ExTwilio.Signature for creating a "x-twilio-signiture" string

[estermer]

I was recently writing some testing for an authorization plug that I wrote that uses the ExTwilio.RequestValidator and could not find a module or method that can create a x-twilio-token to put to my tests Plug.Conn header.

I propose we take this functionality that builds the token in the validator and make a module that creates a twilio signature if you pass in say url and params which may making unit testing controllers and plugs that are using the validator easier!

def create_signature(url, params) do
    token = Config.auth_token()

    url
    |> data_for(params)
    |> compute_hmac(token)
    |> Base.encode64()
  end

  defp data_for(url, params), do: url <> combine(params)

  defp combine(params) do
    params
    |> Map.to_list()
    |> Enum.sort()
    |> Enum.map(fn {key, value} -> key <> value end)
    |> Enum.join()
  end

  defp compute_hmac(data, key), do: :crypto.hmac(:sha, key, data)