Updates gas heaters

Gas heaters now draw power.
Removed the heat_resevoir base type because it was dumb and unused.
Adds a circuit board for gas heaters.

code/ATMOSPHERICS/components/unary/heat_source.dm

@@ -1,43 +1,121 @@
-/obj/machinery/atmospherics/unary/heat_reservoir
-//currently the same code as cold_sink but anticipating process() changes
-
-	icon = 'icons/obj/atmospherics/cold_sink.dmi'
-	icon_state = "intact_off"
+/obj/machinery/atmospherics/unary/heater
+	name = "gas heating system"
+	desc = "Heats gas when connected to a pipe network"
+	icon = 'icons/obj/Cryogenic2.dmi'
+	icon_state = "heater_0"
 	density = 1
-	use_power = 1
 
-	name = "Heat Reservoir"
-	desc = "Heats gas when connected to pipe network"
+	anchored = 1.0
+
+	var/set_temperature = T20C	//thermostat
+	var/max_temperature = T20C + 980
+	var/internal_volume = 600	//L
 
 	var/on = 0
+	use_power = 0
+	idle_power_usage = 5	//5 Watts for thermostat related circuitry
+	active_power_usage = 50000		//50 kW. Also doubles as the power rating of the heater
+	
+	var/heating = 0		//mainly for icon updates
 
-	var/current_temperature = T20C
-	var/current_heat_capacity = 50000 //totally random
+/obj/machinery/atmospherics/unary/heater/New()
+	..()
+	air_contents.volume = internal_volume
+	initialize_directions = dir
+
+/obj/machinery/atmospherics/unary/heater/initialize()
+	if(node) return
+
+	var/node_connect = dir
+
+	for(var/obj/machinery/atmospherics/target in get_step(src,node_connect))
+		if(target.initialize_directions & get_dir(target,src))
+			node = target
+			break
 
 	update_icon()
-		if(node)
-			icon_state = "intact_[on?("on"):("off")]"
+
+
+/obj/machinery/atmospherics/unary/heater/update_icon()
+	if(src.node)
+		if(src.on && src.heating)
+			icon_state = "heater_1"
 		else
-			icon_state = "exposed"
-
-			on = 0
+			icon_state = "heater"
+	else
+		icon_state = "heater_0"
+	return
+	
 
+/obj/machinery/atmospherics/unary/heater/process()
+	..()
+	heating = 0
+	
+	if(stat & (NOPOWER|BROKEN))
 		return
+	if(!on)
+		update_use_power(0)
+		return
+	
+	if (network && air_contents.temperature < set_temperature)
+		update_use_power(2)
+		air_contents.add_thermal_energy(active_power_usage)
+	
+		heating = 1
+		network.update = 1
+	else
+		update_use_power(1)
+	
+	update_icon()
 
-	process()
-		..()
-		if(!on || !network)
-			return 0
-		var/air_heat_capacity = air_contents.heat_capacity()
-		var/combined_heat_capacity = current_heat_capacity + air_heat_capacity
-		var/old_temperature = air_contents.temperature
+/obj/machinery/atmospherics/unary/heater/attack_ai(mob/user as mob)
+	src.ui_interact(user)
 
-		if(combined_heat_capacity > 0)
-			var/combined_energy = current_temperature*current_heat_capacity + air_heat_capacity*air_contents.temperature
-			air_contents.temperature = combined_energy/combined_heat_capacity
+/obj/machinery/atmospherics/unary/heater/attack_paw(mob/user as mob)
+	src.ui_interact(user)
 
-		//todo: have current temperature affected. require power to bring up current temperature again
+/obj/machinery/atmospherics/unary/heater/attack_hand(mob/user as mob)
+	src.ui_interact(user)
+	
+/obj/machinery/atmospherics/unary/heater/ui_interact(mob/user, ui_key = "main", var/datum/nanoui/ui = null)
+	// this is the data which will be sent to the ui
+	var/data[0]
+	data["on"] = on ? 1 : 0
+	data["gasPressure"] = round(air_contents.return_pressure())
+	data["gasTemperature"] = round(air_contents.temperature)
+	data["minGasTemperature"] = 0
+	data["maxGasTemperature"] = round(max_temperature)
+	data["targetGasTemperature"] = round(set_temperature)
+	
+	var/temp_class = "normal"
+	if (air_contents.temperature > (T20C+40))
+		temp_class = "bad"
+	data["gasTemperatureClass"] = temp_class
 
-		if(abs(old_temperature-air_contents.temperature) > 1)
-			network.update = 1
-		return 1
+	// update the ui if it exists, returns null if no ui is passed/found
+	ui = nanomanager.try_update_ui(user, src, ui_key, ui, data)
+	if (!ui)
+		// the ui does not exist, so we'll create a new() one
+        // for a list of parameters and their descriptions see the code docs in \code\modules\nano\nanoui.dm
+		ui = new(user, src, ui_key, "freezer.tmpl", "Gas Heating System", 440, 300)
+		// when the ui is first opened this is the data it will use
+		ui.set_initial_data(data)
+		// open the new ui window
+		ui.open()
+		// auto update every Master Controller tick
+		ui.set_auto_update(1)
+
+/obj/machinery/atmospherics/unary/heater/Topic(href, href_list)
+	if (href_list["toggleStatus"])
+		src.on = !src.on
+		update_use_power(on)
+		update_icon()
+	if(href_list["temp"])
+		var/amount = text2num(href_list["temp"])
+		if(amount > 0)
+			src.set_temperature = min(src.set_temperature+amount, max_temperature)
+		else
+			src.set_temperature = max(src.set_temperature+amount, 0)
+	
+	src.add_fingerprint(usr)
+	return 1