My First Pogramm

local mon = peripheral.wrap("left")
mon.setTextScale(0.5)
mon.setTextColor(colors.white)
local button={}
mon.setBackgroundColor(colors.black)

function setTable(name, xmin, xmax, ymin, ymax, col)
   button[name] = {}
   button[name]["active"] = false
   button[name]["xmin"] = xmin
   button[name]["ymin"] = ymin
   button[name]["xmax"] = xmax
   button[name]["ymax"] = ymax
   button[name]["colour"] = col
end

function fillTable()
   setTable("Einschalten", 2, 16, 10, 14, colours.blue)
   setTable("Ausschalten", 21, 35, 10, 14, colours.red)
end

function fill(text, color, bData)
   mon.setBackgroundColor(color)
   local yspot = math.floor((bData["ymin"] + bData["ymax"]) /2)
   local xspot = math.floor((bData["xmax"] - bData["xmin"] - string.len(text)) /2) +1
   for j = bData["ymin"], bData["ymax"] do
      mon.setCursorPos(bData["xmin"], j)
      if j == yspot then
         for k = 0, bData["xmax"] - bData["xmin"] - string.len(text) +1 do
            if k == xspot then
               mon.write(text)
            else
               mon.write(" ")
            end
         end
      else
         for i = bData["xmin"], bData["xmax"] do
            mon.write(" ")
         end
      end
   end
   mon.setBackgroundColor(colors.black)
end

function screen()
   local currColor
   for name,data in pairs(button) do
      local on = data["active"]
      if on == true then currColor = colors.lime else currColor = colors.lightGray end
      fill(name, currColor, data)
   end
end

function checkxy(x, y)
   local new = false
   local newname
   for name, data in pairs(button) do
      data["active"] = false
      if y>=data["ymin"] and  y <= data["ymax"] then
         if x>=data["xmin"] and x<= data["xmax"] then
            rs.setBundledOutput("bottom", data["colour"])
            new = true
            newname = name
         end
      end
   end
   if new then
      button[newname]["active"] = true
   end
end

function heading(text)
   w, h = mon.getSize()
   mon.setCursorPos((w-string.len(text))/2+1, 1)
   mon.write(text)
end

function checkRedstone()
   local c = rs.getBundledInput("back")
   if rs.getBundledOutput("bottom") ~= c then
      rs.setBundledOutput("bottom", 0)
      for name, data in pairs(button) do
         if data["colour"] == c then
            data["active"] = true
         else
            data["active"] = false
         end
      end
   end
end

fillTable()
while true do
   mon.clear()
   heading("Please Select Floor")
   screen()
   local e,side,x,y = os.pullEvent()
   if e == "monitor_touch" then
      checkxy(x,y)
   else
      if e == "redstone" then
         checkRedstone()
      else
      end
   end
   sleep(.1)
end