rc: add a battery level monitor to statusbar

Consisting of:
- battery object, which is a wrapper around a sysfs dir describing a
  battery
- battery manager, which adds and removes individual batteries as they
  (dis)appear - e.g. wireless input devices, and maps them to widgets
  displayed side by side
- battery widget, which shows the status of one of the batteries;
  the widget used is derived from batteryarc [1], but heavily modified

[1] https://github.com/streetturtle/awesome-wm-widgets/

4 files changed, 467 insertions, 5 deletions

diff --git a/battery.lua b/battery.lua
new file mode 100644
index 0000000..abaf86d
--- /dev/null
+++ b/battery.lua
@@ -0,0 +1,114 @@
+local gio       = require("lgi").Gio
+
+local object    = require("gears.object")
+
+local utils     = require("utils")
+
+local Battery = {}
+Battery.__index = Battery
+
+setmetatable(Battery, {
+    __call = function (cls, ...) return cls.new(...) end,
+})
+
+Battery.STATUS = {
+    UNKNOWN             = 'Unknown',
+    DISCHARGING         = 'Discharging',
+    CHARGING            = 'Charging',
+    ['NOT CHARGING']    = 'Not charging',
+    FULL                = 'Full',
+}
+
+function Battery:_readfile(name)
+    local file = gio.File.new_for_path(self._path  .. name)
+    local contents = file:load_contents(nil)
+
+    -- remove trailing newline
+    if contents then
+        contents = string.gsub(contents, "%s$", "")
+        return string.len(contents) > 0 and contents or nil
+    end
+
+    return nil
+end
+
+function Battery:_readnum(name)
+    local val = self:_readfile(name)
+    return tonumber(val)
+end
+
+function Battery:update()
+    local status = string.upper(self:_readfile('status') or '')
+    self.status = self.STATUS[status]
+    if self.status == nil then
+        utils.log('Battery/' .. self.name, 'Error updating status: %s', tostring(status))
+        return false
+    end
+
+    self.capacity       = self:_readnum('capacity')
+    self.capacity_level = self:_readfile('capacity_level')
+
+    local energy        = self:_readnum('energy_now')
+    local energy_full   = self:_readnum('energy_full')
+    local power         = self:_readnum('power_now')
+
+    -- try to compute remaining seconds to charge/discharge,
+    -- if we have the information
+    self.remaining_seconds = nil
+
+    if self.status == self.STATUS.DISCHARGING then
+        if energy and power then
+            self.remaining_seconds = 3600 * energy / power
+        end
+    elseif self.status == self.STATUS.CHARGING then
+        if energy and energy_full and power then
+            self.remaining_seconds = 3600 * (energy_full - energy) / power
+        end
+    end
+
+    if power ~= nil then
+        self.power = power / 1e6
+    end
+
+    self:emit_signal('updated')
+
+    return true
+end
+
+function Battery.new(name)
+    local self = object({class = Battery})
+
+    self.name  = name
+    self._path = '/sys/class/power_supply/' .. name .. '/'
+
+    -- skip non-battery power supplies, we don't handle them
+    local type = self:_readfile('type')
+    if type ~= 'Battery' then
+        return nil
+    end
+
+    -- build description string
+    local desc = nil
+
+    -- first try manufacturer+model
+    local manufacturer = self:_readfile('manufacturer')
+    local model        = self:_readfile('model_name')
+    if manufacturer or model then
+        desc = (manufacturer or '') .. (manufacturer and ' ' or '') .. (model or '')
+    end
+
+    if not desc then
+        local technology = self:_readfile('technology')
+        desc = (technology or '') .. (technology and ' ' or '') .. type
+    end
+
+    self.desc = desc
+
+    if not self:update() then
+        return nil
+    end
+
+    return self
+end
+
+return Battery
diff --git a/battery_mng.lua b/battery_mng.lua
new file mode 100644
index 0000000..c04c52f
--- /dev/null
+++ b/battery_mng.lua
@@ -0,0 +1,139 @@
+local GFile             = require("lgi").Gio.File
+
+local gears             = require("gears")
+local spawn             = require("awful.spawn")
+local wibox             = require("wibox")
+
+local utils             = require('utils')
+
+local BatteryWidget     = require('battery_wgt')
+local Battery           = require('battery')
+
+
+local BatteryManager = {}
+BatteryManager.__index = BatteryManager
+
+setmetatable(BatteryManager, {
+    __call = function (cls, ...) return cls.new(...) end,
+})
+
+function BatteryManager:_log(msg, ...)
+    utils.log('BatteryManager', msg, ...)
+end
+
+function BatteryManager:_warn(msg, ...)
+    utils.warn('BatteryManager', msg, ...)
+end
+
+function BatteryManager:_battery_add(name)
+    if self._batteries[name] ~= nil then
+        -- only warn for usable batteries that are added twice for some reason
+        if self._batteries[name] ~= false then
+            self:_warn('Battery %s already exists', name)
+        end
+        return
+    end
+
+    self:_log('Trying power supply: ' .. name)
+
+    local bat = Battery(name)
+    if not bat then
+        self:_log('Skipping ' .. name .. ': could not be opened or is not a battery')
+        -- remember device as unusable
+        self._batteries[name] = false
+        return
+    end
+    self:_log('Opened battery %s: %s', name, bat.desc)
+
+    local wgt = BatteryWidget(bat)
+
+    self._layout:add(wgt)
+
+    self._batteries[name] = { widget = wgt, battery = bat }
+end
+
+function BatteryManager:_battery_remove(name)
+    self:_log('Removing battery ' .. name)
+
+    local tbl = self._batteries[name]
+    if tbl then
+        self._layout:remove_widgets(tbl.widget)
+    end
+    self._batteries[name] = nil
+end
+
+function BatteryManager:_refresh()
+    for name, item in pairs(self._batteries) do
+        if item and not item.battery:update() then
+            self:_log('Could not update battery %s, removing', name)
+            self:_battery_remove(name)
+        end
+    end
+end
+
+function BatteryManager.new()
+    local self = setmetatable({}, BatteryManager)
+
+    -- the layout containing the individual battery widgets
+    self._layout    = wibox.layout.flex.horizontal()
+
+    -- entries are either
+    -- - tables { battery, widget } for existing batteries
+    -- - false for devices that we've seen, but are not valid batteries
+    self._batteries = {}
+
+    -- try adding all existing batteries
+    local ps = GFile.new_for_path('/sys/class/power_supply')
+    local ret = ps:enumerate_children('*', 0)
+    while true do
+        local file_info = ret:next_file()
+        if not file_info then
+            break
+        end
+
+        self:_battery_add(file_info:get_name())
+    end
+
+    -- monitor udev events
+    local function monitor_stdout(line)
+        local action, device = string.match(line, '^KERNEL%[%d+.%d*%]%s+(%a+)%s+([^%s]+)%s+%(power_supply%)$')
+        if action then
+            local name = string.match(device, '([^/]+)$')
+            if name == nil then
+                self:_warn('Could not extract device name from path: %s', device)
+                return
+            end
+
+            if action == 'add' or action == 'change' then
+                -- battery device not seen before, try adding
+                if self._batteries[name] == nil then
+                    self:_battery_add(name)
+                end
+
+                -- device is a valid battery, refresh state
+                if self._batteries[name] then
+                    self._batteries[name].battery:update()
+                end
+            elseif action == 'remove' then
+                self:_battery_remove(name)
+            end
+        end
+    end
+
+    local function monitor_exit(reason, code)
+        self:_warn('udevadm monitor exited: %s/%d', reason, code)
+    end
+
+    spawn.with_line_callback('udevadm monitor --kernel --subsystem-match=power_supply',
+                             { stdout = monitor_stdout, exit = monitor_exit, })
+
+    self:_refresh()
+    gears.timer.start_new(5, function ()
+        self:_refresh()
+        return true
+    end)
+
+    return self._layout
+end
+
+return BatteryManager
diff --git a/battery_wgt.lua b/battery_wgt.lua
new file mode 100644
index 0000000..ddf4120
--- /dev/null
+++ b/battery_wgt.lua
@@ -0,0 +1,204 @@
+-- Battery status widget
+--
+-- Based on Battery Arc Widget by Pavel Makhov
+-- https://github.com/streetturtle/awesome-wm-widgets/tree/master/batteryarc-widget
+-- @copyright 2020 Pavel Makhov
+-- The MIT License (MIT)
+--
+-- Copyright (c) 2017
+--
+-- Permission is hereby granted, free of charge, to any person obtaining a copy
+-- of this software and associated documentation files (the "Software"), to deal
+-- in the Software without restriction, including without limitation the rights
+-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+-- copies of the Software, and to permit persons to whom the Software is
+-- furnished to do so, subject to the following conditions:
+--
+-- The above copyright notice and this permission notice shall be included in all
+-- copies or substantial portions of the Software.
+--
+-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+-- SOFTWARE.
+
+local awful             = require("awful")
+local beautiful         = require("beautiful")
+-- local menubar_it        = require("menubar.icon_theme")
+-- local menubar_utils     = require("menubar.utils")
+local naughty           = require("naughty")
+local wibox             = require("wibox")
+
+local BatteryWidget = {}
+BatteryWidget.__index = BatteryWidget
+
+setmetatable(BatteryWidget, {
+    __call = function (cls, ...) return cls.new(...) end,
+})
+
+local COLORS = {
+    MAIN_FG       = beautiful.fg_color,
+    MAIN_BG       = '#ffffff11',
+
+
+    CHARGING      = "#43a047",
+    CHARGE_MEDIUM = "#c0ca33",
+    CHARGE_LOW    = "#e53935",
+
+    NOTIFY_LOW_FG = "#EEE9EF",
+    NOTIFY_LOW_BG = "#F06060",
+}
+
+function BatteryWidget:_show_battery_warning(charge_percent)
+    naughty.notify({
+        -- icon = warning_msg_icon,
+        -- icon_size = 100,
+        title = 'Low battery',
+        text  = string.format('battery at %d%%', charge_percent),
+        timeout = 25, -- show the warning for a longer time
+        hover_timeout = 0.5,
+        bg = COLORS.NOTIFY_LOW_BG,
+        fg = COLORS.NOTIFY_LOW_FG,
+        width = 300,
+    })
+end
+
+function BatteryWidget:_update()
+    local capacity = self._bat.capacity
+    if not capacity then
+        local cl = self._bat.capacity_level
+        if     cl == 'Full'     then capacity = 100
+        elseif cl == 'High'     then capacity = 75
+        elseif cl == 'Normal'   then capacity = 50
+        elseif cl == 'Low'      then capacity = 25
+        elseif cl == 'Critical' then capacity = 5
+        end
+    end
+
+    -- hide the widget if the battery is full
+    if self._bat.status == self._bat.STATUS.FULL then
+        self._placeholder:set_children({})
+        return
+    end
+
+    -- show the widget if it was previously hidden
+    if next(self._placeholder.children) == nil then
+        self._placeholder:set_children({self._arc})
+    end
+
+    if self._level_text ~= nil then
+        --- if battery is fully charged (100) there is not enough place for three digits, so we don't show any text
+        self._level_text.text = (capacirty and capacity >= 100) and '' or
+                                string.format('%d', capacity // 1)
+    end
+
+    if self._bat.status == self._bat.STATUS.CHARGING then
+        self._arc.bg = COLORS.CHARGING
+    else
+        self._arc.bg = COLORS.MAIN_BG
+    end
+
+    if capacity then
+        self._arc.value = capacity
+
+        if capacity < 15 then
+            self._arc.colors = { COLORS.CHARGE_LOW }
+            if self._bat.status == self._bat.STATUS.DISCHARGING and
+               os.difftime(os.time(), self._last_battery_check) > 300 then
+                self:_show_battery_warning(capacity)
+                self._last_battery_check = os.time()
+            end
+        elseif capacity < 40 then
+            self._arc.colors = { COLORS.CHARGE_MEDIUM }
+        else
+            self._arc.colors = { COLORS.MAIN_FG }
+        end
+    end
+
+    -- build tooltip text
+    -- start with name + description
+    local tooltip_text = self._bat.name
+    if self._bat.desc then
+        tooltip_text = string.format('%s (%s)', tooltip_text, self._bat.desc)
+    end
+
+    -- percentage/capacity level
+    if self._bat.capacity then
+        tooltip_text = string.format('%s: %d%%', tooltip_text, self._bat.capacity)
+    elseif self._bat.capacity_level then
+        tooltip_text = string.format('%s: %s', tooltip_text, self._bat.capacity_level)
+    end
+
+    -- status + power (if available)
+    tooltip_text = string.format('%s; %s', tooltip_text, self._bat.status)
+    if self._bat.power then
+        tooltip_text = string.format('%s at %.3gW', tooltip_text, self._bat.power)
+    end
+
+    if self._bat.remaining_seconds then
+        local sec = self._bat.remaining_seconds
+
+        local h = sec // 3600
+        sec = sec - 3600 * h
+
+        local m = sec // 60
+        sec = sec - 60 * m
+
+        local s = sec // 1
+
+        local endstate = self._bat.status == self._bat.STATUS.DISCHARGING and 'empty' or 'full'
+        tooltip_text = string.format('%s; %02d:%02d:%02d until %s', tooltip_text, h, m, s, endstate)
+    end
+    self._tooltip.text = tooltip_text
+end
+
+function BatteryWidget.new(battery, user_args)
+    local self = setmetatable({}, BatteryWidget)
+
+    local args = user_args or {}
+
+    self._bat = battery
+
+    -- optional textbox showing battery charge percentage
+    local show_current_level = args.show_current_level or false
+    if show_current_level then
+        self._level_text = wibox.widget.textbox()
+    end
+
+    -- arc indicating battery charge level
+    self._arc = wibox.widget {
+        self._level_text,
+        max_value = 100,
+        rounded_edge = true,
+        thickness = args.arc_thickness or 4,
+        start_angle = 4.71238898, -- 2pi*3/4
+        bg = COLORS.MAIN_BG,
+        paddings = 2,
+        widget = wibox.container.arcchart
+    }
+
+    -- placeholder layout used to hide the widget on full battery
+    self._placeholder = wibox.layout.flex.horizontal()
+
+    -- the actually returned widget, showing the battery only on the primary screen
+    local ret_widget = awful.widget.only_on_screen(self._placeholder, "primary")
+
+    -- tooltip showing extended battery status
+    self._tooltip = awful.tooltip({})
+    self._tooltip:add_to_object(ret_widget)
+
+    self._last_battery_check = os.time()
+
+    -- wibox.widget.imagebox
+    -- local it = menubar_it()
+    -- print(it:find_icon_path('battery-full', 32))
+
+    battery:connect_signal('updated', function () self:_update() end)
+
+    return ret_widget
+end
+
+return BatteryWidget
diff --git a/rc.lua b/rc.lua
index 43d5fe3..2bf47ca 100644
--- a/rc.lua
+++ b/rc.lua
@@ -16,8 +16,9 @@ local utils      = require("utils")
 local workspace  = require("workspace")
 
 -- local widgets
-local pager      = require("pager")
-local urgent_wgt = require("urgent_wgt")
+local BatteryManager = require("battery_mng")
+local pager          = require("pager")
+local urgent_wgt     = require("urgent_wgt")
 
 -- {{{ Error handling
 -- Check if awesome encountered an error during startup and fell back to
@@ -79,6 +80,8 @@ update_systray_iconsize()
 -- global, shown only on the primary screen
 local u_wgt = urgent_wgt.UrgentWidget:new()
 
+local b_mng = BatteryManager()
+
 -- Create a wibox for each screen and add it
 mywibox = {}
 mypromptbox = {}
@@ -103,12 +106,14 @@ awful.screen.connect_for_each_screen(function(s)
                       awful.button({ }, 3, function () awful.layout.inc(layouts, -1) end),
                       awful.button({ }, 4, function () awful.layout.inc(layouts, 1) end),
                       awful.button({ }, 5, function () awful.layout.inc(layouts, -1) end)))
-    local layoutbox_container = wibox.container.constraint(layoutbox, 'max', beautiful.xresources.apply_dpi(tray_icon_size))
 
     local layout_utils = wibox.layout.fixed.horizontal()
-    layout_utils:add(layoutbox_container)
+    layout_utils:add(layoutbox)
+    layout_utils:add(b_mng)
     layout_utils:add(u_wgt.widget)
 
+    local utils_bar = wibox.container.constraint(layout_utils, 'max', nil, beautiful.xresources.apply_dpi(tray_icon_size))
+
     -- Create a tasklist widget
     local pgr = pager.Pager:new(wsp, s)
 
@@ -117,7 +122,7 @@ awful.screen.connect_for_each_screen(function(s)
 
     layout_bottom:add(systray)
 
-    layout_bottom:add(layout_utils)
+    layout_bottom:add(utils_bar)
     layout_bottom:add(clock_time)
     layout_bottom:add(clock_date)