Fix battery widget charging/discharging state and use direct io instead of cat command

https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-class-power

default_config.lua

@@ -171,7 +171,8 @@ config.widgets = {
         battery = {
             enabled = true,
             screens = { 1, 2 },
-            refresh_interval = 30, -- In seconds
+            refresh_interval = 15, -- In seconds
+            list_refresh_interval = 2, -- In seconds
             precision = 0, -- How many decimals
         },
     },

simple/widgets/system_resources.lua

@@ -1,3 +1,4 @@
+local awful = require("awful")
 local beautiful = require("beautiful")
 local gears = require("gears")
 local naughty = require("naughty")
@@ -50,6 +51,13 @@ function readCommand(command)
     return r
 end
 
+function readFile(file)
+	local handle = io.open(file, "r")
+	local r = handle:read("*a")
+	handle:close()
+	return r
+end
+
 
 local cpuBar = bars:get_children()[1]:get_children()[1]:get_children()[1]
 function getCpuData()
@@ -131,72 +139,106 @@ gears.timer {
 
 
 
-
-local battery = wibox.widget {
-    {
-        markup = "-- %",
-        align = "center",
-        valign = "center",
-        widget = wibox.widget.textbox,
-    },
-    margins = beautiful.system_resources_widget_battery_margin,
-    widget = wibox.container.margin,
-}
-
-local batteryText = battery:get_children()[1]
-
-local rawBatteries = readCommand("ls -A1 /sys/class/power_supply")
-
-function getBatteries()
-    return rawBatteries:gmatch("([^\n]+)")
+---
+--- Batteries
+---
+rawBatteries = {}
+function refreshRawBatteries()
+	rawBatteries = readCommand("ls -A1 /sys/class/power_supply")
 end
 
-function hasBattery()
-    return rawBatteries:len() > 0
-end
-
-function getBatteryCapacity()
+function getBatteryLevel(battery)
     local charge = 0
     local capacity = 0
-    for b in getBatteries() do
-        if b:sub(1,3) ~= 'hid' and readCommand("cat /sys/class/power_supply/" .. b .. "/type"):match("Battery") then
-            if fileExists("/sys/class/power_supply/" .. b .. "/energy_now") then
-                charge = charge + readCommand("cat /sys/class/power_supply/" .. b .. "/energy_now")
-                capacity = capacity + readCommand("cat /sys/class/power_supply/" .. b .. "/energy_full")
-            else
-                charge = charge + readCommand("cat /sys/class/power_supply/" .. b .. "/charge_now")
-                capacity = capacity + readCommand("cat /sys/class/power_supply/" .. b .. "/charge_full")
-            end
-        end
+    if fileExists(battery .. "/energy_now") then
+        charge = charge + readFile(battery .. "/energy_now")
+        capacity = capacity + readFile(battery .. "/energy_full")
+    elseif fileExists(battery .. "/charge_now") then
+        charge = charge + readFile(battery .. "/charge_now")
+        capacity = capacity + readFile(battery .. "/charge_full")
+    elseif fileExists(battery .. "/capacity_level") then
+        return readFile(battery .. "/capacity_level")
+    else
+        return "Unsupported"
     end
-    return charge / capacity
+    return string.format("%." .. config.battery.precision .. "f", (charge / capacity) * 100) .. "%"
 end
 
-function isCharging()
-    for b in getBatteries() do
-        if readCommand("cat /sys/class/power_supply/" .. b .. "/type"):match("Battery") then
-            return readCommand("cat /sys/class/power_supply/" .. b .. "/status") ~= "Discharging"
-        end
+function isCharging(battery)
+    return readFile(battery .. "/status") == "Charging\n"
+end
+
+
+local batteryContainer = wibox.widget {
+    layout = wibox.layout.fixed.horizontal
+}
+local timers = {}
+function refreshBatteries()
+	-- refresh raw batteries and check for change
+	local oldBatteries = rawBatteries
+	refreshRawBatteries()
+	if rawBatteries == oldBatteries then
+		return
+	end
+
+	-- clear timers
+	for i,v in ipairs(timers) do
+		v:stop()
+	end
+	timers = {};
+
+	-- clear layout
+	batteryContainer:set_children({})
+
+	for battery in rawBatteries:gmatch("([^\n]+)") do
+		local path = "/sys/class/power_supply/" .. battery
+		if readFile(path .. "/type"):match("Battery") then
+			-- widget
+			local widget = wibox.widget {
+				{
+					markup = "-- %",
+					align = "center",
+					valign = "center",
+					widget = wibox.widget.textbox,
+				},
+				margins = beautiful.system_resources_widget_battery_margin,
+				widget = wibox.container.margin,
+			}
+
+			-- tooltip
+			local name = readFile(path .. "/model_name")
+			local tooltip = awful.tooltip {
+				text = name
+			}
+			tooltip:add_to_object(widget)
+
+			-- update battery level
+			local batteryText = widget:get_children()[1]
+			local timer = gears.timer {
+				timeout = config.battery.refresh_interval,
+				call_now = true,
+				autostart = true,
+				callback = function()
+					batteryText.markup = (isCharging(path) and "+" or "") .. getBatteryLevel(path)
+				end
+			}
+			table.insert(timers, timer)
+
+			batteryContainer:add(widget)
+		end
+	end
+end
+
+gears.timer {
+    timeout = config.battery.list_refresh_interval,
+    call_now = true,
+    autostart = true,
+    callback = function()
+        refreshBatteries()
     end
-    return nil
-end
-
-if hasBattery() then
-    gears.timer {
-        timeout = config.battery.refresh_interval,
-        call_now = true,
-        autostart = true,
-        callback = function()
-            batteryText.markup = string.format("%." .. config.battery.precision .. "f", getBatteryCapacity() * 100) .. "%"
-        end
-    }
-else
-    battery = nil
-end
-
-
+}
 
 return {
     bars = bars,
-    battery = battery,
+    battery = batteryContainer,
 }