Springlock MODule now only activates when you have at least a single sealed piece (#89222)

## About The Pull Request

Springlocks no longer trigger when you only have a back piece deployed,
only damages bodyparts covered by deployed pieces, and prevents you from
retracting them when it's been set off

Closes #89218

## Changelog
🆑
fix: Springlock MODule now only activates when you have at least a
single sealed piece
fix: Springlock MODule no longer damages bodyparts not covered by your
MODsuit
/🆑

code/__DEFINES/dcs/signals/signals_mod.dm

@@ -8,7 +8,8 @@
 /// Called when a MOD deploys a part. (mob/user, datum/mod_part/part)
 #define COMSIG_MOD_PART_DEPLOYED "mod_part_deployed"
 /// Called when a MOD retracts a part. (mob/user, datum/mod_part/part)
-#define COMSIG_MOD_PART_RETRACTED "mod_part_retracted"
+#define COMSIG_MOD_PART_RETRACTING "mod_part_retracting"
+	#define MOD_CANCEL_RETRACTION (1 << 0)
 /// Called when a MOD seals/unseals a part. (datum/mod_part/part)
 #define COMSIG_MOD_PART_SEALED "mod_part_sealed"
 /// Called when a MOD is finished toggling itself.

code/modules/mod/mod_activation.dm

@@ -127,6 +127,8 @@
 		balloon_alert(user, "already retracted!")
 		playsound(src, 'sound/machines/scanner/scanbuzz.ogg', 25, TRUE, SILENCED_SOUND_EXTRARANGE)
 		return FALSE
+	if(SEND_SIGNAL(src, COMSIG_MOD_PART_RETRACTING, user, part_datum) & MOD_CANCEL_RETRACTION)
+		return FALSE
 	if(active && part_datum.sealed)
 		if(instant)
 			seal_part(part, is_sealed = FALSE)
@@ -141,7 +143,6 @@
 		if(!QDELING(wearer) && !wearer.equip_to_slot_if_possible(overslot, overslot.slot_flags, qdel_on_fail = FALSE, disable_warning = TRUE))
 			wearer.dropItemToGround(overslot, force = TRUE, silent = TRUE)
 	wearer.update_clothing(slot_flags)
-	SEND_SIGNAL(src, COMSIG_MOD_PART_RETRACTED, user, part_datum)
 	if(!user)
 		return TRUE
 	wearer.visible_message(span_notice("[wearer]'s [part.name] retract[part.p_s()] back into [src] with a mechanical hiss."),

code/modules/mod/modules/modules_maint.dm

@@ -32,12 +32,23 @@
 
 ///Registers the signal COMSIG_MOD_ACTIVATE and calls the proc snap_shut() after a timer
 /obj/item/mod/module/springlock/proc/snap_signal()
-	if(set_off || mod.wearer.stat == DEAD)
+	if (set_off || mod.wearer.stat == DEAD)
 		return
+
+	var/found_part = FALSE
+	for (var/obj/item/part as anything in mod.get_parts())
+		// Don't snap if no parts besides the MOD itself are active
+		if (part.loc != mod && mod.get_part_datum(part)?.sealed)
+			found_part = TRUE
+			break
+
+	if (!found_part)
+		return
+
 	to_chat(mod.wearer, span_danger("[src] makes an ominous click sound..."))
 	playsound(src, 'sound/items/modsuit/springlock.ogg', 75, TRUE)
 	addtimer(CALLBACK(src, PROC_REF(snap_shut)), rand(3 SECONDS, 5 SECONDS))
-	RegisterSignal(mod, COMSIG_MOD_ACTIVATE, PROC_REF(on_activate_spring_block))
+	RegisterSignals(mod, list(COMSIG_MOD_ACTIVATE, COMSIG_MOD_PART_RETRACTING), PROC_REF(on_activate_spring_block))
 	set_off = TRUE
 
 ///Calls snap_signal() when exposed to a reagent via VAPOR, PATCH or TOUCH
@@ -66,7 +77,7 @@
 
 ///Delayed death proc of the suit after the wearer is exposed to reagents
 /obj/item/mod/module/springlock/proc/snap_shut()
-	UnregisterSignal(mod, COMSIG_MOD_ACTIVATE)
+	UnregisterSignal(mod, list(COMSIG_MOD_ACTIVATE, COMSIG_MOD_PART_RETRACTING))
 	if(!mod.wearer) //while there is a guaranteed user when on_wearer_exposed() fires, that isn't the same case for this proc
 		return
 	mod.wearer.visible_message("[src] inside [mod.wearer]'s [mod.name] snaps shut, mutilating the user inside!", span_userdanger("*SNAP*"))
@@ -74,7 +85,16 @@
 	playsound(mod.wearer, 'sound/effects/snap.ogg', 75, TRUE, frequency = 0.5)
 	playsound(mod.wearer, 'sound/effects/splat.ogg', 50, TRUE, frequency = 0.5)
 	mod.wearer.client?.give_award(/datum/award/achievement/misc/springlock, mod.wearer)
-	mod.wearer.apply_damage(500, BRUTE, forced = TRUE, spread_damage = TRUE, sharpness = SHARP_POINTY) //boggers, bogchamp, etc
+
+	mod.wearer.get_bodypart(BODY_ZONE_CHEST)?.receive_damage(200, forced = TRUE, sharpness = SHARP_POINTY) // Chest always gets hit, from the back piece you're wearing
+	for (var/obj/item/part as anything in mod.get_parts())
+		if (part.loc == mod || !mod.get_part_datum(part)?.sealed)
+			continue
+
+		for (var/obj/item/bodypart/bodypart as anything in mod.wearer.get_damageable_bodyparts())
+			if (part.body_parts_covered & bodypart.body_part) // can hit chest again
+				bodypart.receive_damage(100, forced = TRUE, sharpness = SHARP_POINTY) //boggers, bogchamp, etc
+
 	if(!HAS_TRAIT(mod.wearer, TRAIT_NODEATH))
 		mod.wearer.investigate_log("has been killed by [src].", INVESTIGATE_DEATHS)
 		mod.wearer.death() //just in case, for some reason, they're still alive