Larva surge is limited by marines/xenos ratio (#3592)

# About the pull request

Xenos after hijack now get larva based on marines/xenos ratio. Instead
of infinite larva, larva surge will try to increase the initial amount
of xenos on hijack to 50% of marines forces over time (with a minimum of
5 larvas, if xenos already have good numbers).

# Explain why it's good for the game

Initially, if I remember correctly, larva surge was brought into the
game to discourage marines from early meta-evacuations, which is fair.
But consequently, it really hurt the hijack sequence. Even if marines
evac fair and square, larva surge still comes in action and makes
situation for marines even worse, utterly discouraging everything but
either boomrushing the Alamo or holding lifeboats to evac.

This resulted in hijacks being very repetitive and boring. More than
that, larva surge is extremely busted on lowpop due to the fact you can
get around 20 xenos from nothing, making lowpop hijack even less
interesting. So with this change marines will still get punished for
evaccing with good numbers, but won't be penalized as much for honest
evacuations.

So hopefully, we will see more variety of hijacks and more interesting
stories!

P.S. if you have a better formula, let me know.


# Testing Photographs and Procedure
<details>
My friend @Diegoflores31 tested this for me, thanks!
<summary>Screenshots & Videos</summary>

Put screenshots and videos here with an empty line between the
screenshots and the `<details>` tags.

</details>


# Changelog
:cl: ihatethisengine
balance: larva surge is limited by marines/xenos ratio
fix: xenos no longer get free larva from abandoned facehuggers during
hijack
/:cl:

---------

Co-authored-by: ihatethisengine <[email protected]>
Co-authored-by: fira <[email protected]>

code/modules/cm_aliens/structures/special/pylon_core.dm

@@ -162,9 +162,14 @@
 		if(linked_hive.hijack_burrowed_surge && (last_surge_time + surge_cooldown) < world.time)
 			last_surge_time = world.time
 			linked_hive.stored_larva++
+			linked_hive.hijack_burrowed_left--
 			announce_dchat("The hive has gained another burrowed larva! Use the Join As Xeno verb to take it.", src)
 			if(surge_cooldown > 30 SECONDS) //mostly for sanity purposes
 				surge_cooldown = surge_cooldown - surge_incremental_reduction //ramps up over time
+			if(linked_hive.hijack_burrowed_left < 1)
+				linked_hive.hijack_burrowed_surge = FALSE
+				xeno_message(SPAN_XENOANNOUNCE("The hive's power wanes. You will no longer gain pooled larva over time."), 3, linked_hive.hivenumber)
+
 
 	// Hive core can repair itself over time
 	if(health < maxhealth && last_healed <= world.time)

code/modules/mob/living/carbon/xenomorph/xeno_defines.dm

@@ -285,6 +285,8 @@
 	var/larva_gestation_multiplier = 1
 	var/bonus_larva_spawn_chance = 1
 	var/hijack_burrowed_surge = FALSE //at hijack, start spawning lots of burrowed
+	/// how many burrowed is going to spawn during larva surge
+	var/hijack_burrowed_left = 0 
 
 	var/ignore_slots = FALSE
 	var/dynamic_evolution = TRUE
@@ -877,6 +879,8 @@
 
 /datum/hive_status/proc/abandon_on_hijack()
 	var/area/hijacked_dropship = get_area(living_xeno_queen)
+	var/shipside_humans_weighted_count = 0
+	var/xenos_count = 0
 	for(var/name_ref in hive_structures)
 		for(var/obj/effect/alien/resin/special/S in hive_structures[name_ref])
 			if(get_area(S) == hijacked_dropship)
@@ -885,6 +889,10 @@
 			qdel(S)
 	for(var/mob/living/carbon/xenomorph/xeno as anything in totalXenos)
 		if(get_area(xeno) != hijacked_dropship && xeno.loc && is_ground_level(xeno.loc.z))
+			if(isfacehugger(xeno))
+				to_chat(xeno, SPAN_XENOANNOUNCE("The Queen has left without you, you quickly find a hiding place to enter hibernation as you lose touch with the hive mind."))
+				qdel(xeno)
+				continue
 			if(xeno.hunter_data.hunted && !isqueen(xeno))
 				to_chat(xeno, SPAN_XENOANNOUNCE("The Queen has left without you, seperating you from her hive! You must defend yourself from the headhunter before you can enter hibernation..."))
 				xeno.set_hive_and_update(XENO_HIVE_FORSAKEN)
@@ -895,6 +903,9 @@
 					xeno.handle_stomach_contents()
 				qdel(xeno)
 			stored_larva++
+			continue
+		if(!isfacehugger(xeno))
+			xenos_count++
 	for(var/i in GLOB.alive_mob_list)
 		var/mob/living/potential_host = i
 		if(!(potential_host.status_flags & XENO_HOST))
@@ -907,7 +918,13 @@
 		for(var/obj/item/alien_embryo/embryo in potential_host)
 			embryo.hivenumber = XENO_HIVE_FORSAKEN
 		potential_host.update_med_icon()
+	for(var/mob/living/carbon/human/current_human as anything in GLOB.alive_human_list)
+		if((isspecieshuman(current_human) || isspeciessynth(current_human)) && current_human.job)
+			var/turf/turf = get_turf(current_human)
+			if(is_mainship_level(turf?.z))
+				shipside_humans_weighted_count += RoleAuthority.calculate_role_weight(current_human.job)
 	hijack_burrowed_surge = TRUE
+	hijack_burrowed_left = max(n_ceil(shipside_humans_weighted_count * 0.5) - xenos_count, 5)
 	hivecore_cooldown = FALSE
 	xeno_message(SPAN_XENOBOLDNOTICE("The weeds have recovered! A new hive core can be built!"),3,hivenumber)