from __future__ import annotations

import asyncio
import time


class AdminEventBus:
    def __init__(self):
        self._subscribers: set[asyncio.Queue] = set()
        self._counter = 0
        self._lock = asyncio.Lock()

    async def subscribe(self) -> asyncio.Queue:
        queue: asyncio.Queue = asyncio.Queue(maxsize=64)
        async with self._lock:
            self._subscribers.add(queue)
        return queue

    async def unsubscribe(self, queue: asyncio.Queue) -> None:
        async with self._lock:
            self._subscribers.discard(queue)

    def subscriber_count(self) -> int:
        return len(self._subscribers)

    async def publish(self, event_type: str, payload):
        self._counter += 1
        event = {
            "id": self._counter,
            "type": event_type,
            "ts": time.time(),
            "payload": payload,
        }
        for queue in list(self._subscribers):
            if queue.full():
                try:
                    queue.get_nowait()
                except asyncio.QueueEmpty:
                    pass
            try:
                queue.put_nowait(event)
            except asyncio.QueueFull:
                pass