Ambience Buzz Handling Changes + Ambience buzz requires enviorment power (#84479)

## About The Pull Request
Partial port of https://github.com/DaedalusDock/daedalusdock/pull/996
- Fixes ambience prefrence inconsistancy issues with Observers unable to
turn off the ambience buzz.
- Ambience buzz requires a working, existing, charged APC with power to
the enviorment.
- Moves ``update_ambience_area()`` and ``refresh_looping_ambience()``
into ``code\controllers\subsystem\ambience.dm`` for better organization.

## Why It's Good For The Game

Mostly to tackle a prefrence bug where ghosts are unable to turn off
ambience buzz. But this also includes ambience buzz requiring a powered
area. Makes the station feel more dead when there's no enviorment power.
There should also be no buzzing inside space.

## Changelog

🆑 Kapu (ported by StrangeWeirdKitten)
fix: Ambience buzz will now respect ship ambience prefrences for
observers.
sound: Ambience buzz requires APC enviorment power to function
/🆑

---------

Co-authored-by: Ghom <42542238+Ghommie@users.noreply.github.com>

code/controllers/subsystem/ambience.dm

@@ -86,3 +86,52 @@ SUBSYSTEM_DEF(ambience)
 	if(!M.has_light_nearby() && prob(0.5))
 		return ..(M, pick(minecraft_cave_noises))
 	return ..()
+
+/**
+ * Ambience buzz handling called by either area/Enter() or refresh_looping_ambience()
+ */
+
+/mob/proc/update_ambience_area(area/new_area)
+
+	var/old_tracked_area = ambience_tracked_area
+	if(old_tracked_area)
+		UnregisterSignal(old_tracked_area, COMSIG_AREA_POWER_CHANGE)
+		ambience_tracked_area = null
+	if(!client)
+		return
+	if(new_area)
+		ambience_tracked_area = new_area
+		RegisterSignal(ambience_tracked_area, COMSIG_AREA_POWER_CHANGE, PROC_REF(refresh_looping_ambience), TRUE)
+
+	refresh_looping_ambience()
+
+/mob/proc/refresh_looping_ambience()
+	SIGNAL_HANDLER
+
+	if(!client) // If a tree falls in the woods.
+		return
+
+	var/area/my_area = get_area(src)
+	var/sound_to_use = my_area.ambient_buzz
+
+	if(!sound_to_use || !(client.prefs.read_preference(/datum/preference/toggle/sound_ship_ambience)))
+		SEND_SOUND(src, sound(null, repeat = 0, wait = 0, channel = CHANNEL_BUZZ))
+		client.current_ambient_sound = null
+		return
+
+	if(!can_hear()) // Can the mob hear?
+		SEND_SOUND(src, sound(null, repeat = 0, wait = 0, channel = CHANNEL_BUZZ))
+		client.current_ambient_sound = null
+		return
+
+	//Station ambience is dependant on a functioning and charged APC with enviorment power enabled.
+	if(!is_mining_level(my_area.z) && ((!my_area.apc || !my_area.apc.operating || !my_area.apc.cell?.charge && my_area.requires_power || !my_area.power_environ)))
+		SEND_SOUND(src, sound(null, repeat = 0, wait = 0, channel = CHANNEL_BUZZ))
+		client.current_ambient_sound = null
+		return
+	else
+		if(sound_to_use == client.current_ambient_sound) // Don't reset current loops
+			return
+
+		client.current_ambient_sound = sound_to_use
+		SEND_SOUND(src, sound(my_area.ambient_buzz, repeat = 1, wait = 0, volume = my_area.ambient_buzz_vol, channel = CHANNEL_BUZZ))

code/game/area/areas.dm

@@ -540,39 +540,9 @@ GLOBAL_LIST_EMPTY(teleportlocs)
 	for(var/atom/movable/recipient as anything in arrived.important_recursive_contents[RECURSIVE_CONTENTS_AREA_SENSITIVE])
 		SEND_SIGNAL(recipient, COMSIG_ENTER_AREA, src)
 
-	if(!isliving(arrived))
-		return
-
-	var/mob/living/L = arrived
-	if(!L.ckey)
-		return
-
-	if(ambient_buzz != old_area.ambient_buzz)
-		L.refresh_looping_ambience()
-
-///Tries to play looping ambience to the mobs.
-/mob/proc/refresh_looping_ambience()
-	if(!client) //if a tree falls in the woods...
-		return
-	var/area/my_area = get_area(src)
-	var/sound_to_use = my_area.ambient_buzz
-
-	if(!sound_to_use || !(client.prefs.read_preference(/datum/preference/toggle/sound_ship_ambience)))
-		SEND_SOUND(src, sound(null, repeat = 0, wait = 0, channel = CHANNEL_BUZZ))
-		client.current_ambient_sound = null
-		return
-
-	if(!can_hear())
-		SEND_SOUND(src, sound(null, repeat = 0, wait = 0, channel = CHANNEL_BUZZ))
-		client.current_ambient_sound = null
-		return
-
-	if(sound_to_use == client.current_ambient_sound)
-		return //don't reset current loops.
-
-	client.current_ambient_sound = sound_to_use
-	SEND_SOUND(src, sound(sound_to_use, repeat = 1, wait = 0, volume = my_area.ambient_buzz_vol, channel = CHANNEL_BUZZ))
-
+	if(ismob(arrived))
+		var/mob/mob = arrived
+		mob.update_ambience_area(src)
 
 /**
  * Called when an atom exits an area

code/modules/mob/dead/observer/observer.dm

@@ -359,6 +359,12 @@ This is the proc mobs get to turn into a ghost. Forked from ghostize due to comp
 	abstract_move(destination) // move like the wind
 	return TRUE
 
+/mob/dead/observer/Moved(atom/old_loc, movement_dir, forced, list/old_locs, momentum_change)
+	. = ..()
+	var/area/new_area = get_area(src)
+	if(new_area != ambience_tracked_area)
+		update_ambience_area(new_area)
+
 /mob/dead/observer/verb/reenter_corpse()
 	set category = "Ghost"
 	set name = "Re-enter Corpse"

code/modules/mob/login.dm

@@ -99,7 +99,8 @@
 
 	update_client_colour()
 	update_mouse_pointer()
-	refresh_looping_ambience()
+	update_ambience_area(get_area(src))
+
 	if(!can_hear())
 		stop_sound_channel(CHANNEL_AMBIENCE)
 

code/modules/mob/logout.dm

@@ -3,6 +3,7 @@
 	log_message("[key_name(src)] is no longer owning mob [src]([src.type])", LOG_OWNERSHIP)
 	SStgui.on_logout(src)
 	remove_from_player_list()
+	update_ambience_area(null) // Unset ambience vars so it plays again on login
 	..()
 
 	if(loc)

code/modules/mob/mob_defines.dm

@@ -191,3 +191,6 @@
 	var/active_typing_indicator
 	///the icon currently used for the thinking indicator's bubble
 	var/active_thinking_indicator
+
+	/// A ref of the area we're taking our ambient loop from.
+	var/area/ambience_tracked_area