Initial project structure: reusable isometric bot engine with D2R implementation

engine/state/events.py

@@ -0,0 +1,34 @@
+"""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()