Yogstation/code/datums/components/wall_mounted.dm

// This element should be applied to wall-mounted machines/structures, so that if the wall it's "hanging" from is broken or deconstructed, the wall-hung structure will deconstruct.
/datum/component/wall_mounted
	dupe_mode = COMPONENT_DUPE_ALLOWED
	/// The wall our object is currently linked to.
	var/turf/hanging_wall_turf
	/// Callback to the parent's proc to call on the linked object when the wall disappear's or changes.
	var/datum/callback/on_drop

/datum/component/wall_mounted/Initialize(target_wall, on_drop_callback)
	. = ..()
	if(!isobj(parent))
		return COMPONENT_INCOMPATIBLE
	if(!isturf(target_wall))
		return COMPONENT_INCOMPATIBLE
	hanging_wall_turf = target_wall
	on_drop = on_drop_callback

/datum/component/wall_mounted/RegisterWithParent()
	RegisterSignal(hanging_wall_turf, COMSIG_ATOM_EXAMINE, PROC_REF(on_examine))
	RegisterSignal(parent, COMSIG_QDELETING, PROC_REF(on_linked_destroyed))

/datum/component/wall_mounted/UnregisterFromParent()
	UnregisterSignal(hanging_wall_turf, list(COMSIG_ATOM_EXAMINE, COMSIG_TURF_CHANGE))
	UnregisterSignal(parent, list(COMSIG_QDELETING, COMSIG_MOVABLE_MOVED))
	hanging_wall_turf = null

/**
 * Basic reference handling if the hanging/linked object is destroyed first.
 */
/datum/component/wall_mounted/proc/on_linked_destroyed()
	SIGNAL_HANDLER
	if(!QDELING(src))
		qdel(src)

/**
 * When the wall is examined, explains that it's supporting the linked object.
 */
/datum/component/wall_mounted/proc/on_examine(datum/source, mob/user, list/examine_list)
	SIGNAL_HANDLER
	examine_list += span_notice("\The [hanging_wall_turf] is currently supporting [span_bold("[parent]")]. Deconstruction or excessive damage would cause it to [span_bold("fall to the ground")].")

/**
 *	Checks object direction and then verifies if there's a wall in that direction. Finally, applies a wall_mounted component to the object.
 *
 * 	@param directional If TRUE, will use the direction of the object to determine the wall to attach to. If FALSE, will use the object's loc.
 *	@param custom_drop_callback If set, will use this callback instead of the default deconstruct callback.
 */
/obj/proc/find_and_hang_on_wall(directional = TRUE, custom_drop_callback)
	if(istype(get_area(src), /area/shuttle))
		return FALSE //For now, we're going to keep the component off of shuttles to avoid the turf changing issue. We'll hit that later really;
	var/turf/attachable_wall
	if(directional)
		attachable_wall = get_step(src, dir)
	else
		attachable_wall = loc ///Pull from the curent object loc
	if(!iswallturf(attachable_wall))
		return FALSE//Nothing to latch onto, or not the right thing.
	src.AddComponent(/datum/component/wall_mounted, attachable_wall, custom_drop_callback)
	return TRUE