Contract record system

local Categories = {{"property","construction","service","product"},{0.05,0.02,0.05,0.03}}

local function Clear()
term.clear()
term.setCursorPos(1,1)
end

local function TextField()
local input
local TX, TY = term.getCursorPos()
TY = TY - 1
while true do
  term.setCursorPos(TX,TY)
  term.clearLine()
  term.write()
  local e, a, b, c = os.pullEvent("key")
  if a == keys.enter then break elseif e == "key" then input = read(C) end
end
return input
end

local function OptionListSide(Y,Options)
local n = 1
while true do
  term.setCursorPos(1,Y)
  term.clearLine()
  term.write(Options[n])
  local a, b = os.pullEvent("key")
  if b == keys.a and n > 1 then n = n - 1 end
  if b == keys.d and n < #Options then n = n + 1 end
  if b == keys.enter then break end
end
return n
end

local function Menu()
Clear()
print("==Contract Recorder==")
print("1. Enter Company Name")
local C1 = TextField()
print("2. Enter Customer name/ Company")
local C2 = TextField()
print("3. Enter Amount")
local Amount = tonumber(TextField())
print("4. select Category")
local Opt = OptionListSide(9,Categories[1])
local Tax = Categories[2][Opt]
print("processing, please wait")
print("Subtotal: "..Amount)
print("Tax ("..Tax.."): "..(Amount*Tax))
print("total: "..(Amount+(Amount*Tax)))
print("creating file")
end