mem

m = peripheral.wrap("top")
m.setTextScale(0.5)
p = peripheral.wrap("back")
noplayer = "No Player"
cplayer = noplayer
color = {}
color.bc = colors.gray
color.vc = colors.lime
color.tc = colors.black

function draw_bar(y)
  size = {term.getSize()}
  term.setCursorPos(1,y)
  for i = 1,size[1] do
    term.write(" ")
  end
end

function cprint(y,text)
  size = {term.getSize()}
  term.setCursorPos(math.ceil((size[1]/2)-(#text/2)+1),y)
  term.write(text)
end

while true do
  --print(cplayer)
  term.redirect(m)
  term.setBackgroundColor(color.bc)
  term.clear()
  term.setBackgroundColor(color.vc)
  size = {term.getSize()}
  draw_bar(1)
  draw_bar(size[2])
  term.setTextColor(color.tc)
  term.setCursorPos(1,1)
  evnt = {os.pullEvent()}
  if evnt[1] == "player_on" then
    if cplayer == noplayer then
      cplayer = evnt[2]
    end
  elseif evnt[1] == "player_off" then
    if cplayer ~= noplayer then
      cplayer = noplayer
    end
  end
  cprint(1,cplayer)
  term.restore()
end