#!/usr/bin/env -S ERL_FLAGS=+B elixir
Mix.install([{:nimble_totp, ">= 1.0.0"},{:yaml_elixir, "~> 2.9"}])

if System.get_env("DEPS_ONLY") == "true" do
  System.halt(0)
  Process.sleep(:infinity)
end

defmodule TOTP do
  @moduledoc """

  ## Usage

      $ totp-code get-code identifier

      $ totp-code list-identifiers

      $ totp-code set-secret identifier secret # men at work

  """
  def main([]), do: cmd("help", [])
  def main(argv) do
    [command | args] = argv
    cmd(command, args)
  end

  defp cmd("get-code", [identifier]) do
    get_secret(identifier)
    |> Base.decode32!()
    |> NimbleTOTP.verification_code()
    |> IO.write()
  end

  defp cmd("list-identifiers", _) do
    read_config()
    |> Map.get("secrets")
    |> Map.keys()
    |> Enum.join("\n")
    |> IO.puts()
  end

  defp cmd("help", _), do: IO.puts(@moduledoc)

  defp read_config() do
    System.user_home()
    |> Path.join(".totp-code.conf")
    |> YamlElixir.read_from_file!()
  end

  defp get_secret(identifier) do
    read_config()
    |> Map.get("secrets")
    |> Map.get(identifier)
  end
end

TOTP.main(System.argv())