-- Program by TheOriginalBIT
-- CC Forums Profile: http://www.computercraft.info/forums2/index.php?/user/1217-theoriginalbit/

local function niceError( msg )
  printError( msg )
  error()
end

local function findPeripheral( t )
  for _,side in pairs(rs.getSides()) do
    if peripheral.getType(side) == t then
      return side
    end
  end

  niceError( 'No '..t..' attached to the computer' )
end

local monitorSide = findPeripheral('monitor')
local monitor = peripheral.wrap( monitorSide )

if not monitor.isColor() then
  niceError( 'No advanced monitor attached to the computer' )
end

term.redirect(monitor)

local sw, sh = term.getSize()

--[[
#################################

EDIT THESE VARIABLES TO CUSTOMISE

#################################
]]--

local redstoneSide = 'back'
local pulseLength = 1

local topLine = 'Some Text'
local topLineX = sw / 2 - #topLine / 2 + (#topLine % 2 == 0 and 1 or 0) -- centre of screen
local topLineY = sh / 2 - 3

local buttonLine = 'Teleport'
local buttonW = #buttonLine + 2
local buttonH = 3
local buttonX = sw / 2 - buttonW / 2
local buttonY = sh / 2 - 1

local bottomLine = 'Some Text'
local bottomLineX = sw / 2 - #topLine / 2 + (#topLine % 2 == 0 and 1 or 0) -- centre of screen
local bottomLineY = sh / 2 + 3

local backColor = colors.black
local topLineTextColor = colors.white
local bottomLineTextColor = colors.white
local buttonBackColor = colors.lightBlue
local buttonTextColor = colors.white

-- END EDITABLE VARIABLES --

local function drawGui()
  term.setBackgroundColor(backColor)
  term.setTextColor(topLineTextColor)

  term.setCursorPos(topLineX, topLineY)
  write(topLine)

  term.setTextColor(bottomLineTextColor)

  term.setCursorPos(bottomLineX, bottomLineY)
  write(bottomLine)

  term.setBackgroundColor(buttonBackColor)
  term.setTextColor(buttonTextColor)

  for i = 0, buttonH - 1 do
    term.setCursorPos(buttonX, buttonY + i)
    write( string.rep( ' ', buttonW) )
  end

  term.setCursorPos(math.ceil(buttonX + (buttonW / 2) - (#buttonLine / 2) - 1), math.ceil(buttonY + (buttonH / 2) - 1) )
  write(buttonLine)
end

local function processInput(mouseX, mouseY)
  if mouseX >= buttonX - 1 and mouseX <= buttonX + buttonW - 1 and mouseY >= buttonY and mouseY <= buttonY + buttonH then
    rs.setOutput(redstoneSide, true)
    os.startTimer(pulseLength)
    os.pullEvent('timer')
    rs.setOutput(redstoneSide, false)
  end
end

term.setBackgroundColor(backColor)
term.setTextColor(textColor)
term.clear()

while true do
  drawGui()
  local e, s, x, y = os.pullEventRaw()
  if e == 'monitor_touch' and s == monitorSide then
    processInput(x, y)
  elseif e == 'terminate' then
    term.restore()
    error()
  end
end