Datumizes changelings and refactors related code (#17774)

* it's finally here

unfucks tgui

* oops, I don't want to change the mode

* charlie and moxian review

* charlie review II + some GC fixes

* rebase to fix conflicts + tgui bundle deconflict

* charlie review III + affected review

* final? tweaks

code/datums/mind.dm

@@ -51,7 +51,6 @@
 
 	var/miming = 0 // Mime's vow of silence
 	var/list/antag_datums
-	var/datum/changeling/changeling		//changeling holder
 	var/linglink
 
 	var/antag_hud_icon_state = null //this mind's ANTAG_HUD should have this icon_state
@@ -278,12 +277,15 @@
 
 /datum/mind/proc/memory_edit_changeling(mob/living/carbon/human/H)
 	. = _memory_edit_header("changeling", list("traitorchan"))
-	if(src in SSticker.mode.changelings)
+	var/datum/antagonist/changeling/cling = has_antag_datum(/datum/antagonist/changeling)
+	if(cling)
 		. += "<b><font color='red'>CHANGELING</font></b>|<a href='?src=[UID()];changeling=clear'>no</a>"
-		if(objectives.len==0)
+		if(!length(cling.objectives))
 			. += "<br>Objectives are empty! <a href='?src=[UID()];changeling=autoobjectives'>Randomize!</a>"
-		if(changeling && changeling.absorbed_dna.len && (current.real_name != changeling.absorbed_dna[1]))
-			. += "<br><a href='?src=[UID()];changeling=initialdna'>Transform to initial appearance.</a>"
+		if(length(cling.absorbed_dna))
+			var/datum/dna/DNA = cling.absorbed_dna[1]
+			if(current.real_name != DNA.real_name)
+				. += "<br><a href='?src=[UID()];changeling=initialdna'>Transform to initial appearance.</a>"
 	else
 		. += "<a href='?src=[UID()];changeling=changeling'>changeling</a>|<b>NO</b>"
 
@@ -952,41 +954,30 @@
 	else if(href_list["changeling"])
 		switch(href_list["changeling"])
 			if("clear")
-				if(src in SSticker.mode.changelings)
-					SSticker.mode.changelings -= src
-					special_role = null
-					if(changeling)
-						current.remove_changeling_powers()
-						qdel(current.middleClickOverride) // In case the old changeling has a targeted sting prepared (`datum/middleClickOverride`), delete it.
-						current.middleClickOverride = null
-						qdel(changeling)
-						changeling = null
-					SSticker.mode.update_change_icons_removed(src)
-					to_chat(current, "<FONT color='red' size = 3><B>You grow weak and lose your powers! You are no longer a changeling and are stuck in your current form!</B></FONT>")
+				if(ischangeling(current))
+					remove_antag_datum(/datum/antagonist/changeling)
 					log_admin("[key_name(usr)] has de-changelinged [key_name(current)]")
 					message_admins("[key_name_admin(usr)] has de-changelinged [key_name_admin(current)]")
 			if("changeling")
-				if(!(src in SSticker.mode.changelings))
-					SSticker.mode.changelings += src
-					SSticker.mode.grant_changeling_powers(current)
-					SSticker.mode.update_change_icons_added(src)
-					special_role = SPECIAL_ROLE_CHANGELING
-					SEND_SOUND(current, sound('sound/ambience/antag/ling_aler.ogg'))
-					to_chat(current, "<B><font color='red'>Your powers have awoken. A flash of memory returns to us... we are a changeling!</font></B>")
+				if(!ischangeling(current))
+					add_antag_datum(/datum/antagonist/changeling)
+					to_chat(current, "<span class='biggerdanger'>Your powers have awoken. A flash of memory returns to us... we are a changeling!</span>")
 					log_admin("[key_name(usr)] has changelinged [key_name(current)]")
 					message_admins("[key_name_admin(usr)] has changelinged [key_name_admin(current)]")
 
 			if("autoobjectives")
-				SSticker.mode.forge_changeling_objectives(src)
+				var/datum/antagonist/changeling/cling = has_antag_datum(/datum/antagonist/changeling)
+				cling.give_objectives()
 				to_chat(usr, "<span class='notice'>The objectives for changeling [key] have been generated. You can edit them and announce manually.</span>")
 				log_admin("[key_name(usr)] has automatically forged objectives for [key_name(current)]")
 				message_admins("[key_name_admin(usr)] has automatically forged objectives for [key_name_admin(current)]")
 
 			if("initialdna")
-				if(!changeling || !changeling.absorbed_dna.len)
+				var/datum/antagonist/changeling/cling = has_antag_datum(/datum/antagonist/changeling)
+				if(!cling || !length(cling.absorbed_dna))
 					to_chat(usr, "<span class='warning'>Resetting DNA failed!</span>")
 				else
-					current.dna = changeling.absorbed_dna[1]
+					current.dna = cling.absorbed_dna[1]
 					current.real_name = current.dna.real_name
 					current.UpdateAppearance()
 					domutcheck(current)
@@ -1608,15 +1599,6 @@
 	if(!has_antag_datum(/datum/antagonist/vampire))
 		add_antag_datum(/datum/antagonist/vampire)
 
-/datum/mind/proc/make_Changeling()
-	if(!(src in SSticker.mode.changelings))
-		SSticker.mode.changelings += src
-		SSticker.mode.grant_changeling_powers(current)
-		special_role = SPECIAL_ROLE_CHANGELING
-		SSticker.mode.forge_changeling_objectives(src)
-		SSticker.mode.greet_changeling(src)
-		SSticker.mode.update_change_icons_added(src)
-
 /datum/mind/proc/make_Overmind()
 	if(!(src in SSticker.mode.blob_overminds))
 		SSticker.mode.blob_overminds += src

code/datums/status_effects/buffs.dm

@@ -358,34 +358,38 @@
 	tick_interval = 4 SECONDS
 	alert_type = null
 	var/stacks = 0
+	/// A reference to the changeling's changeling antag datum.
+	var/datum/antagonist/changeling/cling
 
 /datum/status_effect/speedlegs/on_apply()
-	ADD_TRAIT(owner, TRAIT_GOTTAGOFAST, "changeling")
+	cling = owner.mind.has_antag_datum(/datum/antagonist/changeling)
+	ADD_TRAIT(owner, TRAIT_GOTTAGOFAST, CHANGELING_TRAIT)
 	return TRUE
 
 /datum/status_effect/speedlegs/tick()
-	if(owner.stat || owner.staminaloss >= 90 || owner.mind.changeling.chem_charges <= (stacks + 1) * 3)
+	if(owner.stat || owner.staminaloss >= 90 || cling.chem_charges <= (stacks + 1) * 3)
 		to_chat(owner, "<span class='danger'>Our muscles relax without the energy to strengthen them.</span>")
 		owner.Weaken(6 SECONDS)
-		owner.remove_status_effect(STATUS_EFFECT_SPEEDLEGS)
+		qdel(src)
 	else
 		stacks++
-		owner.mind.changeling.chem_charges -= stacks * 3 //At first the changeling may regenerate chemicals fast enough to nullify fatigue, but it will stack
+		cling.chem_charges -= stacks * 3 //At first the changeling may regenerate chemicals fast enough to nullify fatigue, but it will stack
 		if(stacks == 7) //Warning message that the stacks are getting too high
 			to_chat(owner, "<span class='warning'>Our legs are really starting to hurt...</span>")
 
 /datum/status_effect/speedlegs/before_remove()
-	if(stacks < 3 && !(owner.stat || owner.staminaloss >= 90 || owner.mind.changeling.chem_charges <= (stacks + 1) * 3)) //We don't want people to turn it on and off fast, however, we need it forced off if the 3 later conditions are met.
+	if(stacks < 3 && !(owner.stat || owner.staminaloss >= 90 || cling.chem_charges <= (stacks + 1) * 3)) //We don't want people to turn it on and off fast, however, we need it forced off if the 3 later conditions are met.
 		to_chat(owner, "<span class='notice'>Our muscles just tensed up, they will not relax so fast.</span>")
 		return FALSE
 	return TRUE
 
 /datum/status_effect/speedlegs/on_remove()
-	REMOVE_TRAIT(owner, TRAIT_GOTTAGOFAST, "changeling")
+	REMOVE_TRAIT(owner, TRAIT_GOTTAGOFAST, CHANGELING_TRAIT)
 	if(!owner.IsWeakened())
 		to_chat(owner, "<span class='notice'>Our muscles relax.</span>")
 		if(stacks >= 7)
 			to_chat(owner, "<span class='danger'>We collapse in exhaustion.</span>")
 			owner.Weaken(6 SECONDS)
 			owner.emote("gasp")
-	owner.mind.changeling.geneticdamage += stacks
+	cling.genetic_damage += stacks
+	cling = null

code/datums/uplink_item.dm

@@ -1755,7 +1755,7 @@ GLOBAL_LIST_INIT(uplink_items, subtypesof(/datum/uplink_item))
 	else if(!AT)
 		to_chat(usr, "<span class='warning'>Error: Embedded Syndicate credentials not found.</span>")
 		return
-	else if(mind.changeling || mind.has_antag_datum(/datum/antagonist/vampire))
+	else if(ischangeling(usr) || mind.has_antag_datum(/datum/antagonist/vampire))
 		to_chat(usr, "<span class='warning'>Error: Embedded Syndicate credentials contain an abnormal signature. Aborting.</span>")
 		return