src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/ServerApp.java

@@ -210,6 +210,20 @@ public class ServerApp {
                         new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.call
                                 .PlayerCallHandler(responseDispatcher, userRegistry, lobbyManager));
 
+        // FOLD registration
+        parserDispatcher.register(
+                "FOLD",
+                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold
+                        .PlayerFoldParser());
+        commandRouter.register(
+                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold.PlayerFoldRequest
+                        .class,
+                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
+                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold
+                                        .PlayerFoldRequest>)
+                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold
+                                .PlayerFoldHandler(responseDispatcher, userRegistry, lobbyManager));
+
         // GET_LOBBY_STATUS registration
         parserDispatcher.register(
                 "GET_LOBBY_STATUS",

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/fold/PlayerFoldHandler.java

@@ -0,0 +1,96 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.GameController;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.player.PlayerId;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyId;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyManager;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserRegistry;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.ErrorResponse;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.OkResponse;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatcher.ResponseDispatcher;
+import java.util.Optional;
+
+/**
+ * Handler for the `FOLD` command.
+ *
+ * <p>This handler validates the session, resolves the lobby (by `GAME_ID` when provided or by
+ * session username otherwise), checks for a running game and forwards the fold action to the {@code
+ * GameController}.
+ */
+public class PlayerFoldHandler extends CommandHandler<PlayerFoldRequest> {
+    private final UserRegistry userRegistry;
+    private final LobbyManager lobbyManager;
+
+    /**
+     * Creates a new {@code PlayerFoldHandler}.
+     *
+     * @param responseDispatcher dispatcher used to send responses back to the client
+     * @param userRegistry registry to resolve users from session ids
+     * @param lobbyManager manager used to lookup lobbies and their game controllers
+     */
+    public PlayerFoldHandler(
+            ResponseDispatcher responseDispatcher,
+            UserRegistry userRegistry,
+            LobbyManager lobbyManager) {
+        super(responseDispatcher);
+        this.userRegistry = userRegistry;
+        this.lobbyManager = lobbyManager;
+    }
+
+    /**
+     * Execute the fold request: resolve lobby by `GAME_ID` if present, otherwise by session user,
+     * verify game is running, and forward the fold to the game controller.
+     *
+     * @param request the parsed {@link PlayerFoldRequest}
+     */
+    @Override
+    public void execute(PlayerFoldRequest request) {
+        Optional<ch.unibas.dmi.dbis.cs108.casono.server.domain.user.User> opt =
+                userRegistry.getBySessionId(request.getSessionId());
+        if (opt.isEmpty()) {
+            responseDispatcher.dispatch(
+                    new ErrorResponse(request.getContext(), "NOT_LOGGED_IN", "User not logged in"));
+            return;
+        }
+
+        String username = opt.get().getName();
+
+        Integer gameId = request.getGameId();
+        var lobby =
+                (gameId != null)
+                        ? lobbyManager.getLobby(LobbyId.of(gameId))
+                        : lobbyManager.getLobbyByUsername(username);
+
+        if (lobby == null) {
+            if (gameId != null) {
+                responseDispatcher.dispatch(
+                        new ErrorResponse(
+                                request.getContext(), "LOBBY_NOT_FOUND", "Lobby not found"));
+            } else {
+                responseDispatcher.dispatch(
+                        new ErrorResponse(
+                                request.getContext(), "NOT_IN_LOBBY", "User not in a lobby"));
+            }
+            return;
+        }
+
+        GameController game = lobby.getGameController();
+        if (game == null) {
+            responseDispatcher.dispatch(
+                    new ErrorResponse(
+                            request.getContext(), "GAME_NOT_STARTED", "Game not started"));
+            return;
+        }
+
+        try {
+            game.playerFold(PlayerId.of(username));
+        } catch (RuntimeException e) {
+            responseDispatcher.dispatch(
+                    new ErrorResponse(request.getContext(), "GAME_ACTION_FAILED", e.getMessage()));
+            return;
+        }
+
+        responseDispatcher.dispatch(new OkResponse(request.getContext()));
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/fold/PlayerFoldParser.java

@@ -0,0 +1,28 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.parsing.CommandParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.PrimitiveRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.accessor.RequestParameterAccessor;
+
+/**
+ * Parser for the `FOLD` command.
+ *
+ * <p>Accepts an optional `GAME_ID` parameter. If provided, the handler will target the specified
+ * lobby; otherwise the server resolves the lobby by the requesting session's user.
+ */
+public class PlayerFoldParser implements CommandParser<PlayerFoldRequest> {
+    @Override
+    public PlayerFoldRequest parse(PrimitiveRequest primitiveRequest) {
+        RequestParameterAccessor accessor =
+                new RequestParameterAccessor(primitiveRequest.parameters());
+
+        Integer gameId = null;
+        try {
+            gameId = accessor.optional("GAME_ID", null, Integer::parseInt);
+        } catch (Exception e) {
+            // parse handled by framework
+        }
+
+        return new PlayerFoldRequest(primitiveRequest.context(), gameId);
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/fold/PlayerFoldRequest.java

@@ -0,0 +1,34 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.Request;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.RequestContext;
+
+/**
+ * Request for the `FOLD` command.
+ *
+ * <p>Contains an optional `gameId` when the client targets a specific lobby, otherwise the server
+ * will resolve the lobby from the requesting session's user.
+ */
+public class PlayerFoldRequest extends Request {
+    private final Integer gameId;
+
+    /**
+     * Creates a new {@code PlayerFoldRequest}.
+     *
+     * @param context the request context
+     * @param gameId optional game id of the targeted lobby (may be {@code null})
+     */
+    public PlayerFoldRequest(RequestContext context, Integer gameId) {
+        super(context);
+        this.gameId = gameId;
+    }
+
+    /**
+     * Returns the optional target game id.
+     *
+     * @return the game id or {@code null} if not provided
+     */
+    public Integer getGameId() {
+        return gameId;
+    }
+}