Prevent from going on unloaded chunks

src/main/java/fr/themode/minestom/entity/Player.java

@@ -1,7 +1,9 @@
 package fr.themode.minestom.entity;
 
 import fr.themode.minestom.Main;
+import fr.themode.minestom.instance.Chunk;
 import fr.themode.minestom.net.packet.server.play.EntityTeleportPacket;
+import fr.themode.minestom.net.packet.server.play.PlayerPositionAndLookPacket;
 import fr.themode.minestom.net.packet.server.play.UpdateViewPositionPacket;
 import fr.themode.minestom.net.player.PlayerConnection;
 
@@ -42,6 +44,23 @@ public class Player extends LivingEntity {
         playerConnection.sendPacket(new UpdateViewPositionPacket(Math.floorDiv((int) x, 16), Math.floorDiv((int) z, 16)));
     }
 
+    public boolean chunkTest(double x, double z) {
+        Chunk newChunk = getInstance().getChunk((int) Math.floor(x / 16), (int) Math.floor(z / 16));
+        if (newChunk == null) {
+            PlayerPositionAndLookPacket positionAndLookPacket = new PlayerPositionAndLookPacket();
+            positionAndLookPacket.x = getX();
+            positionAndLookPacket.y = getY();
+            positionAndLookPacket.z = getZ();
+            positionAndLookPacket.yaw = getYaw();
+            positionAndLookPacket.pitch = getPitch();
+            positionAndLookPacket.flags = 0x00;
+            positionAndLookPacket.teleportId = 67;
+            getPlayerConnection().sendPacket(positionAndLookPacket);
+            return true;
+        }
+        return false;
+    }
+
     public String getUsername() {
         return username;
     }

src/main/java/fr/themode/minestom/instance/Instance.java

@@ -8,15 +8,16 @@ import fr.themode.minestom.utils.GroupedCollections;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
+import java.util.UUID;
 
 public class Instance {
 
-    private int id;
+    private UUID uniqueId;
 
     private Set<Chunk> chunksSet = Collections.synchronizedSet(new HashSet<>());
 
-    public Instance(int id) {
+    public Instance(UUID uniqueId) {
-        this.id = id;
+        this.uniqueId = uniqueId;
     }
 
     // TODO BlockBatch with pool
@@ -98,8 +99,8 @@ public class Instance {
         return players;
     }
 
-    public int getId() {
+    public UUID getUniqueId() {
-        return id;
+        return uniqueId;
     }
 
     private Chunk createChunk(int chunkX, int chunkZ) {

src/main/java/fr/themode/minestom/instance/InstanceManager.java

@@ -3,19 +3,14 @@ package fr.themode.minestom.instance;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
+import java.util.UUID;
 
 public class InstanceManager {
 
-    private static volatile int lastInstanceId;
-
     private Set<Instance> instances = Collections.synchronizedSet(new HashSet<>());
 
-    private static int generateId() {
-        return ++lastInstanceId;
-    }
-
     public Instance createInstance() {
-        Instance instance = new Instance(generateId());
+        Instance instance = new Instance(UUID.randomUUID());
         this.instances.add(instance);
         return instance;
     }

src/main/java/fr/themode/minestom/net/packet/client/play/ClientPlayerPositionAndLookPacket.java

@@ -12,6 +12,10 @@ public class ClientPlayerPositionAndLookPacket implements ClientPlayPacket {
 
     @Override
     public void process(Player player) {
+        boolean chunkTest = player.chunkTest(x, z);
+        if (chunkTest)
+            return;
+
         player.refreshPosition(x, y, z);
         player.refreshView(yaw, pitch);
         player.refreshOnGround(onGround);

src/main/java/fr/themode/minestom/net/packet/client/play/ClientPlayerPositionPacket.java

@@ -11,6 +11,10 @@ public class ClientPlayerPositionPacket implements ClientPlayPacket {
 
     @Override
     public void process(Player player) {
+        boolean chunkTest = player.chunkTest(x, z);
+        if (chunkTest)
+            return;
+
         player.refreshPosition(x, y, z);
         player.refreshOnGround(onGround);
     }