Refactor configuration variable lookup (#13)

Refactor configuration variable lookup.

Change the `Application.get_env/3` calls to use  `Recaptcha.Config.get_env/3` to perform the lookups. Doing so allows the project to defer environment variable lookup to runtime instead of only at compile-time.

4 files changed, 30 insertions, 4 deletions

diff --git a/lib/recaptcha.ex b/lib/recaptcha.ex
index 3108add..0757785 100644
--- a/lib/recaptcha.ex
+++ b/lib/recaptcha.ex
@@ -5,6 +5,9 @@ defmodule Recaptcha do
     See the [documentation](https://developers.google.com/recaptcha/docs/verify)
     for more details.
   """
+
+  alias Recaptcha.Config
+
   @http_client Application.get_env(:recaptcha, :http_client, Recaptcha.Http)
 
   @doc """
@@ -48,7 +51,7 @@ defmodule Recaptcha do
 
   defp request_body(response, options) do
     body_options = Keyword.take(options, [:remote_ip, :secret])
-    application_options = [secret: Application.get_env(:recaptcha, :secret)]
+    application_options = [secret: Config.get_env(:recaptcha, :secret)]
 
     # override application secret with options secret if it exists
     application_options
diff --git a/lib/recaptcha/config.ex b/lib/recaptcha/config.ex
new file mode 100644
index 0000000..022fe41
--- /dev/null
+++ b/lib/recaptcha/config.ex
@@ -0,0 +1,19 @@
+defmodule Recaptcha.Config do
+  @moduledoc """
+  Provides application/system environment variable lookup at runtime
+  """
+
+  @doc """
+  Returns the requested variable
+  """
+  @spec get_env(atom, atom, atom | map) :: term
+  def get_env(application, key, default \\ nil) do
+    application
+    |> Application.get_env(key, default)
+    |> _get_env()
+  end
+
+  defp _get_env({:system, env_variable}), do: System.get_env(env_variable)
+  defp _get_env(value), do: value
+
+end
diff --git a/lib/recaptcha/http.ex b/lib/recaptcha/http.ex
index b21f8f0..a9aaf0f 100644
--- a/lib/recaptcha/http.ex
+++ b/lib/recaptcha/http.ex
@@ -2,6 +2,9 @@ defmodule Recaptcha.Http do
   @moduledoc """
    Responsible for managing HTTP requests to the reCAPTCHA API
   """
+
+  alias Recaptcha.Config
+
   @headers [
     {"Content-type", "application/x-www-form-urlencoded"},
     {"Accept", "application/json"}
@@ -34,8 +37,8 @@ defmodule Recaptcha.Http do
   """
   @spec request_verification(map, [timeout: integer]) :: {:ok, map} | {:error, [atom]}
   def request_verification(body, options \\ []) do
-    timeout = options[:timeout] || Application.get_env(:recaptcha, :timeout, 5000)
-    url = Application.get_env(:recaptcha, :verify_url, @default_verify_url)
+    timeout = options[:timeout] || Config.get_env(:recaptcha, :timeout, 5000)
+    url = Config.get_env(:recaptcha, :verify_url, @default_verify_url)
 
     result =
       with {:ok, response} <- HTTPoison.post(url, body, @headers, timeout: timeout),
diff --git a/lib/recaptcha/template.ex b/lib/recaptcha/template.ex
index 008a63d..d3970d5 100644
--- a/lib/recaptcha/template.ex
+++ b/lib/recaptcha/template.ex
@@ -8,6 +8,7 @@ defmodule Recaptcha.Template do
     In future this module may be separated out into a Phoenix specific library.
   """
   require Elixir.EEx
+  alias Recaptcha.Config
 
   EEx.function_from_file :defp, :render_template, "lib/template.html.eex", [:assigns]
 
@@ -17,7 +18,7 @@ defmodule Recaptcha.Template do
   To convert the string to html code, use Phoenix.HTML.Raw/1 method
   """
   def display(options \\ []) do
-    public_key = options[:public_key] || Application.get_env(:recaptcha, :public_key)
+    public_key = options[:public_key] || Config.get_env(:recaptcha, :public_key)
     render_template(public_key: public_key, options: options)
   end
 end