"""
نظام أولوية المالك - Priority Queue
- رسائل المالك لها الأولوية القصوى
- تُعالَج قبل رسائل المستخدمين الآخرين حتى لو وصلت متأخرة
"""
import asyncio
import logging
import time
from dataclasses import dataclass, field
from typing import Any, Callable, Optional

from config import config

logger = logging.getLogger(__name__)


@dataclass(order=True)
class PriorityTask:
    """مهمة في طابور الأولوية - أقل priority = أعلى أولوية"""
    priority: int                          # 0 = owner (highest), 10 = regular user
    sequence: int                          # ترتيب الوصول (للـ FIFO داخل نفس الأولوية)
    task_id: str = field(compare=False)    # معرّف فريد
    func: Callable = field(compare=False)  # الدالة المطلوب تنفيذها
    args: tuple = field(compare=False, default=())
    kwargs: dict = field(compare=False, default_factory=dict)


class PriorityProcessor:
    """معالج طابور الأولوية"""

    def __init__(self, max_workers: int = 4):
        self.queue: asyncio.PriorityQueue = asyncio.PriorityQueue()
        self.max_workers = max_workers
        self._workers: list = []
        self._sequence = 0
        self._running = False
        self._counter_lock = asyncio.Lock()
        self._task_results: dict = {}  # task_id -> result
        self._task_events: dict = {}   # task_id -> asyncio.Event

    async def start(self):
        """بدء عمال المعالجة"""
        if self._running:
            return
        self._running = True
        for i in range(self.max_workers):
            worker = asyncio.create_task(self._worker(i))
            self._workers.append(worker)
        logger.info(f"Started {self.max_workers} priority queue workers")

    async def stop(self):
        """إيقاف العمال"""
        self._running = False
        # Send sentinel tasks to wake up workers
        for _ in self._workers:
            await self.queue.put(PriorityTask(
                priority=999, sequence=0, task_id="__stop__",
                func=lambda: None,
            ))
        for w in self._workers:
            try:
                await asyncio.wait_for(w, timeout=5)
            except (asyncio.TimeoutError, asyncio.CancelledError):
                w.cancel()
        self._workers.clear()

    async def _next_sequence(self) -> int:
        async with self._counter_lock:
            self._sequence += 1
            return self._sequence

    async def submit(
        self,
        user_id: int,
        func: Callable,
        *args,
        task_id: str = "",
        **kwargs,
    ) -> Any:
        """
        إرسال مهمة للطابور.
        - user_id يحدد الأولوية (المالك = 0، مشرف = 2، مستخدم = 10)
        - يعيد نتيجة الدالة مباشرة
        """
        priority = config.priority_for(user_id)
        seq = await self._next_sequence()
        if not task_id:
            task_id = f"task-{seq}"

        event = asyncio.Event()
        self._task_events[task_id] = event

        task = PriorityTask(
            priority=priority,
            sequence=seq,
            task_id=task_id,
            func=func,
            args=args,
            kwargs=kwargs,
        )
        await self.queue.put(task)
        logger.info(f"Submitted task {task_id} for user {user_id} with priority {priority}")

        # انتظر النتيجة
        await event.wait()
        result = self._task_results.pop(task_id, None)
        self._task_events.pop(task_id, None)
        if isinstance(result, Exception):
            raise result
        return result

    async def _worker(self, worker_id: int):
        """عامل معالجة الطابور"""
        logger.info(f"Priority queue worker {worker_id} started")
        while self._running:
            try:
                task: PriorityTask = await asyncio.wait_for(self.queue.get(), timeout=1.0)
            except asyncio.TimeoutError:
                continue

            if task.task_id == "__stop__":
                self.queue.task_done()
                break

            try:
                logger.debug(
                    f"Worker {worker_id} processing task {task.task_id} "
                    f"(priority={task.priority})"
                )
                if asyncio.iscoroutinefunction(task.func):
                    result = await task.func(*task.args, **task.kwargs)
                else:
                    result = await asyncio.to_thread(task.func, *task.args, **task.kwargs)
                self._task_results[task.task_id] = result
            except Exception as e:
                logger.error(f"Task {task.task_id} failed: {e}", exc_info=True)
                self._task_results[task.task_id] = e
            finally:
                event = self._task_events.get(task.task_id)
                if event:
                    event.set()
                self.queue.task_done()


# Singleton
priority_processor = PriorityProcessor(max_workers=4)