local wibox = require("wibox")
local widgets = require("util.widgets")

-- this is directly adapted from slstatus's cpu.c module
local cpu_time = { 0,0,0,0,0,0,0 } -- user, nice, system, idle, iowait, irq, softirq

function linux_cpu_usage(widget)
	-- read stat
	local statf = io.open("/proc/stat")
	local stat_iter = statf:read():gmatch("%d+")
	statf:close()

	-- calc
	local sum = 0
	local a, b = cpu_time, {} -- set cpu_time as a for smaller code
	table.move(a, 1, 7, 1, b) -- copy first 7 to b

	for i = 1, 7 do
		a[i] = stat_iter()
		sum = sum + b[i] - a[i]
	end

	if sum == 0 then
		return
	end

	local usage = ((b[1] + b[2] + b[3] + b[6] + b[7]) -
	               (a[1] + a[2] + a[3] + a[6] + a[7])) * 100 / sum

	widget:set_text(math.floor(usage))
end

-- return correct widget for os
if osname == "Linux" then
	return widgets.watchfn(linux_cpu_usage, 5)
end

return wibox.widget.textbox("unsupported os")