//#define ZASDBG
#define MULTIZAS

#define AIR_BLOCKED 1
#define ZONE_BLOCKED 2
#define BLOCKED 3

#define ZONE_MIN_SIZE 14 //zones with less than this many turfs will always merge, even if the connection is not direct
#define EDGE_KNOCKDOWN_MAX_DISTANCE 16	// Maximum distance between an airflow origin and a movable before knockdown no longer applies.

#define CANPASS_ALWAYS 1
#define CANPASS_DENSITY 2
#define CANPASS_PROC 3
#define CANPASS_NEVER 4

#define TURF_HAS_VALID_ZONE(T) (istype(T, /turf/simulated) && T:zone && !T:zone:invalid)

#ifdef MULTIZAS

var/list/csrfz_check = list(NORTHEAST, NORTHWEST, SOUTHEAST, SOUTHWEST, NORTHUP, EASTUP, WESTUP, SOUTHUP, NORTHDOWN, EASTDOWN, WESTDOWN, SOUTHDOWN)
var/list/gzn_check = list(NORTH, SOUTH, EAST, WEST, UP, DOWN)

#define ATMOS_CANPASS_TURF(ret,A,B) \
	if (A.blocks_air & AIR_BLOCKED || B.blocks_air & AIR_BLOCKED) { \
		ret = BLOCKED; \
	} \
	else if (B.z != A.z) { \
		if (B.z < A.z) { \
			if (!isopenturf(A)) { \
				ret = BLOCKED; \
			} else { \
				ret = ZONE_BLOCKED; \
			} \
		} \
		else { \
			if (!isopenturf(B)) { \
				ret = BLOCKED; \
			} else { \
				ret = ZONE_BLOCKED; \
			} \
		} \
	} \
	else if (A.blocks_air & ZONE_BLOCKED || B.blocks_air & ZONE_BLOCKED) { \
		ret = (A.z == B.z) ? ZONE_BLOCKED : AIR_BLOCKED; \
	} \
	else if (A.contents.len) { \
		ret = 0;\
		for (var/thing in A) { \
			var/atom/movable/AM = thing; \
			switch (AM.atmos_canpass) { \
				if (CANPASS_ALWAYS) { \
					continue; \
				} \
				if (CANPASS_DENSITY) { \
					if (AM.density) { \
						ret |= AIR_BLOCKED; \
					} \
				} \
				if (CANPASS_PROC) { \
					ret |= AM.c_airblock(B); \
				} \
				if (CANPASS_NEVER) { \
					ret = BLOCKED; \
				} \
			} \
			if (ret == BLOCKED) { \
				break;\
			}\
		}\
	}
#else

var/list/csrfz_check = list(NORTHEAST, NORTHWEST, SOUTHEAST, SOUTHWEST)
var/list/gzn_check = list(NORTH, SOUTH, EAST, WEST)

#define ATMOS_CANPASS_TURF(ret,A,B) \
	if (A.blocks_air & AIR_BLOCKED || B.blocks_air & AIR_BLOCKED) { \
		ret = BLOCKED; \
	} \
	else if (A.blocks_air & ZONE_BLOCKED || B.blocks_air & ZONE_BLOCKED) { \
		ret = ZONE_BLOCKED; \
	} \
	else if (A.contents.len) { \
		ret = 0;\
		for (var/thing in A) { \
			var/atom/movable/AM = thing; \
			switch (AM.atmos_canpass) { \
				if (CANPASS_ALWAYS) { \
					continue; \
				} \
				if (CANPASS_DENSITY) { \
					if (AM.density) { \
						ret |= AIR_BLOCKED; \
					} \
				} \
				if (CANPASS_PROC) { \
					ret |= AM.c_airblock(B); \
				} \
				if (CANPASS_NEVER) { \
					ret = BLOCKED; \
				} \
			} \
			if (ret == BLOCKED) { \
				break;\
			}\
		}\
	}

#endif