defmodule AocHelpers do
  @moduledoc """
  Documentation for `AocHelpers`.
  """

  @doc """
  Returns the input given the year and day
  """
  @spec get_input(year :: number(), day :: number(), cookie :: String.t()) :: String.t()
  def get_input(year, day, cookie \\ nil) do
    get_input_request(year, day, cookie)
    |> Map.get(:body)
  end

  @doc """
  Returns the input HTTPoison request given the year and day
  """
  @spec get_input_request(year :: number(), day :: number, cookie :: String.t()) ::
          HTTPoison.Response.t()
  def get_input_request(year, day, cookie \\ nil) do
    {:ok, {{_protocol, 200, 'OK'}, headers, body}} =
      :httpc.request(
        :get,
        {'https://adventofcode.com/#{year}/day/#{day}/input',
         build_cookie(cookie)},
        [],
        []
      )
    %{
      headers: parse_headers(headers),
      body: to_string(body)
    }
  end

  defp parse_headers(headers, parsed \\ %{})
  defp parse_headers([], parsed), do: parsed
  defp parse_headers([{key, value} | rest], parsed) do
    parse_headers(rest, Map.put(parsed, to_string(key), to_string(value)))
  end

  defp build_cookie(nil), do: System.fetch_env!("AOC_COOKIE") |> build_cookie()
  defp build_cookie(cookie), do: [{'cookie', String.to_charlist("session=" <> cookie)}]
end