Changed the packet listener api, allowing for listener override

src/main/java/fr/themode/demo/PlayerInit.java

@@ -106,10 +106,9 @@ public class PlayerInit {
             }
         }, new UpdateOption(5, TimeUnit.TICK));
 
-        connectionManager.addPacketConsumer((player, packet) -> {
+        connectionManager.addPacketConsumer((player, packetController, packet) -> {
             // Listen to all received packet
-            // Returning true means cancelling the packet
-            return false;
+            packetController.setCancel(false);
         });
 
         connectionManager.addPlayerInitialization(player -> {

src/main/java/net/minestom/server/listener/AnimationListener.java

@@ -12,7 +12,8 @@ public class AnimationListener {
         player.callCancellableEvent(AnimationEvent.class, animationEvent, () -> {
             EntityAnimationPacket entityAnimationPacket = new EntityAnimationPacket();
             entityAnimationPacket.entityId = player.getEntityId();
-            entityAnimationPacket.animation = animationEvent.getHand() == Player.Hand.MAIN ? EntityAnimationPacket.Animation.SWING_MAIN_ARM : EntityAnimationPacket.Animation.SWING_OFF_HAND;
+            entityAnimationPacket.animation = animationEvent.getHand() == Player.Hand.MAIN ?
+                    EntityAnimationPacket.Animation.SWING_MAIN_ARM : EntityAnimationPacket.Animation.SWING_OFF_HAND;
             player.sendPacketToViewers(entityAnimationPacket);
         });
     }

src/main/java/net/minestom/server/listener/KeepAliveListener.java

@@ -16,5 +16,4 @@ public class KeepAliveListener {
         int latency = (int) (System.currentTimeMillis() - packet.id);
         player.refreshLatency(latency);
     }
-
 }

src/main/java/net/minestom/server/listener/PlayerDiggingListener.java

@@ -115,8 +115,10 @@ public class PlayerDiggingListener {
             case SWAP_ITEM_HAND:
                 PlayerSwapItemEvent swapItemEvent = new PlayerSwapItemEvent(offHand.clone(), mainHand.clone());
                 player.callCancellableEvent(PlayerSwapItemEvent.class, swapItemEvent, () -> {
-                    playerInventory.setItemInMainHand(swapItemEvent.getMainHandItem());
-                    playerInventory.setItemInOffHand(swapItemEvent.getOffHandItem());
+                    synchronized (playerInventory) {
+                        playerInventory.setItemInMainHand(swapItemEvent.getMainHandItem());
+                        playerInventory.setItemInOffHand(swapItemEvent.getOffHandItem());
+                    }
                 });
                 break;
         }

src/main/java/net/minestom/server/listener/UseEntityListener.java

@@ -14,6 +14,11 @@ public class UseEntityListener {
         if (entity == null)
             return;
         ClientInteractEntityPacket.Type type = packet.type;
+
+        // Player cannot interact entities that he cannot see
+        if (!entity.isViewer(player))
+            return;
+
         if (type == ClientInteractEntityPacket.Type.ATTACK) {
             if (entity instanceof LivingEntity && ((LivingEntity) entity).isDead()) // Can't attack dead entities
                 return;

src/main/java/net/minestom/server/listener/UseItemListener.java

@@ -21,6 +21,7 @@ public class UseItemListener {
 
         Material material = Material.fromId(itemStack.getMaterialId());
 
+        // Equip armor with right click
         if (material.isArmor()) {
             PlayerInventory playerInventory = player.getInventory();
             if (useItemEvent.isCancelled()) {

src/main/java/net/minestom/server/listener/manager/PacketConsumer.java

@@ -1,10 +1,10 @@
 package net.minestom.server.listener.manager;
 
 import net.minestom.server.entity.Player;
-import net.minestom.server.network.packet.client.ClientPacket;
+import net.minestom.server.network.packet.client.ClientPlayPacket;
 
 @FunctionalInterface
 public interface PacketConsumer {
     // Cancel the packet if return true
-    boolean accept(Player player, ClientPacket packet);
+    void accept(Player player, PacketController packetController, ClientPlayPacket packet);
 }

src/main/java/net/minestom/server/listener/manager/PacketController.java

@@ -0,0 +1,33 @@
+package net.minestom.server.listener.manager;
+
+public class PacketController {
+
+    private boolean cancel;
+    private PacketListenerConsumer packetListenerConsumer;
+
+    protected PacketController(PacketListenerConsumer packetListenerConsumer) {
+        this.packetListenerConsumer = packetListenerConsumer;
+    }
+
+    public boolean isCancel() {
+        return cancel;
+    }
+
+    /**
+     * @param cancel true if the packet should be cancelled
+     */
+    public void setCancel(boolean cancel) {
+        this.cancel = cancel;
+    }
+
+    public PacketListenerConsumer getPacketListenerConsumer() {
+        return packetListenerConsumer;
+    }
+
+    /**
+     * @param packetListenerConsumer the new listener (do not override the default listener)
+     */
+    public void setPacketListenerConsumer(PacketListenerConsumer packetListenerConsumer) {
+        this.packetListenerConsumer = packetListenerConsumer;
+    }
+}

src/main/java/net/minestom/server/listener/manager/PacketListenerConsumer.java

@@ -0,0 +1,9 @@
+package net.minestom.server.listener.manager;
+
+import net.minestom.server.entity.Player;
+import net.minestom.server.network.packet.client.ClientPlayPacket;
+
+@FunctionalInterface
+public interface PacketListenerConsumer<T extends ClientPlayPacket> {
+    void accept(T packet, Player player);
+}

src/main/java/net/minestom/server/listener/manager/PacketListenerManager.java

@@ -9,13 +9,12 @@ import net.minestom.server.network.packet.client.play.*;
 
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
-import java.util.function.BiConsumer;
 
 public class PacketListenerManager {
 
     private static ConnectionManager connectionManager = MinecraftServer.getConnectionManager();
 
-    private Map<Class<? extends ClientPlayPacket>, BiConsumer<? extends ClientPlayPacket, Player>> listeners = new ConcurrentHashMap<>();
+    private Map<Class<? extends ClientPlayPacket>, PacketListenerConsumer> listeners = new ConcurrentHashMap<>();
 
     public PacketListenerManager() {
         addListener(ClientKeepAlivePacket.class, KeepAliveListener::listener);
@@ -46,22 +45,30 @@ public class PacketListenerManager {
 
     public <T extends ClientPlayPacket> void process(T packet, Player player) {
 
-        boolean cancel = false;
-        for (PacketConsumer packetConsumer : connectionManager.getPacketConsumers()) {
-            cancel = packetConsumer.accept(player, packet);
+        PacketListenerConsumer<T> packetListenerConsumer = listeners.get(packet.getClass());
+
+        // Listener can be null if none has been set before, call PacketConsumer anyway
+        if (packetListenerConsumer == null) {
+            System.err.println("Packet " + packet.getClass() + " does not have any listener!");
         }
-        if (cancel)
+
+
+        PacketController packetController = new PacketController(packetListenerConsumer);
+        for (PacketConsumer packetConsumer : connectionManager.getPacketConsumers()) {
+            packetConsumer.accept(player, packetController, packet);
+        }
+
+        if (packetController.isCancel())
             return;
 
-        BiConsumer<T, Player> biConsumer = (BiConsumer<T, Player>) listeners.get(packet.getClass());
-        if (biConsumer == null) {
-            System.err.println("Packet " + packet.getClass() + " does not have any listener!");
-            return;
+        // Call the listener if not null
+        // (can be null because no listener is set, or because it has been changed by the controller)
+        if (packetListenerConsumer != null) {
+            packetListenerConsumer.accept(packet, player);
         }
-        biConsumer.accept(packet, player);
     }
 
-    public <T extends ClientPlayPacket> void addListener(Class<T> packetClass, BiConsumer<T, Player> consumer) {
+    public <T extends ClientPlayPacket> void addListener(Class<T> packetClass, PacketListenerConsumer<T> consumer) {
         this.listeners.put(packetClass, consumer);
     }