Button API

local mon = peripheral.wrap("left")

mon.setTextScale(1)
mon.setTextColor(colors.white)
mon.setBackgroundColor(colors.black)

local button = {}

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

function funcName()
  print("You clicked 'buttonText'")
end

function fillTable() -- Example
  setTable("ButtonText", funcName, 5, 25, 4, 8)
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.red end

    fill(name, currColor, data)
  end
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 toggleButton(name)
  button[name]["active"] = not button[name]["active"]
  screen()
end

function flash(name)
  toggleButton(name)
  screen()
  sleep(0.15)
  toggleButton(name)
  screen()
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"]()
        return true
        -- data["active"] = not data["active"]
        --print(name)
      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