local modules = {}

local function getIndex(tab, val)
    local index = nil
    for i, v in ipairs (tab) do
        if (v == val) then
          index = i
        end
    end
    return index
end


local kinetic = peripheral.wrap("back")
local canvas = peripheral.wrap("back").canvas()

timer = os.startTimer(0.5)
canvas.clear()

local group = canvas.addGroup({ 0, 0 })
local text = group.addText({ 5, 5 }, "")

text.setText("this is NOT a client")

local moduleText = group.addText({ 5, 15 }, table.concat(modules, "\n"))
moduleText.setScale(0.5)
local function enableModule(module)
  table.insert(modules, module)
  moduleText.setText(table.concat(modules, "\n"))
end

local function disableModule(module)
  local idx = getIndex(modules, module)
  table.remove(modules, idx)
  moduleText.setText(table.concat(modules, "\n"))
end

local function isModuleEnabled(module)
  local idx = getIndex(modules, module)
  return idx ~= nil
end

function checkKey()
  while true do
    local event, key, is_held = os.pullEvent("key")
    if keys.getName(key) == "g" then
      if isModuleEnabled("flight") then
        disableModule("flight")
      else
        enableModule("flight")
        timer = os.startTimer(0.5)
      end
    end

  end
end

function flyEvent()
  while true do
    local _, tid = os.pullEvent("timer")
    if tid == timer and isModuleEnabled("flight") then
      timer = os.startTimer(0.5)
      kinetic.launch(0, -90, 4);
    end
  end
end

parallel.waitForAll(checkKey, flyEvent)