QuikPay

if not fs.exists("/.pay_card") then
    print("Let me guide you through first time setup now...")
    if not fs.exists("/paym.lua") then
        print("Downloading PAYM")
        shell.run("pastebin get JQALyCL6 paym")
        os.loadAPI("paym")
    end
    print("Card number")
    local cardnum = read()
    print("CVV?")
    local cvv = read("*")
    print("PIN?")
    local pin = read("#")
    print("Verifying details...")
    local info = paym.verify(cardnum, cvv, pin)
    for i, v in pairs(info) do
        if v == false then
            error(i .. " invalid.")
        end
    end
    local data = {
        num = cardnum,
        cvv = cvv,
        pin = pin
    }
    local handle = fs.open("/.pay_card","w")
    handle.write(textutils.serialise(data))
    handle.close()
end
os.loadAPI("paym")
local handle = fs.open("/.pay_card","r")
local pdata = textutils.unserialise(handle.readAll())
handle.close()
function mm()
term.clear()
term.setBackgroundColor(colors.white)
term.clear()
term.setTextColor(colors.blue)
local w,h = term.getSize()
term.setCursorPos((w - 7) / 2,1)
term.write("QuikPay")
term.setCursorPos(1,3)
term.setTextColor(colors.white)
term.setBackgroundColor(colors.green)
term.write(" Get paid ")
term.setCursorPos(1,5)
term.setBackgroundColor(colors.orange)
term.write(" Pay someone ")
term.setCursorPos(1,7)
term.setBackgroundColor(colors.red)
term.write(" Exit ")
while true do
local _, _, _, y = os.pullEvent("mouse_click")
if y == 3 then
    return 0
end
if y == 5 then
    return 1
end
if y == 7 then
    error("Terminated",2)
end
end
end
function dr()
    term.setBackgroundColor(colors.white)
    term.clear()
    term.setCursorPos(1,1)
    term.setTextColor(colors.black)
    print("Amount?")
    local amount = tonumber(read())
    if not amount then
        error("Invalid amount")
    end
    print("Reason?")
    local reason = read()
    local ok, id = paym.initContactless(amount, pdata.num, reason)
    if ok == false then
        term.setBackgroundColor(colors.black)
        term.setTextColor(colors.white)
        term.setCursorPos(1,1)
        error(id)
    end
    while true do
    print("ID: " .. id)
    print("Press any key to verify")
    os.pullEvent("char")
    local ok, data = paym.checkContactless(id)
    if data.paid == true then
        print("Paid!")
        break
    else
        print("Not yet paid")
    end
    end
end
function pay()
    term.setBackgroundColor(colors.white)
    term.setTextColor(colors.black)
    term.setCursorPos(1,1)
    term.clear()
    print("Payment ID")
    local id = read()
    print("Contacting API")
    local ok, data = paym.checkContactless(id)
    if ok == false then
        error(data)
    end
    for i,v in pairs(data) do
        print(i .. ":" .. tostring(v))
    end
    print("To pay, press \"Y\", else press any key")
    local _,c = os.pullEvent("char")
    if c == "y" or c == "Y" then
        print("Paying")
        local ok, data = paym.payContactless(pdata.num, pdata.cvv, pdata.pin, id)
        if ok == false then
            error(data)
        end
        print("Paid")
    end
end
while true do
    x = mm()
    if x == 0 then
        dr()
    else
        pay()
    end
end