Telegram Bot API Web App initData validation in Elixir

telegram_web_app_init_data_validation.ex

def validate_web_app_init_data(tg_init_data, bot_api_token) do
  {received_hash, decoded_map} = 
    tg_init_data
    |> URI.decode_query()
    |> Map.pop!("hash")

  data_check_string =
    decoded_map
    |> Enum.sort(fn {k1, _v1}, {k2, _v2} -> k1 <= k2 end)
    |> Enum.map_join("\n", fn {k, v} -> "#{k}=#{v}" end)

  calculated_hash =
    "WebAppData"
    |> hmac(bot_api_token)
    |> hmac(data_check_string)
    |> Base.encode16(case: :lower)

  if received_hash == calculated_hash do
    {:ok, decoded_map}
  else
    :error
  end
end

def hmac(key, data) do
  :crypto.mac(:hmac, :sha256, key, data)
end