
      if (!build_rail && !IsStationTileBlocked(tile)) Company::Get(owner)->infrastructure.rail[rt]--;
 
      DoClearSquare(tile);
      DeleteNewGRFInspectWindow(GSF_STATIONS, tile.base());
      if (build_rail) MakeRailNormal(tile, owner, TrackToTrackBits(track), rt);
      Company::Get(owner)->infrastructure.station--;
      DirtyCompanyInfrastructureWindows(owner);
 
      st->rect.AfterRemoveTile(st, tile);
      AddTrackToSignalBuffer(tile, track, owner);
      YapfNotifyTrackLayoutChange(tile, track);
 
      DeallocateSpecFromStation(st, specindex);
 
      include(affected_stations, st);
 
      if (v != nullptr) RestoreTrainReservation(v);
    }
  }
 
  if (quantity == 0) return error.Failed() ? error : CommandCost(STR_ERROR_THERE_IS_NO_STATION);
 
  for (T *st : affected_stations) {
 
    /* now we need to make the "spanned" area of the railway station smaller
     * if we deleted something at the edges.
     * we also need to adjust train_tile. */
    MakeRailStationAreaSmaller(st);
    UpdateStationSignCoord(st);
 
    /* if we deleted the whole station, delete the train facility. */
    if (st->train_station.tile == INVALID_TILE) {
      st->facilities.Reset(StationFacility::Train);
      SetWindowClassesDirty(WC_VEHICLE_ORDERS);
      SetWindowWidgetDirty(WC_STATION_VIEW, st->index, WID_SV_TRAINS);
      MarkCatchmentTilesDirty();
      st->UpdateVirtCoord();
      DeleteStationIfEmpty(st);
    }
  }
 
  total_cost.AddCost(quantity * removal_cost);
  return total_cost;
}
 
CommandCost CmdRemoveFromRailStation(DoCommandFlags flags, TileIndex start, TileIndex end, bool keep_rail)
{
  if (end == 0) end = start;
  if (start >= Map::Size() || end >= Map::Size()) return CMD_ERROR;
 
  TileArea ta(start, end);
  std::vector<Station *> affected_stations;
 
  CommandCost ret = RemoveFromRailBaseStation(ta, affected_stations, flags, _price[PR_CLEAR_STATION_RAIL], keep_rail);
  if (ret.Failed()) return ret;
 
  /* Do all station specific functions here. */
  for (Station *st : affected_stations) {
 
    if (st->train_station.tile == INVALID_TILE) SetWindowWidgetDirty(WC_STATION_VIEW, st->index, WID_SV_TRAINS);
    st->MarkTilesDirty(false);
    MarkCatchmentTilesDirty();
    st->RecomputeCatchment();
  }
 
  /* Now apply the rail cost to the number that we deleted */
  return ret;
}
 
CommandCost CmdRemoveFromRailWaypoint(DoCommandFlags flags, TileIndex start, TileIndex end, bool keep_rail)
{
  if (end == 0) end = start;
  if (start >= Map::Size() || end >= Map::Size()) return CMD_ERROR;
 
  TileArea ta(start, end);
  std::vector<Waypoint *> affected_stations;
 
  return RemoveFromRailBaseStation(ta, affected_stations, flags, _price[PR_CLEAR_WAYPOINT_RAIL], keep_rail);
}
 
 
template <class T>
CommandCost RemoveRailStation(T *st, DoCommandFlags flags, Money removal_cost)
{
  /* Current company owns the station? */
  if (_current_company != OWNER_WATER) {
    CommandCost ret = CheckOwnership(st->owner);
    if (ret.Failed()) return ret;
  }
 
  /* determine width and height of platforms */
  TileArea ta = st->train_station;
 
  assert(ta.w != 0 && ta.h != 0);
 
  CommandCost cost(EXPENSES_CONSTRUCTION);
  /* clear all areas of the station */
  for (TileIndex tile : ta) {
    /* only remove tiles that are actually train station tiles */
    if (st->TileBelongsToRailStation(tile)) {
      std::vector<T*> affected_stations; // dummy
      CommandCost ret = RemoveFromRailBaseStation(TileArea(tile, 1, 1), affected_stations, flags, removal_cost, false);
      if (ret.Failed()) return ret;
      cost.AddCost(ret.GetCost());
    }
  }
 
  return cost;
}
 
static CommandCost RemoveRailStation(TileIndex tile, DoCommandFlags flags)
{
  /* if there is flooding, remove platforms tile by tile */
  if (_current_company == OWNER_WATER) {
    return Command<CMD_REMOVE_FROM_RAIL_STATION>::Do(DoCommandFlag::Execute, tile, TileIndex{}, false);
  }
 
  Station *st = Station::GetByTile(tile);
  CommandCost cost = RemoveRailStation(st, flags, _price[PR_CLEAR_STATION_RAIL]);
 
  if (flags.Test(DoCommandFlag::Execute)) st->RecomputeCatchment();
 
  return cost;
}
 
static CommandCost RemoveRailWaypoint(TileIndex tile, DoCommandFlags flags)
{
  /* if there is flooding, remove waypoints tile by tile */
  if (_current_company == OWNER_WATER) {
    return Command<CMD_REMOVE_FROM_RAIL_WAYPOINT>::Do(DoCommandFlag::Execute, tile, TileIndex{}, false);
  }
 
  return RemoveRailStation(Waypoint::GetByTile(tile), flags, _price[PR_CLEAR_WAYPOINT_RAIL]);
}
 
 
static RoadStop **FindRoadStopSpot(bool truck_station, Station *st)
{
  RoadStop **primary_stop = (truck_station) ? &st->truck_stops : &st->bus_stops;
 
  if (*primary_stop == nullptr) {
    /* we have no roadstop of the type yet, so write a "primary stop" */
    return primary_stop;
  } else {
    /* there are stops already, so append to the end of the list */
    RoadStop *stop = *primary_stop;
    while (stop->next != nullptr) stop = stop->next;
    return &stop->next;
  }
}
 
static CommandCost RemoveRoadStop(TileIndex tile, DoCommandFlags flags, int replacement_spec_index = -1);
CommandCost RemoveRoadWaypointStop(TileIndex tile, DoCommandFlags flags, int replacement_spec_index = -1);
 
static CommandCost FindJoiningRoadStop(StationID existing_stop, StationID station_to_join, bool adjacent, TileArea ta, Station **st)
{
  return FindJoiningBaseStation<Station, STR_ERROR_MUST_REMOVE_ROAD_STOP_FIRST>(existing_stop, station_to_join, adjacent, ta, st, [](const Station *) -> bool { return true; });
}
 
CommandCost CalculateRoadStopCost(TileArea tile_area, DoCommandFlags flags, bool is_drive_through, StationType station_type, const RoadStopSpec *roadstopspec, Axis axis, DiagDirection ddir, StationID *est, RoadType rt, Money unit_cost)
{
  DiagDirections invalid_dirs{};
  if (is_drive_through) {
    invalid_dirs.Set(AxisToDiagDir(axis));
    invalid_dirs.Set(ReverseDiagDir(AxisToDiagDir(axis)));
  } else {
    invalid_dirs.Set(ddir);
  }
 
  /* Check every tile in the area. */
  int allowed_z = -1;
  CommandCost cost(EXPENSES_CONSTRUCTION);
  for (TileIndex cur_tile : tile_area) {
    CommandCost ret = CheckFlatLandRoadStop(cur_tile, allowed_z, roadstopspec, flags, invalid_dirs, is_drive_through, station_type, axis, est, rt);
    if (ret.Failed()) return ret;
 
    bool is_preexisting_roadstop = IsTileType(cur_tile, MP_STATION) && IsAnyRoadStop(cur_tile);
 
    /* Only add costs if a stop doesn't already exist in the location */
    if (!is_preexisting_roadstop) {
      cost.AddCost(ret.GetCost());
      cost.AddCost(unit_cost);
    }
  }
 
  return cost;
}
 
CommandCost CmdBuildRoadStop(DoCommandFlags flags, TileIndex tile, uint8_t width, uint8_t length, RoadStopType stop_type, bool is_drive_through,
    DiagDirection ddir, RoadType rt, RoadStopClassID spec_class, uint16_t spec_index, StationID station_to_join, bool adjacent)
{
  if (!ValParamRoadType(rt) || !IsValidDiagDirection(ddir) || stop_type >= RoadStopType::End) return CMD_ERROR;
  bool reuse = (station_to_join != NEW_STATION);
  if (!reuse) station_to_join = StationID::Invalid();
  bool distant_join = (station_to_join != StationID::Invalid());
 
  /* Check if the given station class is valid */
  if (static_cast<uint>(spec_class) >= RoadStopClass::GetClassCount()) return CMD_ERROR;
  const RoadStopClass *cls = RoadStopClass::Get(spec_class);
  if (IsWaypointClass(*cls)) return CMD_ERROR;
  if (spec_index >= cls->GetSpecCount()) return CMD_ERROR;
 
  const RoadStopSpec *roadstopspec = cls->GetSpec(spec_index);
  if (roadstopspec != nullptr) {
    if (stop_type == RoadStopType::Truck && roadstopspec->stop_type != ROADSTOPTYPE_FREIGHT && roadstopspec->stop_type != ROADSTOPTYPE_ALL) return CMD_ERROR;
    if (stop_type == RoadStopType::Bus && roadstopspec->stop_type != ROADSTOPTYPE_PASSENGER && roadstopspec->stop_type != ROADSTOPTYPE_ALL) return CMD_ERROR;
    if (!is_drive_through && roadstopspec->flags.Test(RoadStopSpecFlag::DriveThroughOnly)) return CMD_ERROR;
  }
 
  /* Check if the requested road stop is too big */
  if (width > _settings_game.station.station_spread || length > _settings_game.station.station_spread) return CommandCost(STR_ERROR_STATION_TOO_SPREAD_OUT);
  /* Check for incorrect width / length. */
  if (width == 0 || length == 0) return CMD_ERROR;
  /* Check if the first tile and the last tile are valid */
  if (!IsValidTile(tile) || TileAddWrap(tile, width - 1, length - 1) == INVALID_TILE) return CMD_ERROR;
 
  TileArea roadstop_area(tile, width, length);
 
  if (distant_join && (!_settings_game.station.distant_join_stations || !Station::IsValidID(station_to_join))) return CMD_ERROR;
 
  /* Trams only have drive through stops */
  if (!is_drive_through && RoadTypeIsTram(rt)) return CMD_ERROR;
 
  Axis axis = DiagDirToAxis(ddir);
 
  CommandCost ret = CheckIfAuthorityAllowsNewStation(tile, flags);
  if (ret.Failed()) return ret;
 
  bool is_truck_stop = stop_type != RoadStopType::Bus;
 
  /* Total road stop cost. */
  Money unit_cost;
  if (roadstopspec != nullptr) {
    unit_cost = roadstopspec->GetBuildCost(is_truck_stop ? PR_BUILD_STATION_TRUCK : PR_BUILD_STATION_BUS);
  } else {
    unit_cost = _price[is_truck_stop ? PR_BUILD_STATION_TRUCK : PR_BUILD_STATION_BUS];
  }
  StationID est = StationID::Invalid();
  CommandCost cost = CalculateRoadStopCost(roadstop_area, flags, is_drive_through, is_truck_stop ? StationType::Truck : StationType::Bus, roadstopspec, axis, ddir, &est, rt, unit_cost);
  if (cost.Failed()) return cost;
 
  Station *st = nullptr;
  ret = FindJoiningRoadStop(est, station_to_join, adjacent, roadstop_area, &st);
  if (ret.Failed()) return ret;
 
  /* Check if this number of road stops can be allocated. */
  if (!RoadStop::CanAllocateItem(static_cast<size_t>(roadstop_area.w) * roadstop_area.h)) return CommandCost(is_truck_stop ? STR_ERROR_TOO_MANY_TRUCK_STOPS : STR_ERROR_TOO_MANY_BUS_STOPS);
 
  ret = BuildStationPart(&st, flags, reuse, roadstop_area, STATIONNAMING_ROAD);
  if (ret.Failed()) return ret;
 
  /* Check if we can allocate a custom stationspec to this station */
  auto specindex = AllocateSpecToRoadStop(roadstopspec, st);
  if (!specindex.has_value()) return CommandCost(STR_ERROR_TOO_MANY_STATION_SPECS);
 
  if (roadstopspec != nullptr) {
    /* Perform NewGRF checks */
 
    /* Check if the road stop is buildable */
    if (roadstopspec->callback_mask.Test(RoadStopCallbackMask::Avail)) {
      uint16_t cb_res = GetRoadStopCallback(CBID_STATION_AVAILABILITY, 0, 0, roadstopspec, nullptr, INVALID_TILE, rt, is_truck_stop ? StationType::Truck : StationType::Bus, 0);
      if (cb_res != CALLBACK_FAILED && !Convert8bitBooleanCallback(roadstopspec->grf_prop.grffile, CBID_STATION_AVAILABILITY, cb_res)) return CMD_ERROR;
    }
  }
 
  if (flags.Test(DoCommandFlag::Execute)) {
    if (specindex.has_value()) AssignSpecToRoadStop(roadstopspec, st, *specindex);
    /* Check every tile in the area. */
    for (TileIndex cur_tile : roadstop_area) {
      /* Get existing road types and owners before any tile clearing */
      RoadType road_rt = MayHaveRoad(cur_tile) ? GetRoadType(cur_tile, RTT_ROAD) : INVALID_ROADTYPE;
      RoadType tram_rt = MayHaveRoad(cur_tile) ? GetRoadType(cur_tile, RTT_TRAM) : INVALID_ROADTYPE;
      Owner road_owner = road_rt != INVALID_ROADTYPE ? GetRoadOwner(cur_tile, RTT_ROAD) : _current_company;
      Owner tram_owner = tram_rt != INVALID_ROADTYPE ? GetRoadOwner(cur_tile, RTT_TRAM) : _current_company;
 
      if (IsTileType(cur_tile, MP_STATION) && IsStationRoadStop(cur_tile)) {
        RemoveRoadStop(cur_tile, flags, *specindex);
      }
 
      if (roadstopspec != nullptr) {
        /* Include this road stop spec's animation trigger bitmask
         * in the station's cached copy. */
        st->cached_roadstop_anim_triggers.Set(roadstopspec->animation.triggers);
      }
 
      RoadStop *road_stop = RoadStop::Create(cur_tile);
      /* Insert into linked list of RoadStops. */
      RoadStop **currstop = FindRoadStopSpot(is_truck_stop, st);
      *currstop = road_stop;
 
      if (is_truck_stop) {
        st->truck_station.Add(cur_tile);
      } else {
        st->bus_station.Add(cur_tile);
      }
 
      /* Initialize an empty station. */
      st->AddFacility(is_truck_stop ? StationFacility::TruckStop : StationFacility::BusStop, cur_tile);
 
      st->rect.BeforeAddTile(cur_tile, StationRect::ADD_TRY);
 
      RoadStopType rs_type = is_truck_stop ? RoadStopType::Truck : RoadStopType::Bus;
      if (is_drive_through) {
        /* Update company infrastructure counts. If the current tile is a normal road tile, remove the old
         * bits first. */
        if (IsNormalRoadTile(cur_tile)) {
          UpdateCompanyRoadInfrastructure(road_rt, road_owner, -(int)CountBits(GetRoadBits(cur_tile, RTT_ROAD)));
          UpdateCompanyRoadInfrastructure(tram_rt, tram_owner, -(int)CountBits(GetRoadBits(cur_tile, RTT_TRAM)));
        }
 
        if (road_rt == INVALID_ROADTYPE && RoadTypeIsRoad(rt)) road_rt = rt;
        if (tram_rt == INVALID_ROADTYPE && RoadTypeIsTram(rt)) tram_rt = rt;
 
        MakeDriveThroughRoadStop(cur_tile, st->owner, road_owner, tram_owner, st->index, (rs_type == RoadStopType::Bus ? StationType::Bus : StationType::Truck), road_rt, tram_rt, axis);
        road_stop->MakeDriveThrough();
      } else {
        if (road_rt == INVALID_ROADTYPE && RoadTypeIsRoad(rt)) road_rt = rt;
        if (tram_rt == INVALID_ROADTYPE && RoadTypeIsTram(rt)) tram_rt = rt;
        MakeRoadStop(cur_tile, st->owner, st->index, rs_type, road_rt, tram_rt, ddir);
      }
      UpdateCompanyRoadInfrastructure(road_rt, road_owner, ROAD_STOP_TRACKBIT_FACTOR);
      UpdateCompanyRoadInfrastructure(tram_rt, tram_owner, ROAD_STOP_TRACKBIT_FACTOR);
      Company::Get(st->owner)->infrastructure.station++;
 
      SetCustomRoadStopSpecIndex(cur_tile, *specindex);
      if (roadstopspec != nullptr) {
        st->SetRoadStopRandomBits(cur_tile, GB(Random(), 0, 8));
        TriggerRoadStopAnimation(st, cur_tile, StationAnimationTrigger::Built);
      }
 
      MarkTileDirtyByTile(cur_tile);
    }
 
    if (st != nullptr) {
      st->AfterStationTileSetChange(true, is_truck_stop ? StationType::Truck: StationType::Bus);
    }
  }
  return cost;
}
 
static CommandCost RemoveRoadStop(TileIndex tile, DoCommandFlags flags, int replacement_spec_index)
{
  Station *st = Station::GetByTile(tile);
 
  if (_current_company != OWNER_WATER) {
    CommandCost ret = CheckOwnership(st->owner);
    if (ret.Failed()) return ret;
  }
 
  bool is_truck = IsTruckStop(tile);
 
  RoadStop **primary_stop;
  RoadStop *cur_stop;
  if (is_truck) { // truck stop
    primary_stop = &st->truck_stops;
    cur_stop = RoadStop::GetByTile(tile, RoadStopType::Truck);
  } else {
    primary_stop = &st->bus_stops;
    cur_stop = RoadStop::GetByTile(tile, RoadStopType::Bus);
  }
 
  assert(cur_stop != nullptr);
 
  /* don't do the check for drive-through road stops when company bankrupts */
  if (IsDriveThroughStopTile(tile) && flags.Test(DoCommandFlag::Bankrupt)) {
    /* remove the 'going through road stop' status from all vehicles on that tile */
    if (flags.Test(DoCommandFlag::Execute)) {
      for (Vehicle *v : VehiclesOnTile(tile)) {
        if (v->type != VEH_ROAD) continue;
        /* Okay... we are a road vehicle on a drive through road stop.
         * But that road stop has just been removed, so we need to make
         * sure we are in a valid state... however, vehicles can also
         * turn on road stop tiles, so only clear the 'road stop' state
         * bits and only when the state was 'in road stop', otherwise
         * we'll end up clearing the turn around bits. */
        RoadVehicle *rv = RoadVehicle::From(v);
        if (HasBit(rv->state, RVS_IN_DT_ROAD_STOP)) rv->state &= RVSB_ROAD_STOP_TRACKDIR_MASK;
      }
    }
  } else {
    CommandCost ret = EnsureNoVehicleOnGround(tile);
    if (ret.Failed()) return ret;
  }
 
  const RoadStopSpec *spec = GetRoadStopSpec(tile);
 
  if (flags.Test(DoCommandFlag::Execute)) {
    if (*primary_stop == cur_stop) {
      /* removed the first stop in the list */
      *primary_stop = cur_stop->next;
      /* removed the only stop? */
      if (*primary_stop == nullptr) {
        st->facilities.Reset(is_truck ? StationFacility::TruckStop : StationFacility::BusStop);
        SetWindowClassesDirty(WC_VEHICLE_ORDERS);
      }
    } else {
      /* tell the predecessor in the list to skip this stop */
      RoadStop *pred = *primary_stop;
      while (pred->next != cur_stop) pred = pred->next;
      pred->next = cur_stop->next;
    }
 
    /* Update company infrastructure counts. */
    for (RoadTramType rtt : _roadtramtypes) {
      RoadType rt = GetRoadType(tile, rtt);
      UpdateCompanyRoadInfrastructure(rt, GetRoadOwner(tile, rtt), -static_cast<int>(ROAD_STOP_TRACKBIT_FACTOR));
    }
 
    Company::Get(st->owner)->infrastructure.station--;
    DirtyCompanyInfrastructureWindows(st->owner);
 
    uint specindex = GetCustomRoadStopSpecIndex(tile);
 
    DeleteNewGRFInspectWindow(GSF_ROADSTOPS, tile.base());
 
    if (IsDriveThroughStopTile(tile)) {
      /* Clears the tile for us */
      cur_stop->ClearDriveThrough();
      DeleteAnimatedTile(tile);
    } else {
      DoClearSquare(tile);
    }
 
    delete cur_stop;
 
    /* Make sure no vehicle is going to the old roadstop. Narrow the search to any road vehicles with an order to
     * this station, then look for any currently heading to the tile. */
    StationID station_id = st->index;
    FindVehiclesWithOrder(
      [](const Vehicle *v) { return v->type == VEH_ROAD; },
      [station_id](const Order *order) { return order->IsType(OT_GOTO_STATION) && order->GetDestination() == station_id; },
      [station_id, tile](Vehicle *v) {
        if (v->current_order.IsType(OT_GOTO_STATION) && v->dest_tile == tile) {
          v->SetDestTile(v->GetOrderStationLocation(station_id));
        }
      }
    );
 
    st->rect.AfterRemoveTile(st, tile);
 
    if (replacement_spec_index < 0) st->AfterStationTileSetChange(false, is_truck ? StationType::Truck: StationType::Bus);
 
    st->RemoveRoadStopTileData(tile);
    if ((int)specindex != replacement_spec_index) DeallocateSpecFromRoadStop(st, specindex);
 
    /* Update the tile area of the truck/bus stop */
    if (is_truck) {
      st->truck_station.Clear();
      for (const RoadStop *rs = st->truck_stops; rs != nullptr; rs = rs->next) st->truck_station.Add(rs->xy);
    } else {
      st->bus_station.Clear();
      for (const RoadStop *rs = st->bus_stops; rs != nullptr; rs = rs->next) st->bus_station.Add(rs->xy);
    }
  }
 
  Price category = is_truck ? PR_CLEAR_STATION_TRUCK : PR_CLEAR_STATION_BUS;
  return CommandCost(EXPENSES_CONSTRUCTION, spec != nullptr ? spec->GetClearCost(category) : _price[category]);
}
 
CommandCost RemoveRoadWaypointStop(TileIndex tile, DoCommandFlags flags, int replacement_spec_index)
{
  Waypoint *wp = Waypoint::GetByTile(tile);
 
  if (_current_company != OWNER_WATER) {
    CommandCost ret = CheckOwnership(wp->owner);
    if (ret.Failed()) return ret;
  }
 
  /* Ignore vehicles when the company goes bankrupt. The road will remain, any vehicles going to the waypoint will be removed. */
  if (!flags.Test(DoCommandFlag::Bankrupt)) {
    CommandCost ret = EnsureNoVehicleOnGround(tile);
    if (ret.Failed()) return ret;
  }
 
  const RoadStopSpec *spec = GetRoadStopSpec(tile);
 
  if (flags.Test(DoCommandFlag::Execute)) {
    /* Update company infrastructure counts. */
    for (RoadTramType rtt : _roadtramtypes) {
      RoadType rt = GetRoadType(tile, rtt);
      UpdateCompanyRoadInfrastructure(rt, GetRoadOwner(tile, rtt), -static_cast<int>(ROAD_STOP_TRACKBIT_FACTOR));
    }
 
    Company::Get(wp->owner)->infrastructure.station--;
    DirtyCompanyInfrastructureWindows(wp->owner);
 
    uint specindex = GetCustomRoadStopSpecIndex(tile);
 
    DeleteNewGRFInspectWindow(GSF_ROADSTOPS, tile.base());
 
    DoClearSquare(tile);
 
    wp->rect.AfterRemoveTile(wp, tile);
 
    wp->RemoveRoadStopTileData(tile);
    if ((int)specindex != replacement_spec_index) DeallocateSpecFromRoadStop(wp, specindex);
 
    if (replacement_spec_index < 0) {
      MakeRoadWaypointStationAreaSmaller(wp, wp->road_waypoint_area);
 
      UpdateStationSignCoord(wp);
 
      /* if we deleted the whole waypoint, delete the road facility. */
      if (wp->road_waypoint_area.tile == INVALID_TILE) {
        wp->facilities.Reset({StationFacility::BusStop, StationFacility::TruckStop});
        SetWindowWidgetDirty(WC_STATION_VIEW, wp->index, WID_SV_ROADVEHS);
        wp->UpdateVirtCoord();
        DeleteStationIfEmpty(wp);
      }
    }
  }
 
  return CommandCost(EXPENSES_CONSTRUCTION, spec != nullptr ? spec->GetClearCost(PR_CLEAR_STATION_TRUCK) : _price[PR_CLEAR_STATION_TRUCK]);
}
 
static CommandCost RemoveGenericRoadStop(DoCommandFlags flags, const TileArea &roadstop_area, bool road_waypoint, bool remove_road)
{
  CommandCost cost(EXPENSES_CONSTRUCTION);
  CommandCost last_error(STR_ERROR_THERE_IS_NO_STATION);
  bool had_success = false;
 
  for (TileIndex cur_tile : roadstop_area) {
    /* Make sure the specified tile is a road stop of the correct type */
    if (!IsTileType(cur_tile, MP_STATION) || !IsAnyRoadStop(cur_tile) || IsRoadWaypoint(cur_tile) != road_waypoint) continue;
 
    /* Save information on to-be-restored roads before the stop is removed. */
    RoadBits road_bits = ROAD_NONE;
    RoadType road_type[] = { INVALID_ROADTYPE, INVALID_ROADTYPE };
    Owner road_owner[] = { OWNER_NONE, OWNER_NONE };
    if (IsDriveThroughStopTile(cur_tile)) {
      for (RoadTramType rtt : _roadtramtypes) {
        road_type[rtt] = GetRoadType(cur_tile, rtt);
        if (road_type[rtt] == INVALID_ROADTYPE) continue;
        road_owner[rtt] = GetRoadOwner(cur_tile, rtt);
        /* If we don't want to preserve our roads then restore only roads of others. */
        if (remove_road && road_owner[rtt] == _current_company) road_type[rtt] = INVALID_ROADTYPE;
      }
      road_bits = AxisToRoadBits(GetDriveThroughStopAxis(cur_tile));
    }
 
    CommandCost ret;
    if (road_waypoint) {
      ret = RemoveRoadWaypointStop(cur_tile, flags);
    } else {
      ret = RemoveRoadStop(cur_tile, flags);
    }
    if (ret.Failed()) {
      last_error = std::move(ret);
      continue;
    }
    cost.AddCost(ret.GetCost());
    had_success = true;
 
    /* Restore roads. */
    if (flags.Test(DoCommandFlag::Execute) && (road_type[RTT_ROAD] != INVALID_ROADTYPE || road_type[RTT_TRAM] != INVALID_ROADTYPE)) {
      MakeRoadNormal(cur_tile, road_bits, road_type[RTT_ROAD], road_type[RTT_TRAM], ClosestTownFromTile(cur_tile, UINT_MAX)->index,
          road_owner[RTT_ROAD], road_owner[RTT_TRAM]);
 
      /* Update company infrastructure counts. */
      int count = CountBits(road_bits);
      UpdateCompanyRoadInfrastructure(road_type[RTT_ROAD], road_owner[RTT_ROAD], count);
      UpdateCompanyRoadInfrastructure(road_type[RTT_TRAM], road_owner[RTT_TRAM], count);
    }
  }
 
  return had_success ? cost : last_error;
}
 
CommandCost CmdRemoveRoadStop(DoCommandFlags flags, TileIndex tile, uint8_t width, uint8_t height, RoadStopType stop_type, bool remove_road)
{
  if (stop_type >= RoadStopType::End) return CMD_ERROR;
  /* Check for incorrect width / height. */
  if (width == 0 || height == 0) return CMD_ERROR;
  /* Check if the first tile and the last tile are valid */
  if (!IsValidTile(tile) || TileAddWrap(tile, width - 1, height - 1) == INVALID_TILE) return CMD_ERROR;
  /* Bankrupting company is not supposed to remove roads, there may be road vehicles. */
  if (remove_road && flags.Test(DoCommandFlag::Bankrupt)) return CMD_ERROR;
 
  TileArea roadstop_area(tile, width, height);
 
  return RemoveGenericRoadStop(flags, roadstop_area, false, remove_road);
}
 
CommandCost CmdRemoveFromRoadWaypoint(DoCommandFlags flags, TileIndex start, TileIndex end)
{
  if (end == 0) end = start;
  if (start >= Map::Size() || end >= Map::Size()) return CMD_ERROR;
 
  TileArea roadstop_area(start, end);
 
  return RemoveGenericRoadStop(flags, roadstop_area, true, false);
}
 
uint8_t GetAirportNoiseLevelForDistance(const AirportSpec *as, uint distance)
{
  /* 0 cannot be accounted, and 1 is the lowest that can be reduced from town.
   * So no need to go any further*/
  if (as->noise_level < 2) return as->noise_level;
 
  /* The steps for measuring noise reduction are based on the "magical" (and arbitrary) 8 base distance
   * adding the town_council_tolerance 4 times, as a way to graduate, depending of the tolerance.
   * Basically, it says that the less tolerant a town is, the bigger the distance before
   * an actual decrease can be granted */
  uint8_t town_tolerance_distance = 8 + (_settings_game.difficulty.town_council_tolerance * 4);
 
  /* now, we want to have the distance segmented using the distance judged bareable by town
   * This will give us the coefficient of reduction the distance provides. */
  uint noise_reduction = distance / town_tolerance_distance;
 
  /* If the noise reduction equals the airport noise itself, don't give it for free.
   * Otherwise, simply reduce the airport's level. */
  return noise_reduction >= as->noise_level ? 1 : as->noise_level - noise_reduction;
}
 
Town *AirportGetNearestTown(const AirportSpec *as, Direction rotation, TileIndex tile, TileIterator &&it, uint &mindist)
{
  assert(Town::GetNumItems() > 0);
 
  Town *nearest = nullptr;
 
  auto width = as->size_x;
  auto height = as->size_y;
  if (rotation == DIR_E || rotation == DIR_W) std::swap(width, height);
 
  uint perimeter_min_x = TileX(tile);
  uint perimeter_min_y = TileY(tile);
  uint perimeter_max_x = perimeter_min_x + width - 1;
  uint perimeter_max_y = perimeter_min_y + height - 1;
 
  mindist = UINT_MAX - 1; // prevent overflow
 
  for (TileIndex cur_tile = *it; cur_tile != INVALID_TILE; cur_tile = ++it) {
    assert(IsInsideBS(TileX(cur_tile), perimeter_min_x, width));
    assert(IsInsideBS(TileY(cur_tile), perimeter_min_y, height));
    if (TileX(cur_tile) == perimeter_min_x || TileX(cur_tile) == perimeter_max_x || TileY(cur_tile) == perimeter_min_y || TileY(cur_tile) == perimeter_max_y) {
      Town *t = CalcClosestTownFromTile(cur_tile, mindist + 1);
      if (t == nullptr) continue;
 
      uint dist = DistanceManhattan(t->xy, cur_tile);
      if (dist == mindist && t->index < nearest->index) nearest = t;
      if (dist < mindist) {
        nearest = t;
        mindist = dist;
      }
    }
  }
 
  return nearest;
}
 
static Town *AirportGetNearestTown(const Station *st, uint &mindist)
{
  return AirportGetNearestTown(st->airport.GetSpec(), st->airport.rotation, st->airport.tile, AirportTileIterator(st), mindist);
}
 
 
void UpdateAirportsNoise()
{
  for (Town *t : Town::Iterate()) t->noise_reached = 0;
 
  for (const Station *st : Station::Iterate()) {
    if (st->airport.tile != INVALID_TILE && st->airport.type != AT_OILRIG) {
      uint dist;
      Town *nearest = AirportGetNearestTown(st, dist);
      nearest->noise_reached += GetAirportNoiseLevelForDistance(st->airport.GetSpec(), dist);
    }
  }
}
 
CommandCost CmdBuildAirport(DoCommandFlags flags, TileIndex tile, uint8_t airport_type, uint8_t layout, StationID station_to_join, bool allow_adjacent)
{
  bool reuse = (station_to_join != NEW_STATION);
  if (!reuse) station_to_join = StationID::Invalid();
  bool distant_join = (station_to_join != StationID::Invalid());
 
  if (distant_join && (!_settings_game.station.distant_join_stations || !Station::IsValidID(station_to_join))) return CMD_ERROR;
 
  if (airport_type >= NUM_AIRPORTS) return CMD_ERROR;
 
  CommandCost ret = CheckIfAuthorityAllowsNewStation(tile, flags);
  if (ret.Failed()) return ret;
 
  /* Check if a valid, buildable airport was chosen for construction */
  const AirportSpec *as = AirportSpec::Get(airport_type);
  if (!as->IsAvailable() || layout >= as->layouts.size()) return CMD_ERROR;
  if (!as->IsWithinMapBounds(layout, tile)) return CMD_ERROR;
 
  Direction rotation = as->layouts[layout].rotation;
  int w = as->size_x;
  int h = as->size_y;
  if (rotation == DIR_E || rotation == DIR_W) std::swap(w, h);
  TileArea airport_area = TileArea(tile, w, h);
 
  if (w > _settings_game.station.station_spread || h > _settings_game.station.station_spread) {
    return CommandCost(STR_ERROR_STATION_TOO_SPREAD_OUT);
  }
 
  AirportTileTableIterator tile_iter(as->layouts[layout].tiles, tile);
  CommandCost cost = CheckFlatLandAirport(tile_iter, flags);
  if (cost.Failed()) return cost;
 
  /* The noise level is the noise from the airport and reduce it to account for the distance to the town center. */
  uint dist;
  Town *nearest = AirportGetNearestTown(as, rotation, tile, std::move(tile_iter), dist);
  uint newnoise_level = GetAirportNoiseLevelForDistance(as, dist);
 
  /* Check if local auth would allow a new airport */
  StringID authority_refuse_message = STR_NULL;
  Town *authority_refuse_town = nullptr;
 
  if (_settings_game.economy.station_noise_level) {
    /* do not allow to build a new airport if this raise the town noise over the maximum allowed by town */
    if ((nearest->noise_reached + newnoise_level) > nearest->MaxTownNoise()) {
      authority_refuse_message = STR_ERROR_LOCAL_AUTHORITY_REFUSES_NOISE;
      authority_refuse_town = nearest;
    }
  } else if (_settings_game.difficulty.town_council_tolerance != TOWN_COUNCIL_PERMISSIVE) {
    Town *t = ClosestTownFromTile(tile, UINT_MAX);
    uint num = 0;
    for (const Station *st : Station::Iterate()) {
      if (st->town == t && st->facilities.Test(StationFacility::Airport) && st->airport.type != AT_OILRIG) num++;
    }
    if (num >= 2) {
      authority_refuse_message = STR_ERROR_LOCAL_AUTHORITY_REFUSES_AIRPORT;
      authority_refuse_town = t;
    }
  }
 
  if (authority_refuse_message != STR_NULL) {
    return CommandCostWithParam(authority_refuse_message, authority_refuse_town->index);
  }
 
  Station *st = nullptr;
  ret = FindJoiningStation(StationID::Invalid(), station_to_join, allow_adjacent, airport_area, &st);
  if (ret.Failed()) return ret;
 
  /* Distant join */
  if (st == nullptr && distant_join) st = Station::GetIfValid(station_to_join);
 
  ret = BuildStationPart(&st, flags, reuse, airport_area, GetAirport(airport_type)->flags.Test(AirportFTAClass::Flag::Airplanes) ? STATIONNAMING_AIRPORT : STATIONNAMING_HELIPORT);
  if (ret.Failed()) return ret;
 
  if (st != nullptr && st->airport.tile != INVALID_TILE) {
    return CommandCost(STR_ERROR_TOO_CLOSE_TO_ANOTHER_AIRPORT);
  }
 
  for (AirportTileTableIterator iter(as->layouts[layout].tiles, tile); iter != INVALID_TILE; ++iter) {
    cost.AddCost(_price[PR_BUILD_STATION_AIRPORT]);
  }
 
  if (flags.Test(DoCommandFlag::Execute)) {
    /* Always add the noise, so there will be no need to recalculate when option toggles */
    nearest->noise_reached += newnoise_level;
 
    st->AddFacility(StationFacility::Airport, tile);
    st->airport.type = airport_type;
    st->airport.layout = layout;
    st->airport.blocks = {};
    st->airport.rotation = rotation;
 
    st->rect.BeforeAddRect(tile, w, h, StationRect::ADD_TRY);
 
    for (AirportTileTableIterator iter(as->layouts[layout].tiles, tile); iter != INVALID_TILE; ++iter) {
      Tile t(iter);
      MakeAirport(t, st->owner, st->index, iter.GetStationGfx(), WaterClass::Invalid);
      SetStationTileRandomBits(t, GB(Random(), 0, 4));
      st->airport.Add(iter);
 
      if (AirportTileSpec::Get(GetTranslatedAirportTileID(iter.GetStationGfx()))->animation.status != AnimationStatus::NoAnimation) AddAnimatedTile(t);
    }
 
    /* Only call the animation trigger after all tiles have been built */
    for (AirportTileTableIterator iter(as->layouts[layout].tiles, tile); iter != INVALID_TILE; ++iter) {
      TriggerAirportTileAnimation(st, iter, AirportAnimationTrigger::Built);
    }
 
    UpdateAirplanesOnNewStation(st);
 
    Company::Get(st->owner)->infrastructure.airport++;
 
    st->AfterStationTileSetChange(true, StationType::Airport);
    InvalidateWindowData(WC_STATION_VIEW, st->index, -1);
 
    if (_settings_game.economy.station_noise_level) {
      SetWindowDirty(WC_TOWN_VIEW, nearest->index);
    }
  }
 
  return cost;
}
 
static CommandCost RemoveAirport(TileIndex tile, DoCommandFlags flags)
{
  Station *st = Station::GetByTile(tile);
 
  if (_current_company != OWNER_WATER) {
    CommandCost ret = CheckOwnership(st->owner);
    if (ret.Failed()) return ret;
  }
 
  tile = st->airport.tile;
 
  CommandCost cost(EXPENSES_CONSTRUCTION);
 
  for (const Aircraft *a : Aircraft::Iterate()) {
    if (!a->IsNormalAircraft()) continue;
    if (a->targetairport == st->index && a->state != FLYING) {
      return CommandCost(STR_ERROR_AIRCRAFT_IN_THE_WAY);
    }
  }
 
  if (flags.Test(DoCommandFlag::Execute)) {
    for (uint i = 0; i < st->airport.GetNumHangars(); ++i) {
      TileIndex tile_cur = st->airport.GetHangarTile(i);
      OrderBackup::Reset(tile_cur, false);
      CloseWindowById(WC_VEHICLE_DEPOT, tile_cur);
    }
 
    /* The noise level is the noise from the airport and reduce it to account for the distance to the town center.
     * And as for construction, always remove it, even if the setting is not set, in order to avoid the
     * need of recalculation */
    uint dist;
    Town *nearest = AirportGetNearestTown(st, dist);
    nearest->noise_reached -= GetAirportNoiseLevelForDistance(st->airport.GetSpec(), dist);
 
    if (_settings_game.economy.station_noise_level) {
      SetWindowDirty(WC_TOWN_VIEW, nearest->index);
    }
  }
 
  for (TileIndex tile_cur : st->airport) {
    if (!st->TileBelongsToAirport(tile_cur)) continue;
 
    CommandCost ret = EnsureNoVehicleOnGround(tile_cur);
    if (ret.Failed()) return ret;
 
    cost.AddCost(_price[PR_CLEAR_STATION_AIRPORT]);
 
    if (flags.Test(DoCommandFlag::Execute)) {
      DoClearSquare(tile_cur);
      DeleteNewGRFInspectWindow(GSF_AIRPORTTILES, tile_cur.base());
    }
  }
 
  if (flags.Test(DoCommandFlag::Execute)) {
    /* Clear the persistent storage. */
    delete st->airport.psa;
 
    st->rect.AfterRemoveRect(st, st->airport);
 
    st->airport.Clear();
    st->facilities.Reset(StationFacility::Airport);
    SetWindowClassesDirty(WC_VEHICLE_ORDERS);
 
    InvalidateWindowData(WC_STATION_VIEW, st->index, -1);
 
    Company::Get(st->owner)->infrastructure.airport--;
 
    st->AfterStationTileSetChange(false, StationType::Airport);
 
    DeleteNewGRFInspectWindow(GSF_AIRPORTS, st->index);
  }
 
  return cost;
}
 
CommandCost CmdOpenCloseAirport(DoCommandFlags flags, StationID station_id)
{
  if (!Station::IsValidID(station_id)) return CMD_ERROR;
  Station *st = Station::Get(station_id);
 
  if (!st->facilities.Test(StationFacility::Airport) || st->owner == OWNER_NONE) return CMD_ERROR;
 
  CommandCost ret = CheckOwnership(st->owner);
  if (ret.Failed()) return ret;
 
  if (flags.Test(DoCommandFlag::Execute)) {
    st->airport.blocks.Flip(AirportBlock::AirportClosed);
    SetWindowWidgetDirty(WC_STATION_VIEW, st->index, WID_SV_CLOSE_AIRPORT);
  }
  return CommandCost();
}
 
bool HasStationInUse(StationID station, bool include_company, CompanyID company)
{
  for (const OrderList *orderlist : OrderList::Iterate()) {
    const Vehicle *v = orderlist->GetFirstSharedVehicle();
    assert(v != nullptr);
    if ((v->owner == company) != include_company) continue;
 
    for (const Order &order : orderlist->GetOrders()) {
      if (order.GetDestination() == station && (order.IsType(OT_GOTO_STATION) || order.IsType(OT_GOTO_WAYPOINT))) {
        return true;
      }
    }
  }
  return false;
}
 
static const TileIndexDiffC _dock_tileoffs_chkaround[] = {
  {-1,  0},
  { 0,  0},
  { 0,  0},
  { 0, -1}
};
static const uint8_t _dock_w_chk[4] = { 2, 1, 2, 1 };
static const uint8_t _dock_h_chk[4] = { 1, 2, 1, 2 };
 
CommandCost CmdBuildDock(DoCommandFlags flags, TileIndex tile, StationID station_to_join, bool adjacent)
{
  bool reuse = (station_to_join != NEW_STATION);
  if (!reuse) station_to_join = StationID::Invalid();
  bool distant_join = (station_to_join != StationID::Invalid());
 
  if (distant_join && (!_settings_game.station.distant_join_stations || !Station::IsValidID(station_to_join))) return CMD_ERROR;
 
  DiagDirection direction = GetInclinedSlopeDirection(GetTileSlope(tile));
  if (direction == INVALID_DIAGDIR) return CommandCost(STR_ERROR_SITE_UNSUITABLE);
  direction = ReverseDiagDir(direction);
 
  /* Docks cannot be placed on rapids */
  if (HasTileWaterGround(tile)) return CommandCost(STR_ERROR_SITE_UNSUITABLE);
 
  CommandCost ret = CheckIfAuthorityAllowsNewStation(tile, flags);
  if (ret.Failed()) return ret;
 
  ret = IsDockBridgeAboveOk(tile, to_underlying(direction));
  if (ret.Failed()) return ret;
 
  CommandCost cost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_STATION_DOCK]);
  ret = Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile);
  if (ret.Failed()) return ret;
  cost.AddCost(ret.GetCost());
 
  TileIndex tile_cur = tile + TileOffsByDiagDir(direction);
 
  if (!HasTileWaterGround(tile_cur) || !IsTileFlat(tile_cur)) {
    return CommandCost(STR_ERROR_SITE_UNSUITABLE);
  }
 
  ret = IsDockBridgeAboveOk(tile_cur, GFX_DOCK_BASE_WATER_PART + to_underlying(DiagDirToAxis(direction)));
  if (ret.Failed()) return ret;
 
  /* Get the water class of the water tile before it is cleared.*/
  WaterClass wc = GetWaterClass(tile_cur);
 
  bool add_cost = !IsWaterTile(tile_cur);
  ret = Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile_cur);
  if (ret.Failed()) return ret;
  if (add_cost) cost.AddCost(ret.GetCost());
 
  tile_cur += TileOffsByDiagDir(direction);
  if (!IsTileType(tile_cur, MP_WATER) || !IsTileFlat(tile_cur)) {
    return CommandCost(STR_ERROR_SITE_UNSUITABLE);
  }
 
  TileArea dock_area = TileArea(tile + ToTileIndexDiff(_dock_tileoffs_chkaround[direction]),
      _dock_w_chk[direction], _dock_h_chk[direction]);
 
  /* middle */
  Station *st = nullptr;
  ret = FindJoiningStation(StationID::Invalid(), station_to_join, adjacent, dock_area, &st);
  if (ret.Failed()) return ret;
 
  /* Distant join */
  if (st == nullptr && distant_join) st = Station::GetIfValid(station_to_join);
 
  ret = BuildStationPart(&st, flags, reuse, dock_area, STATIONNAMING_DOCK);
  if (ret.Failed()) return ret;
 
  if (flags.Test(DoCommandFlag::Execute)) {
    st->ship_station.Add(tile);
    TileIndex flat_tile = tile + TileOffsByDiagDir(direction);
    st->ship_station.Add(flat_tile);
    st->AddFacility(StationFacility::Dock, tile);
 
    st->rect.BeforeAddRect(dock_area.tile, dock_area.w, dock_area.h, StationRect::ADD_TRY);
 
    /* If the water part of the dock is on a canal, update infrastructure counts.
     * This is needed as we've cleared that tile before.
     * Clearing object tiles may result in water tiles which are already accounted for in the water infrastructure total.
     * See: MakeWaterKeepingClass() */
    if (wc == WaterClass::Canal && !(HasTileWaterClass(flat_tile) && GetWaterClass(flat_tile) == WaterClass::Canal && IsTileOwner(flat_tile, _current_company))) {
      Company::Get(st->owner)->infrastructure.water++;
    }
    Company::Get(st->owner)->infrastructure.station += 2;
 
    MakeDock(tile, st->owner, st->index, direction, wc);
    UpdateStationDockingTiles(st);
 
    st->AfterStationTileSetChange(true, StationType::Dock);
  }
 
  return cost;
}
 
void RemoveDockingTile(TileIndex t)
{
  for (DiagDirection d = DIAGDIR_BEGIN; d != DIAGDIR_END; d++) {
    TileIndex tile = t + TileOffsByDiagDir(d);
    if (!IsValidTile(tile)) continue;
 
    if (IsTileType(tile, MP_STATION)) {
      Station *st = Station::GetByTile(tile);
      if (st != nullptr) UpdateStationDockingTiles(st);
    } else if (IsTileType(tile, MP_INDUSTRY)) {
      Station *neutral = Industry::GetByTile(tile)->neutral_station;
      if (neutral != nullptr) UpdateStationDockingTiles(neutral);
    }
  }
}
 
void ClearDockingTilesCheckingNeighbours(TileIndex tile)
{
  assert(IsValidTile(tile));
 
  /* Clear and maybe re-set docking tile */
  for (DiagDirection d = DIAGDIR_BEGIN; d != DIAGDIR_END; d++) {
    TileIndex docking_tile = tile + TileOffsByDiagDir(d);
    if (!IsValidTile(docking_tile)) continue;
 
    if (IsPossibleDockingTile(docking_tile)) {
      SetDockingTile(docking_tile, false);
      CheckForDockingTile(docking_tile);
    }
  }
}
 
static TileIndex FindDockLandPart(TileIndex t)
{
  assert(IsDockTile(t));
 
  StationGfx gfx = GetStationGfx(t);
  if (gfx < GFX_DOCK_BASE_WATER_PART) return t;
 
  for (DiagDirection d = DIAGDIR_BEGIN; d != DIAGDIR_END; d++) {
    TileIndex tile = t + TileOffsByDiagDir(d);
    if (!IsValidTile(tile)) continue;
    if (!IsDockTile(tile)) continue;
    if (GetStationGfx(tile) < GFX_DOCK_BASE_WATER_PART && tile + TileOffsByDiagDir(GetDockDirection(tile)) == t) return tile;
  }
 
  return INVALID_TILE;
}
 
static CommandCost RemoveDock(TileIndex tile, DoCommandFlags flags)
{
  Station *st = Station::GetByTile(tile);
  CommandCost ret = CheckOwnership(st->owner);
  if (ret.Failed()) return ret;
 
  if (!IsDockTile(tile)) return CMD_ERROR;
 
  TileIndex tile1 = FindDockLandPart(tile);
  if (tile1 == INVALID_TILE) return CMD_ERROR;
  TileIndex tile2 = tile1 + TileOffsByDiagDir(GetDockDirection(tile1));
 
  ret = EnsureNoVehicleOnGround(tile1);
  if (ret.Succeeded()) ret = EnsureNoVehicleOnGround(tile2);
  if (ret.Failed()) return ret;
 
  if (flags.Test(DoCommandFlag::Execute)) {
    DoClearSquare(tile1);
    MarkTileDirtyByTile(tile1);
    MakeWaterKeepingClass(tile2, st->owner);
 
    st->rect.AfterRemoveTile(st, tile1);
    st->rect.AfterRemoveTile(st, tile2);
 
    MakeShipStationAreaSmaller(st);
    if (st->ship_station.tile == INVALID_TILE) {
      st->ship_station.Clear();
      st->docking_station.Clear();
      st->facilities.Reset(StationFacility::Dock);
      SetWindowClassesDirty(WC_VEHICLE_ORDERS);
    }
 
    Company::Get(st->owner)->infrastructure.station -= 2;
 
    st->AfterStationTileSetChange(false, StationType::Dock);
 
    ClearDockingTilesCheckingNeighbours(tile1);
    ClearDockingTilesCheckingNeighbours(tile2);
 
    for (Ship *s : Ship::Iterate()) {
      /* Find all ships going to our dock. */
      if (s->current_order.GetDestination() != st->index) {
        continue;
      }
 
      /* Find ships that are marked as "loading" but are no longer on a
       * docking tile. Force them to leave the station (as they were loading
       * on the removed dock). */
      if (s->current_order.IsType(OT_LOADING) && !(IsDockingTile(s->tile) && IsShipDestinationTile(s->tile, st->index))) {
        s->LeaveStation();
      }
 
      /* If we no longer have a dock, mark the order as invalid and send
       * the ship to the next order (or, if there is none, make it
       * wander the world). */
      if (s->current_order.IsType(OT_GOTO_STATION) && !st->facilities.Test(StationFacility::Dock)) {
        s->SetDestTile(s->GetOrderStationLocation(st->index));
      }
    }
  }
 
  return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_CLEAR_STATION_DOCK]);
}
 
const DrawTileSprites *GetStationTileLayout(StationType st, uint8_t gfx)
{
  const auto &layouts = _station_display_datas[to_underlying(st)];
  if (gfx >= layouts.size()) gfx &= 1;
  return layouts.data() + gfx;
}
 
bool SplitGroundSpriteForOverlay(const TileInfo *ti, SpriteID *ground, RailTrackOffset *overlay_offset)
{
  bool snow_desert;
  switch (*ground) {
    case SPR_RAIL_TRACK_X:
    case SPR_MONO_TRACK_X:
    case SPR_MGLV_TRACK_X:
      snow_desert = false;
      *overlay_offset = RTO_X;
      break;
 
    case SPR_RAIL_TRACK_Y:
    case SPR_MONO_TRACK_Y:
    case SPR_MGLV_TRACK_Y:
      snow_desert = false;
      *overlay_offset = RTO_Y;
      break;
 
    case SPR_RAIL_TRACK_X_SNOW:
    case SPR_MONO_TRACK_X_SNOW:
    case SPR_MGLV_TRACK_X_SNOW:
      snow_desert = true;
      *overlay_offset = RTO_X;
      break;
 
    case SPR_RAIL_TRACK_Y_SNOW:
    case SPR_MONO_TRACK_Y_SNOW:
    case SPR_MGLV_TRACK_Y_SNOW:
      snow_desert = true;
      *overlay_offset = RTO_Y;
      break;
 
    default:
      return false;
  }
 
  if (ti != nullptr) {
    /* Decide snow/desert from tile */
    switch (_settings_game.game_creation.landscape) {
      case LandscapeType::Arctic:
        snow_desert = (uint)ti->z > GetSnowLine() * TILE_HEIGHT;
        break;
 
      case LandscapeType::Tropic:
        snow_desert = GetTropicZone(ti->tile) == TROPICZONE_DESERT;
        break;
 
      default:
        break;
    }
  }
 
  *ground = snow_desert ? SPR_FLAT_SNOW_DESERT_TILE : SPR_FLAT_GRASS_TILE;
  return true;
}
 
static BridgePillarFlags GetStationBlockedPillars(std::span<const BridgeableTileInfo> bridgeable_info, uint8_t layout)
{
  if (layout < std::size(bridgeable_info)) return bridgeable_info[layout].disallowed_pillars;
  return BRIDGEPILLARFLAGS_ALL;
}
 
static bool DrawCustomStationFoundations(const StationSpec *statspec, BaseStation *st, TileInfo *ti, StationGfx gfx)
{
  if (statspec == nullptr || !statspec->flags.Test(StationSpecFlag::CustomFoundations)) return false;
 
  /* Station has custom foundations.
   * Check whether the foundation continues beyond the tile's upper sides. */
  uint edge_info = 0;
  auto [slope, z] = GetFoundationPixelSlope(ti->tile);
  if (!HasFoundationNW(ti->tile, slope, z)) SetBit(edge_info, 0);
  if (!HasFoundationNE(ti->tile, slope, z)) SetBit(edge_info, 1);
 
  SpriteID image = GetCustomStationFoundationRelocation(statspec, st, ti->tile, gfx, edge_info);
  if (image == 0) return false;
 
  if (statspec->flags.Test(StationSpecFlag::ExtendedFoundations)) {
    /* Station provides extended foundations. */
    static constexpr uint8_t foundation_parts[] = {
      UINT8_MAX, UINT8_MAX, UINT8_MAX,         0, // Invalid,  Invalid,   Invalid,   SLOPE_SW
      UINT8_MAX,         1,         2,         3, // Invalid,  SLOPE_EW,  SLOPE_SE,  SLOPE_WSE
      UINT8_MAX,         4,         5,         6, // Invalid,  SLOPE_NW,  SLOPE_NS,  SLOPE_NWS
              7,         8,         9,            // SLOPE_NE, SLOPE_ENW, SLOPE_SEN
    };
    assert(ti->tileh < std::size(foundation_parts));
    if (foundation_parts[ti->tileh] == UINT8_MAX) return false;
 
    AddSortableSpriteToDraw(image + foundation_parts[ti->tileh], PAL_NONE, *ti, {{}, {TILE_SIZE, TILE_SIZE, TILE_HEIGHT - 1}, {}});
  } else {
    /* Draw simple foundations, built up from 8 possible foundation sprites.
     * Each set bit represents one of the eight composite sprites to be drawn.
     * 'Invalid' entries will not drawn but are included for completeness. */
    static constexpr uint8_t composite_foundation_parts[] = {
      0b0000'0000, 0b1101'0001, 0b1110'0100, 0b1110'0000, // Invalid,  Invalid,   Invalid,   SLOPE_SW
      0b1100'1010, 0b1100'1001, 0b1100'0100, 0b1100'0000, // Invalid,  SLOPE_EW,  SLOPE_SE,  SLOPE_WSE
      0b1101'0010, 0b1001'0001, 0b1110'0100, 0b1010'0000, // Invalid,  SLOPE_NW,  SLOPE_NS,  SLOPE_NWS
      0b0100'1010, 0b0000'1001, 0b0100'0100,              // SLOPE_NE, SLOPE_ENW, SLOPE_SEN
    };
    assert(ti->tileh < std::size(composite_foundation_parts));
 
    uint8_t parts = composite_foundation_parts[ti->tileh];
 
    /* If foundations continue beyond the tile's upper sides then mask out the last two pieces. */
    if (HasBit(edge_info, 0)) ClrBit(parts, 6);
    if (HasBit(edge_info, 1)) ClrBit(parts, 7);
 
    /* We always have to draw at least one sprite, so if we have no parts to draw fall back to default foundation. */
    if (parts == 0) return false;
 
    StartSpriteCombine();
    for (uint i : SetBitIterator(parts)) {
      AddSortableSpriteToDraw(image + i, PAL_NONE, *ti, {{}, {TILE_SIZE, TILE_SIZE, TILE_HEIGHT - 1}, {}});
    }
    EndSpriteCombine();
  }
 
  OffsetGroundSprite(0, -static_cast<int>(TILE_HEIGHT));
  ti->z += ApplyPixelFoundationToSlope(FOUNDATION_LEVELED, ti->tileh);
 
  return true;
}
 
static void DrawTile_Station(TileInfo *ti)
{
  const NewGRFSpriteLayout *layout = nullptr;
  SpriteLayoutProcessor processor; // owns heap, borrowed by tmp_layout and t
  DrawTileSpriteSpan tmp_layout;
  const DrawTileSprites *t = nullptr;
  int32_t total_offset;
  const RailTypeInfo *rti = nullptr;
  uint32_t relocation = 0;
  uint32_t ground_relocation = 0;
  BaseStation *st = nullptr;
  const StationSpec *statspec = nullptr;
  uint tile_layout = 0;
  auto bridgeable_info = GetStationBridgeableTileInfo(GetStationType(ti->tile));
 
  if (HasStationRail(ti->tile)) {
    rti = GetRailTypeInfo(GetRailType(ti->tile));
    total_offset = rti->GetRailtypeSpriteOffset();
 
    if (IsCustomStationSpecIndex(ti->tile)) {
      /* look for customization */
      st = BaseStation::GetByTile(ti->tile);
      statspec = st->speclist[GetCustomStationSpecIndex(ti->tile)].spec;
 
      if (statspec != nullptr) {
        tile_layout = GetStationGfx(ti->tile);
 
        if (statspec->callback_mask.Test(StationCallbackMask::DrawTileLayout)) {
          uint16_t callback = GetStationCallback(CBID_STATION_DRAW_TILE_LAYOUT, 0, 0, statspec, st, ti->tile);
          if (callback != CALLBACK_FAILED) tile_layout = (callback & ~1) + GetRailStationAxis(ti->tile);
        }
 
        /* Ensure the chosen tile layout is valid for this custom station */
        if (!statspec->renderdata.empty()) {
          layout = &statspec->renderdata[tile_layout < statspec->renderdata.size() ? tile_layout : (uint)GetRailStationAxis(ti->tile)];
          if (!layout->NeedsPreprocessing()) {
            t = layout;
            layout = nullptr;
          }
        }
      }
    }
    if (statspec != nullptr) bridgeable_info = statspec->bridgeable_info;
  } else {
    total_offset = 0;
  }
 
  StationGfx gfx = GetStationGfx(ti->tile);
  if (IsAirport(ti->tile)) {
    gfx = GetAirportGfx(ti->tile);
    if (gfx >= NEW_AIRPORTTILE_OFFSET) {
      const AirportTileSpec *ats = AirportTileSpec::Get(gfx);
      if (ats->grf_prop.HasSpriteGroups() && DrawNewAirportTile(ti, Station::GetByTile(ti->tile), ats)) {
        return;
      }
      /* No sprite group (or no valid one) found, meaning no graphics associated.
       * Use the substitute one instead */
      assert(ats->grf_prop.subst_id != INVALID_AIRPORTTILE);
      gfx = ats->grf_prop.subst_id;
    }
    switch (gfx) {
      case APT_RADAR_GRASS_FENCE_SW:
        t = &_station_display_datas_airport_radar_grass_fence_sw[GetAnimationFrame(ti->tile)];
        break;
      case APT_GRASS_FENCE_NE_FLAG:
        t = &_station_display_datas_airport_flag_grass_fence_ne[GetAnimationFrame(ti->tile)];
        break;
      case APT_RADAR_FENCE_SW:
        t = &_station_display_datas_airport_radar_fence_sw[GetAnimationFrame(ti->tile)];
        break;
      case APT_RADAR_FENCE_NE:
        t = &_station_display_datas_airport_radar_fence_ne[GetAnimationFrame(ti->tile)];
        break;
      case APT_GRASS_FENCE_NE_FLAG_2:
        t = &_station_display_datas_airport_flag_grass_fence_ne_2[GetAnimationFrame(ti->tile)];
        break;
    }
  }
 
  Owner owner = GetTileOwner(ti->tile);
 
  PaletteID palette;
  if (Company::IsValidID(owner)) {
    palette = GetCompanyPalette(owner);
  } else {
    /* Some stations are not owner by a company, namely oil rigs */
    palette = PALETTE_TO_GREY;
  }
 
  if (layout == nullptr && t == nullptr) t = GetStationTileLayout(GetStationType(ti->tile), gfx);
 
  /* don't show foundation for docks */
  if (ti->tileh != SLOPE_FLAT && !IsDock(ti->tile)) {
    if (!DrawCustomStationFoundations(statspec, st, ti, tile_layout)) {
      DrawFoundation(ti, FOUNDATION_LEVELED);
    }
  }
 
  bool draw_ground = false;
 
  if (IsBuoy(ti->tile)) {
    DrawWaterClassGround(ti);
    SpriteID sprite = GetCanalSprite(CF_BUOY, ti->tile);
    if (sprite != 0) total_offset = sprite - SPR_IMG_BUOY;
  } else if (IsDock(ti->tile) || (IsOilRig(ti->tile) && IsTileOnWater(ti->tile))) {
    if (ti->tileh == SLOPE_FLAT) {
      DrawWaterClassGround(ti);
    } else {
      assert(IsDock(ti->tile));
      TileIndex water_tile = ti->tile + TileOffsByDiagDir(GetDockDirection(ti->tile));
      WaterClass wc = HasTileWaterClass(water_tile) ? GetWaterClass(water_tile) : WaterClass::Invalid;
      if (wc == WaterClass::Sea) {
        DrawShoreTile(ti->tileh);
      } else {
        DrawClearLandTile(ti, 3);
      }
    }
  } else if (IsRoadWaypointTile(ti->tile)) {
    RoadBits bits = AxisToRoadBits(GetDriveThroughStopAxis(ti->tile));
    RoadType road_rt = GetRoadTypeRoad(ti->tile);
    RoadType tram_rt = GetRoadTypeTram(ti->tile);
    RoadBits road = (road_rt != INVALID_ROADTYPE) ? bits : ROAD_NONE;
    RoadBits tram = (tram_rt != INVALID_ROADTYPE) ? bits : ROAD_NONE;
    const RoadTypeInfo *road_rti = (road_rt != INVALID_ROADTYPE) ? GetRoadTypeInfo(road_rt) : nullptr;
    const RoadTypeInfo *tram_rti = (tram_rt != INVALID_ROADTYPE) ? GetRoadTypeInfo(tram_rt) : nullptr;
 
    if (ti->tileh != SLOPE_FLAT) {
      DrawFoundation(ti, FOUNDATION_LEVELED);
    }
 
    DrawRoadGroundSprites(ti, road, tram, road_rti, tram_rti, GetRoadWaypointRoadside(ti->tile), IsRoadWaypointOnSnowOrDesert(ti->tile));
  } else {
    if (layout != nullptr) {
      /* Sprite layout which needs preprocessing */
      bool separate_ground = statspec->flags.Test(StationSpecFlag::SeparateGround);
      processor = SpriteLayoutProcessor(*layout, total_offset, rti->fallback_railtype, 0, 0, separate_ground);
      GetCustomStationRelocation(processor, statspec, st, ti->tile);
      tmp_layout = processor.GetLayout();
      t = &tmp_layout;
      total_offset = 0;
    } else if (statspec != nullptr) {
      /* Simple sprite layout */
      ground_relocation = relocation = GetCustomStationRelocation(statspec, st, ti->tile, 0);
      if (statspec->flags.Test(StationSpecFlag::SeparateGround)) {
        ground_relocation = GetCustomStationRelocation(statspec, st, ti->tile, 1);
      }
      ground_relocation += rti->fallback_railtype;
    }
 
    draw_ground = true;
  }
 
  if (draw_ground && !IsAnyRoadStop(ti->tile)) {
    SpriteID image = t->ground.sprite;
    PaletteID pal  = t->ground.pal;
    RailTrackOffset overlay_offset;
    if (rti != nullptr && rti->UsesOverlay() && SplitGroundSpriteForOverlay(ti, &image, &overlay_offset)) {
      SpriteID ground = GetCustomRailSprite(rti, ti->tile, RTSG_GROUND);
      DrawGroundSprite(image, PAL_NONE);
      DrawGroundSprite(ground + overlay_offset, PAL_NONE);
 
      if (_game_mode != GM_MENU && _settings_client.gui.show_track_reservation && HasStationReservation(ti->tile)) {
        SpriteID overlay = GetCustomRailSprite(rti, ti->tile, RTSG_OVERLAY);
        DrawGroundSprite(overlay + overlay_offset, PALETTE_CRASH);
      }
    } else {
      image += HasBit(image, SPRITE_MODIFIER_CUSTOM_SPRITE) ? ground_relocation : total_offset;
      if (HasBit(pal, SPRITE_MODIFIER_CUSTOM_SPRITE)) pal += ground_relocation;
      DrawGroundSprite(image, GroundSpritePaletteTransform(image, pal, palette));
 
      /* PBS debugging, draw reserved tracks darker */
      if (_game_mode != GM_MENU && _settings_client.gui.show_track_reservation && HasStationRail(ti->tile) && HasStationReservation(ti->tile)) {
        DrawGroundSprite(GetRailStationAxis(ti->tile) == AXIS_X ? rti->base_sprites.single_x : rti->base_sprites.single_y, PALETTE_CRASH);
      }
    }
  }
 
  if (HasStationRail(ti->tile) && HasRailCatenaryDrawn(GetRailType(ti->tile))) DrawRailCatenary(ti);
 
  if (IsAnyRoadStop(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);
 
    StationGfx view = GetStationGfx(ti->tile);
    StationType type = GetStationType(ti->tile);
 
    const RoadStopSpec *stopspec = GetRoadStopSpec(ti->tile);
    RoadStopDrawModes stop_draw_mode{};
    if (stopspec != nullptr) {
      stop_draw_mode = stopspec->draw_mode;
      st = BaseStation::GetByTile(ti->tile);
      std::array<int32_t, 1> regs100;
      auto result = GetRoadStopLayout(ti, stopspec, st, type, view, regs100);
      if (result.has_value()) {
        if (stopspec->flags.Test(RoadStopSpecFlag::DrawModeRegister)) {
          stop_draw_mode = static_cast<RoadStopDrawModes>(regs100[0]);
        }
        if (type == StationType::RoadWaypoint && stop_draw_mode.Test(RoadStopDrawMode::WaypGround)) {
          draw_ground = true;
        }
        processor = std::move(*result);
        tmp_layout = processor.GetLayout();
        t = &tmp_layout;
      }
    }
 
    /* Draw ground sprite */
    if (draw_ground) {
      SpriteID image = t->ground.sprite;
      PaletteID pal  = t->ground.pal;
      image += HasBit(image, SPRITE_MODIFIER_CUSTOM_SPRITE) ? ground_relocation : total_offset;
      if (GB(image, 0, SPRITE_WIDTH) != 0) {
        if (HasBit(pal, SPRITE_MODIFIER_CUSTOM_SPRITE)) pal += ground_relocation;
        DrawGroundSprite(image, GroundSpritePaletteTransform(image, pal, palette));
      }
    }
 
    if (IsDriveThroughStopTile(ti->tile)) {
      if (type != StationType::RoadWaypoint && (stopspec == nullptr || stop_draw_mode.Test(RoadStopDrawMode::Overlay))) {
        uint sprite_offset = GetDriveThroughStopAxis(ti->tile) == AXIS_X ? 1 : 0;
        DrawRoadOverlays(ti, PAL_NONE, road_rti, tram_rti, sprite_offset, sprite_offset);
      }
    } else {
      /* Non-drivethrough road stops are only valid for roads. */
      assert(road_rt != INVALID_ROADTYPE && tram_rt == INVALID_ROADTYPE);
 
      if ((stopspec == nullptr || stop_draw_mode.Test(RoadStopDrawMode::Road)) && road_rti->UsesOverlay()) {
        SpriteID ground = GetCustomRoadSprite(road_rti, ti->tile, ROTSG_ROADSTOP);
        DrawGroundSprite(ground + view, PAL_NONE);
      }
    }
    if (stopspec != nullptr) bridgeable_info = stopspec->bridgeable_info;
 
    if (stopspec == nullptr || !stopspec->flags.Test(RoadStopSpecFlag::NoCatenary)) {
      /* Draw road, tram catenary */
      DrawRoadCatenary(ti);
    }
  }
 
  if (IsRailWaypoint(ti->tile)) {
    /* Don't offset the waypoint graphics; they're always the same. */
    total_offset = 0;
  }
 
  DrawRailTileSeq(ti, t, TO_BUILDINGS, total_offset, relocation, palette);
  DrawBridgeMiddle(ti, GetStationBlockedPillars(bridgeable_info, GetStationGfx(ti->tile)));
}
 
void StationPickerDrawSprite(int x, int y, StationType st, RailType railtype, RoadType roadtype, int image)
{
  int32_t total_offset = 0;
  PaletteID pal = GetCompanyPalette(_local_company);
  const DrawTileSprites *t = GetStationTileLayout(st, image);
  const RailTypeInfo *railtype_info = nullptr;
 
  if (railtype != INVALID_RAILTYPE) {
    railtype_info = GetRailTypeInfo(railtype);
    total_offset = railtype_info->GetRailtypeSpriteOffset();
  }
 
  SpriteID img = t->ground.sprite;
  RailTrackOffset overlay_offset;
  if (railtype_info != nullptr && railtype_info->UsesOverlay() && SplitGroundSpriteForOverlay(nullptr, &img, &overlay_offset)) {
    SpriteID ground = GetCustomRailSprite(railtype_info, INVALID_TILE, RTSG_GROUND);
    DrawSprite(img, PAL_NONE, x, y);
    DrawSprite(ground + overlay_offset, PAL_NONE, x, y);
  } else {
    DrawSprite(img + total_offset, HasBit(img, PALETTE_MODIFIER_COLOUR) ? pal : PAL_NONE, x, y);
  }
 
  if (roadtype != INVALID_ROADTYPE) {
    const RoadTypeInfo *roadtype_info = GetRoadTypeInfo(roadtype);
    if (image >= 4) {
      /* Drive-through stop */
      uint sprite_offset = 5 - image;
 
      /* Road underlay takes precedence over tram */
      if (roadtype_info->UsesOverlay()) {
        SpriteID ground = GetCustomRoadSprite(roadtype_info, INVALID_TILE, ROTSG_GROUND);
        DrawSprite(ground + sprite_offset, PAL_NONE, x, y);
 
        SpriteID overlay = GetCustomRoadSprite(roadtype_info, INVALID_TILE, ROTSG_OVERLAY);
        if (overlay) DrawSprite(overlay + sprite_offset, PAL_NONE, x, y);
      } else if (RoadTypeIsTram(roadtype)) {
        DrawSprite(SPR_TRAMWAY_TRAM + sprite_offset, PAL_NONE, x, y);
      }
    } else {
      /* Bay stop */
      if (RoadTypeIsRoad(roadtype) && roadtype_info->UsesOverlay()) {
        SpriteID ground = GetCustomRoadSprite(roadtype_info, INVALID_TILE, ROTSG_ROADSTOP);
        DrawSprite(ground + image, PAL_NONE, x, y);
      }
    }
  }
 
  /* Default waypoint has no railtype specific sprites */
  DrawRailTileSeqInGUI(x, y, t, (st == StationType::RailWaypoint || st == StationType::RoadWaypoint) ? 0 : total_offset, 0, pal);
}
 
static int GetSlopePixelZ_Station(TileIndex tile, uint, uint, bool)
{
  return GetTileMaxPixelZ(tile);
}
 
static Foundation GetFoundation_Station(TileIndex, Slope tileh)
{
  return FlatteningFoundation(tileh);
}
 
static void FillTileDescRoadStop(TileIndex tile, TileDesc &td)
{
  RoadType road_rt = GetRoadTypeRoad(tile);
  RoadType tram_rt = GetRoadTypeTram(tile);
  Owner road_owner = INVALID_OWNER;
  Owner tram_owner = INVALID_OWNER;
  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);
  }
 
  if (IsDriveThroughStopTile(tile)) {
    /* Is there a mix of owners? */
    if ((tram_owner != INVALID_OWNER && tram_owner != td.owner[0]) ||
        (road_owner != INVALID_OWNER && road_owner != td.owner[0])) {
      uint i = 1;
      if (road_owner != INVALID_OWNER) {
        td.owner_type[i] = STR_LAND_AREA_INFORMATION_ROAD_OWNER;
        td.owner[i] = road_owner;
        i++;
      }
      if (tram_owner != INVALID_OWNER) {
        td.owner_type[i] = STR_LAND_AREA_INFORMATION_TRAM_OWNER;
        td.owner[i] = tram_owner;
      }
    }
  }
}
 
void FillTileDescRailStation(TileIndex tile, TileDesc &td)
{
  const StationSpec *spec = GetStationSpec(tile);
 
  if (spec != nullptr) {
    td.station_class = StationClass::Get(spec->class_index)->name;
    td.station_name  = spec->name;
 
    if (spec->grf_prop.HasGrfFile()) {
      const GRFConfig *gc = GetGRFConfig(spec->grf_prop.grfid);
      td.grf = gc->GetName();
    }
  }
 
  const RailTypeInfo *rti = GetRailTypeInfo(GetRailType(tile));
  td.rail_speed = rti->max_speed;
  td.railtype = rti->strings.name;
}
 
void FillTileDescAirport(TileIndex tile, TileDesc &td)
{
  const AirportSpec *as = Station::GetByTile(tile)->airport.GetSpec();
  td.airport_class = AirportClass::Get(as->class_index)->name;
  td.airport_name = as->name;
 
  const AirportTileSpec *ats = AirportTileSpec::GetByTile(tile);
  td.airport_tile_name = ats->name;
 
  if (as->grf_prop.HasGrfFile()) {
    const GRFConfig *gc = GetGRFConfig(as->grf_prop.grfid);
    td.grf = gc->GetName();
  } else if (ats->grf_prop.HasGrfFile()) {
    const GRFConfig *gc = GetGRFConfig(ats->grf_prop.grfid);
    td.grf = gc->GetName();
  }
}
 
static void GetTileDesc_Station(TileIndex tile, TileDesc &td)
{
  td.owner[0] = GetTileOwner(tile);
  td.build_date = BaseStation::GetByTile(tile)->build_date;
 
  if (IsAnyRoadStop(tile)) FillTileDescRoadStop(tile, td);
  if (HasStationRail(tile)) FillTileDescRailStation(tile, td);
  if (IsAirport(tile)) FillTileDescAirport(tile, td);
 
  StringID str;
  switch (GetStationType(tile)) {
    default: NOT_REACHED();
    case StationType::Rail:     str = STR_LAI_STATION_DESCRIPTION_RAILROAD_STATION; break;
    case StationType::Airport:
      str = (IsHangar(tile) ? STR_LAI_STATION_DESCRIPTION_AIRCRAFT_HANGAR : STR_LAI_STATION_DESCRIPTION_AIRPORT);
      break;
    case StationType::Truck:    str = STR_LAI_STATION_DESCRIPTION_TRUCK_LOADING_AREA; break;
    case StationType::Bus:      str = STR_LAI_STATION_DESCRIPTION_BUS_STATION; break;
    case StationType::Oilrig: {
      const Industry *i = Station::GetByTile(tile)->industry;
      const IndustrySpec *is = GetIndustrySpec(i->type);
      td.owner[0] = i->owner;
      str = is->name;
      if (is->grf_prop.HasGrfFile()) td.grf = GetGRFConfig(is->grf_prop.grfid)->GetName();
      break;
    }
    case StationType::Dock:     str = STR_LAI_STATION_DESCRIPTION_SHIP_DOCK; break;
    case StationType::Buoy:     str = STR_LAI_STATION_DESCRIPTION_BUOY; break;
    case StationType::RailWaypoint: str = STR_LAI_STATION_DESCRIPTION_WAYPOINT; break;
    case StationType::RoadWaypoint: str = STR_LAI_STATION_DESCRIPTION_WAYPOINT; break;
  }
  td.str = str;
}
 
 
static TrackStatus GetTileTrackStatus_Station(TileIndex tile, TransportType mode, uint sub_mode, DiagDirection side)
{
  TrackBits trackbits = TRACK_BIT_NONE;
 
  switch (mode) {
    case TRANSPORT_RAIL:
      if (HasStationRail(tile) && !IsStationTileBlocked(tile)) {
        trackbits = TrackToTrackBits(GetRailStationTrack(tile));
      }
      break;
 
    case TRANSPORT_WATER:
      /* buoy is coded as a station, it is always on open water */
      if (IsBuoy(tile)) {
        trackbits = TRACK_BIT_ALL;
        /* remove tracks that connect NE map edge */
        if (TileX(tile) == 0) trackbits &= ~(TRACK_BIT_X | TRACK_BIT_UPPER | TRACK_BIT_RIGHT);
        /* remove tracks that connect NW map edge */
        if (TileY(tile) == 0) trackbits &= ~(TRACK_BIT_Y | TRACK_BIT_LEFT | TRACK_BIT_UPPER);
      }
      break;
 
    case TRANSPORT_ROAD:
      if (IsAnyRoadStop(tile)) {
        RoadTramType rtt = (RoadTramType)sub_mode;
        if (!HasTileRoadType(tile, rtt)) break;
 
        if (IsBayRoadStopTile(tile)) {
          DiagDirection dir = GetBayRoadStopDir(tile);
          if (side != INVALID_DIAGDIR && dir != side) break;
          trackbits = DiagDirToDiagTrackBits(dir);
        } else {
          Axis axis = GetDriveThroughStopAxis(tile);
          if (side != INVALID_DIAGDIR && axis != DiagDirToAxis(side)) break;
          trackbits = AxisToTrackBits(axis);
        }
      }
      break;
 
    default:
      break;
  }
 
  return CombineTrackStatus(TrackBitsToTrackdirBits(trackbits), TRACKDIR_BIT_NONE);
}
 
 
static void TileLoop_Station(TileIndex tile)
{
  auto *st = BaseStation::GetByTile(tile);
  switch (GetStationType(tile)) {
    case StationType::Airport:
      TriggerAirportTileAnimation(Station::From(st), tile, AirportAnimationTrigger::TileLoop);
      break;
 
    case StationType::Rail:
    case StationType::RailWaypoint:
      TriggerStationAnimation(st, tile, StationAnimationTrigger::TileLoop);
      break;
 
    case StationType::Dock:
      if (!IsTileFlat(tile)) break; // only handle water part
      [[fallthrough]];
 
    case StationType::Oilrig: //(station part)
    case StationType::Buoy:
      TileLoop_Water(tile);
      break;
 
    case StationType::Truck:
    case StationType::Bus:
      TriggerRoadStopAnimation(st, tile, StationAnimationTrigger::TileLoop);
      break;
 
    case StationType::RoadWaypoint: {
      switch (_settings_game.game_creation.landscape) {
        case LandscapeType::Arctic:
          if (IsRoadWaypointOnSnowOrDesert(tile) != (GetTileZ(tile) > GetSnowLine())) {
            ToggleRoadWaypointOnSnowOrDesert(tile);
            MarkTileDirtyByTile(tile);
          }
          break;
 
        case LandscapeType::Tropic:
          if (GetTropicZone(tile) == TROPICZONE_DESERT && !IsRoadWaypointOnSnowOrDesert(tile)) {
            ToggleRoadWaypointOnSnowOrDesert(tile);
            MarkTileDirtyByTile(tile);
          }
          break;
 
        default: break;
      }
 
      HouseZone new_zone = HouseZone::TownEdge;
      const Town *t = ClosestTownFromTile(tile, UINT_MAX);
      if (t != nullptr) {
        new_zone = GetTownRadiusGroup(t, tile);
      }
 
      /* Adjust road ground type depending on 'new_zone' */
      Roadside new_rs = new_zone != HouseZone::TownEdge ? Roadside::Paved : Roadside::Grass;
      Roadside cur_rs = GetRoadWaypointRoadside(tile);
 
      if (new_rs != cur_rs) {
        SetRoadWaypointRoadside(tile, cur_rs == Roadside::Barren ? new_rs : Roadside::Barren);
        MarkTileDirtyByTile(tile);
      }
 
      TriggerRoadStopAnimation(st, tile, StationAnimationTrigger::TileLoop);
      break;
    }
 
    default: break;
  }
}
 
 
static void AnimateTile_Station(TileIndex tile)
{
  if (HasStationRail(tile)) {
    AnimateStationTile(tile);
    return;
  }
 
  if (IsAirport(tile)) {
    AnimateAirportTile(tile);
    return;
  }
 
  if (IsAnyRoadStopTile(tile)) {
    AnimateRoadStopTile(tile);
    return;
  }
}
 
 
static bool ClickTile_Station(TileIndex tile)
{
  const BaseStation *bst = BaseStation::GetByTile(tile);
 
  if (bst->facilities.Test(StationFacility::Waypoint)) {
    ShowWaypointWindow(Waypoint::From(bst));
  } else if (IsHangar(tile)) {
    const Station *st = Station::From(bst);
    ShowDepotWindow(st->airport.GetHangarTile(st->airport.GetHangarNum(tile)), VEH_AIRCRAFT);
  } else {
    ShowStationViewWindow(bst->index);
  }
  return true;
}
 
static VehicleEnterTileStates VehicleEnter_Station(Vehicle *v, TileIndex tile, int x, int y)
{
  if (v->type == VEH_TRAIN) {
    StationID station_id = GetStationIndex(tile);
    if (!v->current_order.ShouldStopAtStation(v, station_id)) return {};
    if (!IsRailStation(tile) || !v->IsFrontEngine()) return {};
 
    int station_ahead;
    int station_length;
    int stop = GetTrainStopLocation(station_id, tile, Train::From(v), &station_ahead, &station_length);
 
    /* Stop whenever that amount of station ahead + the distance from the
     * begin of the platform to the stop location is longer than the length
     * of the platform. Station ahead 'includes' the current tile where the
     * vehicle is on, so we need to subtract that. */
    if (stop + station_ahead - (int)TILE_SIZE >= station_length) return {};
 
    DiagDirection dir = DirToDiagDir(v->direction);
 
    x &= 0xF;
    y &= 0xF;
 
    if (DiagDirToAxis(dir) != AXIS_X) std::swap(x, y);
    if (y == TILE_SIZE / 2) {
      if (dir != DIAGDIR_SE && dir != DIAGDIR_SW) x = TILE_SIZE - 1 - x;
      stop &= TILE_SIZE - 1;
 
      if (x == stop) {
        return VehicleEnterTileState::EnteredStation; // enter station
      } else if (x < stop) {
        v->vehstatus.Set(VehState::TrainSlowing);
        uint16_t spd = std::max(0, (stop - x) * 20 - 15);
        if (spd < v->cur_speed) v->cur_speed = spd;
      }
    }
  } else if (v->type == VEH_ROAD) {
    RoadVehicle *rv = RoadVehicle::From(v);
    if (rv->state < RVSB_IN_ROAD_STOP && !IsReversingRoadTrackdir((Trackdir)rv->state) && rv->frame == 0) {
      if (IsStationRoadStop(tile) && rv->IsFrontEngine()) {
        /* Attempt to allocate a parking bay in a road stop */
        if (RoadStop::GetByTile(tile, GetRoadStopType(tile))->Enter(rv)) return {};
        return VehicleEnterTileState::CannotEnter;
      }
    }
  }
 
  return {};
}
 
void TriggerWatchedCargoCallbacks(Station *st)
{
  /* Collect cargoes accepted since the last big tick. */
  CargoTypes cargoes = 0;
  for (CargoType cargo_type = 0; cargo_type < NUM_CARGO; cargo_type++) {
    if (st->goods[cargo_type].status.Test(GoodsEntry::State::AcceptedBigtick)) SetBit(cargoes, cargo_type);
  }
 
  /* Anything to do? */
  if (cargoes == 0) return;
 
  /* Loop over all houses in the catchment. */
  BitmapTileIterator it(st->catchment_tiles);
  for (TileIndex tile = it; tile != INVALID_TILE; tile = ++it) {
    if (IsTileType(tile, MP_HOUSE)) {
      TriggerHouseAnimation_WatchedCargoAccepted(tile, cargoes);
    }
  }
}
 
static bool StationHandleBigTick(BaseStation *st)
{
  if (!st->IsInUse()) {
    if (++st->delete_ctr >= 8) delete st;
    return false;
  }
 
  if (Station::IsExpected(st)) {
    TriggerWatchedCargoCallbacks(Station::From(st));
 
    for (GoodsEntry &ge : Station::From(st)->goods) {
      ge.status.Reset(GoodsEntry::State::AcceptedBigtick);
    }
  }
 
 
  if (!st->facilities.Test(StationFacility::Waypoint)) UpdateStationAcceptance(Station::From(st), true);
 
  return true;
}
 
static inline void byte_inc_sat(uint8_t *p)
{
  uint8_t b = *p + 1;
  if (b != 0) *p = b;
}
 
static void TruncateCargo(const CargoSpec *cs, GoodsEntry *ge, uint amount = UINT_MAX)
{
  /* If truncating also punish the source stations' ratings to
   * decrease the flow of incoming cargo. */
 
  if (!ge->HasData()) return;
 
  StationCargoAmountMap waiting_per_source;
  ge->GetData().cargo.Truncate(amount, &waiting_per_source);
  for (StationCargoAmountMap::iterator i(waiting_per_source.begin()); i != waiting_per_source.end(); ++i) {
    Station *source_station = Station::GetIfValid(i->first);
    if (source_station == nullptr) continue;
 
    GoodsEntry &source_ge = source_station->goods[cs->Index()];
    source_ge.max_waiting_cargo = std::max(source_ge.max_waiting_cargo, i->second);
  }
}
 
static void UpdateStationRating(Station *st)
{
  bool waiting_changed = false;
 
  byte_inc_sat(&st->time_since_load);
  byte_inc_sat(&st->time_since_unload);
 
  for (const CargoSpec *cs : CargoSpec::Iterate()) {
    GoodsEntry *ge = &st->goods[cs->Index()];
 
    /* The station might not currently be moving this cargo. */
    if (!ge->HasRating()) {
      /* Slowly increase the rating back to its original level in the case we
       *  didn't deliver cargo yet to this station. This happens when a bribe
       *  failed while you didn't moved that cargo yet to a station. */
      if (ge->rating < INITIAL_STATION_RATING) ge->rating++;
 
      /* Nothing else to do with this cargo. */
      continue;
    }
 
    byte_inc_sat(&ge->time_since_pickup);
 
    /* If this cargo hasn't been picked up in a long time, get rid of it. */
    if (ge->time_since_pickup == 255 && _settings_game.order.selectgoods) {
      ge->status.Reset(GoodsEntry::State::Rating);
      ge->last_speed = 0;
      TruncateCargo(cs, ge);
      waiting_changed = true;
      continue;
    }
 
    bool skip = false;
    int rating = 0;
    uint waiting = ge->AvailableCount();
 
    /* num_dests is at least 1 if there is any cargo as
     * StationID::Invalid() is also a destination.
     */
    uint num_dests = ge->HasData() ? static_cast<uint>(ge->GetData().cargo.Packets()->MapSize()) : 0;
 
    /* Average amount of cargo per next hop, but prefer solitary stations
     * with only one or two next hops. They are allowed to have more
     * cargo waiting per next hop.
     * With manual cargo distribution waiting_avg = waiting / 2 as then
     * StationID::Invalid() is the only destination.
     */
    uint waiting_avg = waiting / (num_dests + 1);
 
    if (_cheats.station_rating.value) {
      ge->rating = rating = MAX_STATION_RATING;
      skip = true;
    } else if (cs->callback_mask.Test(CargoCallbackMask::StationRatingCalc)) {
      /* Perform custom station rating. If it succeeds the speed, days in transit and
       * waiting cargo ratings must not be executed. */
 
      /* NewGRFs expect last speed to be 0xFF when no vehicle has arrived yet. */
      uint last_speed = ge->HasVehicleEverTriedLoading() ? ge->last_speed : 0xFF;
 
      uint32_t var18 = ClampTo<uint8_t>(ge->time_since_pickup)
        | (ClampTo<uint16_t>(ge->max_waiting_cargo) << 8)
        | (ClampTo<uint8_t>(last_speed) << 24);
      /* Convert to the 'old' vehicle types */
      uint32_t var10 = (st->last_vehicle_type == VEH_INVALID) ? 0x0 : (st->last_vehicle_type + 0x10);
      uint16_t callback = GetCargoCallback(CBID_CARGO_STATION_RATING_CALC, var10, var18, cs);
      if (callback != CALLBACK_FAILED) {
        skip = true;
        rating = GB(callback, 0, 14);
 
        /* Simulate a 15 bit signed value */
        if (HasBit(callback, 14)) rating -= 0x4000;
      }
    }
 
    if (!skip) {
      int b = ge->last_speed - 85;
      if (b >= 0) rating += b >> 2;
 
      uint8_t waittime = ge->time_since_pickup;
      if (st->last_vehicle_type == VEH_SHIP) waittime >>= 2;
      if (waittime <= 21) rating += 25;
      if (waittime <= 12) rating += 25;
      if (waittime <= 6) rating += 45;
      if (waittime <= 3) rating += 35;
 
      rating -= 90;
      if (ge->max_waiting_cargo <= 1500) rating += 55;
      if (ge->max_waiting_cargo <= 1000) rating += 35;
      if (ge->max_waiting_cargo <= 600) rating += 10;
      if (ge->max_waiting_cargo <= 300) rating += 20;
      if (ge->max_waiting_cargo <= 100) rating += 10;
    }
 
    if (Company::IsValidID(st->owner) && st->town->statues.Test(st->owner)) rating += 26;
 
    uint8_t age = ge->last_age;
    if (age < 3) rating += 10;
    if (age < 2) rating += 10;
    if (age < 1) rating += 13;
 
    {
      int or_ = ge->rating; // old rating
 
      /* only modify rating in steps of -2, -1, 0, 1 or 2 */
      ge->rating = rating = ClampTo<uint8_t>(or_ + Clamp(rating - or_, -2, 2));
 
      /* if rating is <= 64 and more than 100 items waiting on average per destination,
       * remove some random amount of goods from the station */
      if (rating <= 64 && waiting_avg >= 100) {
        int dec = Random() & 0x1F;
        if (waiting_avg < 200) dec &= 7;
        waiting -= (dec + 1) * num_dests;
        waiting_changed = true;
      }
 
      /* if rating is <= 127 and there are any items waiting, maybe remove some goods. */
      if (rating <= 127 && waiting != 0) {
        uint32_t r = Random();
        if (rating <= (int)GB(r, 0, 7)) {
          /* Need to have int, otherwise it will just overflow etc. */
          waiting = std::max((int)waiting - (int)((GB(r, 8, 2) + 1) * num_dests), 0);
          waiting_changed = true;
        }
      }
 
      /* At some point we really must cap the cargo. Previously this
       * was a strict 4095, but now we'll have a less strict, but
       * increasingly aggressive truncation of the amount of cargo. */
      static const uint WAITING_CARGO_THRESHOLD  = 1 << 12;
      static const uint WAITING_CARGO_CUT_FACTOR = 1 <<  6;
      static const uint MAX_WAITING_CARGO        = 1 << 15;
 
      if (waiting > WAITING_CARGO_THRESHOLD) {
        uint difference = waiting - WAITING_CARGO_THRESHOLD;
        waiting -= (difference / WAITING_CARGO_CUT_FACTOR);
 
        waiting = std::min(waiting, MAX_WAITING_CARGO);
        waiting_changed = true;
      }
 
      /* We can't truncate cargo that's already reserved for loading.
       * Thus StoredCount() here. */
      if (waiting_changed && waiting < ge->AvailableCount()) {
        /* Feed back the exact own waiting cargo at this station for the
         * next rating calculation. */
        ge->max_waiting_cargo = 0;
 
        TruncateCargo(cs, ge, ge->AvailableCount() - waiting);
      } else {
        /* If the average number per next hop is low, be more forgiving. */
        ge->max_waiting_cargo = waiting_avg;
      }
    }
  }
 
  StationID index = st->index;
  if (waiting_changed) {
    SetWindowDirty(WC_STATION_VIEW, index); // update whole window
  } else {
    SetWindowWidgetDirty(WC_STATION_VIEW, index, WID_SV_ACCEPT_RATING_LIST); // update only ratings list
  }
}
 
void RerouteCargo(Station *st, CargoType cargo, StationID avoid, StationID avoid2)
{
  GoodsEntry &ge = st->goods[cargo];
 
  /* Reroute cargo in station. */
  if (ge.HasData()) ge.GetData().cargo.Reroute(UINT_MAX, &ge.GetData().cargo, avoid, avoid2, &ge);
 
  /* Reroute cargo staged to be transferred. */
  for (Vehicle *v : st->loading_vehicles) {
    for (Vehicle *u = v; u != nullptr; u = u->Next()) {
      if (u->cargo_type != cargo) continue;
      u->cargo.Reroute(UINT_MAX, &u->cargo, avoid, avoid2, &ge);
    }
  }
}
 
void DeleteStaleLinks(Station *from)
{
  for (CargoType cargo = 0; cargo < NUM_CARGO; ++cargo) {
    const bool auto_distributed = (_settings_game.linkgraph.GetDistributionType(cargo) != DT_MANUAL);
    GoodsEntry &ge = from->goods[cargo];
    LinkGraph *lg = LinkGraph::GetIfValid(ge.link_graph);
    if (lg == nullptr) continue;
    std::vector<NodeID> to_remove{};
    for (Edge &edge : (*lg)[ge.node].edges) {
      Station *to = Station::Get((*lg)[edge.dest_node].station);
      assert(to->goods[cargo].node == edge.dest_node);
      assert(TimerGameEconomy::date >= edge.LastUpdate());
      auto timeout = TimerGameEconomy::Date(LinkGraph::MIN_TIMEOUT_DISTANCE + (DistanceManhattan(from->xy, to->xy) >> 3));
      if (TimerGameEconomy::date - edge.LastUpdate() > timeout) {
        bool updated = false;
 
        if (auto_distributed) {
          /* Have all vehicles refresh their next hops before deciding to
           * remove the node. */
          std::vector<Vehicle *> vehicles;
          for (const OrderList *l : OrderList::Iterate()) {
            bool found_from = false;
            bool found_to = false;
            for (const Order &order : l->GetOrders()) {
              if (!order.IsType(OT_GOTO_STATION) && !order.IsType(OT_IMPLICIT)) continue;
              if (order.GetDestination() == from->index) {
                found_from = true;
                if (found_to) break;
              } else if (order.GetDestination() == to->index) {
                found_to = true;
                if (found_from) break;
              }
            }
            if (!found_to || !found_from) continue;
            vehicles.push_back(l->GetFirstSharedVehicle());
          }
 
          auto iter = vehicles.begin();
          while (iter != vehicles.end()) {
            Vehicle *v = *iter;
            /* Do not refresh links of vehicles that have been stopped in depot for a long time. */
            if (!v->IsStoppedInDepot() || TimerGameEconomy::date - v->date_of_last_service <= LinkGraph::STALE_LINK_DEPOT_TIMEOUT) {
              LinkRefresher::Run(v, false); // Don't allow merging. Otherwise lg might get deleted.
            }
            if (edge.LastUpdate() == TimerGameEconomy::date) {
              updated = true;
              break;
            }
 
            Vehicle *next_shared = v->NextShared();
            if (next_shared) {
              *iter = next_shared;
              ++iter;
            } else {
              iter = vehicles.erase(iter);
            }
 
            if (iter == vehicles.end()) iter = vehicles.begin();
          }
        }
 
        if (!updated) {
          /* If it's still considered dead remove it. */
          to_remove.emplace_back(to->goods[cargo].node);
          if (ge.HasData()) ge.GetData().flows.DeleteFlows(to->index);
          RerouteCargo(from, cargo, to->index, from->index);
        }
      } else if (edge.last_unrestricted_update != EconomyTime::INVALID_DATE && TimerGameEconomy::date - edge.last_unrestricted_update > timeout) {
        edge.Restrict();
        if (ge.HasData()) ge.GetData().flows.RestrictFlows(to->index);
        RerouteCargo(from, cargo, to->index, from->index);
      } else if (edge.last_restricted_update != EconomyTime::INVALID_DATE && TimerGameEconomy::date - edge.last_restricted_update > timeout) {
        edge.Release();
      }
    }
    /* Remove dead edges. */
    for (NodeID r : to_remove) (*lg)[ge.node].RemoveEdge(r);
 
    assert(TimerGameEconomy::date >= lg->LastCompression());
    if (TimerGameEconomy::date - lg->LastCompression() > LinkGraph::COMPRESSION_INTERVAL) {
      lg->Compress();
    }
  }
}
 
void IncreaseStats(Station *st, CargoType cargo, StationID next_station_id, uint capacity, uint usage, uint32_t time, EdgeUpdateModes modes)
{
  GoodsEntry &ge1 = st->goods[cargo];
  Station *st2 = Station::Get(next_station_id);
  GoodsEntry &ge2 = st2->goods[cargo];
  LinkGraph *lg = nullptr;
  if (ge1.link_graph == LinkGraphID::Invalid()) {
    if (ge2.link_graph == LinkGraphID::Invalid()) {
      if (LinkGraph::CanAllocateItem()) {
        lg = LinkGraph::Create(cargo);
        LinkGraphSchedule::instance.Queue(lg);
        ge2.link_graph = lg->index;
        ge2.node = lg->AddNode(st2);
      } else {
        Debug(misc, 0, "Can't allocate link graph");
      }
    } else {
      lg = LinkGraph::Get(ge2.link_graph);
    }
    if (lg) {
      ge1.link_graph = lg->index;
      ge1.node = lg->AddNode(st);
    }
  } else if (ge2.link_graph == LinkGraphID::Invalid()) {
    lg = LinkGraph::Get(ge1.link_graph);
    ge2.link_graph = lg->index;
    ge2.node = lg->AddNode(st2);
  } else {
    lg = LinkGraph::Get(ge1.link_graph);
    if (ge1.link_graph != ge2.link_graph) {
      LinkGraph *lg2 = LinkGraph::Get(ge2.link_graph);
      if (lg->Size() < lg2->Size()) {
        LinkGraphSchedule::instance.Dequeue(lg);
        lg2->Merge(lg); // Updates GoodsEntries of lg
        lg = lg2;
      } else {
        LinkGraphSchedule::instance.Dequeue(lg2);
        lg->Merge(lg2); // Updates GoodsEntries of lg2
      }
    }
  }
  if (lg != nullptr) {
    (*lg)[ge1.node].UpdateEdge(ge2.node, capacity, usage, time, modes);
  }
}
 
void IncreaseStats(Station *st, const Vehicle *front, StationID next_station_id, uint32_t time)
{
  for (const Vehicle *v = front; v != nullptr; v = v->Next()) {
    if (v->refit_cap > 0) {
      /* The cargo count can indeed be higher than the refit_cap if
       * wagons have been auto-replaced and subsequently auto-
       * refitted to a higher capacity. The cargo gets redistributed
       * among the wagons in that case.
       * As usage is not such an important figure anyway we just
       * ignore the additional cargo then.*/
      IncreaseStats(st, v->cargo_type, next_station_id, v->refit_cap,
          std::min<uint>(v->refit_cap, v->cargo.StoredCount()), time, EdgeUpdateMode::Increase);
    }
  }
}
 
/* called for every station each tick */
static void StationHandleSmallTick(BaseStation *st)
{
  if (st->facilities.Test(StationFacility::Waypoint) || !st->IsInUse()) return;
 
  uint8_t b = st->delete_ctr + 1;
  if (b >= Ticks::STATION_RATING_TICKS) b = 0;
  st->delete_ctr = b;
 
  if (b == 0) UpdateStationRating(Station::From(st));
}
 
void OnTick_Station()
{
  if (_game_mode == GM_EDITOR) return;
 
  for (BaseStation *st : BaseStation::Iterate()) {
    StationHandleSmallTick(st);
 
    /* Clean up the link graph about once a week. */
    if (Station::IsExpected(st) && (TimerGameTick::counter + st->index) % Ticks::STATION_LINKGRAPH_TICKS == 0) {
      DeleteStaleLinks(Station::From(st));
    };
 
    /* Spread out big-tick over STATION_ACCEPTANCE_TICKS ticks. */
    if ((TimerGameTick::counter + st->index) % Ticks::STATION_ACCEPTANCE_TICKS == 0) {
      /* Stop processing this station if it was deleted */
      if (!StationHandleBigTick(st)) continue;
    }
 
    /* Spread out station animation over STATION_ACCEPTANCE_TICKS ticks. */
    if ((TimerGameTick::counter + st->index) % Ticks::STATION_ACCEPTANCE_TICKS == 0) {
      TriggerStationAnimation(st, st->xy, StationAnimationTrigger::AcceptanceTick);
      TriggerRoadStopAnimation(st, st->xy, StationAnimationTrigger::AcceptanceTick);
      if (Station::IsExpected(st)) TriggerAirportAnimation(Station::From(st), AirportAnimationTrigger::AcceptanceTick);
    }
  }
}
 
static const IntervalTimer<TimerGameEconomy> _economy_stations_monthly({TimerGameEconomy::MONTH, TimerGameEconomy::Priority::STATION}, [](auto)
{
  for (Station *st : Station::Iterate()) {
    for (GoodsEntry &ge : st->goods) {
      ge.status.Set(GoodsEntry::State::LastMonth, ge.status.Test(GoodsEntry::State::CurrentMonth));
      ge.status.Reset(GoodsEntry::State::CurrentMonth);
    }
  }
});
 
void ModifyStationRatingAround(TileIndex tile, Owner owner, int amount, uint radius)
{
  ForAllStationsRadius(tile, radius, [&](Station *st) {
    if (st->owner == owner && DistanceManhattan(tile, st->xy) <= radius) {
      for (GoodsEntry &ge : st->goods) {
        if (ge.status.Any()) {
          ge.rating = ClampTo<uint8_t>(ge.rating + amount);
        }
      }
    }
  });
}
 
static uint UpdateStationWaiting(Station *st, CargoType cargo, uint amount, Source source)
{
  /* We can't allocate a CargoPacket? Then don't do anything
   * at all; i.e. just discard the incoming cargo. */
  if (!CargoPacket::CanAllocateItem()) return 0;
 
  GoodsEntry &ge = st->goods[cargo];
  amount += ge.amount_fract;
  ge.amount_fract = GB(amount, 0, 8);
 
  amount >>= 8;
  /* No new "real" cargo item yet. */
  if (amount == 0) return 0;
 
  StationID next = ge.GetVia(st->index);
  ge.GetOrCreateData().cargo.Append(CargoPacket::Create(st->index, amount, source), next);
  LinkGraph *lg = nullptr;
  if (ge.link_graph == LinkGraphID::Invalid()) {
    if (LinkGraph::CanAllocateItem()) {
      lg = LinkGraph::Create(cargo);
      LinkGraphSchedule::instance.Queue(lg);
      ge.link_graph = lg->index;
      ge.node = lg->AddNode(st);
    } else {
      Debug(misc, 0, "Can't allocate link graph");
    }
  } else {
    lg = LinkGraph::Get(ge.link_graph);
  }
  if (lg != nullptr) (*lg)[ge.node].UpdateSupply(amount);
 
  if (!ge.HasRating()) {
    InvalidateWindowData(WC_STATION_LIST, st->owner);
    ge.status.Set(GoodsEntry::State::Rating);
  }
 
  TriggerStationRandomisation(st, st->xy, StationRandomTrigger::NewCargo, cargo);
  TriggerStationAnimation(st, st->xy, StationAnimationTrigger::NewCargo, cargo);
  TriggerAirportAnimation(st, AirportAnimationTrigger::NewCargo, cargo);
  TriggerRoadStopRandomisation(st, st->xy, StationRandomTrigger::NewCargo, cargo);
  TriggerRoadStopAnimation(st, st->xy, StationAnimationTrigger::NewCargo, cargo);
 
 
  SetWindowDirty(WC_STATION_VIEW, st->index);
  st->MarkTilesDirty(true);
  return amount;
}
 
static bool IsUniqueStationName(const std::string &name)
{
  for (const Station *st : Station::Iterate()) {
    if (!st->name.empty() && st->name == name) return false;
  }
 
  return true;
}
 
CommandCost CmdRenameStation(DoCommandFlags flags, StationID station_id, const std::string &text)
{
  Station *st = Station::GetIfValid(station_id);
  if (st == nullptr) return CMD_ERROR;
 
  CommandCost ret = CheckOwnership(st->owner);
  if (ret.Failed()) return ret;
 
  bool reset = text.empty();
 
  if (!reset) {
    if (Utf8StringLength(text) >= MAX_LENGTH_STATION_NAME_CHARS) return CMD_ERROR;
    if (!IsUniqueStationName(text)) return CommandCost(STR_ERROR_NAME_MUST_BE_UNIQUE);
  }
 
  if (flags.Test(DoCommandFlag::Execute)) {
    st->cached_name.clear();
    if (reset) {
      st->name.clear();
    } else {
      st->name = text;
    }
 
    st->UpdateVirtCoord();
    InvalidateWindowData(WC_STATION_LIST, st->owner, 1);
  }
 
  return CommandCost();
}
 
std::tuple<CommandCost, StationID> CmdMoveStationName(DoCommandFlags flags, StationID station_id, TileIndex tile)
{
  Station *st = Station::GetIfValid(station_id);
  if (st == nullptr) return { CMD_ERROR, StationID::Invalid() };
 
  if (st->owner != OWNER_NONE) {
    CommandCost ret = CheckOwnership(st->owner);
    if (ret.Failed()) return { ret, StationID::Invalid() };
  }
 
  const StationRect *r = &st->rect;
  if (!r->PtInExtendedRect(TileX(tile), TileY(tile))) {
    return { CommandCost(STR_ERROR_SITE_UNSUITABLE), StationID::Invalid() };
  }
 
  bool other_station = false;
  /* Check if the tile is the base tile of another station */
  ForAllStationsRadius(tile, 0, [&](BaseStation *s) {
    if (s != nullptr) {
      if (s != st && s->xy == tile) other_station = true;
    }
  });
  if (other_station) return { CommandCost(STR_ERROR_SITE_UNSUITABLE), StationID::Invalid() };
 
  if (flags.Test(DoCommandFlag::Execute)) {
    st->MoveSign(tile);
 
    st->UpdateVirtCoord();
  }
  return { CommandCost(), station_id };
}
 
void CcMoveStationName(Commands, const CommandCost &result, StationID station_id)
  {
    if (result.Failed()) return;
 
    ResetObjectToPlace();
    Station *st = Station::Get(station_id);
    SetViewportStationRect(st, false);
  }
 
static void AddNearbyStationsByCatchment(TileIndex tile, StationList &stations, StationList &nearby)
{
  for (Station *st : nearby) {
    if (st->TileIsInCatchment(tile)) stations.insert(st);
  }
}
 
const StationList &StationFinder::GetStations()
{
  if (this->tile != INVALID_TILE) {
    if (IsTileType(this->tile, MP_HOUSE)) {
      /* Town nearby stations need to be filtered per tile. */
      assert(this->w == 1 && this->h == 1);
      AddNearbyStationsByCatchment(this->tile, this->stations, Town::GetByTile(this->tile)->stations_near);
    } else {
      ForAllStationsAroundTiles(*this, [this](Station *st, TileIndex) {
        this->stations.insert(st);
        return true;
      });
    }
    this->tile = INVALID_TILE;
  }
  return this->stations;
}
 
 
static bool CanMoveGoodsToStation(const Station *st, CargoType cargo)
{
  /* Is the station reserved exclusively for somebody else? */
  if (st->owner != OWNER_NONE && st->town->exclusive_counter > 0 && st->town->exclusivity != st->owner) return false;
 
  /* Lowest possible rating, better not to give cargo anymore. */
  if (st->goods[cargo].rating == 0) return false;
 
  /* Selectively servicing stations, and not this one. */
  if (_settings_game.order.selectgoods && !st->goods[cargo].HasVehicleEverTriedLoading()) return false;
 
  if (IsCargoInClass(cargo, CargoClass::Passengers)) {
    /* Passengers are never served by just a truck stop. */
    if (st->facilities == StationFacility::TruckStop) return false;
  } else {
    /* Non-passengers are never served by just a bus stop. */
    if (st->facilities == StationFacility::BusStop) return false;
  }
  return true;
}
 
uint MoveGoodsToStation(CargoType cargo, uint amount, Source source, const StationList &all_stations, Owner exclusivity)
{
  /* Return if nothing to do. Also the rounding below fails for 0. */
  if (all_stations.empty()) return 0;
  if (amount == 0) return 0;
 
  Station *first_station = nullptr;
  typedef std::pair<Station *, uint> StationInfo;
  std::vector<StationInfo> used_stations;
 
  for (Station *st : all_stations) {
    if (exclusivity != INVALID_OWNER && exclusivity != st->owner) continue;
    if (!CanMoveGoodsToStation(st, cargo)) continue;
 
    /* Avoid allocating a vector if there is only one station to significantly
     * improve performance in this common case. */
    if (first_station == nullptr) {
      first_station = st;
      continue;
    }
    if (used_stations.empty()) {
      used_stations.reserve(2);
      used_stations.emplace_back(first_station, 0);
    }
    used_stations.emplace_back(st, 0);
  }
 
  /* no stations around at all? */
  if (first_station == nullptr) return 0;
 
  if (used_stations.empty()) {
    /* only one station around */
    amount *= first_station->goods[cargo].rating + 1;
    return UpdateStationWaiting(first_station, cargo, amount, source);
  }
 
  TypedIndexContainer<std::array<uint32_t, OWNER_END.base()>, Owner> company_best = {};  // best rating for each company, including OWNER_NONE
  TypedIndexContainer<std::array<uint32_t, OWNER_END.base()>, Owner> company_sum = {};   // sum of ratings for each company
  uint best_rating = 0;
  uint best_sum = 0;  // sum of best ratings for each company
 
  for (auto &p : used_stations) {
    auto owner = p.first->owner;
    auto rating = p.first->goods[cargo].rating;
    if (rating > company_best[owner]) {
      best_sum += rating - company_best[owner];  // it's usually faster than iterating companies later
      company_best[owner] = rating;
      if (rating > best_rating) best_rating = rating;
    }
    company_sum[owner] += rating;
  }
 
  /* From now we'll calculate with fractional cargo amounts.
   * First determine how much cargo we really have. */
  amount *= best_rating + 1;
 
  uint moving = 0;
  for (auto &p : used_stations) {
    Owner owner = p.first->owner;
    /* Multiply the amount by (company best / sum of best for each company) to get cargo allocated to a company
     * and by (station rating / sum of ratings in a company) to get the result for a single station. */
    p.second = amount * company_best[owner] * p.first->goods[cargo].rating / best_sum / company_sum[owner];
    moving += p.second;
  }
 
  /* If there is some cargo left due to rounding issues distribute it among the best rated stations. */
  if (amount > moving) {
    std::stable_sort(used_stations.begin(), used_stations.end(), [cargo](const StationInfo &a, const StationInfo &b) {
      return b.first->goods[cargo].rating < a.first->goods[cargo].rating;
    });
 
    assert(amount - moving <= used_stations.size());
    for (uint i = 0; i < amount - moving; i++) {
      used_stations[i].second++;
    }
  }
 
  uint moved = 0;
  for (auto &p : used_stations) {
    moved += UpdateStationWaiting(p.first, cargo, p.second, source);
  }
 
  return moved;
}
 
void UpdateStationDockingTiles(Station *st)
{
  st->docking_station.Clear();
 
  /* For neutral stations, start with the industry area instead of dock area */
  const TileArea *area = st->industry != nullptr ? &st->industry->location : &st->ship_station;
 
  if (area->tile == INVALID_TILE) return;
 
  int x = TileX(area->tile);
  int y = TileY(area->tile);
 
  /* Expand the area by a tile on each side while
   * making sure that we remain inside the map. */
  int x2 = std::min<int>(x + area->w + 1, Map::SizeX());
  int x1 = std::max<int>(x - 1, 0);
 
  int y2 = std::min<int>(y + area->h + 1, Map::SizeY());
  int y1 = std::max<int>(y - 1, 0);
 
  TileArea ta(TileXY(x1, y1), TileXY(x2 - 1, y2 - 1));
  for (TileIndex tile : ta) {
    if (IsValidTile(tile) && IsPossibleDockingTile(tile)) CheckForDockingTile(tile);
  }
}
 
void BuildOilRig(TileIndex tile)
{
  if (!Station::CanAllocateItem()) {
    Debug(misc, 0, "Can't allocate station for oilrig at 0x{:X}, reverting to oilrig only", tile);
    return;
  }
 
  Station *st = Station::Create(tile);
  _station_kdtree.Insert(st->index);
  st->town = ClosestTownFromTile(tile, UINT_MAX);
 
  st->string_id = GenerateStationName(st, tile, STATIONNAMING_OILRIG);
 
  assert(IsTileType(tile, MP_INDUSTRY));
  /* Mark industry as associated both ways */
  st->industry = Industry::GetByTile(tile);
  st->industry->neutral_station = st;
  DeleteAnimatedTile(tile);
  MakeOilrig(tile, st->index, GetWaterClass(tile));
 
  st->owner = OWNER_NONE;
  st->airport.type = AT_OILRIG;
  st->airport.rotation = DIR_N;
  st->airport.Add(tile);
  st->ship_station.Add(tile);
  st->facilities = {StationFacility::Airport, StationFacility::Dock};
  st->build_date = TimerGameCalendar::date;
  UpdateStationDockingTiles(st);
 
  st->rect.BeforeAddTile(tile, StationRect::ADD_FORCE);
 
  st->UpdateVirtCoord();
 
  /* An industry tile has now been replaced with a station tile, this may change the overlap between station catchments and industry tiles.
   * Recalculate the station catchment for all stations currently in the industry's nearby list.
   * Clear the industry's station nearby list first because Station::RecomputeCatchment cannot remove nearby industries in this case. */
  if (_settings_game.station.serve_neutral_industries) {
    StationList nearby = std::move(st->industry->stations_near);
    st->industry->stations_near.clear();
    for (Station *near : nearby) {
      near->RecomputeCatchment(true);
      UpdateStationAcceptance(near, true);
    }
  }
 
  st->RecomputeCatchment();
  UpdateStationAcceptance(st, false);
}
 
void DeleteOilRig(TileIndex tile)
{
  Station *st = Station::GetByTile(tile);
 
  MakeWaterKeepingClass(tile, OWNER_NONE);
 
  /* The oil rig station is not supposed to be shared with anything else */
  [[maybe_unused]] static constexpr StationFacilities expected_facility{StationFacility::Airport, StationFacility::Dock};
  assert(st->facilities == expected_facility && st->airport.type == AT_OILRIG);
  if (st->industry != nullptr && st->industry->neutral_station == st) {
    /* Don't leave dangling neutral station pointer */
    st->industry->neutral_station = nullptr;
  }
  delete st;
}
 
static void ChangeTileOwner_Station(TileIndex tile, Owner old_owner, Owner new_owner)
{
 
  if (IsAnyRoadStopTile(tile)) {
    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 drive-through road-stop has always two road bits. No need to dirty windows here, we'll redraw the whole screen anyway. */
          Company::Get(old_owner)->infrastructure.road[rt] -= 2;
          if (new_owner != INVALID_OWNER) Company::Get(new_owner)->infrastructure.road[rt] += 2;
        }
        SetRoadOwner(tile, rtt, new_owner == INVALID_OWNER ? OWNER_NONE : new_owner);
      }
    }
  }
 
  if (!IsTileOwner(tile, old_owner)) return;
 
  if (new_owner != INVALID_OWNER) {
    /* Update company infrastructure counts. Only do it here
     * if the new owner is valid as otherwise the clear
     * command will do it for us. No need to dirty windows
     * here, we'll redraw the whole screen anyway.*/
    Company *old_company = Company::Get(old_owner);
    Company *new_company = Company::Get(new_owner);
 
    /* Update counts for underlying infrastructure. */
    switch (GetStationType(tile)) {
      case StationType::Rail:
      case StationType::RailWaypoint:
        if (!IsStationTileBlocked(tile)) {
          old_company->infrastructure.rail[GetRailType(tile)]--;
          new_company->infrastructure.rail[GetRailType(tile)]++;
        }
        break;
 
      case StationType::Bus:
      case StationType::Truck:
      case StationType::RoadWaypoint:
        /* Road stops were already handled above. */
        break;
 
      case StationType::Buoy:
      case StationType::Dock:
        if (GetWaterClass(tile) == WaterClass::Canal) {
          old_company->infrastructure.water--;
          new_company->infrastructure.water++;
        }
        break;
 
      default:
        break;
    }
 
    /* Update station tile count. */
    if (!IsBuoy(tile) && !IsAirport(tile)) {
      old_company->infrastructure.station--;
      new_company->infrastructure.station++;
    }
 
    /* for buoys, owner of tile is owner of water, st->owner == OWNER_NONE */
    SetTileOwner(tile, new_owner);
    InvalidateWindowClassesData(WC_STATION_LIST, 0);
  } else {
    if (IsDriveThroughStopTile(tile)) {
      /* Remove the drive-through road stop */
      if (IsRoadWaypoint(tile)) {
        Command<CMD_REMOVE_FROM_ROAD_WAYPOINT>::Do({DoCommandFlag::Execute, DoCommandFlag::Bankrupt}, tile, tile);
      } else {
        Command<CMD_REMOVE_ROAD_STOP>::Do({DoCommandFlag::Execute, DoCommandFlag::Bankrupt}, tile, 1, 1, (GetStationType(tile) == StationType::Truck) ? RoadStopType::Truck : RoadStopType::Bus, false);
      }
      assert(IsTileType(tile, MP_ROAD));
      /* Change owner of tile and all roadtypes */
      ChangeTileOwner(tile, old_owner, new_owner);
    } else {
      Command<CMD_LANDSCAPE_CLEAR>::Do({DoCommandFlag::Execute, DoCommandFlag::Bankrupt}, tile);
      /* Set tile owner of water under (now removed) buoy and dock to OWNER_NONE.
       * Update owner of buoy if it was not removed (was in orders).
       * Do not update when owned by OWNER_WATER (sea and rivers). */
      if ((IsTileType(tile, MP_WATER) || IsBuoyTile(tile)) && IsTileOwner(tile, old_owner)) SetTileOwner(tile, OWNER_NONE);
    }
  }
}
 
static CommandCost CanRemoveRoadWithStop(TileIndex tile, DoCommandFlags flags)
{
  /* Water flooding can always clear road stops. */
  if (_current_company == OWNER_WATER) return CommandCost();
 
  CommandCost ret;
 
  if (GetRoadTypeTram(tile) != INVALID_ROADTYPE) {
    Owner tram_owner = GetRoadOwner(tile, RTT_TRAM);
    if (tram_owner != OWNER_NONE) {
      ret = CheckOwnership(tram_owner);
      if (ret.Failed()) return ret;
    }
  }
 
  if (GetRoadTypeRoad(tile) != INVALID_ROADTYPE) {
    Owner road_owner = GetRoadOwner(tile, RTT_ROAD);
    if (road_owner == OWNER_TOWN) {
      ret = CheckAllowRemoveRoad(tile, GetAnyRoadBits(tile, RTT_ROAD), OWNER_TOWN, RTT_ROAD, flags);
      if (ret.Failed()) return ret;
    } else if (road_owner != OWNER_NONE) {
      ret = CheckOwnership(road_owner);
      if (ret.Failed()) return ret;
    }
  }
 
  return CommandCost();
}
 
CommandCost ClearTile_Station(TileIndex tile, DoCommandFlags flags)
{
  if (flags.Test(DoCommandFlag::Auto)) {
    switch (GetStationType(tile)) {
      default: break;
      case StationType::Rail:     return CommandCost(STR_ERROR_MUST_DEMOLISH_RAILROAD);
      case StationType::RailWaypoint: return CommandCost(STR_ERROR_BUILDING_MUST_BE_DEMOLISHED);
      case StationType::Airport:  return CommandCost(STR_ERROR_MUST_DEMOLISH_AIRPORT_FIRST);
      case StationType::Truck:    return CommandCost(HasTileRoadType(tile, RTT_TRAM) ? STR_ERROR_MUST_DEMOLISH_CARGO_TRAM_STATION_FIRST : STR_ERROR_MUST_DEMOLISH_TRUCK_STATION_FIRST);
      case StationType::Bus:      return CommandCost(HasTileRoadType(tile, RTT_TRAM) ? STR_ERROR_MUST_DEMOLISH_PASSENGER_TRAM_STATION_FIRST : STR_ERROR_MUST_DEMOLISH_BUS_STATION_FIRST);
      case StationType::RoadWaypoint: return CommandCost(STR_ERROR_BUILDING_MUST_BE_DEMOLISHED);
      case StationType::Buoy:     return CommandCost(STR_ERROR_BUOY_IN_THE_WAY);
      case StationType::Dock:     return CommandCost(STR_ERROR_MUST_DEMOLISH_DOCK_FIRST);
      case StationType::Oilrig:
        return CommandCostWithParam(STR_ERROR_GENERIC_OBJECT_IN_THE_WAY, STR_INDUSTRY_NAME_OIL_RIG);
    }
  }
 
  switch (GetStationType(tile)) {
    case StationType::Rail:     return RemoveRailStation(tile, flags);
    case StationType::RailWaypoint: return RemoveRailWaypoint(tile, flags);
    case StationType::Airport:  return RemoveAirport(tile, flags);
    case StationType::Truck:    [[fallthrough]];
    case StationType::Bus:
      if (IsDriveThroughStopTile(tile)) {
        CommandCost remove_road = CanRemoveRoadWithStop(tile, flags);
        if (remove_road.Failed()) return remove_road;
      }
      return RemoveRoadStop(tile, flags);
    case StationType::RoadWaypoint: {
      CommandCost remove_road = CanRemoveRoadWithStop(tile, flags);
      if (remove_road.Failed()) return remove_road;
      return RemoveRoadWaypointStop(tile, flags);
    }
    case StationType::Buoy:     return RemoveBuoy(tile, flags);
    case StationType::Dock:     return RemoveDock(tile, flags);
    default: break;
  }
 
  return CMD_ERROR;
}
 
static CommandCost TerraformTile_Station(TileIndex tile, DoCommandFlags flags, int z_new, Slope tileh_new)
{
  if (_settings_game.construction.build_on_slopes && AutoslopeEnabled()) {
    /* TODO: If you implement newgrf callback 149 'land slope check', you have to decide what to do with it here.
     *       TTDP does not call it.
     */
    if (GetTileMaxZ(tile) == z_new + GetSlopeMaxZ(tileh_new)) {
      switch (GetStationType(tile)) {
        case StationType::RailWaypoint:
        case StationType::Rail: {
          if (!AutoslopeCheckForAxis(tile, z_new, tileh_new, GetRailStationAxis(tile))) break;
          return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
        }
 
        case StationType::Airport:
          return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
 
        case StationType::Truck:
        case StationType::Bus:
        case StationType::RoadWaypoint: {
          if (IsDriveThroughStopTile(tile)) {
            if (!AutoslopeCheckForAxis(tile, z_new, tileh_new, GetDriveThroughStopAxis(tile))) break;
          } else {
            if (!AutoslopeCheckForEntranceEdge(tile, z_new, tileh_new, GetBayRoadStopDir(tile))) break;
          }
          return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
        }
 
        default: break;
      }
    }
  }
  return Command<CMD_LANDSCAPE_CLEAR>::Do(flags, tile);
}
 
uint FlowStat::GetShare(StationID st) const
{
  uint32_t prev = 0;
  for (const auto &it : this->shares) {
    if (it.second == st) {
      return it.first - prev;
    } else {
      prev = it.first;
    }
  }
  return 0;
}
 
StationID FlowStat::GetVia(StationID excluded, StationID excluded2) const
{
  if (this->unrestricted == 0) return StationID::Invalid();
  assert(!this->shares.empty());
  SharesMap::const_iterator it = this->shares.upper_bound(RandomRange(this->unrestricted));
  assert(it != this->shares.end() && it->first <= this->unrestricted);
  if (it->second != excluded && it->second != excluded2) return it->second;
 
  /* We've hit one of the excluded stations.
   * Draw another share, from outside its range. */
 
  uint end = it->first;
  uint begin = (it == this->shares.begin() ? 0 : (--it)->first);
  uint interval = end - begin;
  if (interval >= this->unrestricted) return StationID::Invalid(); // Only one station in the map.
  uint new_max = this->unrestricted - interval;
  uint rand = RandomRange(new_max);
  SharesMap::const_iterator it2 = (rand < begin) ? this->shares.upper_bound(rand) :
      this->shares.upper_bound(rand + interval);
  assert(it2 != this->shares.end() && it2->first <= this->unrestricted);
  if (it2->second != excluded && it2->second != excluded2) return it2->second;
 
  /* We've hit the second excluded station.
   * Same as before, only a bit more complicated. */
 
  uint end2 = it2->first;
  uint begin2 = (it2 == this->shares.begin() ? 0 : (--it2)->first);
  uint interval2 = end2 - begin2;
  if (interval2 >= new_max) return StationID::Invalid(); // Only the two excluded stations in the map.
  new_max -= interval2;
  if (begin > begin2) {
    std::swap(begin, begin2);
    std::swap(end, end2);
    std::swap(interval, interval2);
  }
  rand = RandomRange(new_max);
  SharesMap::const_iterator it3 = this->shares.upper_bound(this->unrestricted);
  if (rand < begin) {
    it3 = this->shares.upper_bound(rand);
  } else if (rand < begin2 - interval) {
    it3 = this->shares.upper_bound(rand + interval);
  } else {
    it3 = this->shares.upper_bound(rand + interval + interval2);
  }
  assert(it3 != this->shares.end() && it3->first <= this->unrestricted);
  return it3->second;
}
 
void FlowStat::Invalidate()
{
  assert(!this->shares.empty());
  SharesMap new_shares;
  uint i = 0;
  for (const auto &it : this->shares) {
    new_shares[++i] = it.second;
    if (it.first == this->unrestricted) this->unrestricted = i;
  }
  this->shares.swap(new_shares);
  assert(!this->shares.empty() && this->unrestricted <= (--this->shares.end())->first);
}
 
void FlowStat::ChangeShare(StationID st, int flow)
{
  /* We assert only before changing as afterwards the shares can actually
   * be empty. In that case the whole flow stat must be deleted then. */
  assert(!this->shares.empty());
 
  uint removed_shares = 0;
  uint added_shares = 0;
  uint last_share = 0;
  SharesMap new_shares;
  for (const auto &it : this->shares) {
    if (it.second == st) {
      if (flow < 0) {
        uint share = it.first - last_share;
        if (flow == INT_MIN || (uint)(-flow) >= share) {
          removed_shares += share;
          if (it.first <= this->unrestricted) this->unrestricted -= share;
          if (flow != INT_MIN) flow += share;
          last_share = it.first;
          continue; // remove the whole share
        }
        removed_shares += (uint)(-flow);
      } else {
        added_shares += (uint)(flow);
      }
      if (it.first <= this->unrestricted) this->unrestricted += flow;
 
      /* If we don't continue above the whole flow has been added or
       * removed. */
      flow = 0;
    }
    new_shares[it.first + added_shares - removed_shares] = it.second;
    last_share = it.first;
  }
  if (flow > 0) {
    new_shares[last_share + (uint)flow] = st;
    if (this->unrestricted < last_share) {
      this->ReleaseShare(st);
    } else {
      this->unrestricted += flow;
    }
  }
  this->shares.swap(new_shares);
}
 
void FlowStat::RestrictShare(StationID st)
{
  assert(!this->shares.empty());
  uint flow = 0;
  uint last_share = 0;
  SharesMap new_shares;
  for (auto &it : this->shares) {
    if (flow == 0) {
      if (it.first > this->unrestricted) return; // Not present or already restricted.
      if (it.second == st) {
        flow = it.first - last_share;
        this->unrestricted -= flow;
      } else {
        new_shares[it.first] = it.second;
      }
    } else {
      new_shares[it.first - flow] = it.second;
    }
    last_share = it.first;
  }
  if (flow == 0) return;
  new_shares[last_share + flow] = st;
  this->shares.swap(new_shares);
  assert(!this->shares.empty());
}
 
void FlowStat::ReleaseShare(StationID st)
{
  assert(!this->shares.empty());
  uint flow = 0;
  uint next_share = 0;
  bool found = false;
  for (SharesMap::reverse_iterator it(this->shares.rbegin()); it != this->shares.rend(); ++it) {
    if (it->first < this->unrestricted) return; // Note: not <= as the share may hit the limit.
    if (found) {
      flow = next_share - it->first;
      this->unrestricted += flow;
      break;
    } else {
      if (it->first == this->unrestricted) return; // !found -> Limit not hit.
      if (it->second == st) found = true;
    }
    next_share = it->first;
  }
  if (flow == 0) return;
  SharesMap new_shares;
  new_shares[flow] = st;
  for (SharesMap::iterator it(this->shares.begin()); it != this->shares.end(); ++it) {
    if (it->second != st) {
      new_shares[flow + it->first] = it->second;
    } else {
      flow = 0;
    }
  }
  this->shares.swap(new_shares);
  assert(!this->shares.empty());
}
 
void FlowStat::ScaleToMonthly(uint runtime)
{
  assert(runtime > 0);
  SharesMap new_shares;
  uint share = 0;
  for (auto i : this->shares) {
    share = std::max(share + 1, i.first * 30 / runtime);
    new_shares[share] = i.second;
    if (this->unrestricted == i.first) this->unrestricted = share;
  }
  this->shares.swap(new_shares);
}
 
void FlowStatMap::AddFlow(StationID origin, StationID via, uint flow)
{
  FlowStatMap::iterator origin_it = this->find(origin);
  if (origin_it == this->end()) {
    this->emplace(origin, FlowStat(via, flow));
  } else {
    origin_it->second.ChangeShare(via, flow);
    assert(!origin_it->second.GetShares()->empty());
  }
}
 
void FlowStatMap::PassOnFlow(StationID origin, StationID via, uint flow)
{
  FlowStatMap::iterator prev_it = this->find(origin);
  if (prev_it == this->end()) {
    FlowStat fs(via, flow);
    fs.AppendShare(StationID::Invalid(), flow);
    this->emplace(origin, fs);
  } else {
    prev_it->second.ChangeShare(via, flow);
    prev_it->second.ChangeShare(StationID::Invalid(), flow);
    assert(!prev_it->second.GetShares()->empty());
  }
}
 
void FlowStatMap::FinalizeLocalConsumption(StationID self)
{
  for (auto &i : *this) {
    FlowStat &fs = i.second;
    uint local = fs.GetShare(StationID::Invalid());
    if (local > INT_MAX) { // make sure it fits in an int
      fs.ChangeShare(self, -INT_MAX);
      fs.ChangeShare(StationID::Invalid(), -INT_MAX);
      local -= INT_MAX;
    }
    fs.ChangeShare(self, -(int)local);
    fs.ChangeShare(StationID::Invalid(), -(int)local);
 
    /* If the local share is used up there must be a share for some
     * remote station. */
    assert(!fs.GetShares()->empty());
  }
}
 
std::vector<StationID> FlowStatMap::DeleteFlows(StationID via)
{
  std::vector<StationID> ret;
  for (FlowStatMap::iterator f_it = this->begin(); f_it != this->end();) {
    FlowStat &s_flows = f_it->second;
    s_flows.ChangeShare(via, INT_MIN);
    if (s_flows.GetShares()->empty()) {
      ret.push_back(f_it->first);
      this->erase(f_it++);
    } else {
      ++f_it;
    }
  }
  return ret;
}
 
void FlowStatMap::RestrictFlows(StationID via)
{
  for (auto &it : *this) {
    it.second.RestrictShare(via);
  }
}
 
void FlowStatMap::ReleaseFlows(StationID via)
{
  for (auto &it : *this) {
    it.second.ReleaseShare(via);
  }
}
 
uint FlowStatMap::GetFlow() const
{
  uint ret = 0;
  for (const auto &it : *this) {
    ret += (--(it.second.GetShares()->end()))->first;
  }
  return ret;
}
 
uint FlowStatMap::GetFlowVia(StationID via) const
{
  uint ret = 0;
  for (const auto &it : *this) {
    ret += it.second.GetShare(via);
  }
  return ret;
}
 
uint FlowStatMap::GetFlowFrom(StationID from) const
{
  FlowStatMap::const_iterator i = this->find(from);
  if (i == this->end()) return 0;
  return (--(i->second.GetShares()->end()))->first;
}
 
uint FlowStatMap::GetFlowFromVia(StationID from, StationID via) const
{
  FlowStatMap::const_iterator i = this->find(from);
  if (i == this->end()) return 0;
  return i->second.GetShare(via);
}
 
static CommandCost CheckBuildAbove_Station(TileIndex tile, DoCommandFlags, Axis, int height)
{
  StationType type = GetStationType(tile);
  auto bridgeable_info = GetStationBridgeableTileInfo(type);
 
  switch (type) {
    case StationType::Rail:
    case StationType::RailWaypoint:
      if (const StationSpec *spec = GetStationSpec(tile); spec != nullptr) bridgeable_info = spec->bridgeable_info;
      break;
 
    case StationType::Bus:
    case StationType::Truck:
    case StationType::RoadWaypoint:
      if (const RoadStopSpec *spec = GetRoadStopSpec(tile); spec != nullptr) bridgeable_info = spec->bridgeable_info;
      break;
 
    default: break;
  }
 
  return IsStationBridgeAboveOk(tile, bridgeable_info, type, GetStationGfx(tile), height);
}
 
extern const TileTypeProcs _tile_type_station_procs = {
  DrawTile_Station,           // draw_tile_proc
  GetSlopePixelZ_Station,     // get_slope_z_proc
  ClearTile_Station,          // clear_tile_proc
  nullptr,                       // add_accepted_cargo_proc
  GetTileDesc_Station,        // get_tile_desc_proc
  GetTileTrackStatus_Station, // get_tile_track_status_proc
  ClickTile_Station,          // click_tile_proc
  AnimateTile_Station,        // animate_tile_proc
  TileLoop_Station,           // tile_loop_proc
  ChangeTileOwner_Station,    // change_tile_owner_proc
  nullptr,                       // add_produced_cargo_proc
  VehicleEnter_Station,       // vehicle_enter_tile_proc
  GetFoundation_Station,      // get_foundation_proc
  TerraformTile_Station,      // terraform_tile_proc
  CheckBuildAbove_Station, // check_build_above_proc
};