#!/usr/bin/lua
local fs = require('nixio.fs')
local uci = require('luci.model.uci').cursor()
local site = require 'gluon.site_config'
local util = require 'luci.util'
local ut = require('autoupdater-wifi-fallback.util')
local gluon = require 'gluon.util'

local configname = 'autoupdater-wifi-fallback'
local force = false
local min_uptime_secs = 3600
local branch_name = uci:get('autoupdater','settings','branch')

local function parse_args()
local i = 1
  while arg[i] do
    if arg[i] == '-f' then
      force = true
    elseif arg[i] == '-b' then
      i=i+1

      if not arg[i] then
        io.stderr:write("Error parsing command line: expected branch name\n")
        os.exit(1)
      end

      branch_name = arg[i]
    else
      io.stderr:write("Error parsing command line: unexpected argument '" .. arg[i] .. "'\n")
      os.exit(1)
    end
    i = i+1
  end
end

local function preflight_check()
  if not uci:get_bool(configname,'settings','enabled') then
    return false
  end
  if not uci:get_bool('autoupdater','settings','enabled') then
    return false
  end
  if tonumber(fs.readfile('/proc/uptime'):match('^([^ ]+) ')) < min_uptime_secs then
    return false
  end

  return true
end

local function connectivity_check()
  for line in io.lines("/sys/kernel/debug/batman_adv/bat0/gateways") do
    local gateway_mac = line:match("^=?>? +([0-9a-f:]+)")
    if gateway_mac then
      if os.execute("batctl ping -t5 -c1 " .. gateway_mac .. " > /dev/null 2>&1") == 0 then
        return true
      end
    end
  end
  
  -- connectivity check against updateserver
  for _, host in ipairs(get_update_hosts(branch_name)) do
    if os.execute("ping -w2 -c1 " .. host .. " > /dev/null 2>&1") == 0 then
      return true
    end
  end

  io.popen('logger -s -t autoupdater-wifi-fallback -p local0.info "connectivity check failed"')
  return false
end

local function run_autoupdater()
  io.popen('logger -s -t autoupdater-wifi-fallback -p local0.info "execute the autoupdater"')
  os.execute("/usr/sbin/autoupdater -f -b " .. branch_name)
end

local function switch_to_fallback_mode(ssid, radio)
  print("connect to: " .. ssid .. " on " .. radio)
  io.popen('logger -s -t autoupdater-wifi-fallback -p local0.info "going to fallback mode"')
  uci:delete_all('wireless', 'wifi-iface')
  uci:section('wireless', 'wifi-iface', 'fallback',
    {
      device = radio,
      network = 'fallback',
      mode = 'sta',
      disabled = 0,
      macaddr = gluon.generate_mac(3, 10),
      ifname = 'fallback',
      encryption = 'none',
    }
  )
  uci:set('wireless', radio, 'disabled', 0)
  uci:save('wireless')

  local f = io.open('/tmp/wpa-supplicant-fake', 'w')
  f:write('#!/bin/sh\niw dev fallback connect -w ' .. ssid)
  f:close()
  fs.chmod('/tmp/wpa-supplicant-fake', 755)

  io.popen("wifi")
  os.execute("sleep 5")
  os.execute("echo \"2\" > /proc/sys/net/ipv6/conf/fallback/accept_ra")
  uci:revert('wireless')
  os.execute("sleep 20")
end

local function revert_to_standard_mode()
  print("Going back to standard config")
  io.popen('logger -s -t autoupdater-wifi-fallback -p local0.info "going back to standard mode"')
  os.execute("/etc/init.d/network restart")
  os.execute("sleep 30")
end

parse_args()

if not uci:get('autoupdater', branch_name) then
  io.stderr:write("Can't find configuration for branch '" .. branch_name .. "'\n")
  os.exit(1)
end

if (force or preflight_check()) and not connectivity_check() then
  local offset = 2 * 3600
  local unreachable_since = os.time()
  if not uci:get('autoupdater-wifi-fallback', 'settings', 'unreachable_since') then
    uci:set(configname, 'settings', 'unreachable_since', unreachable_since)
  else
    uci:set(configname, 'settings', 'last_run', unreachable_since)
    unreachable_since = uci:get(configname, 'settings', 'unreachable_since')
  end
  uci:save(configname)
  
  if force or tonumber(unreachable_since) + offset < os.time() then
    local radio, wifiNetwork = get_available_wifi_networks()
    if wifiNetwork then
      switch_to_fallback_mode(wifiNetwork, radio)
      run_autoupdater()
      -- this is only reached if no updated happened
      revert_to_standard_mode()
    end
  end
else
  uci:delete(configname, 'settings','unreachable_since')
  uci:delete(configname, 'settings','last_run')
  uci:save(configname)
end