Fixes airtight plastic flaps stopping working after shuttles moves (#15687)

code/game/objects/structures/plasticflaps.dm

@@ -8,6 +8,9 @@
 	layer = 4
 	explosion_resistance = 5
 	build_amt = 4
+
+	atmos_canpass = CANPASS_PROC
+
 	var/manipulating = FALSE //Prevents queueing up a ton of deconstructs
 	var/list/mobs_can_pass = list(
 		/mob/living/carbon/slime,
@@ -15,10 +18,34 @@
 		/mob/living/silicon/robot/drone
 		)
 
+	var/airtight = FALSE
+
 /obj/structure/plasticflaps/Initialize()
 	. = ..()
 	material = SSmaterials.get_material_by_name(MATERIAL_PLASTIC)
 
+/obj/structure/plasticflaps/Destroy()
+	if(airtight)
+		clear_airtight()
+	. = ..()
+
+/obj/structure/plasticflaps/proc/become_airtight()
+	airtight = TRUE
+	var/turf/simulated/floor/T = get_turf(loc)
+	if(istype(T))
+		update_nearby_tiles()
+
+/obj/structure/plasticflaps/proc/clear_airtight()
+	airtight = FALSE
+	var/turf/simulated/floor/T = get_turf(loc)
+	if(istype(T))
+		update_nearby_tiles()
+
+/obj/structure/plasticflaps/c_airblock()
+	if(airtight)
+		return AIR_BLOCKED
+	return FALSE
+
 /obj/structure/plasticflaps/CanPass(atom/A, turf/T)
 	if(istype(A) && A.checkpass(PASSGLASS))
 		return prob(60)
@@ -67,40 +94,22 @@
 /obj/structure/plasticflaps/mining //A specific type for mining that doesn't allow airflow because of them damn crates
 	name = "airtight plastic flaps"
 	desc = "Heavy duty, airtight, plastic flaps."
+	airtight = TRUE
 
-/obj/structure/plasticflaps/mining/Initialize() //set the turf below the flaps to block air
-	..()
-	var/turf/T = get_turf(loc)
-	if(T)
-		T.blocks_air = 1
-
-
-/obj/structure/plasticflaps/mining/Destroy() //lazy hack to set the turf to allow air to pass if it's a simulated floor
-	var/turf/T = get_turf(loc)
-	if(T)
-		if(istype(T, /turf/simulated/floor))
-			T.blocks_air = 0
-	return ..()
-
+/obj/structure/plasticflaps/mining/Initialize()
+	. = ..()
+	update_nearby_tiles()
 
 //Airtight plastic flaps made for the kitchen freezer, blocks atmos but not movement
 /obj/structure/plasticflaps/airtight
 	name = "airtight plastic flaps"
 	desc = "Heavy duty, airtight, plastic flaps."
 	layer = 3
+	airtight = TRUE
 
-/obj/structure/plasticflaps/airtight/Initialize() //set the turf below the flaps to block air
-	..()
-	var/turf/T = get_turf(loc)
-	if(T)
-		T.blocks_air = 1
-
-/obj/structure/plasticflaps/airtight/Destroy() //lazy hack to set the turf to allow air to pass if it's a simulated floor
-	var/turf/T = get_turf(loc)
-	if(T)
-		if(istype(T, /turf/simulated/floor))
-			T.blocks_air = 0
-	return ..()
+/obj/structure/plasticflaps/airtight/Initialize()
+	. = ..()
+	update_nearby_tiles()
 
 /obj/structure/plasticflaps/airtight/CanPass(atom/A, turf/T)
 	return 1//Blocks nothing except air