import asyncio
from dataclasses import dataclass, field
from datetime import datetime, timezone


@dataclass(slots=True)
class WisperEvent:
    role: str
    text: str
    timestamp: str = field(
        default_factory=lambda: datetime.now(timezone.utc).isoformat(timespec="seconds")
    )

    def to_dict(self) -> dict[str, str]:
        return {"role": self.role, "text": self.text, "timestamp": self.timestamp}


class WisperBus:
    def __init__(self) -> None:
        self._subscribers: set[asyncio.Queue[WisperEvent]] = set()
        self._lock = asyncio.Lock()

    async def subscribe(self) -> asyncio.Queue[WisperEvent]:
        queue: asyncio.Queue[WisperEvent] = asyncio.Queue()
        async with self._lock:
            self._subscribers.add(queue)
        return queue

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

    async def publish(self, event: WisperEvent) -> None:
        async with self._lock:
            subscribers = list(self._subscribers)
        for queue in subscribers:
            queue.put_nowait(event)