initial commit - cross reference with 5th port - obviously has compile errors

code/modules/events/alien_infestation.dm

@@ -0,0 +1,75 @@
+/datum/round_event_control/alien_infestation
+	name = "Alien Infestation"
+	typepath = /datum/round_event/ghost_role/alien_infestation
+	weight = 5
+
+	min_players = 10
+	max_occurrences = 1
+
+/datum/round_event/ghost_role/alien_infestation
+	announceWhen	= 400
+
+	minimum_required = 1
+	role_name = "alien larva"
+
+	// 50% chance of being incremented by one
+	var/spawncount = 1
+	var/successSpawn = 0	//So we don't make a command report if nothing gets spawned.
+
+
+/datum/round_event/ghost_role/alien_infestation/setup()
+	announceWhen = rand(announceWhen, announceWhen + 50)
+	if(prob(50))
+		spawncount++
+
+/datum/round_event/ghost_role/alien_infestation/kill()
+	if(!successSpawn && control)
+		// This never happened, so let's not deny the future of this round
+		// some xenolovin
+		control.occurrences--
+	return ..()
+
+/datum/round_event/ghost_role/alien_infestation/announce()
+	if(successSpawn)
+		priority_announce("Unidentified lifesigns detected coming aboard [station_name()]. Secure any exterior access, including ducting and ventilation.", "Lifesign Alert", 'sound/AI/aliens.ogg')
+
+
+/datum/round_event/ghost_role/alien_infestation/spawn_role()
+	var/list/vents = list()
+	for(var/obj/machinery/atmospherics/components/unary/vent_pump/temp_vent in machines)
+		if(qdeleted(temp_vent))
+			continue
+		if(temp_vent.loc.z == ZLEVEL_STATION && !temp_vent.welded)
+			var/datum/pipeline/temp_vent_parent = temp_vent.PARENT1
+			//Stops Aliens getting stuck in small networks.
+			//See: Security, Virology
+			if(temp_vent_parent.other_atmosmch.len > 20)
+				vents += temp_vent
+
+	if(!vents.len)
+		message_admins("An event attempted to spawn an alien but no suitable vents were found. Shutting down.")
+		return MAP_ERROR
+
+	var/list/candidates = get_candidates("alien", null, ROLE_ALIEN)
+
+	if(!candidates.len)
+		return NOT_ENOUGH_PLAYERS
+
+	while(spawncount > 0 && vents.len && candidates.len)
+		var/obj/vent = pick_n_take(vents)
+		var/client/C = popleft(candidates)
+
+		var/mob/living/carbon/alien/larva/new_xeno = new(vent.loc)
+		new_xeno.key = C.key
+
+		spawncount--
+		successSpawn = TRUE
+		message_admins("[new_xeno.key] has been made into an alien by an event.")
+		log_game("[new_xeno.key] was spawned as an alien by an event.")
+		spawned_mobs += new_xeno
+
+	if(successSpawn)
+		return SUCCESSFUL_SPAWN
+	else
+		// Like how did we get here?
+		return FALSE