Random Character Gen

local characters = {"`","1","2","3","4","5","6","7","8","9","0","-","=",
  "q","w","e","r","t","y","u","i","o","p","[","]","\\",
  "a","s","d","f","g","h","j","k","l",";","'",
  "z","x","c","v","b","n","m",",",".","/",
  "~","!","@","#","$","%","^","&","*","(",")","_","+",
  "Q","W","E","R","T","Y","U","I","O","P","{","}","|",
  "A","S","D","F","G","H","J","K","L",":",'"',
  "Z","X","C","V","B","N","M","<",">","?"
}
local disabled = {}

local digitnum = 18

while true do
  local code = ""
  term.clear()
  term.setCursorPos(1,1)
  term.setTextColor(colors.white)
  if #characters > 0 then
    for h=1,#characters do
      write(characters[h]..", ")
    end
  end

  term.setTextColor(colors.gray)
  if #disabled > 0 then
    for h=1,#disabled do
      write(disabled[h]..", ")
    end
  end
  term.setTextColor(colors.white)
  print("\n")
  print("Press any key to enable/disable the character or click on any option below.\n")

  print("Digits: <"..digitnum..">")
  print("Generate Code")
  print("Exit\n")

  local event, button, xPos, yPos = os.pullEvent()
  if event == "char" then
    for g=1,94 do
      if button == characters[g] then
        table.insert(disabled, 1, characters[g])
        table.remove(characters, g)
      elseif button == disabled[g] then
        table.insert(characters, 1, disabled[g])
        table.remove(disabled, g)
      end
    end

  elseif event == "key" then
    if button == 203 then
      if digitnum > 1 then
        digitnum = digitnum - 1
      end
    elseif button == 205 then
      digitnum = digitnum + 1
    end
  elseif event == "mouse_click" then
    if xPos >= 1 and xPos <= 13 and yPos == 12 then
      if #characters > 0 then
        for i=1,digitnum do
          local t = math.ceil(math.random(1,#characters))
          code = code..characters[t]
        end

        print(code)

      else
        print("Can't generate a code. All characters are disabled.")
      end

      print("\nPress any button to continue.")
      local event = os.pullEvent("key")

    elseif xPos >= 1 and xPos <= 4 and yPos == 13 then
      break
    elseif xPos == 9 and yPos == 11 then
      if digitnum > 1 then
        digitnum = digitnum - 1
      end
    elseif xPos == 9+string.len(tostring(digitnum))+1 and yPos == 11 then
      digitnum = digitnum + 1
    end
  end
end

shell.run("clear")