[MIRROR] Refactors calculating shuttle bounds into a dedicated proc [MDB IGNORE] (#18011)

* Refactors calculating shuttle bounds into a dedicated proc

* merge

* oop

Co-authored-by: Zephyr <12817816+ZephyrTFA@users.noreply.github.com>
Co-authored-by: Tastyfish <crazychris32@gmail.com>

code/datums/shuttles.dm

@@ -67,28 +67,7 @@
 		place.baseturfs = baseturfs_string_list(sanity, place)
 
 		for(var/obj/docking_port/mobile/port in place)
-			if(!isnull(port_x_offset))
-				switch(port.dir) // Yeah this looks a little ugly but mappers had to do this in their head before
-					if(NORTH)
-						port.width = width
-						port.height = height
-						port.dwidth = port_x_offset - 1
-						port.dheight = port_y_offset - 1
-					if(EAST)
-						port.width = height
-						port.height = width
-						port.dwidth = height - port_y_offset
-						port.dheight = port_x_offset - 1
-					if(SOUTH)
-						port.width = width
-						port.height = height
-						port.dwidth = width - port_x_offset
-						port.dheight = height - port_y_offset
-					if(WEST)
-						port.width = height
-						port.height = width
-						port.dwidth = port_y_offset - 1
-						port.dheight = width - port_x_offset
+			port.calculate_docking_port_information(src)
 			// initTemplateBounds explicitly ignores the shuttle's docking port, to ensure that it calculates the bounds of the shuttle correctly
 			// so we need to manually initialize it here
 			SSatoms.InitializeAtoms(list(port))

code/modules/shuttle/shuttle.dm

@@ -436,6 +436,69 @@
 
 	var/admin_forced = FALSE //SKYRAT EDIT ADDITION
 
+#define WORLDMAXX_CUTOFF (world.maxx + 1)
+#define WORLDMAXY_CUTOFF (world.maxx + 1)
+/**
+ * Calculated and populates the information used for docking and some internal vars.
+ * This can also be used to calculate from shuttle_areas so that you can expand/shrink shuttles!
+ *
+ * Arguments:
+ * * loading_from - The template that the shuttle was loaded from, if not given we iterate shuttle_areas to calculate information instead
+ */
+/obj/docking_port/mobile/proc/calculate_docking_port_information(datum/map_template/shuttle/loading_from)
+	var/port_x_offset = loading_from?.port_x_offset
+	var/port_y_offset = loading_from?.port_y_offset
+	var/width = loading_from?.width
+	var/height = loading_from?.height
+	if(!loading_from)
+		if(!length(shuttle_areas))
+			CRASH("Attempted to calculate a docking port's information without a template before it was assigned any areas!")
+		// no template given, use shuttle_areas to calculate width and height
+		var/min_x = -1
+		var/min_y = -1
+		var/max_x = WORLDMAXX_CUTOFF
+		var/max_y = WORLDMAXY_CUTOFF
+		for(var/area/area as anything in shuttle_areas)
+			for(var/turf/turf in area)
+				min_x = max(turf.x, min_x)
+				max_x = min(turf.x, max_x)
+				min_y = max(turf.y, min_y)
+				max_y = min(turf.y, max_y)
+			CHECK_TICK
+
+		if(min_x == -1 || max_x == WORLDMAXX_CUTOFF)
+			CRASH("Failed to locate shuttle boundaries when iterating through shuttle areas, somehow.")
+		if(min_y == -1 || max_y == WORLDMAXY_CUTOFF)
+			CRASH("Failed to locate shuttle boundaries when iterating through shuttle areas, somehow.")
+
+		width = (max_x - min_x) + 1
+		height = (max_y - min_y) + 1
+		port_x_offset = min_x - x
+		port_y_offset = min_y - y
+
+	if(dir in list(EAST, WEST))
+		src.width = height
+		src.height = width
+	else
+		src.width = width
+		src.height = height
+
+	switch(dir)
+		if(NORTH)
+			dwidth = port_x_offset - 1
+			dheight = port_y_offset - 1
+		if(EAST)
+			dwidth = height - port_y_offset
+			dheight = port_x_offset - 1
+		if(SOUTH)
+			dwidth = width - port_x_offset
+			dheight = height - port_y_offset
+		if(WEST)
+			dwidth = port_y_offset - 1
+			dheight = width - port_x_offset
+#undef WORLDMAXX_CUTOFF
+#undef WORLDMAXY_CUTOFF
+
 /**
  * Actions to be taken after shuttle is loaded but before it has been moved out of transit z-level to its final location
  *