defmodule IsIpv4Address do
  def is_ipv4_address(input_string) do
    parts = String.split(input_string, ".")

    length(parts) == 4 and Enum.all?(parts, &valid_octet?/1)
  end

  defp valid_octet?(v) do
    case Integer.parse(v) do
      {n, ""} -> n >= 0 and n <= 255 and Integer.to_string(n) == v
      _ -> false
    end
  end
end