Recruit Hot Pepper API for Elixir

hot_pepper.ex

defmodule HotPepperApi do
  @hit_per_page 50

  def get_shops({addr, freeword}) do
    iget_shops({addr, freeword}, 1, [])
  end
  # ページング：最終ページ
  def iget_shops({_addr, _freeword}, _offset, [%{:islast => true}|result] ) do
    result
  end

  def iget_shops({addr, freeword}, offset, res_shops) do
    page_max_cnt = @hit_per_page
    res = 
      HTTPoison.get!( access_url("http://webservice.recruit.co.jp/hotpepper/gourmet/v1/",[
        "address=" <> addr,
        "keyword=" <> freeword,
        "count="   <> to_string(page_max_cnt),
        "start="   <> Integer.to_string((offset - 1)* page_max_cnt + 1)
      ]) )
      |> parse_json
      |> case do
            %{"error"   => e} -> e
            %{"results" => res} ->
                res["shop"]
                |> Enum.map( fn r -> { r["name"], "N/A", r["genre"]["catch"], r["open"] } end)
                |> case do shop_list -> [ shops:           shop_list ++ 
                                                           case res_shops do
                                                               [] -> []
                                                               _  -> res_shops[:shops]
                                                           end,
                                          total_hit_count: res["results_available"],
                                          hit_per_page:    @hit_per_page,
                                          hit_count:       res["results_returned"],
                                          offset:          offset] end
      end
    # ページング：残行カウント
    rest_count = res[:total_hit_count] - offset * res[:hit_per_page]
    IO.inspect  res: res
    IO.inspect  res_cnt: rest_count
    iget_shops({addr, freeword}, offset+1, [%{:islast => (rest_count <= 0)}] ++ res)
  end

  def access_url(url_base, opts\\[]) do
    api_key = Application.get_env(:groumet, :apis)[:recruit_api_key]
    url_base
        <> "?"
        <> Enum.join( [ "format="<>"json", "key="<>api_key ] ++ opts, "&")
  end

  def parse_json( %HTTPoison.Response{status_code: 200, body: body} ) do
    body
    |> Poison.decode!
  end
end