[MIRROR] You no longer goofily swap with others trying to move in the…

… same direction as you if you're not faster than them (#4834)

* [MIRROR] You no longer goofily swap with others trying to move in the same direction as you if you're not faster than them [MDB IGNORE] (#4142)

* You no longer goofily swap with others trying to move in the same direction as you if you're not faster than them (#85379)

## About The Pull Request

Currently if you and someone else try to move in the same direction
while standing next to each other, you'll end up swapping places
endlessly which is, while extremely funny, quite frustrating at times to
deal with. This PR prevents this from happening unless you're faster
than the other person, in which case you still push through them. This
way both of you will be able to move forward without goofy ass swapping.

I also moved out the ugly logic tree into its own proc for readability's
sake, I am not piling up more code on that.

## Why It's Good For The Game

Its frustrating to deal with and doesn't make much sense logically. This
just makes sure that if both of you want to move in a certain direction,
you'll be able to do so. You can currently achieve the same effect by
enabling combat mode, so it doesn't change anything balance-wise.

## Changelog
:cl:
qol: You no longer goofily swap with others trying to move in the same
direction as you if you're not faster than them
code: Moved mobswap check logic into a separate proc and made it more
readable
/:cl:

* You no longer goofily swap with others trying to move in the same direction as you if you're not faster than them

---------

Co-authored-by: SmArtKar <[email protected]>
Co-authored-by: NovaBot13 <[email protected]>

* [MIRROR] You no longer goofily swap with others trying to move in the same direction as you if you're not faster than them

---------

Co-authored-by: NovaBot <[email protected]>
Co-authored-by: SmArtKar <[email protected]>
Co-authored-by: NovaBot13 <[email protected]>
Co-authored-by: StealsThePRs <[email protected]>

code/modules/mob/living/living.dm

@@ -174,13 +174,8 @@
 	if(now_pushing)
 		return TRUE
 
-	var/they_can_move = TRUE
-	var/their_combat_mode = FALSE
-
 	if(isliving(M))
 		var/mob/living/L = M
-		their_combat_mode = L.combat_mode
-		they_can_move = L.mobility_flags & MOBILITY_MOVE
 		//Also spread diseases
 		for(var/thing in diseases)
 			var/datum/disease/D = thing
@@ -226,22 +221,7 @@
 		return TRUE
 
 	if(!M.buckled && !M.has_buckled_mobs())
-		var/mob_swap = FALSE
-		var/too_strong = (M.move_resist > move_force) //can't swap with immovable objects unless they help us
-		if(!they_can_move) //we have to physically move them
-			if(!too_strong)
-				mob_swap = TRUE
-		else
-			//You can swap with the person you are dragging on grab intent, and restrained people in most cases
-			if(M.pulledby == src && !too_strong)
-				mob_swap = TRUE
-			else if(
-				!(HAS_TRAIT(M, TRAIT_NOMOBSWAP) || HAS_TRAIT(src, TRAIT_NOMOBSWAP)) &&\
-				((HAS_TRAIT(M, TRAIT_RESTRAINED) && !too_strong) || !their_combat_mode) &&\
-				(HAS_TRAIT(src, TRAIT_RESTRAINED) || !combat_mode)
-			)
-				mob_swap = TRUE
-		if(mob_swap)
+		if(can_mobswap_with(M))
 			//switch our position with M
 			if(loc && !loc.Adjacent(M.loc))
 				return TRUE
@@ -294,6 +274,46 @@
 			if(prob(I.block_chance*2))
 				return
 
+/mob/living/proc/can_mobswap_with(mob/other)
+	if (HAS_TRAIT(other, TRAIT_NOMOBSWAP) || HAS_TRAIT(src, TRAIT_NOMOBSWAP))
+		return FALSE
+
+	var/they_can_move = TRUE
+	var/their_combat_mode = FALSE
+
+	if(isliving(other))
+		var/mob/living/other_living = other
+		their_combat_mode = other_living.combat_mode
+		they_can_move = other_living.mobility_flags & MOBILITY_MOVE
+
+	var/too_strong = other.move_resist > move_force
+
+	// They cannot move, see if we can push through them
+	if (!they_can_move)
+		return !too_strong
+
+	// We are pulling them and can move through
+	if (other.pulledby == src && !too_strong)
+		return TRUE
+
+	// If we're in combat mode and not restrained we don't try to pass through people
+	if (combat_mode && !HAS_TRAIT(src, TRAIT_RESTRAINED))
+		return FALSE
+
+	// Nor can we pass through non-restrained people in combat mode (or if they're restrained but still too strong for us)
+	if (their_combat_mode && (!HAS_TRAIT(other, TRAIT_RESTRAINED) || too_strong))
+		return FALSE
+
+	if (isnull(other.client) || isnull(client))
+		return TRUE
+
+	// If both of us are trying to move in the same direction, let the fastest one through first
+	if (client.intended_direction == other.client.intended_direction)
+		return cached_multiplicative_slowdown < other.cached_multiplicative_slowdown
+
+	// Else, sure, let us pass
+	return TRUE
+
 /mob/living/get_photo_description(obj/item/camera/camera)
 	var/list/holding = list()
 	var/len = length(held_items)