Gun action (and equip) buttons refactor (#5750)

# About the pull request

Refactors the 'gun action' buttons and the 'equip' button to have each
have their own `/atom/movable/screen` subtype, rather than all of their
functionality being done through `if()` checks in
`/atom/movable/screen/clicked()`.

*The 'gun action' buttons being these:*

![image](https://github.com/cmss13-devs/cmss13/assets/57483089/3c73da3e-4b99-4ad5-b66d-f01077f686d4)

*And the 'equip' button being this:*

![image](https://github.com/cmss13-devs/cmss13/assets/57483089/1a60d926-605d-45b4-9a9a-5a6a05cfc657)

# Explain why it's good for the game

Cleaner code, and the gun buttons now show their names in the status bar
when hovered over thanks to this:

https://github.com/cmss13-devs/cmss13/blob/1bc0fa54e985fef991e06a85871b0a62cf15e5b2/code/modules/statusbar/statusbar.dm#L23
(That line has been there for a couple of years, but
`/atom/movable/screen/gun` didn't exist until now.)

# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

Put screenshots and videos here with an empty line between the
screenshots and the `<details>` tags.

</details>


# Changelog
:cl:
refactor: Refactored the 'gun action' buttons, making them show their
names in the status bar when hovered over.
/:cl:

---------

Co-authored-by: harryob <[email protected]>

code/_onclick/hud/human.dm

@@ -272,18 +272,14 @@
 	static_inventory += using
 
 /datum/hud/human/proc/draw_hand_equip(datum/custom_hud/ui_datum, ui_alpha, ui_color)
-	var/atom/movable/screen/using = new /atom/movable/screen()
-	using.name = "equip"
-	using.icon = ui_datum.ui_style_icon
-	using.icon_state = "act_equip"
-	using.screen_loc = ui_datum.ui_equip
-	using.layer = ABOVE_HUD_LAYER
-	using.plane = ABOVE_HUD_PLANE
+	var/atom/movable/screen/equip/equip_button = new()
+	equip_button.icon = ui_datum.ui_style_icon
+	equip_button.screen_loc = ui_datum.ui_equip
 	if(ui_color)
-		using.color = ui_color
+		equip_button.color = ui_color
 	if(ui_alpha)
-		using.alpha = ui_alpha
-	static_inventory += using
+		equip_button.alpha = ui_alpha
+	static_inventory += equip_button
 
 /datum/hud/human/proc/draw_oxygen(datum/custom_hud/ui_datum)
 	oxygen_icon = new /atom/movable/screen/oxygen()
@@ -312,38 +308,28 @@
 	infodisplay += locate_leader
 
 /datum/hud/human/proc/draw_gun_related(datum/custom_hud/ui_datum, ui_alpha)
-	use_attachment = new /atom/movable/screen()
+	use_attachment = new /atom/movable/screen/gun/attachment()
 	use_attachment.icon = ui_datum.ui_style_icon
-	use_attachment.icon_state = "gun_attach"
-	use_attachment.name = "Activate weapon attachment"
 	use_attachment.screen_loc = ui_datum.ui_gun_attachment
 	static_inventory += use_attachment
 
-	toggle_raillight = new /atom/movable/screen()
+	toggle_raillight = new /atom/movable/screen/gun/rail_light()
 	toggle_raillight.icon = ui_datum.ui_style_icon
-	toggle_raillight.icon_state = "gun_raillight"
-	toggle_raillight.name = "Toggle Rail Flashlight"
 	toggle_raillight.screen_loc = ui_datum.ui_gun_railtoggle
 	static_inventory += toggle_raillight
 
-	eject_mag = new /atom/movable/screen()
+	eject_mag = new /atom/movable/screen/gun/eject_magazine()
 	eject_mag.icon = ui_datum.ui_style_icon
-	eject_mag.icon_state = "gun_loaded"
-	eject_mag.name = "Eject magazine"
 	eject_mag.screen_loc = ui_datum.ui_gun_eject
 	static_inventory += eject_mag
 
-	toggle_burst = new /atom/movable/screen()
+	toggle_burst = new /atom/movable/screen/gun/toggle_firemode()
 	toggle_burst.icon = ui_datum.ui_style_icon
-	toggle_burst.icon_state = "gun_burst"
-	toggle_burst.name = "Toggle burst fire"
 	toggle_burst.screen_loc = ui_datum.ui_gun_burst
 	static_inventory += toggle_burst
 
-	unique_action = new /atom/movable/screen()
+	unique_action = new /atom/movable/screen/gun/unique_action()
 	unique_action.icon = ui_datum.ui_style_icon
-	unique_action.icon_state = "gun_unique"
-	unique_action.name = "Use unique action"
 	unique_action.screen_loc = ui_datum.ui_gun_unique
 	static_inventory += unique_action
 

code/_onclick/hud/screen_objects.dm

@@ -213,54 +213,53 @@
 		update_icon(user)
 	return 1
 
-/atom/movable/screen/clicked(mob/user, list/mods)
-	if(!user)
-		return TRUE
+/atom/movable/screen/gun
+	/// The proc/verb which should be called on the gun.
+	var/gun_proc_ref
 
-	if(isobserver(user))
-		return TRUE
+/atom/movable/screen/gun/clicked(mob/user, list/mods)
+	. = ..()
+	if(.)
+		return
+	// If the user has a gun in their active hand, call `gun_proc_ref` on it.
+	var/obj/item/weapon/gun/held_item = user.get_held_item()
+	if(istype(held_item))
+		INVOKE_ASYNC(held_item, gun_proc_ref)
 
-	switch(name)
-		if("equip")
-			if(ishuman(user))
-				var/mob/living/carbon/human/human = user
-				human.quick_equip()
-			return 1
+/atom/movable/screen/gun/attachment
+	name = "Activate weapon attachment"
+	icon_state = "gun_attach"
+	gun_proc_ref = TYPE_VERB_REF(/obj/item/weapon/gun, activate_attachment_verb)
 
-		if("Reset Machine")
-			user.unset_interaction()
-			return 1
+/atom/movable/screen/gun/rail_light
+	name = "Toggle rail flashlight"
+	icon_state = "gun_raillight"
+	gun_proc_ref = TYPE_VERB_REF(/obj/item/weapon/gun, activate_rail_attachment_verb)
 
-		if("Activate weapon attachment")
-			var/obj/item/weapon/gun/held_item = user.get_held_item()
-			if(istype(held_item))
-				held_item.activate_attachment_verb()
-			return 1
+/atom/movable/screen/gun/eject_magazine
+	name = "Eject magazine"
+	icon_state = "gun_loaded"
+	gun_proc_ref = TYPE_VERB_REF(/obj/item/weapon/gun, empty_mag)
 
-		if("Toggle Rail Flashlight")
-			var/obj/item/weapon/gun/held_item = user.get_held_item()
-			if(istype(held_item))
-				held_item.activate_rail_attachment_verb()
-			return 1
+/atom/movable/screen/gun/toggle_firemode
+	name = "Toggle firemode"
+	icon_state = "gun_burst"
+	gun_proc_ref = TYPE_VERB_REF(/obj/item/weapon/gun, use_toggle_burst)
 
-		if("Eject magazine")
-			var/obj/item/weapon/gun/held_item = user.get_held_item()
-			if(istype(held_item))
-				held_item.empty_mag()
-			return 1
+/atom/movable/screen/gun/unique_action
+	name = "Use unique action"
+	icon_state = "gun_unique"
+	gun_proc_ref = TYPE_VERB_REF(/obj/item/weapon/gun, use_unique_action)
 
-		if("Toggle burst fire")
-			var/obj/item/weapon/gun/held_item = user.get_held_item()
-			if(istype(held_item))
-				held_item.use_toggle_burst()
-			return 1
 
-		if("Use unique action")
-			var/obj/item/weapon/gun/held_item = user.get_held_item()
-			if(istype(held_item))
-				held_item.use_unique_action()
-			return 1
-	return 0
+/atom/movable/screen/clicked(mob/user, list/mods)
+	if(!user)
+		return TRUE
+
+	if(isobserver(user))
+		return TRUE
+
+	return FALSE
 
 
 /atom/movable/screen/inventory/clicked(mob/user)
@@ -587,6 +586,19 @@
 			vision_define = XENO_VISION_LEVEL_NO_NVG
 	to_chat(owner, SPAN_NOTICE("Night vision mode switched to <b>[vision_define]</b>."))
 
+/atom/movable/screen/equip
+	name = "equip"
+	icon_state = "act_equip"
+	layer = ABOVE_HUD_LAYER
+	plane = ABOVE_HUD_PLANE
+
+/atom/movable/screen/equip/clicked(mob/user)
+	. = ..()
+	if(. || !ishuman(user))
+		return TRUE
+	var/mob/living/carbon/human/human_user = user
+	human_user.quick_equip()
+
 /atom/movable/screen/bodytemp
 	name = "body temperature"
 	icon_state = "temp0"