"""Shared thread pool for CPU-bound search (ROADMAP #85, tranche 5).

Holder extrait de :mod:`backend.main` sans changement de comportement :
un seul pool (2 workers, préfixe ``"search"``) créé au démarrage et arrêté
à l'extinction par le lifespan de ``main``. Les routers et les endpoints
restants y accèdent via :func:`get_search_executor` au lieu du global de
``main`` (plus d'import circulaire potentiel).
"""

from __future__ import annotations

from concurrent.futures import ThreadPoolExecutor

_executor: ThreadPoolExecutor | None = None


def init_search_executor(max_workers: int = 2) -> ThreadPoolExecutor:
    """Create (or reuse) the shared search thread pool."""
    global _executor
    if _executor is None:
        _executor = ThreadPoolExecutor(max_workers=max_workers, thread_name_prefix="search")
    return _executor


def shutdown_search_executor() -> None:
    """Stop the shared search thread pool (best-effort, non-blocking)."""
    global _executor
    if _executor is not None:
        _executor.shutdown(wait=False)
        _executor = None


def get_search_executor() -> ThreadPoolExecutor | None:
    """Return the shared search thread pool (``None`` before startup)."""
    return _executor