feat(backend_server.py): implement message handling

src/judas_server/backend/backend_server.py

@@ -6,13 +6,18 @@ import selectors
 import socket
 import threading
 import time
+from typing import TYPE_CHECKING, Any
+
 import yaml
-
-from typing import Any
-
 from judas_protocol import Category, ControlAction, Message
 
 from judas_server.backend.client import Client, ClientStatus
+from judas_server.backend.handler.hello_handler import HelloHandler
+
+if TYPE_CHECKING:
+    from typing import Callable
+
+    from judas_protocol import ActionType
 
 
 class BackendServer:
@@ -41,13 +46,25 @@ class BackendServer:
         )
 
         self.clients: dict[str, Client] = {}
-
         self.known_clients: dict[str, dict[str, str | float]] = (
             self._load_known_clients()
         )
 
+        self.message_handlers: dict[
+            tuple[Category, ActionType], Callable[[Client, Message], None]
+        ] = {}
+
         self.running: bool = False
 
+    def _initialize_handlers(self) -> None:
+        """Initialize message handlers."""
+
+        hello_handler = HelloHandler(self)
+
+        self.message_handlers[(Category.CONTROL, ControlAction.HELLO)] = (
+            hello_handler.handle
+        )
+
     def _load_known_clients(self) -> dict[str, dict[str, str | float]]:
         """Load the list of known clients from a YAML file and validate."""
         known_clients: dict[str, dict[str, str | float]] = {}
@@ -286,6 +303,29 @@ class BackendServer:
                     try:
                         msg = Message.from_bytes(line)
                         self.logger.info(f"[.] Parsed message {msg.id}")
+
+                        if client.id is None:
+                            self.logger.debug(
+                                f"Client {client} has no ID, expecting HELLO message..."
+                            )
+                            if (
+                                msg.category != Category.CONTROL
+                                or msg.action != ControlAction.HELLO
+                            ):
+                                self.logger.warning(
+                                    f"First message from {client} must be HELLO, disconnecting..."
+                                )
+                                self._disconnect(client)
+                                return
+
+                        handler: Callable[[Client, Message], None] | None = (
+                            self.message_handlers.get(
+                                (msg.category, msg.action), None
+                            )
+                        )
+                        if handler is not None:
+                            handler(client, msg)
+
                         if msg.ack_required:
                             self.send_ack(client, target_id=msg.id)
                     except Exception as e: