# -------------------------------------------------------------
# queue_helper.py  –  minimalistisch thread‑based wachtrij‑manager
# -------------------------------------------------------------
import threading, queue, uuid, time
from typing import Callable, Any, Dict

# ------------------------------------------------------------------
# Configuratie – pas eventueel aan
# ------------------------------------------------------------------
USER_MAX_QUEUE   = 20   # max. wachtende gebruikers
AGENT_MAX_QUEUE  = 50   # max. wachtende agents (stil)
UPDATE_INTERVAL  = 10.0  # sec tussen “position‑update” berichten
WORKER_TIMEOUT   = 30.0 # max. tijd die een inference mag duren
# ------------------------------------------------------------------

class _Job:
    __slots__ = ("job_id","payload","callback","created_at","event","result","error")
    def __init__(self, payload: Dict, callback: Callable[[Dict], None]):
        self.job_id   = str(uuid.uuid4())
        self.payload  = payload
        self.callback = callback
        self.created_at = time.time()
        self.event    = threading.Event()
        self.result   = None
        self.error    = None
    def set_success(self, answer: Dict):
        self.result = answer
        self.event.set()
        self.callback(answer)
    def set_error(self, exc: Exception):
        self.error = str(exc)
        self.event.set()
        self.callback({"error": self.error})

class QueueManager:
    """Beheert één gedeelde queue + één worker‑thread."""
    def __init__(self, model_infer_fn: Callable[[Dict], Dict]):
        self._infer_fn = model_infer_fn
        self._user_q  = queue.Queue(maxsize=USER_MAX_QUEUE)
        self._agent_q = queue.Queue(maxsize=AGENT_MAX_QUEUE)
        self._shutdown = threading.Event()
        self._worker   = threading.Thread(target=self._run_worker,
                                          daemon=True,
                                          name="LLM‑worker")
        self._worker.start()

    # ---------- public API ----------
    def enqueue_user(
        self,
        payload: Dict,
        progress_cb: Callable[[Dict], None],
        *,
        notify_position: bool = False,
    ) -> tuple[str, int]:
        job = _Job(payload, progress_cb)
        try: self._user_q.put_nowait(job)
        except queue.Full: raise RuntimeError(f"User‑queue vol (≥{USER_MAX_QUEUE})")
        position = self._user_q.qsize()
        if notify_position:
            # start een aparte notifier-thread die periodiek de wachtrijpositie meldt
            start_position_notifier(job, self._user_q)
        return job.job_id, position

    def enqueue_agent(self, payload: Dict, progress_cb: Callable[[Dict], None]) -> str:
        job = _Job(payload, progress_cb)
        try: self._agent_q.put_nowait(job)
        except queue.Full: raise RuntimeError(f"Agent‑queue vol (≥{AGENT_MAX_QUEUE})")
        return job.job_id

    # ---------- sync helper voor agents/tools ----------
    def request_agent_sync(self, payload: Dict, timeout: float = WORKER_TIMEOUT) -> Dict:
        """
        Gebruik dit voor interne calls (agents/tools).
        - Job wordt in de agent-queue gezet (lagere prioriteit dan users).
        - We wachten blokkerend tot de worker klaar is of tot timeout.
        - Er worden GEEN wachtrij-meldingen ("U bent #...") verstuurd.
        """
        result_box: Dict[str, Any] = {}

        def _cb(msg: Dict):
            # alleen het eindresultaat is interessant voor tools/agents
            result_box["answer"] = msg

        job = _Job(payload, _cb)
        try:
            self._agent_q.put_nowait(job)
        except queue.Full:
            raise RuntimeError(f"Agent-queue vol (≥{AGENT_MAX_QUEUE})")

        ok = job.event.wait(timeout)
        if not ok:
            raise TimeoutError(f"LLM-inference duurde langer dan {timeout} seconden.")
        if job.error:
            raise RuntimeError(job.error)
        return result_box.get("answer") or {}
    # ---------- worker ----------
    def _run_worker(self):
        while not self._shutdown.is_set():
            job = self._pop_job(self._user_q) or self._pop_job(self._agent_q)
            if not job:
                time.sleep(0.1)
                continue
            try:
                answer = self._infer_fn(job.payload)
                job.set_success(answer)
            except Exception as exc:
                job.set_error(exc)

    def _pop_job(self, q: queue.Queue):
        try: return q.get_nowait()
        except queue.Empty: return None

    def stop(self):
        self._shutdown.set()
        self._worker.join(timeout=5)

def start_position_notifier(
    job: _Job,
    queue_ref: queue.Queue,
    interval: float = UPDATE_INTERVAL,
    ):
    """Stuurt elke `interval` seconden een bericht met de huidige positie."""
    def _notifier():
        # Stop zodra het job-event wordt gezet (success/fout/timeout upstream)
        while not job.event.wait(interval):
            # Neem een snapshot van de queue-inhoud op een thread-safe manier
            with queue_ref.mutex:
                snapshot = list(queue_ref.queue)
            try:
                pos = snapshot.index(job) + 1   # 1-based
            except ValueError:
                # Job staat niet meer in de wachtrij → geen updates meer nodig
                break
            job.callback({"info": f"U bent #{pos} in de wachtrij. Even geduld…" })
    t = threading.Thread(target=_notifier, daemon=True)
    t.start()
    return t