[MIRROR] Turns squashing mobs into an element (#2606)

* Turns squashing mobs into an element (#55725)

Opens up room for extending squashing behavior for future cytology updates.

* Turns squashing mobs into an element

Co-authored-by: Qustinnus <Floydje123@hotmail.com>

code/__DEFINES/mobs.dm

@@ -391,3 +391,10 @@
 
 ///Define for spawning megafauna instead of a mob for cave gen
 #define SPAWN_MEGAFAUNA "bluh bluh huge boss"
+
+///Squash flags. For squashable element
+
+///Whether or not the squashing requires the squashed mob to be lying down
+#define SQUASHED_SHOULD_BE_DOWN (1<<0)
+///Whether or not to gib when the squashed mob is moved over
+#define SQUASHED_SHOULD_BE_GIBBED (1<<0)

code/datums/elements/squashable.dm

@@ -0,0 +1,68 @@
+///This element allows something to be when crossed, for example for cockroaches.
+/datum/element/squashable
+	element_flags = ELEMENT_BESPOKE | ELEMENT_DETACH
+	id_arg_index = 2
+	///Chance on crossed to be squashed
+	var/squash_chance = 50
+	///How much brute is applied when mob is squashed
+	var/squash_damage = 1
+	///Squash flags, for extra checks etcetera.
+	var/squash_flags = NONE
+	///Special callback to call on squash instead, for things like hauberoach
+	var/datum/callback/on_squash_callback
+
+
+/datum/element/squashable/Attach(mob/living/target, squash_chance, squash_damage, squash_flags, squash_callback)
+	. = ..()
+	if(!istype(target))
+		return ELEMENT_INCOMPATIBLE
+	if(squash_chance)
+		src.squash_chance = squash_chance
+	if(squash_damage)
+		src.squash_damage = squash_damage
+	if(squash_flags)
+		src.squash_flags = squash_flags
+	if(!src.on_squash_callback && squash_callback)
+		on_squash_callback = CALLBACK(target, squash_callback)
+
+	RegisterSignal(target, COMSIG_MOVABLE_CROSSED, .proc/OnCrossed)
+
+/datum/element/squashable/Detach(mob/living/target)
+	UnregisterSignal(target, COMSIG_MOVABLE_CROSSED)
+
+///Handles the squashing of the mob
+/datum/element/squashable/proc/OnCrossed(mob/living/target, atom/movable/crossing_movable)
+	SIGNAL_HANDLER
+
+
+	if(squash_flags & SQUASHED_SHOULD_BE_DOWN && target.body_position != LYING_DOWN)
+		return
+
+	var/should_squash = prob(squash_chance)
+
+	if(should_squash && on_squash_callback)
+		if(on_squash_callback.Invoke(target, crossing_movable))
+			return //Everything worked, we're done!
+	if(isliving(crossing_movable))
+		var/mob/living/crossing_mob = crossing_movable
+		if(crossing_mob.mob_size > MOB_SIZE_SMALL && !(crossing_mob.movement_type & FLYING))
+			if(HAS_TRAIT(crossing_mob, TRAIT_PACIFISM))
+				crossing_mob.visible_message("<span class='notice'>[crossing_mob] carefully steps over [target].</span>", "<span class='notice'>You carefully step over [target] to avoid hurting it.</span>")
+				return
+			if(should_squash)
+				crossing_mob.visible_message("<span class='notice'>[crossing_mob] squashed [target].</span>", "<span class='notice'>You squashed [target].</span>")
+				Squish(target)
+			else
+				target.visible_message("<span class='notice'>[target] avoids getting crushed.</span>")
+	else if(isstructure(crossing_movable))
+		if(should_squash)
+			crossing_movable.visible_message("<span class='notice'>[target] is crushed under [crossing_movable].</span>")
+			Squish(target)
+		else
+			target.visible_message("<span class='notice'>[target] avoids getting crushed.</span>")
+
+/datum/element/squashable/proc/Squish(mob/living/target)
+	if(squash_flags & SQUASHED_SHOULD_BE_GIBBED)
+		target.gib()
+	else
+		target.adjustBruteLoss(squash_damage)

code/modules/mob/living/simple_animal/hostile/cockroach.dm

@@ -36,6 +36,10 @@
 /mob/living/simple_animal/hostile/cockroach/Initialize()
 	. = ..()
 	add_cell_sample()
+	make_squashable()
+
+/mob/living/simple_animal/hostile/cockroach/proc/make_squashable()
+	AddElement(/datum/element/squashable, squash_chance = 50, squash_damage = 1)
 
 /mob/living/simple_animal/hostile/cockroach/add_cell_sample()
 	AddElement(/datum/element/swabable, CELL_LINE_TABLE_COCKROACH, CELL_VIRUS_TABLE_GENERIC_MOB, 1, 7)
@@ -68,26 +72,6 @@
 		return
 	..()
 
-/mob/living/simple_animal/hostile/cockroach/Crossed(atom/movable/AM)
-	. = ..()
-	if(isliving(AM))
-		var/mob/living/A = AM
-		if(A.mob_size > MOB_SIZE_SMALL && !(A.movement_type & FLYING))
-			if(HAS_TRAIT(A, TRAIT_PACIFISM))
-				A.visible_message("<span class='notice'>[A] carefully steps over [src].</span>", "<span class='notice'>You carefully step over [src] to avoid hurting it.</span>")
-				return
-			if(prob(squish_chance))
-				A.visible_message("<span class='notice'>[A] squashed [src].</span>", "<span class='notice'>You squashed [src].</span>")
-				adjustBruteLoss(1) //kills a normal cockroach
-			else
-				visible_message("<span class='notice'>[src] avoids getting crushed.</span>")
-	else if(isstructure(AM))
-		if(prob(squish_chance))
-			AM.visible_message("<span class='notice'>[src] is crushed under [AM].</span>")
-			adjustBruteLoss(1)
-		else
-			visible_message("<span class='notice'>[src] avoids getting crushed.</span>")
-
 /mob/living/simple_animal/hostile/cockroach/ex_act() //Explosions are a terrible way to handle a cockroach.
 	return
 
@@ -110,16 +94,15 @@
 	. = ..()
 	AddComponent(/datum/component/caltrop, 10, 15, 100, (CALTROP_BYPASS_SHOES | CALTROP_SILENT))
 
-/mob/living/simple_animal/hostile/cockroach/hauberoach/Crossed(atom/movable/AM)
-	var/mob/living/A = AM
-	if(istype(A) && A.mob_size > MOB_SIZE_SMALL && !(A.movement_type & FLYING))
-		if(!HAS_TRAIT(A, TRAIT_PIERCEIMMUNE))
-			A.visible_message("<span class='danger'>[A] steps onto [src]'s spike!</span>", "<span class='userdanger'>You step onto [src]'s spike!</span>")
-		else if(HAS_TRAIT(A, TRAIT_PACIFISM))
-			A.visible_message("<span class='notice'>[A] carefully steps over [src].</span>", "<span class='notice'>You carefully step over [src] to avoid hurting it.</span>")
-		else if(HAS_TRAIT(A, TRAIT_PIERCEIMMUNE))
-			A.visible_message("<span class='danger'>[A] steps onto [src]'s spike, but is unfazed!</span>", "<span class='userdanger'>You step onto [src]'s spike, but you're unaffected!</span>")
-		else
-			A.visible_message("<span class='notice'>[A] squashes [src], not even noticing its spike.</span>", "<span class='notice'>You squashed [src], not even noticing its spike.</span>")
-			adjustBruteLoss(1) //kills a normal cockroach
-	..()
+/mob/living/simple_animal/hostile/cockroach/hauberoach/make_squashable()
+	AddElement(/datum/element/squashable, squash_chance = 100, squash_damage = 1, squash_callback = /mob/living/simple_animal/hostile/cockroach/hauberoach/.proc/on_squish)
+
+///Proc used to override the squashing behavior of the normal cockroach.
+/mob/living/simple_animal/hostile/cockroach/hauberoach/proc/on_squish(mob/living/cockroach, mob/living/living_target)
+	if(!istype(living_target))
+		return FALSE //We failed to run the invoke. Might be because we're a structure. Let the squashable element handle it then!
+	if(!HAS_TRAIT(living_target, TRAIT_PIERCEIMMUNE))
+		living_target.visible_message("<span class='danger'>[living_target] steps onto [cockroach]'s spike!</span>", "<span class='userdanger'>You step onto [cockroach]'s spike!</span>")
+		return TRUE
+	living_target.visible_message("<span class='notice'>[living_target] squashes [cockroach], not even noticing its spike.</span>", "<span class='notice'>You squashed [cockroach], not even noticing its spike.</span>")
+	return FALSE

tgstation.dme

@@ -628,6 +628,7 @@
 #include "code\datums\elements\ridable.dm"
 #include "code\datums\elements\selfknockback.dm"
 #include "code\datums\elements\snail_crawl.dm"
+#include "code\datums\elements\squashable.dm"
 #include "code\datums\elements\squish.dm"
 #include "code\datums\elements\swabbable.dm"
 #include "code\datums\elements\tool_flash.dm"