Completing experiments after their associated nodes have been researched gives back a partial refund of the discount lost (#73814)

## About The Pull Request

So we're like simultaneously moving two vague directions with research.
One being "experisci grants discounts for prohibitively expensive nodes
so you want to do the experiments to discount them" and the other being
"Let's give Heads of Staff a way to research anything they want without
any communication to the research department, including the very
expensive nodes that scientists may be working on"

You already see the issue, right? You can't have your cake and eat it
too.

It sucks for scientists to be working on a complex experiment like
weapons tech for that huge 90% discount only for the HoS to stumble onto
the bridge and research it anyways. Your time is wasted and RND is
slowed down massively.

We can do something to assuage that.

This PR makes it so completing an experiment which discounts already
completed nodes will refund a partial amount of the discount that
would've applied.

For example, researching industrial engineering without scanning the
iron toilets will refund ~5000 points.

This can only apply once per experiment, so if an experiment discounts
multiple technologies, they will only get a refund based on the first
technology researched.

## Why It's Good For The Game

This accomplishes the following: 

- Expensive research nodes with difficult experiments remain expensive
without completing the experiments. If no one does the experiment, they
act the same as before.
- Expensive research nodes with very easy experiments (but time
consuming) no longer put RND on a time crunch to beat the itchy trigger
finger of the Heads of Staff. Stuff like scanning lathes allow the
scientists to work more at their own pace: they can talk to people or
maybe stop at the bar or kitchen between departments without feeling
pressure to get it done urgently.
- Scientists are able to complete experiments which previously were no
longer deemed relevant if they need a point injection. Experiments left
behind are no longer completely useless bricks. Maybe even gives
latejoin scientists something to do.
- Scientists mid experiment can still complete it to not feel like their
time is wasted.

Overall I think this has many benefits to the current science system
where many have complaints.

## Changelog

🆑 Melbert
qol: Completing an experiment which discounts a researched tech node
will give a partial refund of the discount lost. For example,
researching the industrial engineering research without scanning iron
toilets will refund ~5000 points if you complete it afterwards. This
only applies once per experiment, so experiments which discount multiple
nodes only refund the first researched.
/🆑

---------

Co-authored-by: san7890 <the@san7890.com>

code/modules/research/techweb/_techweb.dm

@@ -38,10 +38,19 @@
 	var/list/discovered_mutations = list()
 	/// Assoc list, id = number, 1 is available, 2 is all reqs are 1, so on
 	var/list/tiers = list()
-	/// Available experiments
-	var/list/available_experiments = list()
-	/// Completed experiments
-	var/list/completed_experiments = list()
+	/// This is a list of all incomplete experiment datums that are accessible for scientists to complete
+	var/list/datum/experiment/available_experiments = list()
+	/// A list of all experiment datums that have been complete
+	var/list/datum/experiment/completed_experiments = list()
+	/// Assoc list of all experiment datums that have been skipped, to tech point reward for completing them -
+	/// That is, upon researching a node without completing its associated discounts, their experiments go here.
+	/// Completing these experiments will have a refund.
+	var/list/datum/experiment/skipped_experiment_types = list()
+
+	/// If science researches something without completing its discount experiments,
+	/// they have the option to complete them later for a refund
+	/// This ratio determines how much of the original discount is refunded
+	var/skipped_experiment_refund_ratio = 0.66
 
 	///All RD consoles connected to this individual techweb.
 	var/list/obj/machinery/computer/rdconsole/consoles_accessing = list()
@@ -294,7 +303,19 @@
 /datum/techweb/proc/complete_experiment(datum/experiment/completed_experiment)
 	available_experiments -= completed_experiment
 	completed_experiments[completed_experiment.type] = completed_experiment
-	log_research("[completed_experiment.name] ([completed_experiment.type]) has been completed on techweb [id]/[organization]")
+
+	var/result_text = "[completed_experiment] has been completed"
+	var/refund = skipped_experiment_types[completed_experiment.type] || 0
+	if(refund > 0)
+		add_point_list(list(TECHWEB_POINT_TYPE_GENERIC = refund))
+		result_text += ", refunding [refund] points."
+		// Nothing more to gain here, but we keep it in the list to prevent double dipping
+		skipped_experiment_types[completed_experiment.type] = -1
+	else
+		result_text += "!"
+
+	log_research("[completed_experiment.name] ([completed_experiment.type]) has been completed on techweb [id]/[organization][refund ? ", refunding [refund] points" : ""].")
+	return result_text
 
 /datum/techweb/proc/printout_points()
 	return techweb_point_display_generic(research_points)
@@ -311,10 +332,20 @@
 			return FALSE
 	var/log_message = "[id]/[organization] researched node [node.id]"
 	if(auto_adjust_cost)
-		var/node_cost = node.get_price(src)
+		var/list/node_cost = node.get_price(src)
 		remove_point_list(node_cost)
-		log_message += " at the cost of [node_cost]"
-	researched_nodes[node.id] = TRUE //Add to our researched list
+		log_message += " at the cost of [json_encode(node_cost)]"
+
+	//Add to our researched list
+	researched_nodes[node.id] = TRUE
+
+	// Track any experiments we skipped relating to this
+	for(var/missed_experiment in node.discount_experiments)
+		if(completed_experiments[missed_experiment] || skipped_experiment_types[missed_experiment])
+			continue
+		skipped_experiment_types[missed_experiment] = node.discount_experiments[missed_experiment] * skipped_experiment_refund_ratio
+
+	// Gain the experiments from the new node
 	for(var/id in node.unlock_ids)
 		visible_nodes[id] = TRUE
 		var/datum/techweb_node/unlocked_node = SSresearch.techweb_node_by_id(id)
@@ -323,6 +354,8 @@
 		if (unlocked_node.discount_experiments.len > 0)
 			add_experiments(unlocked_node.discount_experiments)
 		update_node_status(unlocked_node)
+
+	// Unlock what the research actually unlocks
 	for(var/id in node.design_ids)
 		add_design_by_id(id)
 	update_node_status(node)
@@ -477,9 +510,9 @@
 			continue
 
 		experiment.completed = TRUE
-		complete_experiment(experiment)
+		var/announcetext = complete_experiment(experiment)
 		if(length(GLOB.experiment_handlers))
 			var/datum/component/experiment_handler/handler = GLOB.experiment_handlers[1]
-			handler.announce_message_to_all("The [experiment.name] has been completed!")
+			handler.announce_message_to_all(announcetext)
 
 	return TRUE