"""In-process event fan-out for Server-Sent Events clients."""

from __future__ import annotations

import asyncio
from collections.abc import AsyncIterator
from typing import Any


class EventBus:
    def __init__(self) -> None:
        self._subscribers: set[asyncio.Queue[dict[str, Any]]] = set()

    async def publish(self, event_type: str, data: dict[str, Any]) -> None:
        event = {"type": event_type, "data": data}
        dead: list[asyncio.Queue[dict[str, Any]]] = []
        for queue in self._subscribers:
            try:
                queue.put_nowait(event)
            except asyncio.QueueFull:
                dead.append(queue)
        for queue in dead:
            self._subscribers.discard(queue)

    async def subscribe(self) -> AsyncIterator[dict[str, Any]]:
        queue: asyncio.Queue[dict[str, Any]] = asyncio.Queue(maxsize=100)
        self._subscribers.add(queue)
        try:
            while True:
                try:
                    yield await asyncio.wait_for(queue.get(), timeout=20)
                except TimeoutError:
                    yield {"type": "heartbeat", "data": {}}
        finally:
            self._subscribers.discard(queue)