Implement two player chess game

gradle.properties

@@ -8,11 +8,11 @@ org.gradle.jvmargs=-Xmx2G
 	minecraft_version_list=1.21.11
 	minecraft_version_list_presentable=1.21.11
 	loader_version=0.18.1
-	loom_version=1.14-SNAPSHOT
+	loom_version=1.15-SNAPSHOT
 
 	# check these on https://maven.parchmentmc.org/org/parchmentmc/data/
-	parchment_mcversion=1.21.10
-	parchment_version=2025.10.12
+	parchment_mcversion=1.21.11
+	parchment_version=2025.12.20
 
 # Mod Properties
 	mod_version=2.13.1

src/main/java/net/earthcomputer/clientcommands/ClientCommands.java

@@ -136,6 +136,7 @@ public static void registerCommands(CommandDispatcher<FabricClientCommandSource>
         CalcCommand.register(dispatcher);
         CalcStackCommand.register(dispatcher, context);
         CallbackCommand.register(dispatcher);
+        ChessCommand.register(dispatcher);
         CDebugCommand.register(dispatcher);
         CEnchantCommand.register(dispatcher, context);
         CFunctionCommand.register(dispatcher);

src/main/java/net/earthcomputer/clientcommands/c2c/C2CPacketHandler.java

@@ -7,15 +7,22 @@
 import com.mojang.logging.LogUtils;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
+import net.earthcomputer.clientcommands.c2c.chess.ChessGame;
+import net.earthcomputer.clientcommands.c2c.packets.ChessDrawOfferC2CPacket;
+import net.earthcomputer.clientcommands.c2c.packets.ChessMoveC2CPacket;
+import net.earthcomputer.clientcommands.c2c.packets.ChessResignC2CPacket;
 import net.earthcomputer.clientcommands.c2c.packets.MessageC2CPacket;
 import net.earthcomputer.clientcommands.c2c.packets.PutConnectFourPieceC2CPacket;
 import net.earthcomputer.clientcommands.c2c.packets.PutTicTacToeMarkC2CPacket;
 import net.earthcomputer.clientcommands.c2c.packets.StartTwoPlayerGameC2CPacket;
+import net.earthcomputer.clientcommands.c2c.packets.StopTwoPlayerGameC2CPacket;
+import net.earthcomputer.clientcommands.command.ClientCommandHelper;
 import net.earthcomputer.clientcommands.command.ConnectFourCommand;
 import net.earthcomputer.clientcommands.command.ListenCommand;
 import net.earthcomputer.clientcommands.command.TicTacToeCommand;
 import net.earthcomputer.clientcommands.command.arguments.ExtendedMarkdownArgument;
 import net.earthcomputer.clientcommands.features.TwoPlayerGame;
+import net.earthcomputer.clientcommands.util.CComponentUtil;
 import net.fabricmc.fabric.api.networking.v1.PacketByteBufs;
 import net.minecraft.ChatFormatting;
 import net.minecraft.SharedConstants;
@@ -28,6 +35,7 @@
 import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.network.ProtocolInfo;
 import net.minecraft.network.chat.Component;
+import net.minecraft.network.chat.ComponentUtils;
 import net.minecraft.network.chat.MutableComponent;
 import net.minecraft.network.chat.RemoteChatSession;
 import net.minecraft.network.protocol.Packet;
@@ -52,8 +60,12 @@ public class C2CPacketHandler implements C2CPacketListener {
     public static final ProtocolInfo<C2CPacketListener> C2C = ProtocolInfoBuilder.<C2CPacketListener, C2CFriendlyByteBuf>clientboundProtocol(ConnectionProtocol.PLAY, builder -> builder
         .addPacket(MessageC2CPacket.ID, MessageC2CPacket.CODEC)
         .addPacket(StartTwoPlayerGameC2CPacket.ID, StartTwoPlayerGameC2CPacket.CODEC)
+        .addPacket(StopTwoPlayerGameC2CPacket.ID, StopTwoPlayerGameC2CPacket.CODEC)
         .addPacket(PutTicTacToeMarkC2CPacket.ID, PutTicTacToeMarkC2CPacket.CODEC)
         .addPacket(PutConnectFourPieceC2CPacket.ID, PutConnectFourPieceC2CPacket.CODEC)
+        .addPacket(ChessResignC2CPacket.ID, ChessResignC2CPacket.CODEC)
+        .addPacket(ChessMoveC2CPacket.ID, ChessMoveC2CPacket.CODEC)
+        .addPacket(ChessDrawOfferC2CPacket.ID, ChessDrawOfferC2CPacket.CODEC)
     ).bind(b -> (C2CFriendlyByteBuf) b);
 
     public static final String C2C_PACKET_HEADER = "CCΕNC:";
@@ -211,6 +223,11 @@ public void onStartTwoPlayerGameC2CPacket(StartTwoPlayerGameC2CPacket packet) {
         TwoPlayerGame.onStartTwoPlayerGame(packet);
     }
 
+    @Override
+    public void onStopTwoPlayerGameC2CPacket(StopTwoPlayerGameC2CPacket packet) {
+        TwoPlayerGame.onStopTwoPlayerGame(packet);
+    }
+
     @Override
     public void onPutTicTacToeMarkC2CPacket(PutTicTacToeMarkC2CPacket packet) {
         TicTacToeCommand.onPutTicTacToeMarkC2CPacket(packet);
@@ -221,6 +238,72 @@ public void onPutConnectFourPieceC2CPacket(PutConnectFourPieceC2CPacket packet)
         ConnectFourCommand.onPutConnectFourPieceC2CPacket(packet);
     }
 
+    @Override
+    public void onChessResignPacket(ChessResignC2CPacket packet) {
+        ChessGame activeGame = TwoPlayerGame.CHESS_TYPE.getActiveGame(packet.senderUUID());
+        if (activeGame == null) {
+            return;
+        }
+        String opponent = activeGame.opponent.getProfile().name();
+        TwoPlayerGame.CHESS_TYPE.removeActiveGame(packet.senderUUID());
+        ClientCommandHelper.sendFeedback(Component.translatable("chessGame.opponentResigned", opponent));
+    }
+
+    @Override
+    public void onChessMovePacket(ChessMoveC2CPacket packet) {
+        ChessGame activeGame = TwoPlayerGame.CHESS_TYPE.getActiveGame(packet.senderUUID());
+        if (activeGame == null) {
+            return;
+        }
+
+        // validate move
+        if (activeGame.colorToMove == activeGame.yourColor) {
+            return;
+        }
+        if (!activeGame.legalMoves().contains(packet.move())) {
+            return;
+        }
+
+        String moveNotation = activeGame.getAlgebraicNotation(packet.move());
+        activeGame.makeMove(packet.move());
+
+        Component clickable = CComponentUtil.getCommandTextComponent("twoPlayerGame.clickToMakeYourMove", "/cchess open " + packet.sender());
+        ClientCommandHelper.sendFeedback(Component.translatable("chessGame.opponentMoved", activeGame.opponent.getProfile().name(), moveNotation, ComponentUtils.wrapInSquareBrackets(clickable)));
+
+        Component endCondition = activeGame.detectEndCondition();
+        if (endCondition != null) {
+            TwoPlayerGame.CHESS_TYPE.removeActiveGame(packet.senderUUID());
+            ClientCommandHelper.sendFeedback(endCondition);
+        }
+    }
+
+    @Override
+    public void onChessDrawOfferPacket(ChessDrawOfferC2CPacket packet) {
+        ChessGame activeGame = TwoPlayerGame.CHESS_TYPE.getActiveGame(packet.senderUUID());
+        if (activeGame == null) {
+            return;
+        }
+
+        String opponent = activeGame.opponent.getProfile().name();
+
+        // TODO: there are possibilities of desyncs here, not really sure how to fix it tbh
+        switch (packet.operation()) {
+            case OFFER -> {
+                activeGame.drawOfferedBy = activeGame.yourColor.opposite();
+                ClientCommandHelper.sendFeedback(Component.translatable("chessGame.drawOffered", opponent));
+            }
+            case RETRACT -> {
+                activeGame.drawOfferedBy = null;
+                ClientCommandHelper.sendFeedback(Component.translatable("chessGame.drawOfferRetracted", opponent));
+            }
+            case ACCEPT -> {
+                TwoPlayerGame.CHESS_TYPE.removeActiveGame(packet.senderUUID());
+                ClientCommandHelper.sendFeedback(Component.translatable("chessGame.drawOfferAccepted", opponent));
+                ClientCommandHelper.sendFeedback(Component.translatable("chessGame.draw.agreement"));
+            }
+        }
+    }
+
     public static @Nullable C2CFriendlyByteBuf wrapByteBuf(ByteBuf buf, @Nullable String sender, @Nullable UUID senderUUID) {
         ClientPacketListener connection = Minecraft.getInstance().getConnection();
         if (connection == null) {

src/main/java/net/earthcomputer/clientcommands/c2c/C2CPacketListener.java

@@ -1,17 +1,29 @@
 package net.earthcomputer.clientcommands.c2c;
 
+import net.earthcomputer.clientcommands.c2c.packets.ChessDrawOfferC2CPacket;
+import net.earthcomputer.clientcommands.c2c.packets.ChessMoveC2CPacket;
+import net.earthcomputer.clientcommands.c2c.packets.ChessResignC2CPacket;
 import net.earthcomputer.clientcommands.c2c.packets.MessageC2CPacket;
 import net.earthcomputer.clientcommands.c2c.packets.PutConnectFourPieceC2CPacket;
 import net.earthcomputer.clientcommands.c2c.packets.PutTicTacToeMarkC2CPacket;
 import net.earthcomputer.clientcommands.c2c.packets.StartTwoPlayerGameC2CPacket;
+import net.earthcomputer.clientcommands.c2c.packets.StopTwoPlayerGameC2CPacket;
 import net.minecraft.network.ClientboundPacketListener;
 
 public interface C2CPacketListener extends ClientboundPacketListener {
     void onMessageC2CPacket(MessageC2CPacket packet);
 
     void onStartTwoPlayerGameC2CPacket(StartTwoPlayerGameC2CPacket packet);
 
+    void onStopTwoPlayerGameC2CPacket(StopTwoPlayerGameC2CPacket packet);
+
     void onPutTicTacToeMarkC2CPacket(PutTicTacToeMarkC2CPacket packet);
 
     void onPutConnectFourPieceC2CPacket(PutConnectFourPieceC2CPacket packet);
+
+    void onChessResignPacket(ChessResignC2CPacket packet);
+
+    void onChessMovePacket(ChessMoveC2CPacket packet);
+
+    void onChessDrawOfferPacket(ChessDrawOfferC2CPacket packet);
 }

src/main/java/net/earthcomputer/clientcommands/c2c/chess/ChessColor.java

@@ -0,0 +1,9 @@
+package net.earthcomputer.clientcommands.c2c.chess;
+
+public enum ChessColor {
+    WHITE, BLACK;
+
+    public ChessColor opposite() {
+        return this == WHITE ? BLACK : WHITE;
+    }
+}