/* $Id$ */

/** @file ai_map.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.
 *
 * Roads are always build from tile center to tile center.
 * Furthermore stations and depots need to be build on tiles
 * that already have road on them. For depots and non-drive
 * through stations that means that only one roadbit may be
 * built at the location. The advantage of this method is
 * that the AI does not need to think about pointing the
 * exit of the depots and roadstations towards the correct
 * direction. For drive-through roadstops this works about
 * the same, though they have to be built on straight roads.
 */
class AIRoad : public AIObject {
public:
	/**
	 * Checks whether the given tile is actually a tile with road.
	 * @param tile the tile to check.
	 * @pre tile is always positive and smaller than AIMap::GetMapSize().
	 * @return true if and only if the tile has road.
	 */
	bool IsRoadTile(TileIndex tile);

	/**
	 * 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 start is always positive and smaller than AIMap::GetMapSize().
	 * @pre end is always positive and smaller than AIMap::GetMapSize().
	 * @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.
	 */
	bool BuildRoad(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 tile is always positive and smaller than AIMap::GetMapSize().
	 * @pre front is always positive and smaller than AIMap::GetMapSize().
	 * @pre tile is not equal to front
	 * @return whether the road depot has been/can be build or not.
	 */
	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 bus   whether to build a bus or truck station.
	 * @param drive_through whether to make the station drive through or not.
	 * @pre tile is always positive and smaller than AIMap::GetMapSize().
	 * @pre front is always positive and smaller than AIMap::GetMapSize().
	 * @pre tile is not equal to front
	 * @return whether the station has been/can be build or not.
	 */
	bool BuildRoadStation(TileIndex tile, TileIndex front, bool bus, 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 start is always positive and smaller than AIMap::GetMapSize().
	 * @pre end is always positive and smaller than AIMap::GetMapSize().
	 * @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.
	 */
	bool RemoveRoad(TileIndex start, TileIndex end);

	/**
	 * Removes a road depot.
	 * @param tile place to remove the depot from.
	 * @pre tile is always positive and smaller than AIMap::GetMapSize().
	 * @pre tile is a road depot.
	 * @return whether the road depot has been/can be removed or not.
	 */
	bool RemoveRoadDepot(TileIndex tile);

	/**
	 * Removes a road bus or truck station.
	 * @param tile place to remove the station from.
	 * @pre tile is always positive and smaller than AIMap::GetMapSize().
	 * @pre tile is a road station.
	 * @return whether the station has been/can be removed or not.
	 */
	bool RemoveRoadStation(TileIndex tile);
};

#ifdef DEFINE_SQUIRREL_CLASS
void SQAIRoadRegister(Squirrel *engine) {
	DefSQClass <AIRoad> SQAIRoad("AIRoad");
	SQAIRoad.PreRegister(engine);
	SQAIRoad.AddConstructor(engine);
	SQAIRoad.DefSQFunction(engine, &AIRoad::IsRoadTile,        "IsRoadTile");
	SQAIRoad.DefSQFunction(engine, &AIRoad::BuildRoad,         "BuildRoad");
	SQAIRoad.DefSQFunction(engine, &AIRoad::BuildRoadDepot,    "BuildRoadDepot");
	SQAIRoad.DefSQFunction(engine, &AIRoad::BuildRoadStation,  "BuildRoadStation");
	SQAIRoad.DefSQFunction(engine, &AIRoad::RemoveRoad,        "RemoveRoad");
	SQAIRoad.DefSQFunction(engine, &AIRoad::RemoveRoadDepot,   "RemoveRoadDepot");
	SQAIRoad.DefSQFunction(engine, &AIRoad::RemoveRoadStation, "RemoveRoadStation");
	SQAIRoad.PostRegister(engine);
}
#endif /* SQUIRREL_CLASS */

#endif /* AI_ROAD_HPP */