[MIRROR] Subsystem For Overmap Shuttle's Star Movement Effects (#10897)

Co-authored-by: Will <7099514+Willburd@users.noreply.github.com>

code/controllers/subsystems/starmover.dm

@@ -0,0 +1,69 @@
+//
+// Handles the moving star effects behind overmap shuttles during travel.
+//
+SUBSYSTEM_DEF(starmover)
+	name = "Shuttle Star Movement"
+	init_order = INIT_ORDER_STARMOVER
+	priority = FIRE_PRIORITY_STARMOVER
+	wait = 1 // This needs to be done pretty quickly
+	var/list/zqueue = list()
+	var/list/current_movement = null
+	//list used to track which zlevels are being 'moved' by the proc below
+	var/list/moving_levels = list()
+	var/list/currentrun = null
+	var/current_direction = 0
+
+/datum/controller/subsystem/starmover/Initialize()
+	return SS_INIT_SUCCESS
+
+#define CR_ZLEVEL 1
+#define CR_DIRECTION 2
+#define CR_TURFS 3
+
+/datum/controller/subsystem/starmover/fire(resumed)
+	// Get next in queue or dropout
+	if(!resumed && !current_movement)
+		if(!zqueue.len)
+			return
+		current_movement = zqueue[1]
+		zqueue[1] = null
+		zqueue -= null
+		// Setup data
+		var/zlevel = current_movement[CR_ZLEVEL]
+		var/new_dir = current_movement[CR_DIRECTION]
+		var/list/turf_list = current_movement[CR_TURFS]
+		if(!turf_list.len || moving_levels["[zlevel]"] == new_dir)
+			clear_movement_run()
+			return
+		moving_levels["[zlevel]"] = new_dir
+		currentrun = turf_list
+
+	// Has a movement queued, process all turfs
+	while(currentrun.len)
+		var/turf/space/T = currentrun[currentrun.len]
+		currentrun.len--
+		if(istype(T))
+			T.toggle_transit(current_movement[CR_DIRECTION])
+		if(MC_TICK_CHECK)
+			return
+	clear_movement_run()
+
+/datum/controller/subsystem/starmover/proc/clear_movement_run()
+	current_movement.Cut()
+	current_movement = null
+	currentrun = null
+
+/datum/controller/subsystem/starmover/stat_entry(msg)
+	msg = "Q:[zqueue.len] C:[currentrun ? currentrun.len : "-"]"
+	return ..()
+
+/// Used to 'move' stars in spess. null direction stops movement
+/datum/controller/subsystem/starmover/proc/toggle_move_stars(zlevel, direction)
+	if(!zlevel)
+		return
+	var/list/spaceturfs = block(locate(1, 1, zlevel), locate(world.maxx, world.maxy, zlevel))
+	zqueue += list(list(zlevel,direction,spaceturfs))
+
+#undef CR_ZLEVEL
+#undef CR_DIRECTION
+#undef CR_TURFS