defmodule WykopAPI do
  @moduledoc """

  """

  @doc false
  def get_api_url, do: "http://a.wykop.pl/"

  @doc """
  Returns map as formatted string `"key1,val1,key2,map2"`.
  Keys have to be ordered alfabetically.
  """
  def param_api(map \\ %{}) do
    Map.merge(%{appkey: get_app_key}, map)
    |> Enum.reduce("", fn {k,v}, acc ->
      acc <> ",#{Atom.to_string k},#{v}" end)
    |> String.lstrip(?,)
  end

  def get!(url) do
    HTTPoison.get!(url, [{"apisign", sign(url)}])
    |> Map.get(:body)
  end

  def sign(url, post \\ "") do
    md5(get_secret <> url <> post)
  end

  def sign(app_key, login, token) do
    md5(get_secret <> app_key <> login <> token)
  end

  def get_secret do
    conf = Application.get_env :wykop_api, :app
    conf[:secret]
  end

  def get_app_key do
    conf = Application.get_env :wykop_api, :app
    conf[:app_key]
  end

  defp md5(s) do
    :crypto.hash(:md5, s)
      |> :erlang.bitstring_to_list
      |> Enum.map(&(:io_lib.format("~2.16.0b", [&1])))
      |> List.flatten
      |> :erlang.list_to_bitstring
  end
end