#!/usr/bin/env lua
--[[
Copyright 2017 Marcos Gutierrez <gmarcos87@gmail.com>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
    http://www.apache.org/licenses/LICENSE-3.0
]]--

require "ubus"
local nixio = require "nixio",require "nixio.fs"
local json = require 'luci.jsonc'
local utils = require("lime.utils")

local function printJson (obj)
    print(json.stringify(obj))
end


local conn = ubus.connect()
if not conn then
    error("Failed to connect to ubus")
end

local function spectral_scan(msg)
    if utils.is_installed("fft-eval") == false then
        local result = { error = "fft-eval not installed" }
        printJson(result)
        return
    end

	local device = utils.shell_quote(msg.device)
	local spectrum = msg.spectrum

	local result = {
		spectrum = {}
	}
	local fd = assert(io.open("/sys/class/net/" .. device .. "/phy80211/name"))
    local phy = assert(fd:read("*l"))
    fd:close()

    local path_ath9k = "/sys/kernel/debug/ieee80211/" .. phy .. "/ath9k/"

    local freqs = { }
    freqs["2ghz"] = { 2412, 2422, 2432, 2442, 2452, 2462 }
    freqs["5ghz"] = { } -- scan all possible channels

    if spectrum == "2ghz" or spectrum == "5ghz" then
        samples = sample_whole_spectrum(device, path_ath9k, freqs[spectrum])
    elseif spectrum == "current" then
        samples = sample_current_channel(path_ath9k)
    end

	samples = json.parse( samples )

	-- Convert values to string (avoid ubus bug)
	for _, dev in pairs(samples[1].data) do
		samples[1].data[_][1] = tostring(samples[1].data[_][1])
		samples[1].data[_][2] = tostring(samples[1].data[_][2])
	end

	local json_reply = {
		samples = samples,
		epoch = os.time()
	}

    result.spectrum = json_reply
	printJson(result)
end

function sample_current_channel(path_ath9k)
    -- sample current channel only, no freq hopping
    -- grab only one sample per trigger
    nixio.fs.writefile(path_ath9k .. "spectral_count", "1")
    -- empty buffer
    nixio.fs.readfile(path_ath9k .. "spectral_scan0")
    -- trigger sampling
    nixio.fs.writefile(path_ath9k .. "spectral_scan_ctl", "manual")
    nixio.fs.writefile(path_ath9k .. "spectral_scan_ctl", "trigger")
	print("fft_eval " .. path_ath9k .. "spectral_scan0")
    local samples = utils.unsafe_shell(utils.shell_quote("fft_eval " .. path_ath9k .. "spectral_scan0"))
    nixio.fs.writefile(path_ath9k .. "spectral_scan_ctl", "disable")

    return samples
end

function sample_whole_spectrum(device, path_ath9k, freqs)
    -- grab samples over the whole spectrum
    -- grab only one sample per trigger
    nixio.fs.writefile(path_ath9k .. "spectral_count", "1")
    -- empty buffer
    nixio.fs.readfile(path_ath9k .. "spectral_scan0")
    -- trigger sampling hopping channels
    nixio.fs.writefile(path_ath9k .. "spectral_scan_ctl", "chanscan")

    local cmd = "iw dev " .. device .. " scan"
    if #freqs > 0 then cmd = cmd .. " freq " .. table.concat(freqs, " ") end
    utils.unsafe_shell(cmd)

    nixio.fs.writefile(path_ath9k .. "spectral_scan_ctl", "disable")
    local samples = utils.unsafe_shell("fft_eval " .. path_ath9k .. "spectral_scan0")

    return samples
end

local methods = {
	spectral_scan = { device = 'value', spectrum = 'value' }
}

if arg[1] == 'list' then
    printJson(methods)
end

if arg[1] == 'call' then
    local msg = io.read()
    msg = json.parse(msg)
    if   arg[2] == 'spectral_scan'          then spectral_scan(msg)
    else      printJson({ error = "Method not found" })
    end
end