/*
This object is contained within zone/var/connections. It's generated whenever two turfs from different zones are linked.
Indirect connections will not merge the two zones after they reach equilibrium.
*/
#define CONNECTION_DIRECT   2
#define CONNECTION_INDIRECT 1
#define CONNECTION_CLOSED   0


connection
	var
		turf/simulated //The turfs involved in the connection.
			A
			B
		zone
			zone_A
			zone_B
		ref_A
		ref_B
		indirect = CONNECTION_DIRECT //If the connection is purely indirect, the zones should not join.
		last_updated //The tick at which this was last updated.
		no_zone_count = 0


	New(turf/T,turf/O)
		A = T
		B = O
		if(A.zone && B.zone)
			if(!A.zone.connections) A.zone.connections = list()
			A.zone.connections += src
			zone_A = A.zone
			ref_A = "\ref[A]"

			if(!B.zone.connections) B.zone.connections = list()
			B.zone.connections += src
			zone_B = B.zone
			ref_B = "\ref[B]"

			if(ref_A in air_master.turfs_with_connections)
				var/list/connections = air_master.turfs_with_connections[ref_A]
				connections.Add(src)
			else
				air_master.turfs_with_connections[ref_A] = list(src)

			if(ref_B in air_master.turfs_with_connections)
				var/list/connections = air_master.turfs_with_connections[ref_B]
				connections.Add(src)
			else
				air_master.turfs_with_connections[ref_B] = list(src)

			if(A.CanPass(null, B, 0, 0))

				ConnectZones(A.zone, B.zone, 1)

				if(A.HasDoor(B) || B.HasDoor(A))
					indirect = CONNECTION_INDIRECT

			else
				ConnectZones(A.zone, B.zone)
				indirect = CONNECTION_CLOSED


		else
			world.log << "Attempted to create connection object for non-zone tiles: [T] ([T.x],[T.y],[T.z]) -> [O] ([O.x],[O.y],[O.z])"
			del(src)


	Del()
		//remove connections from master lists.
		if(ref_B in air_master.turfs_with_connections)
			var/list/connections = air_master.turfs_with_connections[ref_B]
			connections.Remove(src)

		if(ref_A in air_master.turfs_with_connections)
			var/list/connections = air_master.turfs_with_connections[ref_A]
			connections.Remove(src)

		//Ensure we delete the right values by sanity checkign right before deletion.
		Sanitize()

		//Remove connection from current zones.
		if(A)
			if(A.zone && A.zone.connections)
				A.zone.connections.Remove(src)
				if(!A.zone.connections.len)
					A.zone.connections = null
		if(B)
			if(B.zone && B.zone.connections)
				B.zone.connections.Remove(src)
				if(!B.zone.connections.len)
					B.zone.connections = null

		//Disconnect zones while handling unusual conditions.
		//	e.g. loss of a zone on a turf
		if(A && A.zone && B && B.zone)
			DisconnectZones(A.zone, B.zone)

		//Finally, preform actual deletion.
		. = ..()


	proc/ConnectZones(var/zone/zone_1, var/zone/zone_2, open = 0)

		//Sanity checking
		if(!istype(zone_1) || !istype(zone_2))
			return

		//Handle zones connecting indirectly/directly.
		if(open)

			//Create the lists if necessary.
			if(!zone_1.connected_zones)
				zone_1.connected_zones = list()

			if(!zone_2.connected_zones)
				zone_2.connected_zones = list()

			//Increase the number of connections between zones.
			if(zone_2 in zone_1.connected_zones)
				zone_1.connected_zones[zone_2]++
			else
				zone_1.connected_zones += zone_2
				zone_1.connected_zones[zone_2] = 1

			if(zone_1 in zone_2.connected_zones)
				zone_2.connected_zones[zone_1]++
			else
				zone_2.connected_zones += zone_1
				zone_2.connected_zones[zone_1] = 1

		//Handle closed connections.
		else

			//Create the lists
			if(!zone_1.closed_connection_zones)
				zone_1.closed_connection_zones = list()

			if(!zone_2.closed_connection_zones)
				zone_2.closed_connection_zones = list()

			//Increment the connections.
			if(zone_2 in zone_1.closed_connection_zones)
				zone_1.closed_connection_zones[zone_2]++
			else
				zone_1.closed_connection_zones += zone_2
				zone_1.closed_connection_zones[zone_2] = 1

			if(zone_1 in zone_2.closed_connection_zones)
				zone_2.closed_connection_zones[zone_1]++
			else
				zone_2.closed_connection_zones += zone_1
				zone_2.closed_connection_zones[zone_1] = 1


	proc/DisconnectZones(var/zone/zone_1, var/zone/zone_2)

		//Sanity checking
		if(!istype(zone_1) || !istype(zone_2))
			return

		//Handle disconnection of indirectly or directly connected zones.
		if( (zone_1 in zone_2.connected_zones) || (zone_2 in zone_1.connected_zones) )

			//If there are more than one connection, decrement the number of connections
			//Otherwise, remove all connections between the zones.
			if(zone_1 in zone_2.connected_zones)
				if(zone_1.connected_zones[zone_2] > 1)
					zone_1.connected_zones[zone_2]--
				else
					zone_1.connected_zones -= zone_2
					//remove the list if it is empty
					if(!zone_1.connected_zones.len)
						zone_1.connected_zones = null

			//Then do the same for the other zone.
			if(zone_2 in zone_1.connected_zones)
				if(zone_2.connected_zones[zone_1] > 1)
					zone_2.connected_zones[zone_1]--
				else
					zone_2.connected_zones -= zone_1
					if(!zone_2.connected_zones.len)
						zone_2.connected_zones = null

		//Handle disconnection of closed zones.
		if( (zone_1 in zone_2.closed_connection_zones) || (zone_2 in zone_1.closed_connection_zones) )

			//If there are more than one connection, decrement the number of connections
			//Otherwise, remove all connections between the zones.
			if(zone_1 in zone_2.connected_zones)
				if(zone_1.closed_connection_zones[zone_2] > 1)
					zone_1.closed_connection_zones[zone_2]--
				else
					zone_1.closed_connection_zones -= zone_2
					//remove the list if it is empty
					if(!zone_1.closed_connection_zones.len)
						zone_1.closed_connection_zones = null

			//Then do the same for the other zone.
			if(zone_2 in zone_1.connected_zones)
				if(zone_2.closed_connection_zones[zone_1] > 1)
					zone_2.closed_connection_zones[zone_1]--
				else
					zone_2.closed_connection_zones -= zone_1
					if(!zone_2.closed_connection_zones.len)
						zone_2.closed_connection_zones = null


	proc/Cleanup()

		//Check sanity: existance of turfs
		if(!A || !B)
			del src

		//Check sanity: zones are different
		if(A.zone == B.zone)
			del src

		//Check sanity: same turfs as before.
		if(ref_A != "\ref[A]" || ref_B != "\ref[B]")
			del src

		//Handle zones changing on a turf.
		if((A.zone && A.zone != zone_A) || (B.zone && B.zone != zone_B))
			Sanitize()

		//Manage sudden loss of a turfs zone. (e.g. a wall being built)
		if(!A.zone || !B.zone)
			no_zone_count++
			if(no_zone_count >= 5)
				//world.log << "Connection removed: [A] or [B] missing a zone."
				del src
			return 0

		return 1


	proc/CheckPassSanity()
		//Sanity check, first.
		Cleanup()

		if(A.zone && B.zone)

			//If no walls are blocking us...
			if(A.ZAirPass(B))
				//...we check to see if there is a door in the way...
				var/door_pass = A.CanPass(null,B,1.5,1)
				//...and if it is opened.
				if(door_pass || A.CanPass(null,B,0,0))

					//Make and remove connections to let air pass.
					if(indirect == CONNECTION_CLOSED)
						DisconnectZones(A.zone, B.zone)
						ConnectZones(A.zone, B.zone, 1)

					if(door_pass)
						indirect = CONNECTION_DIRECT
					else if(!door_pass)
						indirect = CONNECTION_INDIRECT

				//The door is instead closed.
				else if(indirect > CONNECTION_CLOSED)
					indirect = CONNECTION_CLOSED

					DisconnectZones(A.zone, B.zone)
					ConnectZones(A.zone, B.zone)

			//If I can no longer pass air, better delete
			else
				del src

	proc/Sanitize()
		//If the zones change on connected turfs, update it.

		//Both zones changed (wat)
		if(A.zone && A.zone != zone_A && B.zone && B.zone != zone_B)

			//If the zones have gotten swapped
			//	(do not ask me how, I am just being anal retentive about sanity)
			if(A.zone == zone_B && B.zone == zone_A)
				var/turf/temp = B
				B = A
				A = temp
				zone_B = B.zone
				zone_A = A.zone
				var/temp_ref = ref_A
				ref_A = ref_B
				ref_B = temp_ref
				return

			//Handle removal of connections from archived zones.
			if(zone_A && zone_A.connections)
				zone_A.connections.Remove(src)
				if(!zone_A.connections.len)
					zone_A.connections = null

			if(zone_B && zone_B.connections)
				zone_B.connections.Remove(src)
				if(!zone_B.connections.len)
					zone_B.connections = null

			if(A.zone)
				if(!A.zone.connections)
					A.zone.connections = list()
				A.zone.connections |= src

			if(B.zone)
				if(!B.zone.connections)
					B.zone.connections = list()
				B.zone.connections |= src

			//If either zone is null, we disconnect the archived ones after cleaning up the connections.
			if(!A.zone || !B.zone)
				if(zone_A && zone_B)
					DisconnectZones(zone_B, zone_A)

				if(!A.zone)
					zone_A = A.zone

				if(!B.zone)
					zone_B = B.zone
				return

			//Handle diconnection and reconnection of zones.
			if(zone_A && zone_B)
				DisconnectZones(zone_A, zone_B)
			ConnectZones(A.zone, B.zone, indirect)

			//resetting values of archived values.
			zone_B = B.zone
			zone_A = A.zone

		//The "A" zone changed.
		else if(A.zone && A.zone != zone_A)

			//Handle connection cleanup
			if(zone_A)
				if(zone_A.connections)
					zone_A.connections.Remove(src)
					if(!zone_A.connections.len)
						zone_A.connections = null

			if(A.zone)
				if(!A.zone.connections)
					A.zone.connections = list()
				A.zone.connections |= src

			//If the "A" zone is null, we disconnect the archived ones after cleaning up the connections.
			if(!A.zone)
				if(zone_A && zone_B)
					DisconnectZones(zone_A, zone_B)
				zone_A = A.zone
				return

			//Handle diconnection and reconnection of zones.
			if(zone_A && zone_B)
				DisconnectZones(zone_A, zone_B)
			ConnectZones(A.zone, B.zone, indirect)

		//The "B" zone changed.
		else if(B.zone && B.zone != zone_B)

			//Handle connection cleanup
			if(zone_B)
				if(zone_B.connections)
					zone_B.connections.Remove(src)
					if(!zone_B.connections.len)
						zone_B.connections = null

			if(B.zone)
				if(!B.zone.connections)
					B.zone.connections = list()
				B.zone.connections |= src

			//If the "B" zone is null, we disconnect the archived ones after cleaning up the connections.
			if(!B.zone)
				if(zone_A && zone_B)
					DisconnectZones(zone_A, zone_B)
				zone_B = B.zone
				return

			//Handle diconnection and reconnection of zones.
			if(zone_A && zone_B)
				DisconnectZones(zone_A, zone_B)
			ConnectZones(A.zone,	B.zone, indirect)


#undef CONNECTION_DIRECT
#undef CONNECTION_INDIRECT
#undef CONNECTION_CLOSED