ComputerCraft Tutorial: key_test0_3

-- ###########################
-- key_test
-- version 0.3
-- http://hevohevo.hatenablog.com/


-- ###########################
-- config
MENU = {}
MENU[1] = "EASY"
MENU[2] = "NORMAL"
MENU[3] = "DIFFICULT"
MENU[4] = "EXIT"

BASE_X = 7
BASE_Y = 7


-- ###########################
-- functions
function moveSymbol(x,y)
  term.write(" ")
  term.setCursorPos(x,y)
  term.write(">")
  term.setCursorPos(x,y)
end

function drowMenu()
  term.clear()
  term.setCursorPos(BASE_X,BASE_Y)
  for i,v in ipairs(MENU) do
    term.write("  "..v)
    term.setCursorPos(BASE_X,BASE_Y+i)
  end
  moveSymbol(BASE_X,BASE_Y)
end

function choose(y)
  if y==1 or y==2 or y==3 then
    term.clear()
    term.setCursorPos(1,1)
    print(MENU[y])
  elseif y == 4 then
    --
  end
end


-- ###########################
-- main
drowMenu()

while true do
  local event, key = os.pullEvent("key")

  if event == "key" then
    local x, y = term.getCursorPos() -- current position
    local rel_y = y - BASE_Y + 1 -- relative position x
    local rel_x = x - BASE_X + 1 -- relative position y

    if key == keys.up and rel_y > 1 then
      moveSymbol(x,y-1)
    elseif key == keys.down and rel_y < #MENU then
      moveSymbol(x,y+1)
    elseif key == keys.space then
      choose(rel_y)
      break
    end
  end

  sleep(0)
end