awesomewm battery widget

gistfile1.lua

-- Create a battery widget on laptops
mybattery = nil
mybattery_timer = nil
if lucasb.file_exists("/sys/class/power_supply/BAT0/status") then
    mybattery = awful.widget.progressbar()
    mybattery:set_width(13)
    mybattery:set_vertical(true)
    mybattery_tip = awful.tooltip({objects = {mybattery}})
    lastalarm = 0

    if not mybattery_timer then
        battery_timer = timer({timeout = 1})
        battery_timer:connect_signal("timeout", function()
            local fcap = io.open("/sys/class/power_supply/BAT0/capacity", "r")
            local fstat = io.open("/sys/class/power_supply/BAT0/status", "r")
            if fcap and fstat then
                local cap = tonumber(fcap:read())
                local stat = fstat:read()
                io.close(fcap)
                io.close(fstat)

                mybattery:set_value(cap/100.0)
                mybattery_tip:set_text(cap .. "%, " .. stat)

                if stat == "Charging" or stat == "Full" then
                    mybattery:set_color(beautiful.bg_focus)
                else
                    if cap >= 4 then
                        mybattery:set_color(beautiful.colors.yellow)
                    else
                        mybattery:set_color(beautiful.bg_urgent)

                        -- Don't spam that thing, that'd be annoying
                        if lastalarm == 0 then
                            naughty.notify({
                                preset = naughty.config.presets.critical,
                                title = "Low Battery",
                                text = "Battery's almost empty! (" .. cap .. "% left)",
                                font = "Liberation 20",
                                timeout = 30
                            })
                        end
                        lastalarm = lastalarm + 1
                        if lastalarm > 30 then lastalarm = 0 end
                    end
                end
            end
        end)
        battery_timer:start()
        battery_timer:emit_signal("timeout")
    end
end