/* $Id$ */

/** @file pathfind.h The oldest pathfinder that's supported. */

#ifndef PATHFIND_H
#define PATHFIND_H

#include "direction_type.h"

enum {
	STR_FACTOR  = 2,
	DIAG_FACTOR = 3
};

//#define PF_BENCH // perform simple benchmarks on the train pathfinder (not
//supported on all archs)

struct TrackPathFinder;
typedef bool TPFEnumProc(TileIndex tile, void *data, Trackdir trackdir, uint length);
typedef void TPFAfterProc(TrackPathFinder *tpf);

typedef bool NTPEnumProc(TileIndex tile, void *data, int track, uint length);

#define PATHFIND_GET_LINK_OFFS(tpf, link) ((byte*)(link) - (byte*)tpf->links)
#define PATHFIND_GET_LINK_PTR(tpf, link_offs) (TrackPathFinderLink*)((byte*)tpf->links + (link_offs))

/* y7 y6 y5 y4 y3 y2 y1 y0 x7 x6 x5 x4 x3 x2 x1 x0
 * y7 y6 y5 y4 y3 y2 y1 y0 x4 x3 x2 x1 x0  0  0  0
 *  0  0 y7 y6 y5 y4 y3 y2 y1 y0 x4 x3 x2 x1 x0  0
 *  0  0  0  0 y5 y4 y3 y2 y1 y0 x4 x3 x2 x1 x0  0
 */
#define PATHFIND_HASH_TILE(tile) (TileX(tile) & 0x1F) + ((TileY(tile) & 0x1F) << 5)

struct TrackPathFinderLink {
	TileIndex tile;
	uint16 flags;
	uint16 next;
};

struct RememberData {
	uint16 cur_length;
	byte depth;
	Track last_choosen_track;
};

struct TrackPathFinder {
	int num_links_left;
	TrackPathFinderLink *new_link;

	TPFEnumProc *enum_proc;

	void *userdata;

	RememberData rd;

	TrackdirByte the_dir;

	TransportType tracktype;
	uint sub_type;

	bool disable_tile_hash;

	uint16 hash_head[0x400];
	TileIndex hash_tile[0x400];       ///< stores the link index when multi link.

	TrackPathFinderLink links[0x400]; ///< hopefully, this is enough.
};

/** Some flags to modify the behaviour of original pathfinder */
enum PathfindFlags {
	PATHFIND_FLAGS_NONE              = 0,
	PATHFIND_FLAGS_SHIP_MODE         = 0x0800, ///< pathfinder with some optimizations for ships, but does not work for other types.
	PATHFIND_FLAGS_DISABLE_TILE_HASH = 0x1000, ///< do not check for searching in circles
};
DECLARE_ENUM_AS_BIT_SET(PathfindFlags)

void FollowTrack(TileIndex tile, PathfindFlags flags, TransportType tt, uint sub_type, DiagDirection direction, TPFEnumProc* enum_proc, TPFAfterProc* after_proc, void* data);
void NewTrainPathfind(TileIndex tile, TileIndex dest, RailTypes railtypes, DiagDirection direction, NTPEnumProc* enum_proc, void* data);

#endif /* PATHFIND_H */