defmodule VtexWs.Authorization.Admin do
  @moduledoc false

  import Plug.Conn
  @realm "Basic realm=\"Admin\""

  def init(opts), do: opts

  def call(conn, _) do
    correct_auth = [username: System.get_env("ADMIN_USERNAME"), password: System.get_env("ADMIN_PASSWORD")]
    case get_req_header(conn, "authorization") do
      ["Basic " <> attempted_auth] -> verify(conn, attempted_auth, correct_auth)
      _                            -> unauthorized(conn)
    end
  end

  defp verify(conn, attempted_auth, [username: username, password: password]) do
    case encode(username, password) do
      ^attempted_auth -> conn
      _               -> unauthorized(conn)
    end
  end

  defp encode(username, password), do: Base.encode64(username <> ":" <> password)

  defp unauthorized(conn) do
    conn
    |> put_resp_header("www-authenticate", @realm)
    |> send_resp(401, "unauthorized")
    |> halt()
  end
end