root

local component = require("component")
local event = require("event")
local m = component.modem
local ttf = require("ttf")
local fs = require("filesystem")

lookup = {}
dns = {}
mac_me = ""
for k,v in component.list("modem") do
  mac_me = k
end

function split(inputstr, sep)
  if sep == nil then
    sep = "%s"
  end
  local t={}
  for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
    table.insert(t, str)
  end
  return t
end

function getIPPart(a, t)
  local ip = split(a, ".")
  local len = 0
  for k,v in pairs(ip) do
    len = len + 1
  end
  if (t == "last") then
    return ip[len]
  else
    return ip[len - (tonumber(t) - 1)]
  end
end

function getNodeCount(a)
  local ip = split(a, ".")
  local len = 0
  for k,v in pairs(ip) do
    len = len + 1
  end
  return len
end

function getUnitParentIP(a)
  local ip = split(a, ".")
  local ret = ""
  for k,v in pairs(ip) do
    if (v == getIPPart(a, "last")) then
      break
    end
    if (v == getIPPart(a, "2")) then
      ret = ret .. v
    else
      ret = ret .. v .. "."
    end
  end
  return ret
end

function stop()
  event.ignore("touch", stop)
  event.ignore("modem_message", listen)
  print("(:) Stopping...")
end

function start()
  m.open(1110)
  print("(:) Start...")
  if (fs.exists("/home/QuarksRouter/lookup.table")) then
    lookup = ttf.load("/home/QuarksRouter/lookup.table")
    print("(:) Lookups loaded")
  else
    print("(X) No lookups!")
  end
  if (fs.exists("/home/QuarksRouter/dns.table")) then
    dns = ttf.load("/home/QuarksRouter/dns.table")
    print("(:) DNS Lookups loaded!")
  else
    print("(X) No DNS lookups!")
  end
  print("(:) Booted up!")
  print("(:) MAC: " .. mac_me)
  event.listen("touch", stop)
  event.listen("modem_message", listen)
end

function listen(_, _, from, _, _, msg)
  packet = split(msg, ";")
  print("(:) Received packet! Resolving packet type... [" .. msg .."]")
  if (packet[3] == "DATA") then
    print("(:)       TYPE: DATA")
    handleData(from, packet, msg)
  elseif (packet[3] == "DNSLOOKUP") then
    print("(:)       TYPE: DNSLOOKUP")
    handleLookup(from, packet)
  elseif (packet[3] == "DNSANSWER") then
    print("(:)       TYPE: DNSANSWER")
    handleAnswer(from, packet)
  elseif (packet[3] == "DNSREG") then
    print("(:)       TYPE: DNSREG")
    handleReg(from, packet)
  elseif (packet[3] == "FINDPARENT") then
    print("(:)       TYPE: FINDPARENT")
    handleFind(from, packet)
  else
    print("(X) Unknown packet type (" .. packet[3] .. ")")
  end
end

function handleData(from, p, mm)
  print("(:) Rerouting packet to client in my subnet... (" ..
  lookup[tonumber(split(p[2], ".")[1]) ].. ")[".. mm .."]")
  m.send(lookup[tonumber(split(p[2], ".")[1])], 1110, mm)
end

function handleLookup(from, p, mm)
  if (dns[p[4]] == nil) then
    m.send(from,1110,"0;".. p[1] ..";DNSANSWER;QDNS:DOMAINNOTFOUND")
  else
    ip = dns[p[4]]
    m.send(from,1110,"0;".. p[1] ..";DNSANSWER;QNDS:".. ip)
    print("(:) " .. p[4] .. " is " .. ip)
  end
end

function handleAnswer(from, p, mm)
  print("(!) Skipping DNSANSWER packet. Does your network have cycles or it wasn't set up correctly?")
end

function handleReg(from, p, mm)
  if (dns[p[4]] == nil) then
    dns[p[4]] = p[1]
    m.send(from,1110,"0;".. p[1] ..";DNSANSWER;QDNS:SUCCESSREG")
  else
    print("(X) Domain ".. p[4] .." already registered ")
    m.send(from,1110,"0;".. p[1] ..";DNSANSWER;QDNS:ALREADYREGISTERED")
  end
end

function handleFind(from, p)
  if (p[4] == "find") then
    m.send(from, 1110, "FINDROUTER:ME")
  elseif (p[4] == mac_me) then
    print("(:) Registering new client... (" .. from .. ")")
    local id = 1
    for k,v in pairs(lookup) do
      id = id + 1
    end
    local userip = tostring(id)
    lookup[id] = from
    print("(:) Allocated IP " .. userip .. " for MAC " .. from)
    m.send(from, 1110, userip)
  end
  print("(:) Handled FINDPARENT:[" .. p .. "]")
end



-- MAIN
start()
event.pull("touch")
print("(:) Saving lookups...")
ttf.save(lookup, "/home/QuarksRouter/lookup.table")
ttf.save(dns, "/home/QuarksRouter/dns.table")
print("(:) Stopped!")