[Computercraft] Login Mask

--(C) Corona 2013
--DO NOT STEAL THIS CODE!!!
os.loadAPI(shell.dir().."/screen")

local version = 1.2
local maxx,maxy = term.getSize()
local cb = false
local cp=1
local tmpstr = ""
local password = "Corona"
local msg = "Please Log In:"

local loginButton = {x1=(maxx/2-15),x2=(maxx/2+15),y1=(maxy/2+6),y2=(maxy/2+10),color=colors.lightBlue,text="LOGIN"}
local loginArea = {x1=(maxx/2-20),x2=(maxx/2+20),y1=(maxy/2),y2=(maxy/2+3),color=colors.lightBlue,text={}}
local wrongPassword = {x1=(maxx/2-20),x2=(maxx/2+20),y1=(maxy/2-5),y2=(maxy/2+5),text="WRONG PASSWORD",color=colors.red}

function cls()
  term.clear()
  term.setCursorPos(1,1)
end
function empty(tab)
  for i=1,#tab do
    tab[i]=nil
  end
end
function login()
  term.setCursorPos(1,1)

  for i=1,#loginArea["text"] do
    tmpstr = tmpstr..(loginArea["text"][i])
  end
  if tmpstr == password then
    cls()
    print("Correct Password! Login Mask Version "..version)
    error()
  end
  term.setCursorBlink(false)
  screen.drawButton(wrongPassword)
  sleep(2)
  tmpstr=""
  cp=1
  empty(loginArea["text"])
  cls()
  term.setCursorBlink(true)
end


cls()
while true do

  term.setCursorPos(maxx/2-#msg/2,maxy/2-5)
  term.write(msg)
  screen.drawBox(loginArea)
  screen.drawButton(loginButton)
  screen.getFocus(loginArea)
  local tx,ty = term.getCursorPos()
  term.setCursorPos(tx+cp-1,ty)
  local evn,mixed,x,y = os.pullEvent()
  if evn == "mouse_click" then
    if screen.pressed(loginButton,x,y) then
      login()
    end
    if screen.pressed(loginArea,x,y) then
      term.setCursorBlink(true)
      cb = true
    else
      term.setCursorBlink(false)
      cb = false
    end
  end
  if (evn == "char") and (cb) and (cp<(loginArea["x2"]-loginArea["x1"]-1)) then
    loginArea["text"][cp] = mixed
    write("*")
    cp = cp+1
  end
  if (evn == "key") and (cb) then
    if (mixed == 14) and (cp>1) then
      cp = cp-1
      local xt,yt = term.getCursorPos()
      term.setCursorPos(xt-1,yt)
      write(" ")
      loginArea["text"][cp] = nil
      elseif mixed == 28 then
      login()
    end
  end
end