Turns blood walking into an element (#64162)

Refactoring things to elements/components is better in general, and I thought this was a perfect thing to turn into one.

code/datums/elements/blood_walk.dm

@@ -0,0 +1,50 @@
+///Blood walk, a bespoke element that causes you to make blood wherever you walk.
+/datum/element/blood_walk
+	element_flags = ELEMENT_BESPOKE|ELEMENT_DETACH
+	id_arg_index = 2
+
+	///A unique blood type we might want to spread
+	var/blood_type
+	///The sound that plays when we spread blood.
+	var/sound_played
+	///How loud will the sound be, if there is one.
+	var/sound_volume
+	///The chance of spawning blood whenever walking
+	var/blood_spawn_chance
+
+
+/datum/element/blood_walk/Attach(
+	datum/target,
+	blood_type = /obj/effect/decal/cleanable/blood,
+	sound_played,
+	sound_volume = 80,
+	blood_spawn_chance = 100,
+)
+	. = ..()
+	if(!ismovable(target))
+		return ELEMENT_INCOMPATIBLE
+
+	src.blood_type = blood_type
+	src.sound_played = sound_played
+	src.sound_volume = sound_volume
+	src.blood_spawn_chance = blood_spawn_chance
+	RegisterSignal(target, COMSIG_MOVABLE_MOVED, .proc/spread_blood)
+
+/datum/element/blood_walk/Detach(datum/target)
+	. = ..()
+	UnregisterSignal(target, COMSIG_MOVABLE_MOVED)
+
+///Spawns blood (if possible) under the source, and plays a sound effect (if any)
+/datum/element/blood_walk/proc/spread_blood(datum/source)
+	SIGNAL_HANDLER
+
+	var/atom/movable/movable_source = source
+	var/turf/current_turf = movable_source.loc
+	if(!isturf(current_turf))
+		return
+	if(!prob(blood_spawn_chance))
+		return
+
+	new blood_type(current_turf)
+	if(!isnull(sound_played))
+		playsound(movable_source, sound_played, sound_volume, TRUE, 2, TRUE)