MFR spawner system

if fs.exists("events")==false then
    shell.run("pastebin get bmKBU4Rv events")
end
os.loadAPI("events")

if fs.exists("button")==false then
    shell.run("pastebin get hbeLn1ni button")
end
os.loadAPI("button")

--button.setDebugMode(true)
local timer=os.startTimer(1)
button.setMonitorSide("monitor_0")
button.setBackgroundColor(32768)
local monitor=peripheral.wrap("monitor_0")
local spawner=peripheral.wrap("top")
local essenceTank=peripheral.wrap("rcirontankvalvetile_0")

redstone.setOutput("top",true)
function toggleSpawner(bool)
    redstone.setOutput("top",not bool)
    drawDisplay()
end

function setupDisplay()
    local screenx,screeny=monitor.getSize()
    button.removeAllButtons()
    button.addButton(1,screeny-2,screenx,3,"Toggle spawner",toggleSpawner,true,false,128,256)
end
setupDisplay()

function clearLines(start,stop)
    local screenx,screeny=monitor.getSize()
    monitor.setBackgroundColor(128)
    local clearString=""
    for i=1,screenx do
        clearString=clearString.." "
    end
    for i=start,stop do
        monitor.setCursorPos(1,i)
        monitor.write(clearString)
    end
end

function drawDisplay(timer)
    local energy=spawner.getEnergyStored()
    local internalTank=spawner.getTankInfo()
    local exact=spawner.getSpawnExact()
    local fluidAmmount=0
    if internalTank[1]~=nil then
        fluidAmmount=fluidAmmount+internalTank[1].contents.amount
    end
    local essence=essenceTank.getTankInfo()
    if essence[1]~=nil then
        fluidAmmount=fluidAmmount+essence[1].contents.amount
    end
    clearLines(1,7)
    monitor.setCursorPos(5,2)
    monitor.write("Energy : "..energy.." RF")
    monitor.setCursorPos(5,3)
    monitor.write("Essence : "..math.floor(fluidAmmount/100+0.5)*0.1 .." Buckets")
    monitor.setCursorPos(5,5)
    monitor.write("Exact copy : "..tostring(exact))
    monitor.setCursorPos(5,6)
    monitor.write("Active : "..tostring(not redstone.getOutput("top")))
    timer=os.startTimer(1)
end
events.addEventHandler("timer",drawDisplay)
drawDisplay()

while true do
    events.handleCCEvents()
end