mon = peripheral.find("monitor")

if not mon then
  error("no monitor")
end

mon.setTextScale(1)
mon.setTextColor(colors.white)
mon.setBackgroundColor(colors.black)
button = {}


function clearAll()
  button = {}
  mon.clear()
end

function addButton(name, func, xmin, xmax, ymin, ymax, color, activeColor)
  color = color or colors.red
  activeColor = activeColor or colors.lime
  button[name] = {}
  button[name]["func"] = func
  button[name]["active"] = false
  button[name]["xmin"] = xmin
  button[name]["ymin"] = ymin
  button[name]["xmax"] = xmax
  button[name]["ymax"] = ymax
  button[name]["color"] = color
  button[name]["activeColor"] = activeColor
end


function screenButton()
  local currColor
  for name, data in pairs(button)do
    local active = data["active"]
    if active  == true then
      currColor = data["activeColor"]
    else
      currColor = data["color"]
    end
    fillButton(name, currColor, data)
  end
end



function fillButton(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 toggleButton(name)
  button[name]["active"] = not button[name]["active"]
  screenButton()
end

function flash(name)
  toggleButton(name)
  sleep(0.15)
  toggleButton(name)
end

function checkxy(x, y)
  for name, data in pairs(button) do
    if y>=data["ymin"] and y<= data["ymax"] then
      if x>=data["xmin"] and x<=data["xmax"] then
        data["func"]()
        flash(name)
        return true
      end
    end
  end
  return false
end


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

function label(w, h, text)
  mon.setCursorPos(w, h)
  mon.write(text)
end