Gather statistics in LuCI enabled router and encode in JSON

stats.lua

require "luci.jsonc"

function to_map(obj, key)
    local rv = { }
    for _,el in ipairs(obj) do
       rv[string.upper(el[key])] = el
       el[key]=nil
    end
    return rv
end

function wifi_networks()
	local ntm = require "luci.model.network".init()

	local dev = ntm:get_wifidevs()[1]
	local net = dev:get_wifinets()[1]
	local rv = {
				up         = net:is_up(),
				mode       = net:active_mode(),
				ssid       = net:active_ssid(),
				bssid      = net:active_bssid(),
				encryption = net:active_encryption(),
				frequency  = net:frequency(),
				channel    = net:channel(),
				quality    = net:signal_percent(),
				noise      = net:noise(),
				bitrate    = net:bitrate(),
				ifname     = net:ifname(),
				assoclist  = net:assoclist(),
				txpower    = net:txpower()
			}

	return rv
end


local fs = require "nixio.fs"
local util = require "luci.util"
local stat = require "luci.tools.status"
local ver = require "luci.version"
local sys = require "luci.sys"
local sysinfo = luci.util.ubus("system", "info") or { }
local boardinfo = luci.util.ubus("system", "board") or { }
local unameinfo = nixio.uname() or { }
local meminfo = sysinfo.memory or {
	total = 0,
	free = 0,
	buffered = 0,
	shared = 0
}

local ntm = require "luci.model.network".init()
local wan = ntm:get_wannet()
local conn_count = tonumber(
	fs.readfile("/proc/sys/net/netfilter/nf_conntrack_count")) or 0
local conn_max = tonumber((
	luci.sys.exec("sysctl net.nf_conntrack_max") or
	luci.sys.exec("sysctl net.ipv4.netfilter.ip_conntrack_max") or
	""):match("%d+")) or 4096
local rv = {
	uptime     = sysinfo.uptime or 0,
	localtime  = os.date(),
	loadavg    = sysinfo.load or { 0, 0, 0 },
	memory     = meminfo,
	connmax    = conn_max,
	conncount  = conn_count,
	leases     = to_map(stat.dhcp_leases(),"macaddr"),
	wifinets   = wifi_networks()
}

rv.wan = {
	ipaddr  = wan:ipaddr(),
	gwaddr  = wan:gwaddr(),
	netmask = wan:netmask(),
	dns     = wan:dnsaddrs(),
	uptime  = wan:uptime(),
	ifname  = wan:ifname()
}

local dsl_stat = sys.exec("/etc/init.d/dsl_control lucistat")
local dsl_func = loadstring(dsl_stat)
if dsl_func then
        local dsl = dsl_func()
        rv.dsl = {
            errors_loss_far  = dsl.errors_loss_far,
            errors_fec_far   = dsl.errors_fec_far,
            errors_ses_far   = dsl.errors_ses_far,
            errors_crc_p_far     = dsl.errors_crc_p_far,
            errors_hec_near  = dsl.errors_hec_near,
            errors_es_far    = dsl.errors_es_far,
            max_data_rate_up     = dsl.max_data_rate_up,
            max_data_rate_down   = dsl.max_data_rate_down,
            actatp_up    = dsl.actatp_up,
            actatp_down  = dsl.actatp_down,
            signal_attenuation_up    = dsl.signal_attenuation_up,
            signal_attenuation_down  = dsl.signal_attenuation_down,
            noise_margin_up  = dsl.noise_margin_up,
            line_attenuation_down    = dsl.line_attenuation_down,
            data_rate_up     = dsl.data_rate_up,
            errors_uas_near  = dsl.errors_uas_near,
            errors_fec_near  = dsl.errors_fec_near,
            data_rate_down   = dsl.data_rate_down,
            noise_margin_down    = dsl.noise_margin_down,
            power_mode_num   = dsl.power_mode_num,
            errors_es_near   = dsl.errors_es_near,
            errors_crcp_p_far    = dsl.errors_crcp_p_far,
            errors_crcp_p_near   = dsl.errors_crcp_p_near,
            errors_loss_near     = dsl.errors_loss_near,
            errors_uas_far   = dsl.errors_uas_far,
            errors_crc_p_near    = dsl.errors_crc_p_near,
            errors_hec_far   = dsl.errors_hec_far,
            line_state_detail    = dsl.line_state_detail,
            errors_ses_near  = dsl.errors_ses_near,
            line_state   = dsl.line_state,
            line_attenuation_up  = dsl.line_attenuation_up,
            line_uptime  = dsl.line_uptime
        }
end

print(luci.jsonc.stringify(rv))

based on code from LuCI project https://github.com/openwrt/luci/blob/master/modules/luci-mod-admin-full/luasrc/view/admin_status/index.htm