/* $Id: ai_tile.hpp 18955 2010-01-29 23:56:42Z yexo $ */

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

/** @file ai_tile.hpp Everything to query and manipulate tiles. */

#ifndef AI_TILE_HPP
#define AI_TILE_HPP

#include "ai_abstractlist.hpp"
#include "ai_error.hpp"
#include "ai_company.hpp"

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

	/**
	 * Error messages related to modifying tiles.
	 */
	enum ErrorMessages {

		/** Base for tile related errors */
		ERR_TILE_BASE = AIError::ERR_CAT_TILE << AIError::ERR_CAT_BIT_SIZE,

		/** Tile can't be raised any higher */
		ERR_TILE_TOO_HIGH,                     // [STR_ERROR_ALREADY_AT_SEA_LEVEL]

		/** Tile can't be lowered any lower */
		ERR_TILE_TOO_LOW,                      // [STR_ERROR_ALREADY_AT_SEA_LEVEL]

		/** The area was already flat */
		ERR_AREA_ALREADY_FLAT,                 // [STR_ERROR_ALREADY_LEVELLED]

		/** There is a tunnel underneed */
		ERR_EXCAVATION_WOULD_DAMAGE,           // [STR_ERROR_EXCAVATION_WOULD_DAMAGE]
	};

	/**
	 * Enumeration for corners of tiles.
	 */
	enum Corner {
		CORNER_W       = 0,      //!< West corner
		CORNER_S       = 1,      //!< South corner
		CORNER_E       = 2,      //!< East corner
		CORNER_N       = 3,      //!< North corner

		CORNER_INVALID = 0xFF,
	};

	/**
	 * Enumeration for the slope-type.
	 *
	 * This enumeration use the chars N, E, S, W corresponding the
	 *  direction North, East, South and West. The top corner of a tile
	 *  is the north-part of the tile.
	 */
	enum Slope {
		/* Values are important, as they represent the internal state of the game. */
		SLOPE_FLAT     = 0x00,                                  //!< A flat tile
		SLOPE_W        = 1 << CORNER_W,                         //!< The west corner of the tile is raised
		SLOPE_S        = 1 << CORNER_S,                         //!< The south corner of the tile is raised
		SLOPE_E        = 1 << CORNER_E,                         //!< The east corner of the tile is raised
		SLOPE_N        = 1 << CORNER_N,                         //!< The north corner of the tile is raised
		SLOPE_STEEP    = 0x10,                                  //!< Indicates the slope is steep (The corner opposite of the not-raised corner is raised two times)
		SLOPE_NW       = SLOPE_N | SLOPE_W,                     //!< North and west corner are raised
		SLOPE_SW       = SLOPE_S | SLOPE_W,                     //!< South and west corner are raised
		SLOPE_SE       = SLOPE_S | SLOPE_E,                     //!< South and east corner are raised
		SLOPE_NE       = SLOPE_N | SLOPE_E,                     //!< North and east corner are raised
		SLOPE_EW       = SLOPE_E | SLOPE_W,                     //!< East and west corner are raised
		SLOPE_NS       = SLOPE_N | SLOPE_S,                     //!< North and south corner are raised
		SLOPE_ELEVATED = SLOPE_N | SLOPE_E | SLOPE_S | SLOPE_W, //!< Bit mask containing all 'simple' slopes. Does not appear as a slope.
		SLOPE_NWS      = SLOPE_N | SLOPE_W | SLOPE_S,           //!< North, west and south corner are raised
		SLOPE_WSE      = SLOPE_W | SLOPE_S | SLOPE_E,           //!< West, south and east corner are raised
		SLOPE_SEN      = SLOPE_S | SLOPE_E | SLOPE_N,           //!< South, east and north corner are raised
		SLOPE_ENW      = SLOPE_E | SLOPE_N | SLOPE_W,           //!< East, north and west corner are raised
		SLOPE_STEEP_W  = SLOPE_STEEP | SLOPE_NWS,               //!< A steep slope falling to east (from west)
		SLOPE_STEEP_S  = SLOPE_STEEP | SLOPE_WSE,               //!< A steep slope falling to north (from south)
		SLOPE_STEEP_E  = SLOPE_STEEP | SLOPE_SEN,               //!< A steep slope falling to west (from east)
		SLOPE_STEEP_N  = SLOPE_STEEP | SLOPE_ENW,               //!< A steep slope falling to south (from north)

		SLOPE_INVALID  = 0xFFFF,                                //!< An invalid slope
	};

	/**
	 * The different transport types a tile can have.
	 */
	enum TransportType {
		/* Values are important, as they represent the internal state of the game. */
		TRANSPORT_RAIL    =  0, //!< Tile with rail.
		TRANSPORT_ROAD    =  1, //!< Tile with road.
		TRANSPORT_WATER   =  2, //!< Tile with navigable waterways.
		TRANSPORT_AIR     =  3, //!< Tile with airport.

		TRANSPORT_INVALID = -1, //!< Tile without any transport type.
	};

	/**
	 * Get the base cost for building/clearing several things.
	 */
	enum BuildType {
		BT_FOUNDATION,   //!< Build a foundation under something
		BT_TERRAFORM,    //!< Terraform
		BT_BUILD_TREES,  //!< Build trees
		BT_CLEAR_GRASS,  //!< Clear a tile with just grass
		BT_CLEAR_ROUGH,  //!< Clear a rough tile
		BT_CLEAR_ROCKY,  //!< Clear a tile with rocks
		BT_CLEAR_FIELDS, //!< Clear a tile with farm fields
		BT_CLEAR_HOUSE,  //!< Clear a tile with a house
	};

	/**
	 * Check if this tile is buildable, i.e. no things on it that needs
	 *  demolishing.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if it is buildable, false if not.
	 * @note For trams you also might want to check for AIRoad::IsRoad(),
	 *   as you can build tram-rails on road-tiles.
	 * @note For rail you also might want to check for AIRoad::IsRoad(),
	 *   as in some cases you can build rails on road-tiles.
	 */
	static bool IsBuildable(TileIndex tile);

	/**
	 * Check if this tile is buildable in a rectangle around a tile, with the
	 *  entry in the list as top-left.
	 * @param tile The tile to check on.
	 * @param width The width of the rectangle.
	 * @param height The height of the rectangle.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if it is buildable, false if not.
	 */
	static bool IsBuildableRectangle(TileIndex tile, uint width, uint height);

	/**
	 * Checks whether the given tile is actually a water tile.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile is a water tile.
	 */
	static bool IsWaterTile(TileIndex tile);

	/**
	 * Checks whether the given tile is actually a coast tile.
	 * @param tile The tile to check.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile is a coast tile.
	 * @note Building on coast tiles in general is more expensive. This is not
	 *  true if there are also trees on the tile, see #HasTreeOnTile.
	 */
	static bool IsCoastTile(TileIndex tile);

	/**
	 * Checks whether the given tile is a station tile of any station.
	 * @param tile The tile to check.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile is a station tile.
	 */
	static bool IsStationTile(TileIndex tile);

	/**
	 * Check if a tile has a steep slope.
	 * Steep slopes are slopes with a height difference of 2 across one diagonal of the tile.
	 * @param slope The slope to check on.
	 * @pre slope != SLOPE_INVALID.
	 * @return True if the slope is a steep slope.
	 */
	static bool IsSteepSlope(Slope slope);

	/**
	 * Check if a tile has a halftile slope.
	 * Halftile slopes appear on top of halftile foundations. E.g. the slope you get when building a horizontal railtrack on the top of a SLOPE_N or SLOPE_STEEP_N.
	 * @param slope The slope to check on.
	 * @pre slope != SLOPE_INVALID.
	 * @return True if the slope is a halftile slope.
	 * @note Currently there is no API function that would return or accept a halftile slope.
	 */
	static bool IsHalftileSlope(Slope slope);

	/**
	 * Check if the tile has any tree on it.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if there is a tree on the tile.
	 */
	static bool HasTreeOnTile(TileIndex tile);

	/**
	 * Check if the tile is a farmland tile.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile is farmland.
	 */
	static bool IsFarmTile(TileIndex tile);

	/**
	 * Check if the tile is a rock tile.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile is rock tile.
	 */
	static bool IsRockTile(TileIndex tile);

	/**
	 * Check if the tile is a rough tile.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile is rough tile.
	 */
	static bool IsRoughTile(TileIndex tile);

	/**
	 * Check if the tile is a snow tile.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile is snow tile.
	 */
	static bool IsSnowTile(TileIndex tile);

	/**
	 * Check if the tile is a desert tile.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if the tile is desert tile.
	 */
	static bool IsDesertTile(TileIndex tile);

	/**
	 * Get the slope of a tile.
	 * This is the slope of the bare tile. A possible foundation on the tile does not influence this slope.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return Bit mask encoding the slope. See #Slope for a description of the returned values.
	 */
	static Slope GetSlope(TileIndex tile);

	/**
	 * Get the complement of the slope.
	 * @param slope The slope to get the complement of.
	 * @pre slope != SLOPE_INVALID.
	 * @pre !IsSteepSlope(slope).
	 * @pre !IsHalftileSlope(slope).
	 * @return The complement of a slope. This means that all corners that
	 *  weren't raised, are raised, and visa versa.
	 */
	static Slope GetComplementSlope(Slope slope);

	/**
	 * Get the minimal height on a tile.
	 * The returned height is the height of the bare tile. A possible foundation on the tile does not influence this height.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return The height of the lowest corner of the tile, ranging from 0 to 15.
	 */
	static int32 GetMinHeight(TileIndex tile);

	/**
	 * Get the maximal height on a tile.
	 * The returned height is the height of the bare tile. A possible foundation on the tile does not influence this height.
	 * @param tile The tile to check on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return The height of the highest corner of the tile, ranging from 0 to 15.
	 */
	static int32 GetMaxHeight(TileIndex tile);

	/**
	 * Get the height of a certain corner of a tile.
	 * The returned height is the height of the bare tile. A possible foundation on the tile does not influence this height.
	 * @param tile The tile to check on.
	 * @param corner The corner to query.
	 * @pre AIMap::IsValidTile(tile).
	 * @return The height of the lowest corner of the tile, ranging from 0 to 15.
	 */
	static int32 GetCornerHeight(TileIndex tile, Corner corner);

	/**
	 * Get the owner of the tile.
	 * @param tile The tile to get the owner from.
	 * @pre AIMap::IsValidTile(tile).
	 * @return The CompanyID of the owner of the tile, or COMPANY_INVALID if
	 *  there is no owner (grass/industry/water tiles, etc.).
	 */
	static AICompany::CompanyID GetOwner(TileIndex tile);

	/**
	 * Checks whether the given tile contains parts suitable for the given
	 *  TransportType.
	 * @param tile The tile to check.
	 * @param transport_type The TransportType to check against.
	 * @pre AIMap::IsValidTile(tile).
	 * @note Returns false on tiles with roadworks and on road tiles with only
	 *       a single piece of road as these tiles cannot be used to transport
	 *       anything on. It furthermore returns true on some coast tile for
	 *       TRANSPORT_WATER because ships can navigate over them.
	 * @return True if and only if the tile has the given TransportType.
	 */
	static bool HasTransportType(TileIndex tile, TransportType transport_type);

	/**
	 * Check how much cargo this tile accepts.
	 *  It creates a radius around the tile, and adds up all acceptance of this
	 *   cargo.
	 * @param tile The tile to check on.
	 * @param cargo_type The cargo to check the acceptance of.
	 * @param width The width of the station.
	 * @param height The height of the station.
	 * @param radius The radius of the station.
	 * @pre AIMap::IsValidTile(tile).
	 * @pre width > 0.
	 * @pre height > 0.
	 * @pre radius >= 0.
	 * @return Value below 8 means no acceptance; the more the better.
	 */
	static int32 GetCargoAcceptance(TileIndex tile, CargoID cargo_type, int width, int height, int radius);

	/**
	 * Checks how many producers in the radius produces this cargo.
	 *  It creates a radius around the tile, and counts all producer of this cargo.
	 * @param tile The tile to check on.
	 * @param cargo_type The cargo to check the production of.
	 * @param width The width of the station.
	 * @param height The height of the station.
	 * @param radius The radius of the station.
	 * @pre AIMap::IsValidTile(tile).
	 * @pre width > 0.
	 * @pre height > 0.
	 * @pre radius >= 0.
	 * @return The number of producers that produce this cargo within radius of the tile.
	 */
	static int32 GetCargoProduction(TileIndex tile, CargoID cargo_type, int width, int height, int radius);

	/**
	 * Get the manhattan distance from the tile to the tile.
	 * @param tile_from The tile to get the distance to.
	 * @param tile_to The tile to get the distance to.
	 * @return The distance between the two tiles.
	 */
	static int32 GetDistanceManhattanToTile(TileIndex tile_from, TileIndex tile_to);

	/**
	 * Get the square distance from the tile to the tile.
	 * @param tile_from The tile to get the distance to.
	 * @param tile_to The tile to get the distance to.
	 * @return The distance between the two tiles.
	 */
	static int32 GetDistanceSquareToTile(TileIndex tile_from, TileIndex tile_to);

	/**
	 * Raise the given corners of the tile. The corners can be combined,
	 *  for example: SLOPE_N | SLOPE_W (= SLOPE_NW) will raise the west and the north corner.
	 * @note The corners will be modified in the order west (first), south, east, north (last).
	 *       Changing one corner might cause another corner to be changed too. So modifiing
	 *       multiple corners may result in changing some corners by multiple steps.
	 * @param tile The tile to raise.
	 * @param slope Corners to raise (SLOPE_xxx).
	 * @pre tile < AIMap::GetMapSize().
	 * @exception AIError::ERR_AREA_NOT_CLEAR
	 * @exception AIError::ERR_TOO_CLOSE_TO_EDGE
	 * @exception AITile::ERR_TILE_TOO_HIGH
	 * @return 0 means failed, 1 means success.
	 */
	static bool RaiseTile(TileIndex tile, int32 slope);

	/**
	 * Lower the given corners of the tile. The corners can be combined,
	 *  for example: SLOPE_N | SLOPE_W (= SLOPE_NW) will lower the west and the north corner.
	 * @note The corners will be modified in the order west (first), south, east, north (last).
	 *       Changing one corner might cause another corner to be changed too. So modifiing
	 *       multiple corners may result in changing some corners by multiple steps.
	 * @param tile The tile to lower.
	 * @param slope Corners to lower (SLOPE_xxx).
	 * @pre tile < AIMap::GetMapSize().
	 * @exception AIError::ERR_AREA_NOT_CLEAR
	 * @exception AIError::ERR_TOO_CLOSE_TO_EDGE
	 * @exception AITile::ERR_TILE_TOO_LOW
	 * @return 0 means failed, 1 means success.
	 */
	static bool LowerTile(TileIndex tile, int32 slope);

	/**
	 * Level all tiles in the rectangle between start_tile and end_tile so they
	 *  are at the same height. All tiles will be raised or lowered until
	 *  they are at height AITile::GetHeight(start_tile).
	 * @param start_tile One corner of the rectangle to level.
	 * @param end_tile The opposite corner of the rectangle.
	 * @pre start_tile < AIMap::GetMapSize().
	 * @pre end_tile < AIMap::GetMapSize().
	 * @exception AIError::ERR_AREA_NOT_CLEAR
	 * @exception AIError::ERR_TOO_CLOSE_TO_EDGE
	 * @return True if one or more tiles were leveled.
	 * @note Even if leveling some part fails, some other part may have been
	 *  succesfully leveled already.
	 * @note This function may return true in AITestMode, although it fails in
	 *  AIExecMode.
	 */
	static bool LevelTiles(TileIndex start_tile, TileIndex end_tile);

	/**
	 * Destroy everything on the given tile.
	 * @param tile The tile to demolish.
	 * @pre AIMap::IsValidTile(tile).
	 * @exception AIError::ERR_AREA_NOT_CLEAR
	 * @return True if and only if the tile was demolished.
	 */
	static bool DemolishTile(TileIndex tile);

	/**
	 * Create a random tree on a tile.
	 * @param tile The tile to build a tree on.
	 * @pre AIMap::IsValidTile(tile).
	 * @return True if and only if a tree was added on the tile.
	 */
	static bool PlantTree(TileIndex tile);

	/**
	 * Create a random tree on a rectangle of tiles.
	 * @param tile The top left tile of the rectangle.
	 * @param width The width of the rectangle.
	 * @param height The height of the rectangle.
	 * @pre AIMap::IsValidTile(tile).
	 * @pre width >= 1 && width <= 20.
	 * @pre height >= 1 && height <= 20.
	 * @return True if and only if a tree was added on any of the tiles in the rectangle.
	 */
	static bool PlantTreeRectangle(TileIndex tile, uint width, uint height);

	/**
	 * Find out if this tile is within the rating influence of a town.
	 *  Stations on this tile influence the rating of the town.
	 * @param tile The tile to check.
	 * @param town_id The town to check.
	 * @return True if the tile is within the rating influence of the town.
	 */
	static bool IsWithinTownInfluence(TileIndex tile, TownID town_id);

	/**
	 * Find the town that is closest to a tile. Stations you build at this tile
	 *  will belong to this town.
	 * @param tile The tile to check.
	 * @return The TownID of the town closest to the tile.
	 */
	static TownID GetClosestTown(TileIndex tile);

	/**
	 * Get the baseprice of building/clearing various tile-related things.
	 * @param build_type the type to build
	 * @return The baseprice of building or removing the given object.
	 */
	static Money GetBuildCost(BuildType build_type);
};

#endif /* AI_TILE_HPP */
