/* $Id$ */

/** @file ai_road.hpp Everything to query and build roads. */

#ifndef AI_ROAD_HPP
#define AI_ROAD_HPP

#include "ai_object.hpp"

/**
 * Class that handles all road related functions.
 */
class AIRoad : public AIObject {
public:
	static const char *GetClassName() { return "AIRoad"; }

	/**
	 * Checks whether the given tile is actually a tile with road that can be
	 *  used to traverse a tile. This excludes road depots and 'normal' road
	 *  stations, but includes drive through stations.
	 * @param tile The tile to check.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile has road.
	 */
	static bool IsRoadTile(TileIndex tile);

	/**
	 * Checks whether the given tile is actually a tile with a road depot.
	 * @param tile The tile to check.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile has a road depot.
	 */
	static bool IsRoadDepotTile(TileIndex tile);

	/**
	 * Checks whether the given tile is actually a tile with a road station.
	 * @param tile The tile to check.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile has a road station.
	 */
	static bool IsRoadStationTile(TileIndex tile);

	/**
	 * Checks whether the given tile is actually a tile with a drive through
	 *  road station.
	 * @param tile The tile to check.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile has a drive through road station.
	 */
	static bool IsDriveThroughRoadStationTile(TileIndex tile);

	/**
	 * Checks whether the given tiles are directly connected, i.e. whether
	 *  a road vehicle can travel from the center of the first tile to the
	  * center of the second tile.
	 * @param tile_from The source tile.
	 * @param tile_to The destination tile.
	 * @pre AIMap::IsValidTile(tile_from).
	 * @pre AIMap::IsValidTile(tile_to).
	 * @pre 'tile_from' and 'tile_to' are directly neighbouring tiles.
	 * @return True if and only if a road vehicle can go from tile_from to tile_to.
	 */
	static bool AreRoadTilesConnected(TileIndex tile_from, TileIndex tile_to);

	/**
	 * Count how many neighbours are road.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return 0 means no neighbour road; max value is 4.
	 */
	static int32 GetNeighbourRoadCount(TileIndex tile);

	/**
	 * Gets the tile in front of a road depot.
	 * @param depot The road depot tile.
	 * @pre IsRoadDepotTile(depot).
	 * @return The tile in front of the depot.
	 */
	static TileIndex GetRoadDepotFrontTile(TileIndex depot);

	/**
	 * Gets the tile in front of a road station.
	 * @param station The road station tile.
	 * @pre IsRoadStationTile(station).
	 * @return The tile in front of the road station.
	 */
	static TileIndex GetRoadStationFrontTile(TileIndex station);

	/**
	 * Gets the tile at the back of a drive through road station.
	 *  So, one side of the drive through station is retrieved with
	 *  GetTileInFrontOfStation, the other with this function.
	 * @param station The road station tile.
	 * @pre IsDriveThroughRoadStationTile(station).
	 * @return The tile at the back of the drive through road station.
	 */
	static TileIndex GetDriveThroughBackTile(TileIndex station);

	/**
	 * Builds a road from the center of tile start to the center of tile end.
	 * @param start The start tile of the road.
	 * @param end The end tile of the road.
	 * @pre 'start' is not equal to 'end'.
	 * @pre AIMap::IsValidTile(start).
	 * @pre AIMap::IsValidTile(end).
	 * @pre 'start' and 'end' are in a straight line, i.e.
	 *  AIMap::GetTileX(start) == AIMap::GetTileX(end) or
	 *  AIMap::GetTileY(start) == AIMap::GetTileY(end).
	 * @return Whether the road has been/can be build or not.
	 */
	static bool BuildRoad(TileIndex start, TileIndex end);

	/**
	 * Builds a road from the edge of tile start to the edge of tile end (both
	 *  included).
	 * @param start The start tile of the road.
	 * @param end The end tile of the road.
	 * @pre 'start' is not equal to 'end'.
	 * @pre AIMap::IsValidTile(start).
	 * @pre AIMap::IsValidTile(end).
	 * @pre 'start' and 'end' are in a straight line, i.e.
	 *  AIMap::GetTileX(start) == AIMap::GetTileX(end) or
	 *  AIMap::GetTileY(start) == AIMap::GetTileY(end).
	 * @return Whether the road has been/can be build or not.
	 */
	static bool BuildRoadFull(TileIndex start, TileIndex end);

	/**
	 * Builds a road depot.
	 * @param tile Place to build the depot.
	 * @param front The tile exactly in front of the depot.
	 * @pre AIMap::IsValidTile(tile).
	 * @pre AIMap::IsValidTile(front).
	 * @pre Tile is not equal to front.
	 * @return Whether the road depot has been/can be build or not.
	 */
	static bool BuildRoadDepot(TileIndex tile, TileIndex front);

	/**
	 * Builds a road bus or truck station.
	 * @param tile Place to build the depot.
	 * @param front The tile exactly in front of the station.
	 *   For drive-through stations either entrance side can be used.
	 * @param truck Whether to build a truck (true) or bus (false) station.
	 * @param drive_through Whether to make the station drive through or not.
	 * @pre AIMap::IsValidTile(tile).
	 * @pre AIMap::IsValidTile(front).
	 * @pre 'tile' is not equal to 'front'.
	 * @return Whether the station has been/can be build or not.
	 */
	static bool BuildRoadStation(TileIndex tile, TileIndex front, bool truck, bool drive_through);

	/**
	 * Removes a road from the center of tile start to the center of tile end.
	 * @param start The start tile of the road.
	 * @param end The end tile of the road.
	 * @pre AIMap::IsValidTile(start).
	 * @pre AIMap::IsValidTile(end).
	 * @pre 'start' and 'end' are in a straight line, i.e.
	 *  AIMap::GetTileX(start) == AIMap::GetTileX(end) or
	 *  AIMap::GetTileY(start) == AIMap::GetTileY(end).
	 * @return Whether the road has been/can be removed or not.
	 */
	static bool RemoveRoad(TileIndex start, TileIndex end);

	/**
	 * Removes a road from the edge of tile start to the edge of tile end (both
	 *  included).
	 * @param start The start tile of the road.
	 * @param end The end tile of the road.
	 * @pre AIMap::IsValidTile(start).
	 * @pre AIMap::IsValidTile(end).
	 * @pre 'start' and 'end' are in a straight line, i.e.
	 *  AIMap::GetTileX(start) == AIMap::GetTileX(end) or
	 *  AIMap::GetTileY(start) == AIMap::GetTileY(end).
	 * @return Whether the road has been/can be removed or not.
	 */
	static bool RemoveRoadFull(TileIndex start, TileIndex end);

	/**
	 * Removes a road depot.
	 * @param tile Place to remove the depot from.
	 * @pre AIMap::IsValidTile(tile).
	 * @pre Tile is a road depot.
	 * @return Whether the road depot has been/can be removed or not.
	 */
	static bool RemoveRoadDepot(TileIndex tile);

	/**
	 * Removes a road bus or truck station.
	 * @param tile Place to remove the station from.
	 * @pre AIMap::IsValidTile(tile).
	 * @pre Tile is a road station.
	 * @return Whether the station has been/can be removed or not.
	 */
	static bool RemoveRoadStation(TileIndex tile);
};

#endif /* AI_ROAD_HPP */