Divides species in subtypes, makes viruses able to infect certain subtypes (#32858)

Species are now separated into Organic, Inorganic, Undead and Robotic. The virusimmune tag was kept for species who are effectively organic but immune to viruses for special reasons (abductors).

You can now set the types of species viruses can infect; i made some adjustments that i thought made sense (beesease infecting zombies, parrot possession infecting anyone).

Added process_dead as an additional effect for the new symptom, allowing the disease to tick on corpses; it doesn't have many uses i can think of, but it can heal up people in case of a defibrillation or something like that.

Fixes #32832

code/datums/diseases/_MobProcs.dm

@@ -143,14 +143,25 @@
 //Proc to use when you 100% want to infect someone, as long as they aren't immune
 /mob/proc/ForceContractDisease(datum/disease/D)
 	if(!CanContractDisease(D))
-		return 0
+		return FALSE
 	AddDisease(D)
 
 
 /mob/living/carbon/human/CanContractDisease(datum/disease/D)
-	if(dna && (VIRUSIMMUNE in dna.species.species_traits) && !D.bypasses_immunity)
-		return 0
+
+	if(dna)
+		if((VIRUSIMMUNE in dna.species.species_traits) && !D.bypasses_immunity)
+			return FALSE
+
+		var/can_infect = FALSE
+		for(var/host_type in D.infectable_hosts)
+			if(host_type in dna.species.species_traits)
+				can_infect = TRUE
+				break
+		if(!can_infect)
+			return FALSE
+
 	for(var/thing in D.required_organs)
 		if(!((locate(thing) in bodyparts) || (locate(thing) in internal_organs)))
-			return 0
+			return FALSE
 	return ..()

code/datums/diseases/_disease.dm

@@ -30,6 +30,8 @@
 	var/list/required_organs = list()
 	var/needs_all_cures = TRUE
 	var/list/strain_data = list() //dna_spread special bullshit
+	var/list/infectable_hosts = list(SPECIES_ORGANIC) //if the disease can spread on organics, synthetics, or undead
+	var/process_dead = FALSE //if this ticks while the host is dead
 
 /datum/disease/Destroy()
 	affected_mob = null

code/datums/diseases/advance/symptoms/species.dm

@@ -0,0 +1,30 @@
+/datum/symptom/undead_adaptation
+	name = "Necrotic Metabolism"
+	desc = "The virus is able to thrive and act even within dead hosts."
+	stealth = 2
+	resistance = -2
+	stage_speed = 1
+	transmittable = 0
+	level = 5
+	severity = 0
+
+/datum/symptom/undead_adaptation/Start(datum/disease/advance/A)
+	if(!..())
+		return
+	A.process_dead = TRUE
+	A.infectable_hosts |= SPECIES_UNDEAD
+
+/datum/symptom/inorganic_adaptation
+	name = "Inorganic Biology"
+	desc = "The virus can survive and replicate even in an inorganic environment, increasing its resistance and infection rate."
+	stealth = -1
+	resistance = 4
+	stage_speed = -2
+	transmittable = 3
+	level = 5
+	severity = 0
+
+/datum/symptom/inorganic_adaptation/Start(datum/disease/advance/A)
+	if(!..())
+		return
+	A.infectable_hosts |= SPECIES_INORGANIC

code/datums/diseases/beesease.dm

@@ -10,6 +10,7 @@
 	viable_mobtypes = list(/mob/living/carbon/human, /mob/living/carbon/monkey)
 	desc = "If left untreated subject will regurgitate bees."
 	severity = VIRUS_SEVERITY_MEDIUM
+	infectable_hosts = list(SPECIES_ORGANIC, SPECIES_UNDEAD) //bees nesting in corpses
 
 /datum/disease/beesease/stage_act()
 	..()

code/datums/diseases/magnitis.dm

@@ -10,6 +10,8 @@
 	permeability_mod = 0.75
 	desc = "This disease disrupts the magnetic field of your body, making it act as if a powerful magnet. Injections of iron help stabilize the field."
 	severity = VIRUS_SEVERITY_MEDIUM
+	infectable_hosts = list(SPECIES_ORGANIC, SPECIES_ROBOTIC)
+	process_dead = TRUE
 
 /datum/disease/magnitis/stage_act()
 	..()

code/datums/diseases/parrotpossession.dm

@@ -11,6 +11,8 @@
 	viable_mobtypes = list(/mob/living/carbon/human)
 	desc = "Subject is possesed by the vengeful spirit of a parrot. Call the priest."
 	severity = VIRUS_SEVERITY_MEDIUM
+	infectable_hosts = list(SPECIES_ORGANIC, SPECIES_UNDEAD, SPECIES_INORGANIC, SPECIES_ROBOTIC)
+	bypasses_immunity = TRUE //2spook
 	var/mob/living/simple_animal/parrot/Poly/ghost/parrot
 
 /datum/disease/parrot_possession/stage_act()

code/datums/diseases/rhumba_beat.dm

@@ -9,6 +9,7 @@
 	viable_mobtypes = list(/mob/living/carbon/human)
 	permeability_mod = 1
 	severity = VIRUS_SEVERITY_BIOHAZARD
+	process_dead = TRUE
 
 /datum/disease/rhumba_beat/stage_act()
 	..()

code/datums/diseases/transformation.dm

@@ -127,7 +127,7 @@
 	stage4	= list("<span class='danger'>Your skin feels very loose.</span>", "<span class='danger'>You can feel... something...inside you.</span>")
 	stage5	= list("<span class='danger'>Your skin feels as if it's about to burst off!</span>")
 	new_form = /mob/living/silicon/robot
-
+	infectable_hosts = list(SPECIES_ORGANIC, SPECIES_UNDEAD, SPECIES_ROBOTIC)
 
 /datum/disease/transformation/robot/stage_act()
 	..()
@@ -240,3 +240,4 @@
 	stage4	= list("<span class='danger'>You're ravenous.</span>")
 	stage5	= list("<span class='danger'>You have become a morph.</span>")
 	new_form = /mob/living/simple_animal/hostile/morph
+	infectable_hosts = list(SPECIES_ORGANIC, SPECIES_INORGANIC, SPECIES_UNDEAD) //magic!