startup

local b = peripheral.wrap("back")
local e=0
local lastE=0
local diff=0
local mon=peripheral.find("monitor")

local function mw(txt,x,y,col)
  for _,name in pairs(peripheral.getNames()) do
    if peripheral.getType(name)=="monitor" then
      mm=peripheral.wrap(name)
      mm.setCursorPos(x,y)
      mm.setTextColour(col)
      mm.write(txt)
    end
  end
end


local function padLeft(str,_w)
  return string.rep(" ",_w)..str
end

local function nf(n,l)
  local str=tostring(n)
  local n=string.len(str)
  local so=""

  while n>2 do
    so=","..string.sub(str,n-2)..so
    str=string.sub(str,1,n-3)
    n=string.len(str)
  end
  so=str..so
  if string.sub(so,1,1)=="," then
    so=string.sub(so,2)
  end

  n=string.len(so)
  if n~=nil then
    if l>n then
      l=l-n
      so=padLeft(so,l)
    end
   end
  return so
end



while true do
  e=b.getEnergyStored()
  diff=math.floor((e-lastE)/20)

  print(nf(e,18))
  print(nf(diff,18))

  mw(nf(e,18),1,1,colors.blue)
  mw(nf(diff,18),1,2,colors.red)

  lastE=e
  os.sleep(1)
end