From b664bfc9d1b6dcb4e442f957fa97156b43a02254 Mon Sep 17 00:00:00 2001
From: SyncIt21 <110812394+SyncIt21@users.noreply.github.com>
Date: Fri, 22 Mar 2024 02:59:12 +0530
Subject: [PATCH] Enforces checks on dual wielding items (#82130)

## About The Pull Request
- Fixes #82043

The issue goes deeper than just the chainsaw. The problem is we are
dropping our item too early if the dual handed checks fail. This doesn't
fully stop the equipping process and still causes the action buttons to
be added as if the equipping process succeeded

The solution is too unequip/drop the item and reverse all steps related
to the equipping process after it has fully completed inside
`COMSIG_ITEM_POST_EQUIPPED` to properly reverse the effects of equipping
and also cancel further actions by returning `COMPONENT_EQUIPPED_FAILED`

## Changelog
:cl:
fix: failing to equip a dual handed item should properly clear out all
status effects related to equipping it, for e.g. remove the action
button from chainsaw
/:cl:
---
 code/datums/components/twohanded.dm | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/code/datums/components/twohanded.dm b/code/datums/components/twohanded.dm
index 45ee6697e53..5a3ff4b4cb0 100644
--- a/code/datums/components/twohanded.dm
+++ b/code/datums/components/twohanded.dm
@@ -122,7 +122,7 @@
 
 // register signals withthe parent item
 /datum/component/two_handed/RegisterWithParent()
-	RegisterSignal(parent, COMSIG_ITEM_EQUIPPED, PROC_REF(on_equip))
+	RegisterSignal(parent, COMSIG_ITEM_POST_EQUIPPED, PROC_REF(on_equip))
 	RegisterSignal(parent, COMSIG_ITEM_DROPPED, PROC_REF(on_drop))
 	RegisterSignal(parent, COMSIG_ITEM_ATTACK_SELF, PROC_REF(on_attack_self))
 	RegisterSignal(parent, COMSIG_ITEM_ATTACK, PROC_REF(on_attack))
@@ -135,7 +135,7 @@
 // Remove all siginals registered to the parent item
 /datum/component/two_handed/UnregisterFromParent()
 	UnregisterSignal(parent, list(
-		COMSIG_ITEM_EQUIPPED,
+		COMSIG_ITEM_POST_EQUIPPED,
 		COMSIG_ITEM_DROPPED,
 		COMSIG_ITEM_ATTACK_SELF,
 		COMSIG_ITEM_ATTACK,
@@ -191,6 +191,7 @@
 /datum/component/two_handed/proc/wield(mob/living/carbon/user)
 	if(wielded)
 		return
+
 	var/atom/atom_parent = parent
 	if(HAS_TRAIT(user, TRAIT_NO_TWOHANDING))
 		if(require_twohands)
@@ -198,23 +199,24 @@
 			user.dropItemToGround(parent, force = TRUE)
 		else
 			atom_parent.balloon_alert(user, "too weak to wield with both hands!")
-		return
+		return COMPONENT_EQUIPPED_FAILED
 	if(user.get_inactive_held_item())
 		if(require_twohands)
 			atom_parent.balloon_alert(user, "can't carry in one hand!")
 			user.dropItemToGround(parent, force = TRUE)
 		else
 			atom_parent.balloon_alert(user, "holding something in other hand!")
-		return
+		return COMPONENT_EQUIPPED_FAILED
 	if(user.usable_hands < 2)
 		if(require_twohands)
-			user.dropItemToGround(parent, force=TRUE)
+			user.dropItemToGround(parent, force = TRUE)
 		atom_parent.balloon_alert(user, "not enough hands!")
-		return
+		return COMPONENT_EQUIPPED_FAILED
 
 	// wield update status
 	if(SEND_SIGNAL(parent, COMSIG_TWOHANDED_WIELD, user) & COMPONENT_TWOHANDED_BLOCK_WIELD)
-		return // blocked wield from item
+		user.dropItemToGround(parent, force = TRUE)
+		return COMPONENT_EQUIPPED_FAILED // blocked wield from item
 	wielded = TRUE
 	ADD_TRAIT(parent, TRAIT_WIELDED, REF(src))
 	RegisterSignal(user, COMSIG_MOB_SWAPPING_HANDS, PROC_REF(on_swapping_hands))