--[[

	 Licensed under GNU General Public License v2
	  * (c) 2013,      Luca CPZ
	  * (c) 2010-2012, Peter Hofmann

--]]

local helpers = require('lain.helpers')
local fs = require('gears.filesystem')
local naughty = require('naughty')
local wibox = require('wibox')
local math = math
local string = string
local ipairs = ipairs
local tonumber = tonumber

-- Battery infos
-- lain.widget.bat

local function factory(args)
	local pspath = args.pspath or '/sys/class/power_supply/'

	if not fs.is_dir(pspath) then
		naughty.notify({ text = 'lain.widget.bat: invalid power supply path', timeout = 0 })
		return
	end

	args = args or {}

	local bat = { widget = args.widget or wibox.widget.textbox() }
	local timeout = args.timeout or 30
	local notify = args.notify or 'on'
	local full_notify = args.full_notify or notify
	local n_perc = args.n_perc or { 5, 15 }
	local batteries = args.batteries or (args.battery and { args.battery }) or {}
	local ac = args.ac or 'AC0'
	local settings = args.settings or function() end

	function bat.get_batteries()
		helpers.line_callback('ls -1 ' .. pspath, function(line)
			local bstr = string.match(line, 'BAT%w+')
			if bstr then
				batteries[#batteries + 1] = bstr
			else
				ac = string.match(line, 'A%w+') or ac
			end
		end)
	end

	if #batteries == 0 then
		bat.get_batteries()
	end

	bat_notification_critical_preset = {
		title = 'Battery exhausted',
		text = 'Shutdown imminent',
		timeout = 15,
		fg = '#000000',
		bg = '#FFFFFF',
	}

	bat_notification_low_preset = {
		title = 'Battery low',
		text = 'Plug the cable!',
		timeout = 15,
		fg = '#202020',
		bg = '#CDCDCD',
	}

	bat_notification_charged_preset = {
		title = 'Battery full',
		text = 'You can unplug the cable',
		timeout = 15,
		fg = '#202020',
		bg = '#CDCDCD',
	}

	bat_now = {
		status = 'N/A',
		ac_status = 'N/A',
		perc = 'N/A',
		time = 'N/A',
		watt = 'N/A',
		capacity = 'N/A',
	}

	bat_now.n_status = {}
	bat_now.n_perc = {}
	bat_now.n_capacity = {}
	for i = 1, #batteries do
		bat_now.n_status[i] = 'N/A'
		bat_now.n_perc[i] = 0
		bat_now.n_capacity[i] = 0
	end

	-- used to notify full charge only once before discharging
	local fullnotification = false

	function bat.update()
		-- luacheck: globals bat_now
		local sum_rate_current = 0
		local sum_rate_voltage = 0
		local sum_rate_power = 0
		local sum_rate_energy = 0
		local sum_energy_now = 0
		local sum_energy_full = 0
		local sum_charge_full = 0
		local sum_charge_design = 0

		for i, battery in ipairs(batteries) do
			local bstr = pspath .. battery
			local present = helpers.first_line(bstr .. '/present')

			if tonumber(present) == 1 then
				-- current_now(I)[uA], voltage_now(U)[uV], power_now(P)[uW]
				local rate_current = tonumber(helpers.first_line(bstr .. '/current_now'))
				local rate_voltage = tonumber(helpers.first_line(bstr .. '/voltage_now'))
				local rate_power = tonumber(helpers.first_line(bstr .. '/power_now'))
				local charge_full = tonumber(helpers.first_line(bstr .. '/charge_full'))
				local charge_design = tonumber(helpers.first_line(bstr .. '/charge_full_design'))

				-- energy_now(P)[uWh], charge_now(I)[uAh]
				local energy_now =
					tonumber(helpers.first_line(bstr .. '/energy_now') or helpers.first_line(bstr .. '/charge_now'))

				-- energy_full(P)[uWh], charge_full(I)[uAh]
				local energy_full = tonumber(helpers.first_line(bstr .. '/energy_full') or charge_full)

				local energy_percentage = tonumber(helpers.first_line(bstr .. '/capacity'))
					or math.floor((energy_now / energy_full) * 100)

				bat_now.n_status[i] = helpers.first_line(bstr .. '/status') or 'N/A'
				bat_now.n_perc[i] = energy_percentage or bat_now.n_perc[i]

				if not charge_design or charge_design == 0 then
					bat_now.n_capacity[i] = 0
				else
					bat_now.n_capacity[i] = math.floor((charge_full / charge_design) * 100)
				end

				sum_rate_current = sum_rate_current + (rate_current or 0)
				sum_rate_voltage = sum_rate_voltage + (rate_voltage or 0)
				sum_rate_power = sum_rate_power + (rate_power or 0)
				sum_rate_energy = sum_rate_energy + (rate_power or (((rate_voltage or 0) * (rate_current or 0)) / 1e6))
				sum_energy_now = sum_energy_now + (energy_now or 0)
				sum_energy_full = sum_energy_full + (energy_full or 0)
				sum_charge_full = sum_charge_full + (charge_full or 0)
				sum_charge_design = sum_charge_design + (charge_design or 0)
			end
		end

		bat_now.capacity = math.floor(math.min(100, (sum_charge_full / sum_charge_design) * 100))

		-- When one of the battery is charging, others' status are either
		-- "Full", "Unknown" or "Charging". When the laptop is not plugged in,
		-- one or more of the batteries may be full, but only one battery
		-- discharging suffices to set global status to "Discharging".
		bat_now.status = bat_now.n_status[1] or 'N/A'
		for _, status in ipairs(bat_now.n_status) do
			if status == 'Discharging' or status == 'Charging' then
				bat_now.status = status
			end
		end
		bat_now.ac_status = tonumber(helpers.first_line(string.format('%s%s/online', pspath, ac))) or 'N/A'

		if bat_now.status ~= 'N/A' then
			if bat_now.status ~= 'Full' and sum_rate_power == 0 and bat_now.ac_status == 1 then
				bat_now.perc = math.floor(math.min(100, (sum_energy_now / sum_energy_full) * 100))
				bat_now.time = '00:00'
				bat_now.watt = 0

			-- update {perc,time,watt} iff battery not full and rate > 0
			elseif bat_now.status ~= 'Full' then
				local rate_time = 0
				-- Calculate time and watt if rates are greater then 0
				if sum_rate_power > 0 or sum_rate_current > 0 then
					local div = (sum_rate_power > 0 and sum_rate_power) or sum_rate_current

					if bat_now.status == 'Charging' then
						rate_time = (sum_energy_full - sum_energy_now) / div
					else -- Discharging
						rate_time = sum_energy_now / div
					end

					if 0 < rate_time and rate_time < 0.01 then -- check for magnitude discrepancies (#199)
						rate_time_magnitude = math.abs(math.floor(math.log10(rate_time)))
						rate_time = rate_time * 10 ^ (rate_time_magnitude - 2)
					end
				end

				local hours = math.floor(rate_time)
				local minutes = math.floor((rate_time - hours) * 60)
				bat_now.perc = math.floor(math.min(100, (sum_energy_now / sum_energy_full) * 100))
				bat_now.time = string.format('%02d:%02d', hours, minutes)
				bat_now.watt = tonumber(string.format('%.2f', sum_rate_energy / 1e6))
			elseif bat_now.status == 'Full' then
				bat_now.perc = 100
				bat_now.time = '00:00'
				bat_now.watt = 0
			end
		end

		widget = bat.widget
		settings()

		-- notifications for critical, low, and full levels
		if notify == 'on' then
			if bat_now.status == 'Discharging' then
				if tonumber(bat_now.perc) <= n_perc[1] then
					bat.id = naughty.notify({
						preset = bat_notification_critical_preset,
						replaces_id = bat.id,
					}).id
				elseif tonumber(bat_now.perc) <= n_perc[2] then
					bat.id = naughty.notify({
						preset = bat_notification_low_preset,
						replaces_id = bat.id,
					}).id
				end
				fullnotification = false
			elseif bat_now.status == 'Full' and full_notify == 'on' and not fullnotification then
				bat.id = naughty.notify({
					preset = bat_notification_charged_preset,
					replaces_id = bat.id,
				}).id
				fullnotification = true
			end
		end
	end

	helpers.newtimer('batteries', timeout, bat.update)

	return bat
end

return factory