#!/usr/local/kinix/luajit/bin/luajit

--[[
  06 FEB 2018: karthik@houseofkodai
]]--

local load_geolite2_city_locations_csv = function(fname, cc)
  --geoname_id,locale_code,continent_code,continent_name,country_iso_code,country_name,subdivision_1_iso_code,subdivision_1_name,subdivision_2_iso_code,subdivision_2_name,city_name,metro_code,time_zone
  --1252653,en,AS,Asia,IN,India,NL,Nagaland,,,Zunheboto,,Asia/Kolkata
  --need 1,7,8,11

  local stime = os.time()
--print('START '..stime)
  local t = {}
  local n = 0
  for ln in io.lines(fname) do
    ln = ln..',' --append , so gmatch regex works
    local regex = '([^,]*),'
    local i = 0
    local id, scode, sname, city
    for w in ln:gmatch(regex) do
      i = i + 1
      if (1 == i) then
        id = w
      elseif ((5 == i) and (w ~= cc)) then
        break
      elseif (7 == i) then
        scode = w
      elseif (8 == i) then
        sname = w
      elseif (11 == i) then
        city = w
      end
    end
    if city then
      n = n + 1
      regex = '"?([^"]*)"?'
      t[id] = {scode, sname:match(regex), city:match(regex)}
    end
  end
--print('END', (os.time()-stime), n)
  return t
end

local load_geolite2_city_blocks_ipv4_csv = function(fname, idtbl)
  --network,geoname_id,registered_country_geoname_id,represented_country_geoname_id,is_anonymous_proxy,is_satellite_provider,postal_code,latitude,longitude,accuracy_radius
  local stime = os.time()
--print('START '..stime)
  local n = 0
  local t = {}

  for ln in io.lines(fname) do
    n = n + 1
    local id = ln:match('^[%d.]+/%d+,(%d+),.*$')
    local r = idtbl[id]
    if r and (r[1]:len() > 0)then
      local o1,o2,o3,o4,range,id,f1,f2,f3,f4,f5,lat,lng,acc = ln:match('^(%d%d?%d?)%.(%d%d?%d?)%.(%d%d?%d?)%.(%d%d?%d?)/(%d+),(%d+),([^,]*),([^,]*),([^,]*),([^,]*),([^,]*),(%d+%.%d+),(%d+%.%d+),(%d+)$')
      local ipstart = 2^24*o1 + 2^16*o2 + 2^8*o3 + o4
      local ipend = ipstart + 2^(32-tonumber(range))
      --t[#t+1] = {tonumber(ipstart),tonumber(ipend),'"'..r[1]..'/'..r[3]..'"',lat,lng,acc}
      t[#t+1] = {tonumber(ipstart),tonumber(ipend),id,lat,lng,acc}
    end
  end
--print('END', (os.time()-stime), n, #t)
  return t
end

local _load = function(locfname, ipv4fname, cc)
  --pndng deal with null-cc to load everything
  local citytbl = load_geolite2_city_locations_csv(locfname, cc)
  local iptbl = load_geolite2_city_blocks_ipv4_csv(ipv4fname, citytbl)
  return citytbl, iptbl
end

local _find = function(s, citytbl, iptbl)
  local o1,o2,o3,o4 = s:match('^(%d%d?%d?)%.(%d%d?%d?)%.(%d%d?%d?)%.(%d%d?%d?)$')
  if not o4 then return {} end
  local ip = 2^24*o1 + 2^16*o2 + 2^8*o3 + o4
  local iptbl = iptbl or {}
  local citytbl = citytbl or {}
  for _,r in ipairs(iptbl) do
    if ip >= r[1] and ip < r[2] then
      local v = citytbl[r[3]]
      if v then r[3] = v[1]..':'..v[3] end
      return r
    end
  end
  return {}
end

local _save = function(fname, citytbl, iptbl)
  local fh,err = io.open(fname, 'w')
  if not fh then
    return false,err
  end
  local t = {}
  for _,r in ipairs(iptbl) do
    if (r[3]:len() > 0) then
      t[#t+1] = '{'..table.concat(r, ',')..'}'
    end
  end
  local iptbl = table.concat(t, ',\n')

  t = {}
  for k,v in pairs(citytbl) do
    t[#t+1] = '['..k..']="'..v[1]..':'..v[3]..'"'
  end
  local citytbl = table.concat(t, ',\n')

  local flines = [=[
return function(s)
  local o1,o2,o3,o4 = s:match('^(%d%d?%d?)%.(%d%d?%d?)%.(%d%d?%d?)%.(%d%d?%d?)$')
  if not o4 then return end
  local ip = 2^24*o1 + 2^16*o2 + 2^8*o3 + o4
  local citytbl = {
]=]..citytbl..[=[
  }
  local iptbl = {
]=]..iptbl..[=[
  }
  for _,r in ipairs(iptbl) do
    if ip >= r[1] and ip < r[2] then
      r[3] = citytbl[r[3]] or 'UNK'
      return r
    end
  end
end
]=]
  fh:write(flines)
  fh:close()
  return true
end

local main = function()
  local locfname = 'GeoLite2-City-Locations-en.csv'
  local ipv4fname = 'GeoLite2-City-Blocks-IPv4.csv'

  if (#arg < 1) then
    print('usage: geolite2.lua <country-code> <ip-to-lookup> ['..locfname..'] ['..ipv4fname..']')
    os.exit(1)
  end

  local cc = arg[1]
  local ip = arg[2]
  if arg[3] then locfname = arg[3] end
  if arg[4] then ipv4fname = arg[4] end

  local citytbl, iptbl = _load(locfname, ipv4fname, cc)
  _save(cc..'.lua', citytbl, iptbl)

  if ip then
    local r = _find(ip, citytbl, iptbl)
    if r then print(table.concat(r,'/')) end
  end
end

if arg ~= nil then
  main()
end