Persistent mobile liquid tanks (#22879)

# Summary

This PR makes liquid tanks (fuel, foam, water) persistent.

code/modules/cargo/bounties/assistant.dm

@@ -80,7 +80,7 @@
 	description = "Send us some water tanks that will be used for botany research, and definitely not for creating a slip 'n slide in %PERSONNAME's office."
 	reward_low = 115
 	reward_high = 135
-	required_count = 3
+	required_count = 1
 	random_count = 1
 	wanted_types = list(/obj/structure/reagent_dispensers/watertank)
 

code/modules/cargo/bounties/engineer.dm

@@ -54,7 +54,7 @@
 	description = "After observing your engineering staff, we think it's best if you send us a few of those fuel tanks so nobody hurts themselves."
 	reward_low = 250
 	reward_high = 350
-	required_count = 4
+	required_count = 1
 	random_count = 2
 	wanted_types = list(/obj/structure/reagent_dispensers/fueltank)
 

code/modules/cargo/items/engineering.dm

@@ -430,6 +430,20 @@
 	groupable = TRUE
 	spawn_amount = 1
 
+/singleton/cargo_item/extinguishertank
+	category = "engineering"
+	name = "extinguisher tank"
+	supplier = "hephaestus"
+	description = "A tank filled with extinguisher fluid."
+	price = 10
+	items = list(
+		/obj/structure/reagent_dispensers/extinguisher
+	)
+	access = ACCESS_ENGINE
+	container_type = "box"
+	groupable = TRUE
+	spawn_amount = 1
+
 /singleton/cargo_item/gasmask
 	category = "engineering"
 	name = "gas mask"

code/modules/cargo/items/miscellaneous.dm

@@ -72,3 +72,17 @@
 	container_type = "crate"
 	groupable = TRUE
 	spawn_amount = 1
+
+/singleton/cargo_item/watertank
+	category = "miscellaneous"
+	name = "water tank"
+	supplier = "orion"
+	description = "A tank filled with water."
+	price = 10
+	items = list(
+		/obj/structure/reagent_dispensers/watertank
+	)
+	access = 0
+	container_type = "box"
+	groupable = TRUE
+	spawn_amount = 1

code/modules/cargo/random_stock/large.dm

@@ -37,12 +37,6 @@ STOCK_ITEM_LARGE(bubbleshield, 0.5)
 			break
 	new /obj/structure/machinery/shield_capacitor(T)
 
-STOCK_ITEM_LARGE(watertank, 2)
-	new /obj/structure/reagent_dispensers/watertank(L)
-
-STOCK_ITEM_LARGE(fueltank, 2)
-	new /obj/structure/reagent_dispensers/fueltank(L)
-
 STOCK_ITEM_LARGE(lubetank, 2)
 	new /obj/structure/reagent_dispensers/lube(L)
 

code/modules/reagents/reagent_dispenser.dm

@@ -5,14 +5,14 @@
 	icon_state = "watertank"
 	density = 1
 	anchored = 0
+	maxhealth = OBJECT_HEALTH_HIGH
 	var/accept_any_reagent = TRUE
-
 	var/amount_per_transfer_from_this = 10
 	var/possible_transfer_amounts = list(5,10,15,25,30,50,60,100,120,250,300)
 	var/capacity = 1000
 	var/can_tamper = TRUE
 	var/is_leaking = FALSE
-	maxhealth = OBJECT_HEALTH_HIGH
+	var/is_persistent = FALSE
 
 /obj/structure/reagent_dispensers/mechanics_hints(mob/user, distance, is_adjacent)
 	. += ..()
@@ -32,6 +32,29 @@
 	create_reagents(capacity)
 	if (!possible_transfer_amounts)
 		src.verbs -= /obj/structure/reagent_dispensers/verb/set_APTFT
+	if(is_persistent)
+		SSpersistence.objectsRegisterTrack(src)
+
+/obj/structure/reagent_dispensers/persistent_objects_get_content()
+	var/list/content = ..()
+	content["remaining_volume"] = reagents ? reagents.total_volume : 0
+	return content
+
+/obj/structure/reagent_dispensers/persistent_objects_apply_content(content, x, y, z)
+	src.x = x
+	src.y = y
+	src.z = z
+	if(!content["remaining_volume"] || content["remaining_volume"] <= 0)
+		qdel(src)
+
+	if(!LAZYLEN(reagents_to_add))
+		return
+
+	// This happens before Initialize, reagents are not generated yet, override to-be-added contents
+	// Keep ratios the same if multiple reagents are within reagents_to_add
+	var/scale = content["remaining_volume"] / capacity
+	for(var/reagent in reagents_to_add)
+		reagents_to_add[reagent] *= scale
 
 /obj/structure/reagent_dispensers/verb/set_APTFT() //set amount_per_transfer_from_this
 	set name = "Set transfer amount"
@@ -56,6 +79,9 @@
 			return
 		if (usr.a_intent == I_HELP)
 			RG.standard_dispenser_refill(user,src)
+			if(!reagents || !reagents.total_volume)
+				SSpersistence.objectsDeregisterTrack(src)
+				return
 			playsound(src.loc, 'sound/machines/reagent_dispense.ogg', 25, 1)
 		else
 			if(!accept_any_reagent)
@@ -113,8 +139,9 @@
 	name = "extinguisher tank"
 	desc = "A tank filled with extinguisher fluid."
 	icon_state = "extinguisher_tank"
-	amount_per_transfer_from_this = 30
+	amount_per_transfer_from_this = 150 // Same volume as extinguisher refillers, quality of life value
 	reagents_to_add = list(/singleton/reagent/toxin/fertilizer/monoammoniumphosphate = 1000)
+	is_persistent = TRUE
 
 // Tanks
 /obj/structure/reagent_dispensers/watertank
@@ -123,6 +150,7 @@
 	icon_state = "watertank"
 	amount_per_transfer_from_this = 300
 	reagents_to_add = list(/singleton/reagent/water = 1000)
+	is_persistent = TRUE
 
 /obj/structure/reagent_dispensers/lube
 	name = "lube tank"
@@ -141,6 +169,7 @@
 	var/armed = 0
 	var/obj/item/assembly_holder/rig = null
 	reagents_to_add = list(/singleton/reagent/fuel = 1000)
+	is_persistent = TRUE
 
 /obj/structure/reagent_dispensers/fueltank/feedback_hints(mob/user, distance, is_adjacent)
 	. += ..()