AI valid target cache (#394)

code/controllers/subsystem/xeno_ai.dm

@@ -11,6 +11,43 @@ SUBSYSTEM_DEF(xeno_ai)
 
 	var/ai_kill = FALSE
 
+	//currently the only caste that has an actual targeting difference is facehugger
+	/// Assoc list of valid targets by hive & caste, in the form of: hive = (/caste = targets)
+	var/list/target_cache = list()
+
+/datum/controller/subsystem/xeno_ai/proc/get_valid_targets(mob/living/carbon/xenomorph/xeno)
+	var/datum/hive_status/hive = xeno.hive
+	LAZYINITLIST(target_cache[hive])
+
+	var/caste = xeno.type
+	if(target_cache[hive][caste])
+		return target_cache[hive][caste]
+
+	var/list/valid_targets = list()
+	target_cache[hive][caste] = valid_targets
+
+	for(var/mob/living/carbon/potential_target in GLOB.alive_mob_list)
+		if(!potential_target.ai_can_target(xeno))
+			continue
+
+		valid_targets += potential_target
+
+	for(var/obj/vehicle/multitile/potential_vehicle_target as anything in GLOB.all_multi_vehicles)
+		if(potential_vehicle_target.health <= 0)
+			continue
+
+		if(hive.faction_is_ally(potential_vehicle_target.vehicle_faction))
+			continue
+
+		if(!length(valid_targets & potential_vehicle_target.interior.get_passengers()))
+			continue
+
+		valid_targets += potential_vehicle_target
+
+	valid_targets += GLOB.all_active_defenses
+
+	return valid_targets
+
 /datum/controller/subsystem/xeno_ai/stat_entry(msg)
 	msg = "P:[length(ai_mobs)]"
 	return ..()
@@ -26,6 +63,10 @@ SUBSYSTEM_DEF(xeno_ai)
 	message_admins("[key_name_admin(usr)] [SSxeno_ai.ai_kill? "killed" : "revived"] all xeno AI.")
 
 /datum/controller/subsystem/xeno_ai/fire(resumed = FALSE)
+	for(var/datum/hive_status/hive as anything in target_cache)
+		for(var/caste as anything in target_cache[hive])
+			target_cache[hive][caste] = null
+
 	if(ai_kill)
 		return
 

code/modules/mob/living/carbon/xenomorph/ai/xeno_ai.dm

@@ -235,16 +235,12 @@
 	var/atom/movable/closest_target
 	var/smallest_distance = INFINITY
 
-	for(var/mob/living/carbon/potential_target as anything in GLOB.alive_mob_list)
-		if(!istype(potential_target))
-			continue
+	var/list/valid_targets = SSxeno_ai.get_valid_targets(src)
 
+	for(var/atom/movable/potential_target as anything in valid_targets)
 		if(z != potential_target.z)
 			continue
 
-		if(!potential_target.ai_can_target(src))
-			continue
-
 		var/distance = get_dist(src, potential_target)
 
 		if(distance > ai_range)
@@ -258,59 +254,6 @@
 		closest_target = potential_target
 		smallest_distance = distance
 
-	for(var/obj/vehicle/multitile/potential_vehicle_target as anything in GLOB.all_multi_vehicles)
-		if(z != potential_vehicle_target.z)
-			continue
-
-		var/distance = get_dist(src, potential_vehicle_target)
-
-		if(distance > ai_range)
-			continue
-
-		if(potential_vehicle_target.health <= 0)
-			continue
-
-		var/multitile_faction = potential_vehicle_target.vehicle_faction
-		if(hive.faction_is_ally(multitile_faction))
-			continue
-
-		var/skip_vehicle
-		var/list/interior_living_mobs = potential_vehicle_target.interior.get_passengers()
-		for(var/mob/living/carbon/human/human_mob in interior_living_mobs)
-			if(!human_mob.ai_can_target(src))
-				continue
-
-			skip_vehicle = FALSE
-			break
-
-		if(skip_vehicle)
-			continue
-
-		viable_targets += potential_vehicle_target
-
-		if(smallest_distance <= distance)
-			continue
-
-		closest_target = potential_vehicle_target
-		smallest_distance = distance
-
-	for(var/obj/structure/machinery/defenses/potential_defense_target as anything in GLOB.all_active_defenses)
-		if(z != potential_defense_target.z)
-			continue
-
-		var/distance = get_dist(src, potential_defense_target)
-
-		if(distance > ai_range)
-			continue
-
-		viable_targets += potential_defense_target
-
-		if(smallest_distance <= distance)
-			continue
-
-		closest_target = potential_defense_target
-		smallest_distance = distance
-
 	var/extra_check_distance = round(smallest_distance * EXTRA_CHECK_DISTANCE_MULTIPLIER)
 
 	if(extra_check_distance < 1)