init version

msgcenterpy/core/message_center.py

@@ -0,0 +1,69 @@
+from typing import Any, Dict, Optional, Type
+
+from msgcenterpy.core.envelope import MessageEnvelope, Properties
+from msgcenterpy.core.message_instance import MessageInstance
+from msgcenterpy.core.types import MessageType
+
+
+class MessageCenter:
+    """Message Center singleton class that manages all message types and instances"""
+
+    _instance: Optional["MessageCenter"] = None
+
+    @classmethod
+    def get_instance(cls) -> "MessageCenter":
+        """Get MessageCenter singleton instance"""
+        if cls._instance is None:
+            cls._instance = cls()
+        return cls._instance
+
+    def __init__(self) -> None:
+        """Private constructor, use get_instance() to get singleton"""
+        self._type_registry: Dict[MessageType, Type[MessageInstance]] = {}
+        self._register_builtin_types()
+
+    def _register_builtin_types(self) -> None:
+        """Register built-in message types with lazy import to avoid circular dependencies"""
+        try:
+            from msgcenterpy.instances.ros2_instance import ROS2MessageInstance
+
+            self._type_registry[MessageType.ROS2] = ROS2MessageInstance
+        except ImportError:
+            pass
+        try:
+            from msgcenterpy.instances.json_schema_instance import (
+                JSONSchemaMessageInstance,
+            )
+
+            self._type_registry[MessageType.JSON_SCHEMA] = JSONSchemaMessageInstance
+        except ImportError:
+            pass
+
+    def get_instance_class(self, message_type: MessageType) -> Type[MessageInstance]:
+        """Get instance class for the specified message type"""
+        instance_class = self._type_registry.get(message_type)
+        if not instance_class:
+            raise ValueError(f"Unsupported message type: {message_type}")
+        return instance_class
+
+    def convert(
+        self,
+        source: MessageInstance,
+        target_type: MessageType,
+        override_properties: Dict[str, Any],
+        **kwargs: Any,
+    ) -> MessageInstance:
+        """Convert message types"""
+        target_class = self.get_instance_class(target_type)
+        dict_data: MessageEnvelope = source.export_to_envelope()
+        if "properties" not in dict_data["metadata"]:
+            dict_data["metadata"]["properties"] = Properties()
+        dict_data["metadata"]["properties"].update(override_properties)  # type: ignore[typeddict-item]
+        target_instance = target_class.import_from_envelope(dict_data)
+        return target_instance
+
+
+# Module-level convenience function using singleton
+def get_message_center() -> MessageCenter:
+    """Get message center singleton"""
+    return MessageCenter.get_instance()