Refactor atom HUDs to track source of HUD gain/loss. (#32091)

* Refactor atom HUDs to track source of HUD gain/loss.

* Retain shared images from different huds on removal.

* Fix some ghost HUD toggles.

* Add HUD sources to more hud add/remove calls.

* Apply suggestions from CRUNCH review.

Co-authored-by: CRUNCH <143041327+CRUNCH-Borg@users.noreply.github.com>
Signed-off-by: Alan <alfalfascout@users.noreply.github.com>

* Check if a user has a hud before removing it, autodoc.

---------

Signed-off-by: Alan <alfalfascout@users.noreply.github.com>
Co-authored-by: CRUNCH <143041327+CRUNCH-Borg@users.noreply.github.com>

code/datums/ai_laws_datums.dm

@@ -98,13 +98,13 @@
 		if(zeroth_law_borg)
 			laws.set_zeroth_law(zeroth_law_borg.law)
 			var/datum/atom_hud/data/human/malf_ai/H = GLOB.huds[DATA_HUD_MALF_AI]
-			H.add_hud_to(src)
+			H.add_hud_to(src, "zeroth law")
 		else if(zeroth_law)
 			laws.set_zeroth_law(zeroth_law.law)
 		else
 			laws.clear_zeroth_laws()
 			var/datum/atom_hud/data/human/malf_ai/H = GLOB.huds[DATA_HUD_MALF_AI]
-			H.remove_hud_from(src)
+			H.remove_hud_from(src, "zeroth law")
 
 /mob/living/silicon/ai/sync_zeroth(datum/ai_law/zeroth_law, datum/ai_law/zeroth_law_borg)
 	if(zeroth_law)

code/datums/atom_hud.dm

@@ -36,9 +36,12 @@ GLOBAL_LIST_INIT(huds, alist(
 	))
 
 /datum/atom_hud
-	var/list/atom/hudatoms = list() //list of all atoms which display this hud
-	var/list/mob/hudusers = list() //list with all mobs who can see the hud
-	var/list/hud_icons = list() //these will be the indexes for the atom's hud_list
+	/// All the atoms that display this hud.
+	var/list/atom/hudatoms = list()
+	/// All the mobs who can see this hud, and their sources. each_mob = list(source/1, source/2).
+	var/list/mob/hudusers = list()
+	/// Indexes for the atom's hud_list.
+	var/list/hud_icons = list()
 	/// Do we ignore the invisibility check? Used by anom huds so we can see our stuff.
 	var/ignore_invisibility_check = FALSE
 
@@ -54,43 +57,57 @@ GLOBAL_LIST_INIT(huds, alist(
 	GLOB.all_huds -= src
 	return ..()
 
-/datum/atom_hud/proc/remove_hud_from(mob/M)
+/// Removes `source` from mob's hud sources, and if mob has no hud sources, removes their ability to see this hud
+/datum/atom_hud/proc/remove_hud_from(mob/M, atom/source)
 	if(!M)
 		return
 	if(src in M.permanent_huds)
 		return
-	for(var/atom/A in hudatoms)
-		remove_from_single_hud(M, A)
-	hudusers -= M
+	if(hudusers[M])
+		hudusers[M] -= source
+	if(hudusers[M] && length(hudusers[M]))
+		return
 
+	for(var/atom/A in hudatoms)
+		remove_hud_images(M, A)
+	hudusers -= M
+	M.reload_huds()
+
+/// Removes a single item from being displayed on this hud, for example, removes one mess from janihud.
 /datum/atom_hud/proc/remove_from_hud(atom/A)
 	if(!A)
 		return
 	for(var/mob/M in hudusers)
-		remove_from_single_hud(M, A)
+		remove_hud_images(M, A)
 	hudatoms -= A
 
-/datum/atom_hud/proc/remove_from_single_hud(mob/M, atom/A) //unsafe, no sanity apart from client
+/// Removes all of the hud pictures that `A` produces from mob `M`'s view.
+/datum/atom_hud/proc/remove_hud_images(mob/M, atom/A) // Unsafe, no sanity apart from client.
 	if(!M || !M.client || !A)
 		return
 	for(var/i in hud_icons)
 		M.client.images -= A.hud_list[i]
 
-/datum/atom_hud/proc/add_hud_to(mob/M)
+/// Adds `source` to mob's sources of this hud, and shows them all the pictures on the hud
+/datum/atom_hud/proc/add_hud_to(mob/M, atom/source)
 	if(!M)
 		return
-	hudusers |= M
+	if(!(M in hudusers))
+		hudusers[M] = list()
+	hudusers[M] |= source
 	for(var/atom/A in hudatoms)
-		add_to_single_hud(M, A)
+		add_hud_images(M, A)
 
+/// Adds single atom `A` to the list of pictures this hud will display. Shows them to mobs with this hud.
 /datum/atom_hud/proc/add_to_hud(atom/A)
 	if(!A)
 		return
 	hudatoms |= A
 	for(var/mob/M in hudusers)
-		add_to_single_hud(M, A)
+		add_hud_images(M, A)
 
-/datum/atom_hud/proc/add_to_single_hud(mob/M, atom/A) //unsafe, no sanity apart from client
+/// Adds all hud images that `A` produces to player `M`'s view.
+/datum/atom_hud/proc/add_hud_images(mob/M, atom/A) // Unsafe, no sanity apart from client.
 	if(!M || !M.client || !A)
 		return
 	if((A.invisibility > M.see_invisible) && !ignore_invisibility_check) // yee yee ass snowflake check for our yee yee ass snowflake huds
@@ -111,10 +128,9 @@ GLOBAL_LIST_INIT(huds, alist(
 		for(var/datum/mindslaves/serv in (SSticker.mode.vampires | SSticker.mode.traitors))
 			serv_huds += serv.thrallhud
 
-
 	for(var/datum/atom_hud/hud in (GLOB.all_huds|serv_huds))//|gang_huds))
 		if(src in hud.hudusers)
-			hud.add_hud_to(src)
+			hud.add_hud_to(src, hud.hudusers[src][1])
 
 /mob/new_player/reload_huds()
 	return

code/datums/status_effects/buffs.dm

@@ -337,7 +337,7 @@
 	//Makes the user passive, it's in their oath not to harm!
 	ADD_TRAIT(owner, TRAIT_PACIFISM, "hippocraticOath")
 	var/datum/atom_hud/H = GLOB.huds[DATA_HUD_MEDICAL_ADVANCED]
-	H.add_hud_to(owner)
+	H.add_hud_to(owner, src)
 	owner.permanent_huds |= H
 	return ..()
 
@@ -345,7 +345,7 @@
 	REMOVE_TRAIT(owner, TRAIT_PACIFISM, "hippocraticOath")
 	var/datum/atom_hud/H = GLOB.huds[DATA_HUD_MEDICAL_ADVANCED]
 	owner.permanent_huds ^= H
-	H.remove_hud_from(owner)
+	H.remove_hud_from(owner, src)
 
 /datum/status_effect/hippocratic_oath/tick()
 	// Death transforms you into a snake after a short grace period