---------------------------------------------------------------------------
-- A battery widget based on the UPower deamon.
--
-- @author Aire-One
-- @copyright 2020 Aire-One
---------------------------------------------------------------------------

local upower = require('lgi').require('UPowerGlib')

local gtable = require('gears.table')
local gtimer = require('gears.timer')
local wbase = require('wibox.widget.base')

local setmetatable = setmetatable -- luacheck: ignore setmetatable

local battery_widget = {}
local mt = {}

--- Helper to get the path of all connected power devices.
-- @treturn table The list of all power devices path.
-- @staticfct battery_widget.list_devices
function battery_widget.list_devices()
	local ret = {}
	local devices = upower.Client():get_devices()

	for _, d in ipairs(devices) do
		table.insert(ret, d:get_object_path())
	end

	return ret
end

--- Helper function to get a device instance from its path.
-- @tparam string path The path of the device to get.
-- @treturn UPowerGlib.Device|nil The device if it was found, `nil` otherwise.
-- @staticfct battery_widget.get_device
function battery_widget.get_device(path)
	local devices = upower.Client():get_devices()

	for _, d in ipairs(devices) do
		if d:get_object_path() == path then
			return d
		end
	end

	return nil
end

--- Helper function to easily get the default BAT0 device path without.
-- @treturn string The BAT0 device path.
-- @staticfct battery_widget.get_BAT0_device_path
function battery_widget.get_BAT0_device_path()
	local bat0_path = '/org/freedesktop/UPower/devices/battery_BAT0'
	return bat0_path
end

--- Helper function to convert seconds into a human readable clock string.
--
-- This translates the given seconds parameter into a human readable string
-- following the notation `HH:MM` (where HH is the number of hours and MM the
-- number of minutes).
-- @tparam number seconds The umber of seconds to translate.
-- @treturn string The human readable generated clock string.
-- @staticfct battery_widget.to_clock
function battery_widget.to_clock(seconds)
	if seconds <= 0 then
		return '00:00'
	else
		local hours = string.format('%02.f', math.floor(seconds / 3600))
		local mins = string.format('%02.f', math.floor(seconds / 60 - hours * 60))
		return hours .. ':' .. mins
	end
end

--- Gives the default widget to use if user didn't specify one.
-- The default widget used is an `empty_widget` instance.
-- @treturn widget The default widget to use.
local function default_template()
	return wbase.empty_widget()
end

--- The device monitored by the widget.
-- @property device
-- @tparam UPowerGlib.Device device

--- Emited when the UPower device notify an update.
-- @signal upower::update
-- @tparam battery_widget widget The widget.
-- @tparam UPowerGlib.Device device The Upower device.

--- battery_widget constructor.
--
-- This function creates a new `battery_widget` instance. This widget watches
-- the `display_device` status and report.
-- @tparam table args The arguments table.
-- @tparam[opt] widget args.widget_template The widget template to use to
--   create the widget instance.
-- @tparam[opt] string args.device_path Path of the device to monitor.
-- @tparam[opt=false] boolean args.use_display_device Should the widget monitor
--   the _display device_?
-- @tparam[opt] boolean args.instant_update Call an update cycle right after the
--   widget creation.
-- @treturn battery_widget The battery_widget instance build.
-- @constructorfct battery_widget.new
function battery_widget.new(args)
	args = gtable.crush({
		widget_template = default_template(),
		device_path = '',
		use_display_device = false,
	}, args or {})

	local widget = wbase.make_widget_from_value(args.widget_template)

	widget.device = args.use_display_device and upower.Client():get_display_device()
		or battery_widget.get_device(args.device_path)

	-- Attach signals:
	widget.device.on_notify = function(d)
		widget:emit_signal('upower::update', d)
	end

	-- Call an update cycle if the user asked to instan update the widget.
	if args.instant_update then
		gtimer.delayed_call(widget.emit_signal, widget, 'upower::update', widget.device)
	end

	return widget
end

function mt.__call(self, ...)
	return battery_widget.new(...)
end

return setmetatable(battery_widget, mt)
