defmodule Mix.Tasks.JoinRequests.CleanupExpired do
  @moduledoc """
  Hard-deletes JoinRequests in status `pending_confirmation` whose confirmation link has expired.

  Retention: records with `confirmation_token_expires_at` older than now are deleted.
  Intended for cron or Oban (e.g. every hour). See docs/onboarding-join-concept.md.

  ## Usage

      mix join_requests.cleanup_expired

  ## Examples

      $ mix join_requests.cleanup_expired
      Deleted 3 expired join request(s).
  """
  use Mix.Task

  require Ash.Query
  require Logger

  alias Mv.Membership.JoinRequest

  @shortdoc "Deletes join requests in pending_confirmation with expired confirmation token"

  @impl Mix.Task
  def run(_args) do
    Mix.Task.run("app.start")

    now = DateTime.utc_now()

    query =
      JoinRequest
      |> Ash.Query.filter(status == :pending_confirmation)
      |> Ash.Query.filter(confirmation_token_expires_at < ^now)

    # Bypass authorization: cleanup is a system maintenance task (cron/Oban).
    # Use bulk_destroy so the data layer can delete in one pass when supported.
    opts = [domain: Mv.Membership, authorize?: false]

    count =
      case Ash.count(query, opts) do
        {:ok, n} -> n
        {:error, _} -> 0
      end

    do_run(query, opts, count)
  end

  defp do_run(_query, _opts, 0) do
    Mix.shell().info("No expired join requests to delete.")
    0
  end

  defp do_run(query, opts, count) do
    case Ash.bulk_destroy(query, :destroy, %{}, opts) do
      %{status: status, errors: errors} when status in [:success, :partial_success] ->
        maybe_log_errors(errors)
        Mix.shell().info("Deleted #{count} expired join request(s).")
        count

      %{status: :error, errors: errors} ->
        Mix.raise("Failed to delete expired join requests: #{inspect(errors)}")
    end
  end

  defp maybe_log_errors(nil), do: :ok
  defp maybe_log_errors([]), do: :ok

  defp maybe_log_errors(errors) do
    Logger.warning(
      "Join requests cleanup: #{length(errors)} error(s) while deleting expired requests: #{inspect(errors)}"
    )
  end
end