Added wallrot event.

Also some updates to changelog.

code/modules/events/event_dynamic.dm

@@ -61,6 +61,7 @@
 	possibleEvents[/datum/event/ionstorm] = 25 + active_with_role["AI"] * 25 + active_with_role["Cyborg"] * 25 + active_with_role["Engineer"] * 10 + active_with_role["Scientist"] * 5
 	possibleEvents[/datum/event/grid_check] = 25 + 10 * active_with_role["Engineer"]
 	possibleEvents[/datum/event/electrical_storm] = 75 + 25 * active_with_role["Janitor"] + 5 * active_with_role["Engineer"]
+	possibleEvents[/datum/event/wallrot] = 50 * active_with_role["Engineer"] + 100 * active_with_role["Botanist"]
 
 	if(!spacevines_spawned)
 		possibleEvents[/datum/event/spacevine] = 5 + 10 * active_with_role["Engineer"]
@@ -180,6 +181,7 @@
 	active_with_role["AI"] = 0
 	active_with_role["Cyborg"] = 0
 	active_with_role["Janitor"] = 0
+	active_with_role["Botanist"] = 0
 
 	for(var/mob/M in player_list)
 		if(!M.mind || !M.client || M.client.inactivity > 10 * 10 * 60) // longer than 10 minutes AFK counts them as inactive
@@ -212,4 +214,7 @@
 		if(M.mind.assigned_role == "Janitor")
 			active_with_role["Janitor"]++
 
+		if(M.mind.assigned_role == "Botanist")
+			active_with_role["Botanist"]++
+
 	return active_with_role

code/modules/events/wallrot.dm

@@ -0,0 +1,37 @@
+/turf/simulated/wall
+
+
+datum/event/wallrot
+	var/severity = 1
+
+datum/event/wallrot/setup()
+	announceWhen = rand(0, 3000)
+	endWhen = announceWhen + 1
+	severity = rand(5, 10)
+
+datum/event/wallrot/announce()
+	command_alert("Harmful fungi detected on station. Station structures may be contaminated.", "Biohazard Alert")
+
+datum/event/wallrot/start()
+	spawn()
+		var/turf/center = null
+
+		// 100 attempts
+		for(var/i=0, i<100, i++)
+			var/turf/candidate = locate(rand(1, world.maxx), rand(1, world.maxy), 1)
+			if(istype(candidate, /turf/simulated/wall))
+				center = candidate
+
+		if(center)
+			// Make sure at least one piece of wall rots!
+			center:rot()
+
+			// Have a chance to rot lots of other walls.
+			var/rotcount = 0
+			for(var/turf/simulated/wall/W in range(5, center)) if(prob(50))
+				W:rot()
+				rotcount++
+
+				// Only rot up to severity walls
+				if(rotcount >= severity)
+					break

code/modules/reagents/Chemistry-Reagents.dm

@@ -1214,6 +1214,17 @@ datum
 				..()
 				return
 
+			// Clear off wallrot fungi
+			reaction_turf(var/turf/T, var/volume)
+				if(istype(T, /turf/simulated/wall))
+					var/turf/simulated/wall/W = T
+					if(W.rotting)
+						W.rotting = 0
+						for(var/obj/effect/E in W) if(E.name == "Wallrot") del E
+
+						for(var/mob/O in viewers(W, null))
+							O.show_message(text("\blue The fungi are completely dissolved by the solution!"), 1)
+
 			reaction_obj(var/obj/O, var/volume)
 				if(istype(O,/obj/effect/alien/weeds/))
 					var/obj/effect/alien/weeds/alien_weeds = O

code/modules/reagents/reagent_containers/spray.dm

@@ -49,12 +49,20 @@
 
 	D.icon += mix_color_from_reagents(D.reagents.reagent_list)
 
+	var/A_turf = get_turf(A)
+
 	spawn(0)
 		for(var/i=0, i<3, i++)
 			step_towards(D,A)
 			D.reagents.reaction(get_turf(D))
 			for(var/atom/T in get_turf(D))
 				D.reagents.reaction(T)
+
+				// When spraying against the wall, also react with the wall, but
+				// not its contents.
+				if(get_dist(D, A_turf) == 1 && A_turf.density)
+					D.reagents.reaction(A_turf)
+				sleep(2)
 			sleep(3)
 		del(D)