"""
Event emitter protocols - abstract interfaces for event-producing components.
"""

from collections.abc import Callable
from typing import Any, Protocol


class EventEmitter(Protocol):
    """Protocol for components that emit events."""

    def subscribe(self, callback: Callable[[Any], None]) -> None: ...
    def unsubscribe(self, callback: Callable[[Any], None]) -> None: ...


class Startable(Protocol):
    """Protocol for components that can be started."""

    def start(self) -> Any: ...


class Stoppable(Protocol):
    """Protocol for components that can be stopped."""

    def stop(self) -> None: ...