Ruin placement will try very hard to place any ruins with negative costs before attempting any other ruins (#28973)

* Ruin placement will try very hard to place all 0-cost ruins before placing any ruins with actual costs

* comment

* account for ruin variants properly please

* cost has a cost of 5

* tweak

code/__HELPERS/cmp.dm

@@ -47,3 +47,5 @@ GLOBAL_VAR_INIT(cmp_field, "name")
 /proc/cmp_clockscripture_priority(datum/clockwork_scripture/A, datum/clockwork_scripture/B)
 	return initial(A.sort_priority) - initial(B.sort_priority)
 
+/proc/cmp_ruincost_priority(datum/map_template/ruin/A, datum/map_template/ruin/B)
+	return initial(A.cost) - initial(B.cost)

code/controllers/subsystem/mapping.dm

@@ -210,7 +210,7 @@ SUBSYSTEM_DEF(mapping)
 	var/list/banned = generateMapList("config/lavaruinblacklist.txt")
 	banned += generateMapList("config/spaceruinblacklist.txt")
 
-	for(var/item in subtypesof(/datum/map_template/ruin))
+	for(var/item in sortList(subtypesof(/datum/map_template/ruin), /proc/cmp_ruincost_priority))
 		var/datum/map_template/ruin/ruin_type = item
 		// screen out the abstract subtypes
 		if(!initial(ruin_type.id))

code/datums/ruins.dm

@@ -6,7 +6,7 @@
 	How is there a wooden container filled with 18th century coinage in the middle of a lavawracked hellscape? \
 	It is clearly a mystery."
 
-	var/cost = null
+	var/cost = null //negative numbers will always be placed, with lower (negative) numbers being placed first; positive and 0 numbers will be placed randomly
 	var/allow_duplicates = TRUE
 
 	var/prefix = null

code/datums/ruins/lavaland.dm

@@ -120,7 +120,7 @@
 	id = "hierophant"
 	description = "A strange, square chunk of metal of massive size. Inside awaits only death and many, many squares."
 	suffix = "lavaland_surface_hierophant.dmm"
-	cost = 0
+	cost = -1
 	allow_duplicates = FALSE
 
 /datum/map_template/ruin/lavaland/ufo_crash

code/modules/mapping/ruins.dm

@@ -14,10 +14,20 @@
 	var/overall_sanity = 100
 	var/list/ruins = potentialRuins.Copy()
 
+	var/is_picking = FALSE
+	var/last_checked_ruin_index = 0
 	while(budget > 0 && overall_sanity > 0)
 		// Pick a ruin
 		var/datum/map_template/ruin/ruin = null
 		if(ruins && ruins.len)
+			last_checked_ruin_index++ //ruins with no cost come first in the ruin list, so they'll get picked really often
+			if(is_picking)
+				ruin = ruins[pick(ruins)]
+			else
+				var/ruin_key = ruins[last_checked_ruin_index] //get the ruin's key via index
+				ruin = ruins[ruin_key] //use that key to get the ruin datum itself
+				if(ruin.cost >= 0) //if it has a non-negative cost, cancel out and pick another, to ensure true randomness
+					is_picking = TRUE
 					ruin = ruins[pick(ruins)]
 		else
 			log_world("Ruin loader had no ruins to pick from with [budget] left to spend.")
@@ -51,9 +61,14 @@
 
 			var/obj/effect/ruin_loader/R = new /obj/effect/ruin_loader(T)
 			R.Load(ruins,ruin)
+			if(ruin.cost >= 0)
 				budget -= ruin.cost
 			if(!ruin.allow_duplicates)
-				ruins -= ruin.name
+				for(var/m in ruins)
+					var/datum/map_template/ruin/ruin_to_remove = ruins[m]
+					if(ruin_to_remove.id == ruin.id) //remove all ruins with the same ID, to make sure that ruins with multiple variants work properly
+						ruins -= ruin_to_remove.name
+						last_checked_ruin_index--
 			break
 
 	if(!overall_sanity)