--[[
												                        
	 Licensed under GNU General Public License v2 
	  * (c) 2013,      Luke Bonham                
	  * (c) 2010-2012, Peter Hofmann              
												                        
--]]

local newtimer     = require("lain.helpers").newtimer
local first_line   = require("lain.helpers").first_line

local naughty      = require("naughty")
local wibox        = require("wibox")

local math         = { floor  = math.floor }
local string       = { format = string.format }
local tonumber     = tonumber

local setmetatable = setmetatable

-- Battery infos
-- lain.widgets.bat

local function worker(args)
    local bat      = {}
    local args     = args or {}
    local timeout  = args.timeout or 30
    local battery  = args.battery or "BAT0"
    local ac       = args.ac or "AC0"
    local notify   = args.notify or "on"
    local settings = args.settings or function() end

    bat.widget = wibox.widget.textbox('')

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

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

    function update()
        bat_now = {
            status    = "Not present",
            ac_status = "N/A",
            perc      = "N/A",
            time      = "N/A",
            watt      = "N/A"
        }

        local bstr    = "/sys/class/power_supply/" .. battery
        local astr    = "/sys/class/power_supply/" .. ac
        local present = first_line(bstr .. "/present")

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

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

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

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

            bat_now.status    = first_line(bstr .. "/status") or "N/A"
            bat_now.ac_status = first_line(astr .. "/online") or "N/A"

            -- update {perc,time,watt} iff rate > 0 and battery not full
            if ((rate_current and rate_current > 0) or (rate_power and rate_power > 0))
                and bat_now.status ~= "N/A" and bat_now.status ~= "Full"
            then
                local rate_time = 0
                if bat_now.status == "Charging" then
                    rate_time = (energy_full - energy_now) / (rate_power or rate_current)
                elseif bat_now.status == "Discharging" then
                    rate_time = energy_now / (rate_power or rate_current)
                end

                local hours   = math.floor(rate_time)
                local minutes = math.floor((rate_time - hours) * 60)
                local watt    = rate_power and (rate_power / 1e6) or (rate_voltage * rate_current) / 1e12

                bat_now.perc = string.format("%d", energy_percentage)
                bat_now.time = string.format("%02d:%02d", hours, minutes)
                bat_now.watt = string.format("%.2fW", watt)
            end
        end

        widget = bat.widget
        settings()

        -- notifications for low and critical states
        if bat_now.status == "Discharging" and notify == "on" and bat_now.perc then
            local nperc = tonumber(bat_now.perc) or 100
            if nperc <= 5 then
                bat.id = naughty.notify({
                    preset = bat_notification_critical_preset,
                    replaces_id = bat.id,
                }).id
            elseif nperc <= 15 then
                bat.id = naughty.notify({
                    preset = bat_notification_low_preset,
                    replaces_id = bat.id,
                }).id
            end
        end
    end

    newtimer(battery, timeout, update)

    return setmetatable(bat, { __index = bat.widget })
end

return setmetatable({}, { __call = function(_, ...) return worker(...) end })