cashRegisterPhone

rednet.open("back")
monitor = peripheral.wrap("top")

server = 3

function displayBalance(balance)
    monitor.clear()
    monitor.setCursorPos(1, 2)
    monitor.write("Welcome!")
    monitor.setCursorPos(1, 4)
    monitor.write("$" .. balance)
end

function checkOut(balance)
    confirmation = false
    rednet.broadcast("buyrequest " .. balance)
    temp, message2 = rednet.receive(nil, 3)
    if message2 == "ping" then
        phoneid = temp
        confirmation = true
    end
    temp, message2 = rednet.receive(nil, 3)
    if message2 == "ping" then
        phoneid = temp
        confirmation = true
    end
    if confirmation then
        print("Request Sent")
        rednet.send(server, "serverbuyrequest " .. balance .. " " .. phoneid)
        id, success = rednet.receive(nil, 60)
        if success ~= "true" then
            print("Server did not return successful payment")
            rednet.send(server, "removebuyrequest " .. balance .. " " .. phoneid)
            newid, success = rednet.receive(nil, 2)
            if success ~= nil then
                print("Order " .. success .. "ly received")
            else
                print("Server did not Respond")
            end
        else
            print("SUCCESS!")
            return true
        end
    else
        print("Phone Response Failed")
    end
    return false
end

function evaluateFormula(formula)
    -- Load the formula as a Lua function
    local func, err = load("return " .. formula)

    -- Check if there was an error compiling the formula
    if not func then
        return nil, "Invalid formula: " .. err
    end

    -- Execute the function and return the result
    local success, result = pcall(func)
    if success then
        return result
    else
        return nil, "Error evaluating formula: " .. result
    end
end

balance = 0
displayBalance(balance)

while true do
    print("type end to confirm order \n")
    print("Current Order: $" .. balance)
    input = io.read()
    if input == "end" then
        success = checkOut(balance)
        if success then
            break
        end
    end
    if input ~= 0 and input ~= "end" then
        balance = balance + evaluateFormula(input)
        displayBalance(balance)
    end
end
monitor.clear()
monitor.setCursorPos(1, 2)
monitor.write("Thank")
monitor.setCursorPos(1, 4)
monitor.write("You!")
os.sleep(5)
displayBalance(0)