chest = peripheral.wrap("back")
dir = "EAST"
chest.pullItem(dir,1)
sleep(1)
local numBooks = #chest.getAllStacks()
print("Portal Randomizer")
print("-----------------")
print("Number of Locations: " .. numBooks)
local useSlot = 1
function showInfo()
  local powered = rs.getInput("top")
  refreshLine("Powered: " .. tostring(powered),7)
  if powered then
    refreshLine("Using: " .. useSlot,8)
  end
end
function refreshLine(t,l)
  term.setCursorPos(1,l)
  term.clearLine()
  term.setCursorPos(1,l)
  term.write(t)
end
while true do
  if rs.getInput("top") then
    useSlot = math.random(numBooks)
    showInfo()
    chest.pushItem(dir,useSlot)
    sleep(1)
    chest.pullItem(dir,1)
  else
    showInfo()
    sleep(1)
  end
end