Rework maintenance loot spawners to fire at roundstart (tgstation#59913)

Maintenance loot spawners now fire at roundstart, rather than during the initialization of the Atoms subsystem.
Maintenance loot spawners do not qdel themselves during the spawning process, but persist, and merely hide themselves from living players.

As a cute side effect, this lets preround observers look at the colourful maintenance loot dice icons before the round starts. Observers can continue to see the loot dice post-round, but they are deliberately
very faint.

code/_globalvars/lists/maintenance_loot.dm

@@ -348,3 +348,6 @@ GLOBAL_LIST_INIT(ratking_coins, list(//Coins: Used by the regal rat mob when spa
 			/obj/item/coin/silver,
 			/obj/item/coin/plastic,
 			/obj/item/coin/titanium))
+
+// List of all maintenance loot spawners, for easy finding at roundstart.
+GLOBAL_LIST_EMPTY(maintenance_loot_spawners)

code/controllers/subsystem/mapping.dm

@@ -127,6 +127,7 @@ SUBSYSTEM_DEF(mapping)
 	setup_map_transitions()
 	generate_station_area_list()
 	initialize_reserved_level(transit.z_value)
+	SSticker.OnRoundstart(CALLBACK(src, .proc/spawn_maintenance_loot))
 	return ..()
 
 /datum/controller/subsystem/mapping/proc/wipe_reservations(wipe_safety_delay = 100)
@@ -590,3 +591,10 @@ GLOBAL_LIST_EMPTY(the_station_areas)
 		isolated_ruins_z = add_new_zlevel("Isolated Ruins/Reserved", list(ZTRAIT_RESERVED = TRUE, ZTRAIT_ISOLATED_RUINS = TRUE))
 		initialize_reserved_level(isolated_ruins_z.z_value)
 	return isolated_ruins_z.z_value
+
+/datum/controller/subsystem/mapping/proc/spawn_maintenance_loot()
+	for(var/obj/effect/spawner/lootdrop/maintenance/spawner as anything in GLOB.maintenance_loot_spawners)
+		CHECK_TICK
+
+		spawner.spawn_loot()
+		spawner.hide()

code/game/objects/effects/spawners/lootdrop.dm

@@ -2,13 +2,25 @@
 	icon = 'icons/effects/landmarks_static.dmi'
 	icon_state = "random_loot"
 	layer = OBJ_LAYER
+	anchored = TRUE // Stops persistent lootdrop spawns from being shoved into lockers
 	var/lootcount = 1 //how many items will be spawned
 	var/lootdoubles = TRUE //if the same item can be spawned twice
 	var/list/loot //a list of possible items to spawn e.g. list(/obj/item, /obj/structure, /obj/effect)
 	var/fan_out_items = FALSE //Whether the items should be distributed to offsets 0,1,-1,2,-2,3,-3.. This overrides pixel_x/y on the spawner itself
+	/// Whether the spawner should immediately spawn loot and cleanup on Initialize()
+	var/spawn_on_init = TRUE
 
 /obj/effect/spawner/lootdrop/Initialize(mapload)
-	..()
+	. = ..()
+
+	if(spawn_on_init)
+		spawn_loot()
+		return INITIALIZE_HINT_QDEL
+
+///If the spawner has any loot defined, randomly picks some and spawns it. Does not cleanup the spawner.
+/obj/effect/spawner/lootdrop/proc/spawn_loot(lootcount_override)
+	var/lootcount = isnull(lootcount_override) ? src.lootcount : lootcount_override
+
 	if(loot?.len)
 		var/loot_spawned = 0
 		while((lootcount-loot_spawned) && loot.len)
@@ -29,7 +41,6 @@
 					if (loot_spawned)
 						spawned_loot.pixel_x = spawned_loot.pixel_y = ((!(loot_spawned%2)*loot_spawned/2)*-1)+((loot_spawned%2)*(loot_spawned+1)/2*1)
 			loot_spawned++
-	return INITIALIZE_HINT_QDEL
 
 /obj/effect/spawner/lootdrop/donkpockets
 	name = "donk pocket box spawner"
@@ -240,19 +251,55 @@
 
 /obj/effect/spawner/lootdrop/maintenance
 	name = "maintenance loot spawner"
+	desc = "Come on Lady Luck, spawn me a pair of sunglasses."
+	spawn_on_init = FALSE
 	// see code/_globalvars/lists/maintenance_loot.dm for loot table
 
+/obj/effect/spawner/lootdrop/maintenance/examine(mob/user)
+	. = ..()
+	. += span_info("This spawner has an effective loot count of [get_effective_lootcount()].")
+
 /obj/effect/spawner/lootdrop/maintenance/Initialize(mapload)
+	. = ..()
+	// There is a single callback in SSmapping to spawn all delayed maintenance loot
+	// so we don't just make one callback per loot spawner
+	GLOB.maintenance_loot_spawners += src
 	loot = GLOB.maintenance_loot
 
+	// Late loaded templates like shuttles can have maintenance loot
+	if(SSticker.current_state >= GAME_STATE_SETTING_UP)
+		spawn_loot()
+		hide()
+
+/obj/effect/spawner/lootdrop/maintenance/Destroy()
+	GLOB.maintenance_loot_spawners -= src
+	return ..()
+
+/obj/effect/spawner/lootdrop/maintenance/proc/hide()
+	invisibility = INVISIBILITY_OBSERVER
+	alpha = 100
+
+/obj/effect/spawner/lootdrop/maintenance/proc/get_effective_lootcount()
+	var/effective_lootcount = lootcount
+
 	if(HAS_TRAIT(SSstation, STATION_TRAIT_FILLED_MAINT))
-		lootcount = FLOOR(lootcount * 1.5, 1)
+		effective_lootcount = FLOOR(lootcount * 1.5, 1)
 
 	else if(HAS_TRAIT(SSstation, STATION_TRAIT_EMPTY_MAINT))
-		lootcount = FLOOR(lootcount * 0.5, 1)
+		effective_lootcount = FLOOR(lootcount * 0.5, 1)
+
+	return effective_lootcount
 
+/obj/effect/spawner/lootdrop/maintenance/spawn_loot(lootcount_override)
+	if(isnull(lootcount_override))
+		lootcount_override = get_effective_lootcount()
 	. = ..()
 
+	// In addition, closets that are closed will have the maintenance loot inserted inside.
+	for(var/obj/structure/closet/closet in get_turf(src))
+		if(!closet.opened)
+			closet.take_contents()
+
 /obj/effect/spawner/lootdrop/maintenance/two
 	name = "2 x maintenance loot spawner"
 	lootcount = 2