Research queue (#84731)

## About The Pull Request

<img alt="2dZbpr8MK1"
src="https://github.com/tgstation/tgstation/assets/3625094/dd78feba-224a-41a1-8d4a-83af3a8b68df">


Added an ability to queue up to one node per player in a techweb for an
automatic research.

You can queue up a node only when all requirements are met, but there
are not enough points.

People can't research when there is something in the queue, only add
things to the queue. So a 40 points node can't be researched if someone
queued up a 200 points node ahead of it.

When a node is enqueued by RD, it is placed in front of the queue.

The research button is available when the queue is empty.

TODO:

- [x] Bypass queue when the node cost is zero

## Why It's Good For The Game

No need to stay at the console to wait for the points. No "Research"
button spamming.

## Changelog

🆑
qol: Research nodes can be queued, one per player. RDs can place their
node at the beginning of the queue.
/🆑

code/modules/research/techweb/_techweb.dm

@@ -70,6 +70,12 @@
 	  * Filled with nulls on init, populated only on publication.
 	*/
 	var/list/published_papers
+	/**
+	  * Assoc list of nodes queued for automatic research when there are enough points available
+	  * research_queue_nodes[node_id] = user_enqueued
+	*/
+	var/list/research_queue_nodes = list()
+
 
 /datum/techweb/New()
 	SSresearch.techwebs += src
@@ -325,6 +331,40 @@
 /datum/techweb/proc/printout_points()
 	return techweb_point_display_generic(research_points)
 
+/datum/techweb/proc/enqueue_node(id, mob/user)
+	var/mob/living/carbon/human/human_user = user
+	var/is_rd = FALSE
+	if(human_user.wear_id)
+		var/list/access = human_user.wear_id.GetAccess()
+		if(ACCESS_RD in access)
+			is_rd = TRUE
+
+	if(id in research_queue_nodes)
+		if(is_rd)
+			research_queue_nodes.Remove(id)
+		else
+			return FALSE
+
+	for(var/node_id in research_queue_nodes)
+		if(research_queue_nodes[node_id] == user)
+			research_queue_nodes.Remove(node_id)
+
+	if (is_rd)
+		research_queue_nodes.Insert(1, id)
+	research_queue_nodes[id] = user
+
+	return TRUE
+
+/datum/techweb/proc/dequeue_node(id, mob/user)
+	if(!(id in research_queue_nodes))
+		return FALSE
+	if(research_queue_nodes[id] != user)
+		return FALSE
+
+	research_queue_nodes.Remove(id)
+
+	return TRUE
+
 /datum/techweb/proc/research_node_id(id, force, auto_update_points, get_that_dosh_id)
 	return research_node(SSresearch.techweb_node_by_id(id), force, auto_update_points, get_that_dosh_id)
 
@@ -377,6 +417,10 @@
 	if (MC_RUNNING())
 		log_research(log_message)
 
+	// Dequeue
+	if(node.id in research_queue_nodes)
+		research_queue_nodes.Remove(node.id)
+
 	return TRUE
 
 /datum/techweb/proc/unresearch_node_id(id)

code/modules/research/techweb/_techweb_node.dm

@@ -95,6 +95,17 @@
 
 	return actual_costs
 
+/datum/techweb_node/proc/is_free(datum/techweb/host)
+	var/list/costs = get_price(host)
+	var/total_points = 0
+
+	for(var/point_type in costs)
+		total_points += costs[point_type]
+
+	if(total_points == 0)
+		return TRUE
+	return FALSE
+
 /datum/techweb_node/proc/price_display(datum/techweb/TN)
 	return techweb_point_display_generic(get_price(TN))