feat: add command handling support to Nginx message handler

apps/nxmesh-agent/src/service/master_handler/handlers.rs

@@ -1,6 +1,8 @@
 use std::sync::{Arc, Weak};
 
-use nxmesh_proto::{AgentMessage, ConfigUpdate, MasterMessage, master_message::Payload};
+use nxmesh_proto::{
+    AgentMessage, ConfigUpdate, MasterMessage, command::Command, master_message::Payload,
+};
 
 use crate::service::master_handler::{MasterHandlerError, MessageResult};
 
@@ -25,28 +27,45 @@ pub trait OnConfigUpdateHandler: Send + Sync + 'static {
     ) -> MessageResult<()>;
 }
 
-pub struct HandlerImpl<OCH>
-where
-    OCH: OnConfigUpdateHandler + ?Sized,
-{
-    on_config_update_handler: Weak<OCH>,
+#[async_trait::async_trait]
+pub trait OnCommandHandler: Send + Sync + 'static {
+    // Handle the command message from master, execute the command and return the result
+    async fn on_command(
+        &self,
+        agent_id: &str,
+        timestamp: i64,
+        message_id: &str,
+        command: Command,
+    ) -> MessageResult<()>;
 }
 
-impl<OCH> HandlerImpl<OCH>
+pub struct HandlerImpl<OCUH, OCH>
 where
-    OCH: OnConfigUpdateHandler + ?Sized,
+    OCUH: OnConfigUpdateHandler + ?Sized,
+    OCH: OnCommandHandler + ?Sized,
 {
-    pub fn new(on_config_update_handler: Weak<OCH>) -> Self {
+    on_config_update_handler: Weak<OCUH>,
+    on_command_handler: Weak<OCH>,
+}
+
+impl<OCUH, OCH> HandlerImpl<OCUH, OCH>
+where
+    OCUH: OnConfigUpdateHandler + ?Sized,
+    OCH: OnCommandHandler + ?Sized,
+{
+    pub fn new(on_config_update_handler: Weak<OCUH>, on_command_handler: Weak<OCH>) -> Self {
         Self {
             on_config_update_handler,
+            on_command_handler,
         }
     }
 }
 
 #[async_trait::async_trait]
-impl<OCH> MasterMessageHandler for HandlerImpl<OCH>
+impl<OCUH, OCH> MasterMessageHandler for HandlerImpl<OCUH, OCH>
 where
-    OCH: OnConfigUpdateHandler + ?Sized,
+    OCUH: OnConfigUpdateHandler + ?Sized,
+    OCH: OnCommandHandler + ?Sized,
 {
     async fn handle_master_message(
         &self,