ex_chimp

defmodule ExChimp.Client do
  @moduledoc """
  API client.
  """
  use HTTPoison.Base

  def process_request_url(url), do: base_url() <> url
  def process_response_body(""), do: nil
  def process_response_body(body), do: Jason.decode!(body)

  def process_request_headers(headers) do
    base_api_key = Base.encode64(":#{api_key()}")

    (headers ++
       [
         {"Authorization", "Basic #{base_api_key}"},
         {"Content-type", "application/json"}
       ])
    |> Enum.uniq_by(fn {key, _} -> key end)
  end

  defp base_url do
    shard = extract_shard()
    "https://#{shard}.api.mailchimp.com/3.0/"
  end

  defp api_key, do: ExChimp.config(:api_key) || ""

  defp extract_shard do
    case String.split(api_key(), "-") do
      [_, shard_key] -> shard_key
      _ -> raise "Could not extract shard from API-key. Please check your API key."
    end
  end
end