Password Encrypter (WIP)

--=== Variables ===--
local filePath = "save.pass"
local settings = {
  back = colors.black,
  text = colors.white
}
local w,h = term.getSize()
os.loadAPI("aes")

--=== Functions ===--
local function clear()
  term.clear()
  term.setCursorPos(1,1)
end

local function scrollRead(x,y,nLength,insertText) --This is a simple scrolling-read function I made
  if insertText then
    insertText = tostring(insertText)
    cPos = #insertText+1
    cInput = insertText
  else
    cPos = 1
    cInput = ""
  end
  term.setCursorBlink(true)
  while true do
    term.setCursorPos(x,y)
    term.write(string.rep(" ",nLength))
    term.setCursorPos(x,y)
    if string.len(cInput) > nLength-1 then
      term.write(string.sub(cInput,(nLength-1)*-1))
    else
      term.write(cInput)
    end
    if cPos > nLength-1 then
      term.setCursorPos(x+nLength-1,y)
    else
     term.setCursorPos(x+cPos-1,y)
    end
    local event,p1 = os.pullEvent()
    if event == "char" then
      cInput = string.sub(cInput,1,cPos)..p1..string.sub(cInput,cPos+1)
      cPos = cPos + 1
    elseif event == "key" then
      if p1 == keys.enter then
        break
      elseif p1 == keys.backspace then
        if cPos > 1 then
          cInput = string.sub(cInput,1,cPos-2)..string.sub(cInput,cPos)
          cPos = cPos - 1
        end
      elseif p1 == keys["end"] then
        cPos = string.len(cInput)+1
      end
    end
  end
  term.setCursorBlink(false)
  return cInput
end

function printC(text,y,screen)--Prints text centered at y on screen (term or monitor)
  if not text then error("expected string,number",2) end
  y = tonumber(y)
  if not y then error("expected string,number",2) end
  screen = screen or term
  local tLenght = #tostring(text)
  local sStart = math.ceil(w/2-tLenght/2)
  local sEnd = sStart + tLenght
  screen.setCursorPos(sStart,y)
  screen.write(text)
  return sStart,sEnd
end


--=== Program ===--
term.setBackgroundColor(settings.back)
clear()
term.setTextColor(settings.text)
printC("Welcome to Password Encrypter",2)

--local hasBeenOpened = false
--if fs.exists(filePath) then -- Was likely used before, get password
--  printC("Enter master password",5)
--  local pass = scrollRead(14,6,10)

--end
local continue = true
while continue do
  printC("Enter a key:",5)
  printC("Enter a secret:",8)
  local key = scrollRead(17,6,17)
  local input = scrollRead(17,9,17)

  printC("Preforming Calculations...",h)

  local enc = aes.encrypt(key,input)
  local f = fs.open(filePath,"wb")
  for i = 1, #enc do
    local cur = string.sub(enc,i,i)
    if cur == "\n" then error("newline Detected!") end
    f.write(string.byte(cur))
  end
  f.close()
  local f2 = fs.open(filePath,"rb")
  local dec = ""
  for byte in f2.read do
    dec = dec..string.char(byte)
  end
  f2.close()
  dec = aes.decrypt(key,dec)

  clear()
  printC("Key:",2)
  printC(key,3)

  printC("Secret",5)
  printC(input,6)

  printC("Encrypted:",8)
  term.setTextColor(colors.black)
  term.setBackgroundColor(colors.white)
  printC(enc,9)
  term.setTextColor(colors.white)
  term.setBackgroundColor(colors.black)

  printC("Decrypted:",11)
  printC(dec,12)

  printC("Press 'Enter' to continue",h)
  repeat
    local event,tKey = os.pullEvent("key")
  until tKey == keys.enter

  clear()
end