Receipt System

function pos(x, y)
 term.setCursorPos(x or 1, y or 1)
end

function c(x, y)
 term.clear()
 pos(x, y)
end

local side
local sides = {"top", "bottom", "left", "right", "front", "back"}

while true do
 local clear
 c()
 print("Printer is on which side?")
 local input = read()
 for i = 1, 6 do
  if sides[i] == input then
   clear = true
  end
 end
 if clear then
  side = input
  break
 end
end

local printer = peripheral.wrap(side)
local name

while true do
 local clear
 c()
 print("Who is this receipt for?")
 local input = read()
 name = input
 break
end

local items = {}
local length = 5

while true do
 c()
 print("Please enter item name")
 print("Try to make it as short as possible")
 print("Leave blank to print receipt")
 local input = read()
 if input:len() == 0 then
  break
 end
 if input:len() + 1 > length then
  length = input:len() + 1
 end
 c()
 while true do
  print("Price in credits? Must be a number.")
  print("Leave blank to cancel.")
  print("Set to 0 if it is free")
  local input2 = read()
  if input2 == "" then
   break
  end
  if tonumber(input2) then
   if input2 == "0" then
    input2 = "FREE"
   end
   items[#items+1] = {input, input2}
   break
  end
 end
end

local totalPrice = 0

printer.newPage()
printer.write("Item" .. string.rep(" ", length - 4) .. "Price")

for i = 1, #items do
 local item = items[i][1]
 local price = items[i][2]
 printer.setCursorPos(1, i + 2)
 printer.write(item .. string.rep(" ", length - item:len()) .. price)
 if tonumber(price) then
  totalPrice = totalPrice + price
 end
end

printer.setCursorPos(1, #items + 4)
printer.write("Total price: " .. totalPrice)

printer.setPageTitle("Receipt: " .. name)
printer.endPage()
c()
print("Page has been printed. The program will now exit.")
sleep(2)
c()