--[[

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

--]]

local helpers = require('lain.helpers')
local wibox = require('wibox')
local math = math
local string = string

-- CPU usage
-- lain.widget.cpu

local function factory(args)
	args = args or {}

	local cpu = { core = {}, widget = args.widget or wibox.widget.textbox() }
	local timeout = args.timeout or 2
	local settings = args.settings or function() end

	function cpu.update()
		-- Read the amount of time the CPUs have spent performing
		-- different kinds of work. Read the first line of /proc/stat
		-- which is the sum of all CPUs.
		for index, time in pairs(helpers.lines_match('cpu', '/proc/stat')) do
			local coreid = index - 1
			local core = cpu.core[coreid] or { last_active = 0, last_total = 0, usage = 0 }
			local at = 1
			local idle = 0
			local total = 0

			for field in string.gmatch(time, '[%s]+([^%s]+)') do
				-- 4 = idle, 5 = ioWait. Essentially, the CPUs have done
				-- nothing during these times.
				if at == 4 or at == 5 then
					idle = idle + field
				end
				total = total + field
				at = at + 1
			end

			local active = total - idle

			if core.last_active ~= active or core.last_total ~= total then
				-- Read current data and calculate relative values.
				local dactive = active - core.last_active
				local dtotal = total - core.last_total
				local usage = math.ceil(math.abs((dactive / dtotal) * 100))

				core.last_active = active
				core.last_total = total
				core.usage = usage

				-- Save current data for the next run.
				cpu.core[coreid] = core
			end
		end

		cpu_now = cpu.core
		cpu_now.usage = cpu_now[0].usage
		widget = cpu.widget

		settings()
	end

	helpers.newtimer('cpu', timeout, cpu.update)

	return cpu
end

return factory