"""Event system for inter-component communication."""

from typing import Callable, Any, Dict, List
import logging

logger = logging.getLogger(__name__)


class EventBus:
    """Simple publish/subscribe event system."""
    
    def __init__(self):
        self._listeners: Dict[str, List[Callable]] = {}
    
    def on(self, event: str, callback: Callable) -> None:
        """Subscribe to an event."""
        self._listeners.setdefault(event, []).append(callback)
    
    def off(self, event: str, callback: Callable) -> None:
        """Unsubscribe from an event."""
        if event in self._listeners:
            self._listeners[event] = [cb for cb in self._listeners[event] if cb != callback]
    
    def emit(self, event: str, **data: Any) -> None:
        """Emit an event to all subscribers."""
        for cb in self._listeners.get(event, []):
            try:
                cb(**data)
            except Exception as e:
                logger.error(f"Event handler error for '{event}': {e}")
    
    def clear(self) -> None:
        """Remove all listeners."""
        self._listeners.clear()