Red Timer

precision = 10
defaultLength = 12000
lines = 4
args = { ... }
timerLength = false

function main()
  if #args > 0 then
     timerLength = tonumber(args[1])
     setFS("time",timerLength)
     setFS("cycle","0")
     setFS("pos","0")
  else
     timerLength = tonumber(getFS("time"))
     if not timerLength then
        timerLength = defaultLength
     end
  end
  resuming = getFS("cycle")
  cycle = 1
  term.clear()
  writeCentered("[RED TIMER]",0,lines)
  while (true) do
    if resuming then
      cycle = resuming
      resuming = false
      timerPos = tonumber(getFS("pos"))
    else
      timerPos = timerLength
    end
    setFS("cycle",cycle)
    while timerPos > 0 do
      percent = 100 - math.ceil( timerPos*100 / timerLength )
      writeCentered("cycle: "..cycle,1,lines)
      writeCentered(timerPos.."/"..timerLength.."  "..percent.."%",2,lines)
      writeCentered(getpString(percent),3,lines)
      os.sleep(precision)
      timerPos = timerPos - precision
      setFS("pos",timerPos)
    end
    rs.setOutput("back", true)
    writeCentered("[EMIT SIGNAL]",3,lines)
    sleep(2)
    rs.setOutput("back", false)
    cycle  = cycle + 1
  end
end

function setFS(name,value)
   file = io.open("timer."..name,"w")
   file:write(value)
   file:close()
end

function getFS(name)
  local result = false
  file = io.open("timer."..name, "r")
  if file==nil then
    return 0
  end
  result = file:read()
  file:close()
  return result
end

function getpString(percent)
  local x, y = term.getSize()
  local string = "["
  for i = 0,x-8 do
     if (i < (percent/100 * (x - 8))) then
       string = string.."#"
     else
       string = string.."-"
     end
  end
  return string.."]"
end

function writeCentered( text , yd , yLines)
  local x, y = term.getSize()
  local centerYPos = ((y - yLines) / 2)
  local centerXStartingPos = ( x - string.len(text) ) / 2
  term.setCursorPos( centerXStartingPos, centerYPos + yd )
  term.clearLine()
  write( text )
end

main()