"""Deprecated, lazy compatibility facade for the Controller v2 service.

New deployments use :mod:`wsgi`.  These functions remain for local callers
that imported the original module, but importing this module never opens the
database, creates directories, starts threads, or connects to MQTT.
"""

from __future__ import annotations

import threading
from typing import Any

from controller.config import ControllerConfig, load_config
from controller.service import ControllerService, ControllerUnavailableError


_lifecycle_lock = threading.Lock()
_service: ControllerService | None = None
_config: ControllerConfig | None = None

# Kept as transition indicators for integrations that inspected the old module.
mqtt_client: Any | None = None
mqtt_started = False


def start_controller() -> None:
    """Construct and start the singleton compatibility service explicitly."""

    global _config, _service, mqtt_client, mqtt_started
    with _lifecycle_lock:
        if _service is not None and _service.started:
            return
        config = load_config()
        service = ControllerService(config)
        service.start()
        _config = config
        _service = service
        mqtt_client = service.mqtt
        mqtt_started = True


def stop_controller() -> None:
    """Stop and discard the singleton compatibility service."""

    global _config, _service, mqtt_client, mqtt_started
    with _lifecycle_lock:
        service = _service
        if service is not None:
            service.stop()
        _service = None
        _config = None
        mqtt_client = None
        mqtt_started = False


def get_service() -> ControllerService:
    """Return the explicitly started compatibility service."""

    with _lifecycle_lock:
        if _service is None or not _service.started:
            raise ControllerUnavailableError(
                "Controller is not started; call start_controller() first"
            )
        return _service


def enqueue_download(
    url: str,
    submitter: str | None = None,
    note: str | None = None,
) -> dict[str, Any]:
    """Queue a download through Controller v2."""

    return get_service().enqueue_download(url, submitter, note)


__all__ = [
    "enqueue_download",
    "get_service",
    "mqtt_client",
    "mqtt_started",
    "start_controller",
    "stop_controller",
]