Add socket cleanup

tello_sim/tello_drone_sim.py

@@ -1,21 +1,63 @@
 from command_server import CommandServer
 from ursina_adapter import UrsinaAdapter
 import threading
+import atexit
+import signal
+import sys
 
 class TelloDroneSim:
     def __init__(self):
         self._ursina_adapter = UrsinaAdapter()
         self._server = CommandServer(self._ursina_adapter)
+        
+        # Register cleanup handlers
+        atexit.register(self.cleanup)
+        signal.signal(signal.SIGINT, self._signal_handler)
+        signal.signal(signal.SIGTERM, self._signal_handler)
+
+    def _signal_handler(self, signum, frame):
+        """Handle termination signals gracefully."""
+        print("\n[Tello Sim] Received shutdown signal, cleaning up...")
+        self.cleanup()
+        sys.exit(0)
+
+    def cleanup(self):
+        """Clean up resources."""
+        if hasattr(self, '_server'):
+            self._server.cleanup()
 
     @property
     def state(self):
         return self._ursina_adapter
 
     def start(self):
+        # Check if port is available before starting
+        if not self._server.check_port_available(9999):
+            print("\n" + "="*70)
+            print("ERROR: Cannot start simulator - Port 9999 is already in use!")
+            print("="*70)
+            print("\nAnother instance of the simulator may be running.")
+            print("\nTo fix this, run one of these commands in your terminal:")
+            print("  macOS/Linux: lsof -ti:9999 | xargs kill -9")
+            print("  Windows:     netstat -ano | findstr :9999")
+            print("               taskkill /PID <PID> /F")
+            print("\nOr simply restart your computer.")
+            print("="*70 + "\n")
+            sys.exit(1)
+        
         server_thread = threading.Thread(target=self._server.listen)
         server_thread.daemon = True
         server_thread.start()
-        self._ursina_adapter.run()
+        
+        try:
+            self._ursina_adapter.run()
+        except KeyboardInterrupt:
+            print("\n[Tello Sim] Interrupted, cleaning up...")
+            self.cleanup()
+        except Exception as e:
+            print(f"[Tello Sim] Error: {e}")
+            self.cleanup()
+            raise
 
     def update(self) -> None:
         self._ursina_adapter.tick()