local modem = peripheral.wrap("top");
local network = peripheral.wrap("back");

--[[

  Networking Variables

]]--

local s_netChannel = 1;
local s_computers = {};

local responseChannels = {};

--[[

  Generic Functions

]]--

function in_table(tbl, val)
  for i,v in pairs(tbl) do
    if(v == val) then
      return true;
    end --if
  end --for
  return false;
end --in_table

--[[

  Network Functions

]]--

function generateResponseChannel()
  while true do
    local channel = math.random(10000,12000);
    if(in_table(reponseChannels, channel) == false) then
      table.insert(responseChannels, channel);
      return channel;
    end --if
  end --while
end --generateResponseChannel

function netTcpReceiveResponse(target)

  local timeout = os.startTimer(5);

  while true do

    local e, v1, sChannel, rChannel, resp = os.pullEvent();

    if( e == "modem_message" ) then

      if( resp == "tcpreceived:"..target ) then

        return true;

      end --if

    elseif( e == "timer" and v1 == timeout ) then

      return false;

    end --if

  end --while

end --netTcpReceiveResponse

function netTcpSendResponse(target)

  network.transmit(target, s_netChannel, "tcpreceived:"..os.getComputerID());

end --netTcpSendResponse

function netSend(target, message, tcp)

  network.transmit(target, s_netChannel, message);

  print("Request Sent");

  if( tcp ~= nil and tcp == true ) then

    for i = 1, 3 do

      if( netTcpReceiveResponse(target) ) then

        return true;

      end --if

    end --for

    return false;

  end --if

  return true;

end --netSend

function netPackage(act, dt)

  local pack = { action = act, data = dt }

  return textutils.serialise(pack);

end --netPackage

function netReceive(target, act)

  local timeout = os.startTimer(5);

  while true do

    local e, v1, sChannel, rChannel, resp = os.pullEvent();

    if( e == "modem_message" ) then

      local data = textutils.unserialise(resp);

      if( data.action == act ) then

        return data.data;

      end --if

    elseif( e == "timer" and v1 == timeout ) then

        break;

    end --if

  end --while

end --netReceive

function getComputers()

  local names = network.getNamesRemote();

  for i = 1, #names do

    local target = peripheral.wrap(names[i])

    if(target.isOn()) then

      local pack = netPackage("requestName")

      if( netSend(target.getID(), pack, true) ) then

        local data = netReceive(target.getID(), "requestName");

        s_computers[target.getID()] = { name = data.name, channel = target.getID() };

      end --if

    end --if

  end --for

end --getComputers


function main()

  network.open(1);

  getComputers();

  term.clear();
  term.setCursorPos(1,1);

  for k,v in pairs(s_computers) do

    print(v);

  end --if

end --main

main();