defmodule WhoNeedHelpWeb.ClientIp do
  @moduledoc """
  Produces a stable, non-secret rate-limit scope from the client address.

  `Plug.RewriteOn` populates `conn.remote_ip` from the forwarding header that
  Caddy sanitizes at the public edge. The PostgreSQL limiter hashes this value
  before storing it.
  """

  alias Plug.Conn

  def rate_limit_scope(%Conn{remote_ip: address}) when is_tuple(address) do
    case :inet.ntoa(address) do
      value when is_list(value) -> List.to_string(value)
      _invalid -> "unknown"
    end
  end

  def rate_limit_scope(_conn), do: "unknown"
end