[MIRROR] Better Viro (#9421)

Co-authored-by: Guti <32563288+TheCaramelion@users.noreply.github.com>
Co-authored-by: Kashargul <144968721+Kashargul@users.noreply.github.com>

code/modules/events/disease_outbreak.dm

@@ -0,0 +1,98 @@
+GLOBAL_LIST_EMPTY(current_pending_diseases)
+/datum/event/disease_outbreak
+	var/datum/disease/chosen_disease
+	var/list/disease_blacklist = list(
+		/datum/disease/advance,
+		/datum/disease/food_poisoning
+	)
+	var/static/list/transmissable_symptoms = list()
+	var/static/list/diseases_minor = list()
+	var/static/list/diseases_moderate_major = list()
+
+/datum/event/disease_outbreak/setup()
+	if(isemptylist(diseases_minor) && isemptylist(diseases_moderate_major))
+		populate_diseases()
+	if(isemptylist(transmissable_symptoms))
+		populate_symptoms()
+	var/datum/disease/virus
+	if(prob(50))
+		switch(severity)
+			if(EVENT_LEVEL_MODERATE)
+				virus = pick(diseases_minor)
+			if(EVENT_LEVEL_MAJOR)
+				virus = pick(diseases_moderate_major)
+			else
+				stack_trace("Disease Outbreak: Invalid Event Level [severity]. Expected: 1-2")
+				virus = /datum/disease/cold
+		chosen_disease = new virus()
+	else
+		if(severity == EVENT_LEVEL_MAJOR)
+			chosen_disease = create_virus(severity * pick(2,3))	//50% chance for a major disease instead of a moderate one
+		else
+			chosen_disease = create_virus(severity * 2)
+
+	chosen_disease.carrier = TRUE
+
+/datum/event/disease_outbreak/start()
+	GLOB.current_pending_diseases += chosen_disease
+
+	var/list/candidates = list()
+	for(var/mob/living/carbon/human/G in player_list)
+		if(G.mind && G.stat != DEAD && G.is_client_active(5) && !player_is_antag(G.mind))
+			var/area/A = get_area(G)
+			if(!A)
+				continue
+			if(!(A.z in using_map.station_levels))
+				continue
+			if(A.flags & RAD_SHIELDED)
+				continue
+			if(isbelly(G.loc))
+				continue
+			if(!G.CanContractDisease())
+				continue
+			candidates += G
+
+	var/chosen_infect = rand(3, 5)
+
+	while(chosen_infect)
+		var/mob/living/carbon/human/H = pick(candidates)
+		H.ContractDisease(chosen_disease)
+		candidates -= H
+
+
+//Creates a virus with a harmful effect, guaranteed to be spreadable by contact or airborne
+/datum/event/disease_outbreak/proc/create_virus(max_severity = 6)
+	var/datum/disease/advance/A = new /datum/disease/advance
+	A.symptoms = A.GenerateSymptomsBySeverity(max_severity - 1, max_severity, 2) //Choose "Payload" symptoms
+	A.AssignProperties(A.GenerateProperties())
+	var/list/symptoms_to_try = transmissable_symptoms.Copy()
+	while(length(symptoms_to_try))
+		if(A.spread_text != "Blood")
+			break
+		if(length(A.symptoms) < VIRUS_SYMPTOM_LIMIT)	//Ensure the virus is spreadable by adding symptoms that boost transmission
+			var/datum/symptom/TS = pick_n_take(symptoms_to_try)
+			A.AddSymptom(new TS)
+		else
+			popleft(A.symptoms)	//We have a full symptom list but are still not transmittable. Try removing one of the "payloads"
+
+		A.AssignProperties(A.GenerateProperties())
+	A.name = pick(alphabet_uppercase) + num2text(rand(1,9)) + pick(alphabet_uppercase) + num2text(rand(1,9)) + pick("v", "V", "-" + num2text(game_year), "")
+	A.Refresh()
+	return A
+
+/datum/event/disease_outbreak/proc/populate_diseases()
+	for(var/candidate in subtypesof(/datum/disease))
+		var/datum/disease/CD = new candidate
+		if(is_type_in_list(CD, disease_blacklist))
+			continue
+		switch(CD.severity)
+			if(NONTHREAT, MINOR)
+				diseases_minor += candidate
+			if(MEDIUM, HARMFUL, DANGEROUS, BIOHAZARD)
+				diseases_moderate_major += candidate
+
+/datum/event/disease_outbreak/proc/populate_symptoms()
+	for(var/candidate in subtypesof(/datum/symptom))
+		var/datum/symptom/CS = candidate
+		if(initial(CS.transmittable) > 1)
+			transmissable_symptoms += candidate