Add digiline interface to power monitor

The power monitor can now be queried for information about the network. They
are retrieved from the associated switching station.

Also export information about the attached batteries.

technic/machines/power_monitor.lua

@@ -6,6 +6,15 @@ local S = technic.getter
 
 local cable_entry = "^technic_cable_connection_overlay.png"
 
+-- return the position of the associated switching station or nil
+local function get_swpos(pos)
+	local network_hash = technic.cables[minetest.hash_node_position(pos)]
+	local network = network_hash and minetest.get_position_from_hash(network_hash)
+	local swpos = network and {x=network.x,y=network.y+1,z=network.z}
+	local is_powermonitor = swpos and minetest.get_node(swpos).name == "technic:switching_station"
+	return is_powermonitor and swpos or nil
+end
+
 minetest.register_craft({
 	output = "technic:power_monitor",
 	recipe = {
@@ -32,7 +41,54 @@ minetest.register_node("technic:power_monitor",{
 	on_construct = function(pos)
 		local meta = minetest.get_meta(pos)
 		meta:set_string("infotext", S("Power Monitor"))
+		meta:set_string("channel", "power_monitor"..minetest.pos_to_string(pos))
+		meta:set_string("formspec", "field[channel;Channel;${channel}]")
 	end,
+	on_receive_fields = function(pos, formname, fields, sender)
+		if not fields.channel then
+			return
+		end
+		local plname = sender:get_player_name()
+    if minetest.is_protected(pos, plname) and not minetest.check_player_privs(sender, "protection_bypass") then
+			minetest.record_protection_violation(pos, plname)
+			return
+		end
+		local meta = minetest.get_meta(pos)
+		meta:set_string("channel", fields.channel)
+	end,
+	digiline = {
+		receptor = {
+			rules = technic.digilines.rules,
+			action = function() end
+		},
+		effector = {
+			rules = technic.digilines.rules,
+			action = function(pos, node, channel, msg)
+				if msg ~= "GET" and msg ~= "get" then
+					return
+				end
+				local meta = minetest.get_meta(pos)
+				if channel ~= meta:get_string("channel") then
+					return
+				end
+
+				local sw_pos = get_swpos(pos)
+				if not sw_pos then
+					return
+				end
+
+				local sw_meta = minetest.get_meta(sw_pos)
+				digilines.receptor_send(pos, technic.digilines.rules, channel, {
+					supply = sw_meta:get_int("supply"),
+					demand = sw_meta:get_int("demand"),
+					lag = sw_meta:get_int("lag"),
+					battery_count = sw_meta:get_int("battery_count"),
+					battery_charge = sw_meta:get_int("battery_charge"),
+					battery_charge_max = sw_meta:get_int("battery_charge_max"),
+				})
+			end
+		},
+	},
 })
 
 minetest.register_abm({
@@ -42,14 +98,12 @@ minetest.register_abm({
 	chance     = 1,
 	action = function(pos, node, active_object_count, active_object_count_wider)
 		local meta = minetest.get_meta(pos)
-		local network_hash = technic.cables[minetest.hash_node_position(pos)]
+		local sw_pos = get_swpos(pos)
-		local network = network_hash and minetest.get_position_from_hash(network_hash)
-		local sw_pos = network and {x=network.x,y=network.y+1,z=network.z}
 		local timeout = 0
 		for tier in pairs(technic.machines) do
 			timeout = math.max(meta:get_int(tier.."_EU_timeout"),timeout)
 		end
-		if timeout > 0 and sw_pos and minetest.get_node(sw_pos).name == "technic:switching_station" then
+		if timeout > 0 and sw_pos then
 			local sw_meta = minetest.get_meta(sw_pos)
 			local supply = sw_meta:get_int("supply")
 			local demand = sw_meta:get_int("demand")

technic/machines/register/battery_box.lua

@@ -240,6 +240,7 @@ function technic.register_battery_box(data)
 		meta:set_int(tier.."_EU_supply",
 				math.min(data.discharge_rate, current_charge))
 			meta:set_int("internal_EU_charge", current_charge)
+		meta:set_int("internal_EU_charge_max", max_charge)
 
 		-- Select node textures
 		local charge_count = math.ceil((current_charge / max_charge) * 8)

technic/machines/switching_station.lua

@@ -306,9 +306,16 @@ technic.switching_station_run = function(pos)
 	local charge_total = 0
 	local battery_count = 0
 
+	local BA_charge = 0
+	local BA_charge_max = 0
+
 	for n, pos1 in pairs(BA_nodes) do
 		meta1 = minetest.get_meta(pos1)
 		local charge = meta1:get_int("internal_EU_charge")
+		local charge_max = meta1:get_int("internal_EU_charge_max")
+
+		BA_charge = BA_charge + charge
+		BA_charge_max = BA_charge_max + charge_max
 
 		if (meta1:get_int(eu_demand_str) ~= 0) then
 			charge_total = charge_total + charge
@@ -378,6 +385,9 @@ technic.switching_station_run = function(pos)
 	-- Data that will be used by the power monitor
 	meta:set_int("supply",PR_eu_supply)
 	meta:set_int("demand",RE_eu_demand)
+	meta:set_int("battery_count",#BA_nodes)
+	meta:set_int("battery_charge",BA_charge)
+	meta:set_int("battery_charge_max",BA_charge_max)
 
 	-- If the PR supply is enough for the RE demand supply them all
 	if PR_eu_supply >= RE_eu_demand then