From ebb2e267bf89af4ddc0da130f0f6c91dc4d5819b Mon Sep 17 00:00:00 2001
From: Lars Simon Winzer <lars.winzer@stud.unibas.ch>
Date: Wed, 8 Apr 2026 17:23:38 +0200
Subject: [PATCH] Add: Implement CommandHandlerExecutor for evaluation of
 pre-execution checks in CommandRouter

---
 .../dbis/cs108/casono/server/ServerApp.java   |  4 ++-
 .../execution/CommandHandlerExecutor.java     | 27 +++++++++++++++++++
 .../command/execution/CommandRouter.java      |  8 +++++-
 3 files changed, 37 insertions(+), 2 deletions(-)
 create mode 100644 src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/execution/CommandHandlerExecutor.java

diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/ServerApp.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/ServerApp.java
index b553a36..febc9a9 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/ServerApp.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/ServerApp.java
@@ -15,6 +15,7 @@ import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.ping.PingRequest;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserCleanupJob;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserRegistry;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.NetworkManager;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandlerExecutor;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandRouter;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.command.parsing.CommandParserDispatcher;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.events.DisconnectEvent;
@@ -48,7 +49,8 @@ public class ServerApp {
         CommandParserDispatcher dispatcher = new CommandParserDispatcher();
         SessionManager sessionManager = new SessionManager(eventBus, dispatcher);
         ResponseDispatcher responseDispatcher = new ResponseDispatcher(sessionManager);
-        CommandRouter router = new CommandRouter();
+        CommandHandlerExecutor handlerExecutor = new CommandHandlerExecutor(responseDispatcher);
+        CommandRouter router = new CommandRouter(handlerExecutor);
 
         eventBus.subscribe(DisconnectEvent.class, event -> sessionManager.onDisconnect(event));
 
diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/execution/CommandHandlerExecutor.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/execution/CommandHandlerExecutor.java
new file mode 100644
index 0000000..7526c1b
--- /dev/null
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/execution/CommandHandlerExecutor.java
@@ -0,0 +1,27 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.checks.HandlerCheck;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.Request;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.Response;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatcher.ResponseDispatcher;
+import java.util.Optional;
+
+public class CommandHandlerExecutor {
+    private final ResponseDispatcher responseDispatcher;
+
+    public CommandHandlerExecutor(ResponseDispatcher responseDispatcher) {
+        this.responseDispatcher = responseDispatcher;
+    }
+
+    public void execute(CommandHandler<Request> handler, Request request) {
+        for (HandlerCheck check : handler.getChecks()) {
+            Optional<Response> result = check.check(request);
+            if (result.isPresent()) {
+                responseDispatcher.dispatch(result.get());
+                return;
+            }
+        }
+
+        handler.execute(request);
+    }
+}
diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/execution/CommandRouter.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/execution/CommandRouter.java
index 269c6a4..366db11 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/execution/CommandRouter.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/execution/CommandRouter.java
@@ -6,6 +6,11 @@ import java.util.Map;
 
 public class CommandRouter {
     private final Map<Class<? extends Request>, CommandHandler<?>> handlers = new HashMap<>();
+    private final CommandHandlerExecutor handlerExecutor;
+
+    public CommandRouter(CommandHandlerExecutor commandHandlerExecutor) {
+        this.handlerExecutor = commandHandlerExecutor;
+    }
 
     public <T extends Request> void register(Class<T> request, CommandHandler<T> handler) {
         handlers.put(request, handler);
@@ -23,6 +28,7 @@ public class CommandRouter {
             throw new UnknownRequestException(
                     "Unable to execute request " + requestName + ". Type unknown", requestName);
         }
-        handler.execute(request);
+
+        handlerExecutor.execute(handler, request);
     }
 }