Refactor/de-duplicate rail station bridge above check methods

src/station_cmd.cpp

@@ -775,22 +775,30 @@ CommandCost CheckBuildableTile(TileIndex tile, uint invalid_dirs, int &allowed_z
 	return cost;
 }
 
-bool IsRailStationBridgeAboveOk(TileIndex tile, const StationSpec *statspec, byte layout)
+bool IsRailStationBridgeAboveOk(TileIndex tile, const StationSpec *statspec, byte layout, TileIndex northern_bridge_end, TileIndex southern_bridge_end, int bridge_height)
 {
 	assert(layout < 8);
-	if (!IsBridgeAbove(tile)) return true;
 
 	if (statspec && HasBit(statspec->internal_flags, SSIF_BRIDGE_HEIGHTS_SET)) {
-		return (GetTileMaxZ(tile) + statspec->bridge_height[layout] <= GetBridgeHeight(GetSouthernBridgeEnd(tile)));
+		return (GetTileMaxZ(tile) + statspec->bridge_height[layout] <= bridge_height);
 	} else if (!statspec) {
 		// default stations/waypoints
 		const int height = layout < 4 ? 2 : 5;
-		return (GetTileMaxZ(tile) + height <= GetBridgeHeight(GetSouthernBridgeEnd(tile)));
+		return (GetTileMaxZ(tile) + height <= bridge_height);
 	} else {
 		return _settings_game.construction.allow_stations_under_bridges;
 	}
 }
 
+bool IsRailStationBridgeAboveOk(TileIndex tile, const StationSpec *statspec, byte layout)
+{
+	if (!IsBridgeAbove(tile)) return true;
+
+	TileIndex southern_bridge_end = GetSouthernBridgeEnd(tile);
+	TileIndex northern_bridge_end = GetNorthernBridgeEnd(tile);
+	return IsRailStationBridgeAboveOk(tile, statspec, layout, northern_bridge_end, southern_bridge_end, GetBridgeHeight(southern_bridge_end));
+}
+
 /**
  * Checks if a rail station can be built at the given area.
  * @param tile_area Area to check.

src/tunnelbridge_cmd.cpp

@@ -65,6 +65,8 @@ extern void DrawTrackBits(TileInfo *ti, TrackBits track);
 extern void DrawRoadBits(TileInfo *ti);
 extern const RoadBits _invalid_tileh_slopes_road[2][15];
 
+extern bool IsRailStationBridgeAboveOk(TileIndex tile, const StationSpec *statspec, byte layout, TileIndex northern_bridge_end, TileIndex southern_bridge_end, int bridge_height);
+
 /**
  * Mark bridge tiles dirty.
  * Note: The bridge does not need to exist, everything is passed via parameters.
@@ -497,16 +499,7 @@ CommandCost CmdBuildBridge(TileIndex end_tile, DoCommandFlag flags, uint32 p1, u
 
 						case STATION_RAIL:
 						case STATION_WAYPOINT: {
-							const StationSpec *statspec = GetStationSpec(tile);
-							if (statspec && HasBit(statspec->internal_flags, SSIF_BRIDGE_HEIGHTS_SET)) {
-								uint layout = GetStationGfx (tile);
-								assert(layout < 8);
-								if (GetTileMaxZ(tile) + statspec->bridge_height[layout] > z_start + 1) goto not_valid_below;
-							} else if (!statspec) {
-								// default stations/waypoints
-								const int height = GetStationGfx(tile) < 4 ? 2 : 5;
-								if (GetTileMaxZ(tile) + height > z_start + 1) goto not_valid_below;
-							} else if (!_settings_game.construction.allow_stations_under_bridges) {
+							if (!IsRailStationBridgeAboveOk(tile, GetStationSpec(tile), GetStationGfx(tile), tile_start, tile_end, z_start + 1)) {
 								goto not_valid_below;
 							}
 							break;