Sound caching, maintenance ambience improvements (#88752)

## About The Pull Request
ports https://github.com/DaedalusDock/daedalusdock/pull/1123
credit to kapu for the code, I just adapted some of it for us
While testing this I noticed that some ambience sounds have no fades, so
I added them, you can see comparisons here:
<details>
<summary> Click me for comparisons! </summary>


https://github.com/user-attachments/assets/0a93ec2f-7600-4510-9773-e2c721f06613


https://github.com/user-attachments/assets/3328a097-5dbc-402f-9dee-ece5aa7f9479


https://github.com/user-attachments/assets/b94157d4-a8a6-4877-94f6-1f07dc6ba860


https://github.com/user-attachments/assets/dc326c0c-7c8c-46ab-8149-97fd02dcc7f7


https://github.com/user-attachments/assets/e3309d6f-6d8d-4595-8c88-172c406f577d


https://github.com/user-attachments/assets/64109759-cbf6-446f-baf9-5705e1c81662


https://github.com/user-attachments/assets/28c0a112-a758-49d6-9f44-8e451a895d7a


https://github.com/user-attachments/assets/fec33b2e-6704-4d97-9c73-d0e58fef52ef


https://github.com/user-attachments/assets/4dc780bf-3fb4-402a-8803-7aef2968e012


https://github.com/user-attachments/assets/93d63a31-36aa-437f-95bc-840427155701


https://github.com/user-attachments/assets/59fd09d4-207d-4f7c-8355-34fb37981df4


https://github.com/user-attachments/assets/8c14e1e8-75be-4081-acac-d2cea05f8638


https://github.com/user-attachments/assets/3dac481c-62ea-4fd9-93c5-36f8cbbfab9b


https://github.com/user-attachments/assets/c92dd2aa-93f8-4c2e-9e00-7dbef3146280


https://github.com/user-attachments/assets/02baae83-2e51-4d83-8d97-be15bc58c6c9


https://github.com/user-attachments/assets/fcd969ac-7f29-4bb4-873c-30874e13516e


https://github.com/user-attachments/assets/24a053a3-1a71-4758-bb90-149ebc6b50b6


https://github.com/user-attachments/assets/40e7adee-d0bf-4636-b4d0-bc1c5c17688f


</details>

## Why It's Good For The Game

- sound caching will open possibilities for seamless sound loops and
overall knowing the length of a sound file is very useful
- closes https://github.com/tgstation/tgstation/issues/87054
- fade ins and fade outs prevent audio glitches on abrupt audio ends and
are nicer for the ears

## Changelog
🆑 kapu and grungussuss
fix: fixed ambience sounds getting cut off mid play
sound: addes fades for maintenance ambiences
refactor: changed the way maintenance sounds are 
/🆑

---------

Co-authored-by: Kapu1178 <75460809+Kapu1178@users.noreply.github.com>

code/controllers/subsystem/ambience.dm

@@ -34,7 +34,7 @@ SUBSYSTEM_DEF(ambience)
 		var/area/current_area = get_area(client_mob)
 		if(!current_area) //Something's gone horribly wrong
 			stack_trace("[key_name(client_mob)] has somehow ended up in nullspace. WTF did you do")
-			ambience_listening_clients -= client_iterator
+			remove_ambience_client(client_iterator)
 			continue
 
 		if(ambience_listening_clients[client_iterator] > world.time)
@@ -59,7 +59,8 @@ SUBSYSTEM_DEF(ambience)
 	new_sound = sound(new_sound, repeat = 0, wait = 0, volume = volume*volume_modifier, channel = CHANNEL_AMBIENCE)
 	SEND_SOUND(M, new_sound)
 
-	return rand(min_ambience_cooldown, max_ambience_cooldown)
+	var/sound_length = SSsounds.get_sound_length(new_sound.file)
+	return sound_length + rand(min_ambience_cooldown, max_ambience_cooldown)
 
 /datum/controller/subsystem/ambience/proc/remove_ambience_client(client/to_remove)
 	ambience_listening_clients -= to_remove
@@ -67,8 +68,6 @@ SUBSYSTEM_DEF(ambience)
 	currentrun -= to_remove
 
 /area/station/maintenance
-	min_ambience_cooldown = 20 SECONDS
-	max_ambience_cooldown = 35 SECONDS
 
 	///A list of rare sound effects to fuck with players. No, it does not contain actual minecraft sounds anymore.
 	var/static/list/minecraft_cave_noises = list(

code/controllers/subsystem/sounds.dm

@@ -26,9 +26,28 @@ SUBSYSTEM_DEF(sounds)
 	/// All valid sound files in the sound directory
 	var/list/all_sounds
 
+	// || Sound caching ||
+	/// k:v list of file_path : length
+	VAR_PRIVATE/list/sound_lengths
+	/// A list of sounds to cache upon initialize.
+	VAR_PRIVATE/list/sounds_to_precache = list()
+	/// Any errors from precaching.
+	VAR_PRIVATE/list/precache_errors = list()
+
 /datum/controller/subsystem/sounds/Initialize()
 	setup_available_channels()
 	find_all_available_sounds()
+
+	if(!(RUST_G))
+		to_chat(world, span_boldnotice("Sounds subsystem: No rust_g detected."))
+		return ..()
+
+	// Precache ambience sounds
+	for(var/key in GLOB.ambience_assoc)
+		sounds_to_precache |= GLOB.ambience_assoc[key]
+
+	precache_sounds()
+
 	return SS_INIT_SUCCESS
 
 /datum/controller/subsystem/sounds/proc/setup_available_channels()
@@ -156,4 +175,54 @@ SUBSYSTEM_DEF(sounds)
 /datum/controller/subsystem/sounds/proc/available_channels_left()
 	return length(channel_list) - random_channels_min
 
+/datum/controller/subsystem/sounds/proc/precache_sounds()
+	if(!length(sounds_to_precache))
+		return
+
+	var/list/lengths = rustg_sound_length_list(sounds_to_precache)
+	precache_errors = lengths[RUSTG_SOUNDLEN_ERRORS]
+	sound_lengths = lengths[RUSTG_SOUNDLEN_SUCCESSES]
+	for(var/sound_path in sound_lengths)
+		sound_lengths[sound_path] = text2num(sound_lengths[sound_path])
+
+	sounds_to_precache = null
+
+/// Cache a list of sound lengths.
+/datum/controller/subsystem/sounds/proc/cache_sounds(list/paths)
+	var/list/reconstructed = list()
+	reconstructed.len = length(paths)
+
+	for(var/i in 1 to length(paths))
+		reconstructed[i] = "[paths[i]]"
+
+	var/list/out = rustg_sound_length_list(paths)
+	var/list/successes = out[RUSTG_SOUNDLEN_SUCCESSES]
+	for(var/sound_path in successes)
+		sound_lengths[sound_path] = text2num(successes[sound_path])
+
+/// Cache and return a single sound.
+/datum/controller/subsystem/sounds/proc/get_sound_length(file_path)
+	. = 0
+	if(!istext(file_path))
+		if(!isfile(file_path))
+			CRASH("rustg_sound_length error: Passed non-text object")
+
+		if(length("[file_path]")) // Runtime generated RSC references stringify into 0-length strings.
+			file_path = "[file_path]"
+		else
+			CRASH("rustg_sound_length does not support non-static file refs.")
+
+	var/cached_length = sound_lengths[file_path]
+	if(!isnull(cached_length))
+		return cached_length
+
+	var/ret = RUSTG_CALL(RUST_G, "sound_len")(file_path)
+	var/as_num = text2num(ret)
+	if(isnull(ret))
+		. = 0
+		CRASH("rustg_sound_length error: [ret]")
+
+	sound_lengths[file_path] = as_num
+	return as_num
+
 #undef DATUMLESS

code/game/area/areas.dm

@@ -95,9 +95,9 @@
 	///The volume of the ambient buzz
 	var/ambient_buzz_vol = 35
 	///Used to decide what the minimum time between ambience is
-	var/min_ambience_cooldown = 30 SECONDS
+	var/min_ambience_cooldown = 4 SECONDS
 	///Used to decide what the maximum time between ambience is
-	var/max_ambience_cooldown = 60 SECONDS
+	var/max_ambience_cooldown = 10 SECONDS
 
 	flags_1 = CAN_BE_DIRTY_1
 

code/game/area/areas/centcom.dm

@@ -278,8 +278,6 @@
 	ambience_index = AMBIENCE_MINING
 	flags_1 = CAN_BE_DIRTY_1
 	sound_environment = SOUND_AREA_ASTEROID
-	min_ambience_cooldown = 70 SECONDS
-	max_ambience_cooldown = 220 SECONDS
 
 /area/centcom/asteroid/nearstation
 	static_lighting = TRUE

code/game/area/areas/mining.dm

@@ -146,8 +146,6 @@
 	requires_power = TRUE
 	ambience_index = AMBIENCE_MINING
 	area_flags = VALID_TERRITORY | UNIQUE_AREA
-	min_ambience_cooldown = 70 SECONDS
-	max_ambience_cooldown = 220 SECONDS
 
 /area/lavaland/underground
 	name = "Lavaland Caves"
@@ -159,8 +157,6 @@
 	power_light = FALSE
 	ambience_index = AMBIENCE_MINING
 	area_flags = VALID_TERRITORY | UNIQUE_AREA | FLORA_ALLOWED
-	min_ambience_cooldown = 70 SECONDS
-	max_ambience_cooldown = 220 SECONDS
 
 /area/lavaland/surface/outdoors
 	name = "Lavaland Wastes"
@@ -206,8 +202,6 @@
 	power_light = FALSE
 	requires_power = TRUE
 	area_flags = UNIQUE_AREA | FLORA_ALLOWED
-	min_ambience_cooldown = 70 SECONDS
-	max_ambience_cooldown = 220 SECONDS
 
 /area/icemoon/surface/outdoors // parent that defines if something is on the exterior of the station.
 	name = "Icemoon Wastes"
@@ -269,8 +263,6 @@
 	power_equip = FALSE
 	power_light = FALSE
 	area_flags = UNIQUE_AREA | FLORA_ALLOWED
-	min_ambience_cooldown = 70 SECONDS
-	max_ambience_cooldown = 220 SECONDS
 
 /area/icemoon/underground/unexplored // mobs and megafauna and ruins spawn here
 	name = "Icemoon Caves"

code/game/area/areas/misc.dm

@@ -16,8 +16,6 @@
 	flags_1 = CAN_BE_DIRTY_1
 	sound_environment = SOUND_AREA_SPACE
 	ambient_buzz = null //Space is deafeningly quiet
-	min_ambience_cooldown = 195 SECONDS //length of ambispace.ogg
-	max_ambience_cooldown = 200 SECONDS
 
 /area/space/nearstation
 	icon_state = "space_near"

code/game/area/areas/station/engineering.dm

@@ -31,8 +31,6 @@
 	sound_environment = SOUND_AREA_SPACE
 	ambience_index = AMBIENCE_SPACE
 	ambient_buzz = null //Space is deafeningly quiet
-	min_ambience_cooldown = 195 SECONDS //length of ambispace.ogg
-	max_ambience_cooldown = 200 SECONDS
 
 /area/station/engineering/atmos/project
 	name = "\improper Atmospherics Project Room"

code/game/area/areas/station/medical.dm

@@ -4,8 +4,6 @@
 	ambience_index = AMBIENCE_MEDICAL
 	airlock_wires = /datum/wires/airlock/medbay
 	sound_environment = SOUND_AREA_STANDARD_STATION
-	min_ambience_cooldown = 90 SECONDS
-	max_ambience_cooldown = 180 SECONDS
 
 /area/station/medical/abandoned
 	name = "\improper Abandoned Medbay"