defmodule WhoNeedHelpWeb.DrainState do
  @moduledoc """
  Tracks whether the current web node is draining before a planned shutdown.

  The flag is node-local by design. Operators can mark one replica as draining
  through a release RPC; readiness then fails on that replica while liveness
  remains available.
  """

  @key {__MODULE__, :draining}

  @spec reset() :: :ok
  def reset do
    :persistent_term.put(@key, false)
    :ok
  end

  @spec begin_drain() :: :ok
  def begin_drain do
    :persistent_term.put(@key, true)
    :ok
  end

  @spec draining?() :: boolean()
  def draining?, do: :persistent_term.get(@key, false)
end