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/* $Id$ */

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/** @file rail.h */

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#ifndef RAIL_H

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#define RAIL_H

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#include "direction.h"

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#include "rail_map.h"

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#include "tile.h"

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/** These are a combination of tracks and directions. Values are 0-5 in one

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direction (corresponding to the Track enum) and 8-13 in the other direction. */

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typedef enum Trackdirs {

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	TRACKDIR_X_NE = 0,

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	TRACKDIR_Y_SE = 1,

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	TRACKDIR_UPPER_E  = 2,

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	TRACKDIR_LOWER_E  = 3,

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	TRACKDIR_LEFT_S   = 4,

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	TRACKDIR_RIGHT_S  = 5,

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	/* Note the two missing values here. This enables trackdir -> track

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	 * conversion by doing (trackdir & 7) */

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	TRACKDIR_X_SW = 8,

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	TRACKDIR_Y_NW = 9,

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	TRACKDIR_UPPER_W  = 10,

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	TRACKDIR_LOWER_W  = 11,

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	TRACKDIR_LEFT_N   = 12,

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	TRACKDIR_RIGHT_N  = 13,

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	TRACKDIR_END,

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	INVALID_TRACKDIR  = 0xFF,

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} Trackdir;

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/** These are a combination of tracks and directions. Values are 0-5 in one

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direction (corresponding to the Track enum) and 8-13 in the other direction. */

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typedef enum TrackdirBits {

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	TRACKDIR_BIT_X_NE     = 0x1,

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	TRACKDIR_BIT_Y_SE     = 0x2,

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	TRACKDIR_BIT_UPPER_E  = 0x4,

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	TRACKDIR_BIT_LOWER_E  = 0x8,

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	TRACKDIR_BIT_LEFT_S   = 0x10,

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	TRACKDIR_BIT_RIGHT_S  = 0x20,

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	/* Again, note the two missing values here. This enables trackdir -> track conversion by doing (trackdir & 0xFF) */

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	TRACKDIR_BIT_X_SW     = 0x0100,

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	TRACKDIR_BIT_Y_NW     = 0x0200,

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	TRACKDIR_BIT_UPPER_W  = 0x0400,

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	TRACKDIR_BIT_LOWER_W  = 0x0800,

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	TRACKDIR_BIT_LEFT_N   = 0x1000,

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	TRACKDIR_BIT_RIGHT_N  = 0x2000,

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	TRACKDIR_BIT_MASK			= 0x3F3F,

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	INVALID_TRACKDIR_BIT  = 0xFFFF,

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} TrackdirBits;

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/** This struct contains all the info that is needed to draw and construct tracks.

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 */

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typedef struct RailtypeInfo {

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	/** Struct containing the main sprites. @note not all sprites are listed, but only

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	 *  the ones used directly in the code */

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	struct {

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		SpriteID track_y;      ///< single piece of rail in Y direction, with ground

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		SpriteID track_ns;     ///< two pieces of rail in North and South corner (East-West direction)

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		SpriteID ground;       ///< ground sprite for a 3-way switch

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		SpriteID single_y;     ///< single piece of rail in Y direction, without ground

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		SpriteID single_x;     ///< single piece of rail in X direction

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		SpriteID single_n;     ///< single piece of rail in the northern corner

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		SpriteID single_s;     ///< single piece of rail in the southern corner

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		SpriteID single_e;     ///< single piece of rail in the eastern corner

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		SpriteID single_w;     ///< single piece of rail in the western corner

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		SpriteID crossing;     ///< level crossing, rail in X direction

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		SpriteID tunnel;       ///< tunnel sprites base

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	} base_sprites;

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	/** struct containing the sprites for the rail GUI. @note only sprites referred to

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	 * directly in the code are listed */

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	struct {

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		SpriteID build_ns_rail;      ///< button for building single rail in N-S direction

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		SpriteID build_x_rail;       ///< button for building single rail in X direction

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		SpriteID build_ew_rail;      ///< button for building single rail in E-W direction

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		SpriteID build_y_rail;       ///< button for building single rail in Y direction

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		SpriteID auto_rail;          ///< button for the autorail construction

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		SpriteID build_depot;        ///< button for building depots

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		SpriteID build_tunnel;       ///< button for building a tunnel

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		SpriteID convert_rail;       ///< button for converting rail

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	} gui_sprites;

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	struct {

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		CursorID rail_ns;

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		CursorID rail_swne;

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		CursorID rail_ew;

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		CursorID rail_nwse;

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		CursorID autorail;

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		CursorID depot;

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		CursorID tunnel;

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		CursorID convert;

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	} cursor;

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	struct {

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		StringID toolbar_caption;

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	} strings;

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	/** sprite number difference between a piece of track on a snowy ground and the corresponding one on normal ground */

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	SpriteID snow_offset;

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	/** bitmask to the OTHER railtypes on which an engine of THIS railtype generates power */

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	RailTypeMask powered_railtypes;

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	/** bitmask to the OTHER railtypes on which an engine of THIS railtype can physically travel */

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	RailTypeMask compatible_railtypes;

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	/**

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	 * Offset between the current railtype and normal rail. This means that:<p>

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	 * 1) All the sprites in a railset MUST be in the same order. This order

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	 *    is determined by normal rail. Check sprites 1005 and following for this order<p>

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	 * 2) The position where the railtype is loaded must always be the same, otherwise

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	 *    the offset will fail.<p>

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	 * @note: Something more flexible might be desirable in the future.

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	 */

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	SpriteID total_offset;

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	/**

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	  * Bridge offset

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	  */

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	SpriteID bridge_offset;

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	/**

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	 * Offset to add to ground sprite when drawing custom waypoints / stations

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	 */

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	byte custom_ground_offset;

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} RailtypeInfo;

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extern RailtypeInfo _railtypes[RAILTYPE_END];

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// these are the maximums used for updating signal blocks, and checking if a depot is in a pbs block

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enum {

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	NUM_SSD_ENTRY = 256, // max amount of blocks

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	NUM_SSD_STACK = 32 ,// max amount of blocks to check recursively

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};

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/**

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 * Maps a Trackdir to the corresponding TrackdirBits value

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 */

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static inline TrackdirBits TrackdirToTrackdirBits(Trackdir trackdir) { return (TrackdirBits)(1 << trackdir); }

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/**

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 * These functions check the validity of Tracks and Trackdirs. assert against

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 * them when convenient.

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 */

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static inline bool IsValidTrack(Track track) { return track < TRACK_END; }

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static inline bool IsValidTrackdir(Trackdir trackdir) { return (TrackdirToTrackdirBits(trackdir) & TRACKDIR_BIT_MASK) != 0; }

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/**

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 * Functions to map tracks to the corresponding bits in the signal

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 * presence/status bytes in the map. You should not use these directly, but

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 * wrapper functions below instead. XXX: Which are these?

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 */

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/**

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 * Maps a trackdir to the bit that stores its status in the map arrays, in the

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 * direction along with the trackdir.

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 */

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extern const byte _signal_along_trackdir[TRACKDIR_END];

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static inline byte SignalAlongTrackdir(Trackdir trackdir) {return _signal_along_trackdir[trackdir];}

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/**

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 * Maps a trackdir to the bit that stores its status in the map arrays, in the

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 * direction against the trackdir.

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 */

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static inline byte SignalAgainstTrackdir(Trackdir trackdir) {

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	extern const byte _signal_against_trackdir[TRACKDIR_END];

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	return _signal_against_trackdir[trackdir];

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}

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/**

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 * Maps a Track to the bits that store the status of the two signals that can

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 * be present on the given track.

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 */

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static inline byte SignalOnTrack(Track track) {

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	extern const byte _signal_on_track[TRACK_END];

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	return _signal_on_track[track];

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}

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/*

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 * Functions describing logical relations between Tracks, TrackBits, Trackdirs

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 * TrackdirBits, Direction and DiagDirections.

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 *

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 * TODO: Add #unndefs or something similar to remove the arrays used below

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 * from the global scope and expose direct uses of them.

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 */

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/**

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 * Maps a trackdir to the reverse trackdir.

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 */

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static inline Trackdir ReverseTrackdir(Trackdir trackdir) {

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	return (Trackdir)(trackdir ^ 8);

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}

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/**

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 * Maps a Track to the corresponding TrackBits value

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 */

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static inline TrackBits TrackToTrackBits(Track track) { return (TrackBits)(1 << track); }

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/**

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 * Returns the Track that a given Trackdir represents

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 */

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static inline Track TrackdirToTrack(Trackdir trackdir) { return (Track)(trackdir & 0x7); }

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/**

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 * Returns a Trackdir for the given Track. Since every Track corresponds to

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 * two Trackdirs, we choose the one which points between NE and S.

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 * Note that the actual implementation is quite futile, but this might change

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 * in the future.

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 */

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static inline Trackdir TrackToTrackdir(Track track) { return (Trackdir)track; }

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/**

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 * Returns a TrackdirBit mask that contains the two TrackdirBits that

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 * correspond with the given Track (one for each direction).

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 */

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/**

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 * Discards all directional information from the given TrackdirBits. Any

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 * Track which is present in either direction will be present in the result.

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 */

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/**

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 * Maps a trackdir to the trackdir that you will end up on if you go straight

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 * ahead. This will be the same trackdir for diagonal trackdirs, but a

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 * different (alternating) one for straight trackdirs

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 */

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static inline Trackdir NextTrackdir(Trackdir trackdir) {

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	extern const Trackdir _next_trackdir[TRACKDIR_END];

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	return _next_trackdir[trackdir];

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}

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/**

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 * Maps a track to all tracks that make 90 deg turns with it.

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 */

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static inline TrackBits TrackCrossesTracks(Track track) {

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	extern const TrackBits _track_crosses_tracks[TRACK_END];

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	return _track_crosses_tracks[track];

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}

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/**

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 * Maps a trackdir to the (4-way) direction the tile is exited when following

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 * that trackdir.

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 */

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static inline DiagDirection TrackdirToExitdir(Trackdir trackdir) {

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	extern const DiagDirection _trackdir_to_exitdir[TRACKDIR_END];

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	return _trackdir_to_exitdir[trackdir];

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}

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/**

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 * Maps a track and an (4-way) dir to the trackdir that represents the track

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 * with the exit in the given direction.

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 */

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static inline Trackdir TrackExitdirToTrackdir(Track track, DiagDirection diagdir) {

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	extern const Trackdir _track_exitdir_to_trackdir[TRACK_END][DIAGDIR_END];

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	return _track_exitdir_to_trackdir[track][diagdir];

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}

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/**

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 * Maps a track and an (4-way) dir to the trackdir that represents the track

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 * with the exit in the given direction.

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 */

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static inline Trackdir TrackEnterdirToTrackdir(Track track, DiagDirection diagdir) {

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	extern const Trackdir _track_enterdir_to_trackdir[TRACK_END][DIAGDIR_END];

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	return _track_enterdir_to_trackdir[track][diagdir];

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}

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/**

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 * Maps a track and a full (8-way) direction to the trackdir that represents

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 * the track running in the given direction.

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 */

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static inline Trackdir TrackDirectionToTrackdir(Track track, Direction dir) {

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	extern const Trackdir _track_direction_to_trackdir[TRACK_END][DIR_END];

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	return _track_direction_to_trackdir[track][dir];

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}

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/**

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 * Maps a (4-way) direction to the diagonal trackdir that runs in that

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 * direction.

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 */

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static inline Trackdir DiagdirToDiagTrackdir(DiagDirection diagdir) {

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	extern const Trackdir _dir_to_diag_trackdir[DIAGDIR_END];

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	return _dir_to_diag_trackdir[diagdir];

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}

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extern const TrackdirBits _exitdir_reaches_trackdirs[DIAGDIR_END];

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/**

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 * Returns all trackdirs that can be reached when entering a tile from a given

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 * (diagonal) direction. This will obviously include 90 degree turns, since no

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 * information is available about the exact angle of entering */

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static inline TrackdirBits DiagdirReachesTrackdirs(DiagDirection diagdir) { return _exitdir_reaches_trackdirs[diagdir]; }

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/**

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 * Returns all tracks that can be reached when entering a tile from a given

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 * (diagonal) direction. This will obviously include 90 degree turns, since no

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 * information is available about the exact angle of entering */

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static inline TrackBits DiagdirReachesTracks(DiagDirection diagdir) { return TrackdirBitsToTrackBits(DiagdirReachesTrackdirs(diagdir)); }

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/**

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 * Maps a trackdir to the trackdirs that can be reached from it (ie, when

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 * entering the next tile. This will include 90 degree turns!

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 */

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static inline TrackdirBits TrackdirReachesTrackdirs(Trackdir trackdir) { return _exitdir_reaches_trackdirs[TrackdirToExitdir(trackdir)]; }

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/* Note that there is no direct table for this function (there used to be),

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 * but it uses two simpeler tables to achieve the result */

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/**

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 * Maps a trackdir to all trackdirs that make 90 deg turns with it.

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 */

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static inline TrackdirBits TrackdirCrossesTrackdirs(Trackdir trackdir) {

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	extern const TrackdirBits _track_crosses_trackdirs[TRACKDIR_END];

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	return _track_crosses_trackdirs[TrackdirToTrack(trackdir)];

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}

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/* Checks if a given Track is diagonal */

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static inline bool IsDiagonalTrack(Track track) { return (track == TRACK_X) || (track == TRACK_Y); }

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/* Checks if a given Trackdir is diagonal. */

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static inline bool IsDiagonalTrackdir(Trackdir trackdir) { return IsDiagonalTrack(TrackdirToTrack(trackdir)); }

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/*

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 * Functions quering signals on tiles.

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 */

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/**

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 * Checks for the presence of signals (either way) on the given track on the

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 * given rail tile.

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 */

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static inline bool HasSignalOnTrack(TileIndex tile, Track track)

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{

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	assert(IsValidTrack(track));

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	return

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		GetRailTileType(tile) == RAIL_TILE_SIGNALS &&

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		(_m[tile].m3 & SignalOnTrack(track)) != 0;

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}

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/**

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 * Checks for the presence of signals along the given trackdir on the given

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 * rail tile.

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 *

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 * Along meaning if you are currently driving on the given trackdir, this is

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 * the signal that is facing us (for which we stop when it's red).

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 */

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static inline bool HasSignalOnTrackdir(TileIndex tile, Trackdir trackdir)

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{

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	assert (IsValidTrackdir(trackdir));

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	return

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		GetRailTileType(tile) == RAIL_TILE_SIGNALS &&

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		_m[tile].m3 & SignalAlongTrackdir(trackdir);

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}

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/**

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 * Gets the state of the signal along the given trackdir.

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 *

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 * Along meaning if you are currently driving on the given trackdir, this is

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 * the signal that is facing us (for which we stop when it's red).

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 */

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static inline SignalState GetSignalStateByTrackdir(TileIndex tile, Trackdir trackdir)

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{

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	assert(IsValidTrackdir(trackdir));

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	assert(HasSignalOnTrack(tile, TrackdirToTrack(trackdir)));

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	return _m[tile].m2 & SignalAlongTrackdir(trackdir) ?

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		SIGNAL_STATE_GREEN : SIGNAL_STATE_RED;

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}

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/**

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 * Return the rail type of tile, or INVALID_RAILTYPE if this is no rail tile.

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 * Note that there is no check if the given trackdir is actually present on

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 * the tile!

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 * The given trackdir is used when there are (could be) multiple rail types on

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 * one tile.

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 */

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RailType GetTileRailType(TileIndex tile, Trackdir trackdir);

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/**

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 * Returns a pointer to the Railtype information for a given railtype

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 * @param railtype the rail type which the information is requested for

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 * @return The pointer to the RailtypeInfo

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 */

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static inline const RailtypeInfo *GetRailTypeInfo(RailType railtype)

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{

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	assert(railtype < RAILTYPE_END);

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	return &_railtypes[railtype];

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}

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/**

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 * Checks if an engine of the given RailType can drive on a tile with a given

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 * RailType. This would normally just be an equality check, but for electric

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 * rails (which also support non-electric engines).

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 * @return Whether the engine can drive on this tile.

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 * @param  enginetype The RailType of the engine we are considering.

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 * @param  tiletype   The RailType of the tile we are considering.

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 */

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static inline bool IsCompatibleRail(RailType enginetype, RailType tiletype)

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{

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	return HASBIT(GetRailTypeInfo(enginetype)->compatible_railtypes, tiletype);

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}

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static inline bool HasPowerOnRail(RailType enginetype, RailType tiletype)

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{

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	return HASBIT(GetRailTypeInfo(enginetype)->powered_railtypes, tiletype);

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}

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/**

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 * Checks if the given tracks overlap, ie form a crossing. Basically this

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 * means when there is more than one track on the tile, exept when there are

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 * two parallel tracks.

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 * @param  bits The tracks present.

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 * @return Whether the tracks present overlap in any way.

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 */

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static inline bool TracksOverlap(TrackBits bits)

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{

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  /* With no, or only one track, there is no overlap */

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  if (bits == 0 || KILL_FIRST_BIT(bits) == 0) return false;

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  /* We know that there are at least two tracks present. When there are more

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   * than 2 tracks, they will surely overlap. When there are two, they will

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   * always overlap unless they are lower & upper or right & left. */

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	return bits != TRACK_BIT_HORZ && bits != TRACK_BIT_VERT;

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}

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void DrawTrainDepotSprite(int x, int y, int image, RailType railtype);

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void DrawDefaultWaypointSprite(int x, int y, RailType railtype);

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/**

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 * Draws overhead wires and pylons for electric railways.

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 * @param ti The TileInfo struct of the tile being drawn

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 * @see DrawCatenaryRailway

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 */

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void DrawCatenary(const TileInfo *ti);

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uint GetRailFoundation(Slope tileh, TrackBits bits);

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#endif /* RAIL_H */