Added PlayerPreLoginEvent

src/main/java/net/minestom/server/entity/Entity.java

@@ -539,6 +539,15 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
         return uuid;
     }
 
+    /**
+     * Change the internal entity UUID, mostly unsafe
+     *
+     * @param uuid the new entity uuid
+     */
+    protected void setUuid(UUID uuid) {
+        this.uuid = uuid;
+    }
+
     /**
      * Return false just after instantiation, set to true after calling {@link #setInstance(Instance)}
      *

src/main/java/net/minestom/server/entity/EntityManager.java

@@ -2,6 +2,7 @@ package net.minestom.server.entity;
 
 import net.minestom.server.MinecraftServer;
 import net.minestom.server.event.player.PlayerLoginEvent;
+import net.minestom.server.event.player.PlayerPreLoginEvent;
 import net.minestom.server.instance.Chunk;
 import net.minestom.server.instance.Instance;
 import net.minestom.server.instance.InstanceManager;
@@ -9,8 +10,10 @@ import net.minestom.server.utils.thread.MinestomThread;
 import net.minestom.server.utils.validate.Check;
 
 import java.util.Set;
+import java.util.UUID;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.ExecutorService;
+import java.util.function.Consumer;
 
 public final class EntityManager {
 
@@ -178,8 +181,38 @@ public final class EntityManager {
         }
     }
 
+    /**
+     * Call the player initialization callbacks and the event {@link PlayerPreLoginEvent}
+     * If the player hasn't been kicked, add him to the waiting list
+     * <p>
+     * Can be considered as a pre-init thing
+     *
+     * @param player the player to add
+     */
     public void addWaitingPlayer(Player player) {
+
+        // Init player (register events)
+        for (Consumer<Player> playerInitialization : MinecraftServer.getConnectionManager().getPlayerInitializations()) {
+            playerInitialization.accept(player);
+        }
+
+        // Call pre login event
+        PlayerPreLoginEvent playerPreLoginEvent = new PlayerPreLoginEvent(player, player.getUsername(), player.getUuid());
+        player.callEvent(PlayerPreLoginEvent.class, playerPreLoginEvent);
+
+        // Ignore the player if he has been disconnected (kick)
+        final boolean online = player.isOnline();
+        if (!online)
+            return;
+
+        // Add him to the list and change his username/uuid if changed
         this.waitingPlayers.add(player);
+
+        String username = playerPreLoginEvent.getUsername();
+        UUID uuid = playerPreLoginEvent.getPlayerUuid();
+
+        player.setUsername(username);
+        player.setUuid(uuid);
     }
 
     /**

src/main/java/net/minestom/server/entity/Player.java

@@ -167,12 +167,6 @@ public class Player extends LivingEntity implements CommandSender {
      * Init the player and spawn him
      */
     protected void init() {
-
-        // Init player (register events)
-        for (Consumer<Player> playerInitialization : MinecraftServer.getConnectionManager().getPlayerInitializations()) {
-            playerInitialization.accept(this);
-        }
-
         // TODO complete login sequence with optionals packets
         JoinGamePacket joinGamePacket = new JoinGamePacket();
         joinGamePacket.entityId = getEntityId();
@@ -950,6 +944,16 @@ public class Player extends LivingEntity implements CommandSender {
         return username;
     }
 
+    /**
+     * Change the internal player name, used for the {@link PlayerPreLoginEvent}
+     * mostly unsafe outside of it
+     *
+     * @param username the new player name
+     */
+    protected void setUsername(String username) {
+        this.username = username;
+    }
+
     private void sendChangeGameStatePacket(ChangeGameStatePacket.Reason reason, float value) {
         ChangeGameStatePacket changeGameStatePacket = new ChangeGameStatePacket();
         changeGameStatePacket.reason = reason;
@@ -1289,6 +1293,7 @@ public class Player extends LivingEntity implements CommandSender {
         disconnectPacket.message = Chat.toJsonString(textComponent);
         playerConnection.sendPacket(disconnectPacket);
         playerConnection.disconnect();
+        playerConnection.refreshOnline(false);
     }
 
     /**

src/main/java/net/minestom/server/event/player/PlayerPreLoginEvent.java

@@ -0,0 +1,71 @@
+package net.minestom.server.event.player;
+
+import net.minestom.server.entity.Player;
+import net.minestom.server.event.Event;
+import net.minestom.server.utils.validate.Check;
+
+import java.util.UUID;
+
+/**
+ * Called before the player initialization, it can be used to kick the player before any connection
+ * or to change its final username/uuid
+ */
+public class PlayerPreLoginEvent extends Event {
+
+    private Player player;
+    private String username;
+    private UUID playerUuid;
+
+    public PlayerPreLoginEvent(Player player, String username, UUID playerUuid) {
+        this.player = player;
+        this.username = username;
+        this.playerUuid = playerUuid;
+    }
+
+    /**
+     * Get the player who is trying to connect
+     *
+     * @return the player
+     */
+    public Player getPlayer() {
+        return player;
+    }
+
+    /**
+     * Get the player username
+     *
+     * @return the player username
+     */
+    public String getUsername() {
+        return username;
+    }
+
+    /**
+     * Change the player username
+     *
+     * @param username the new player username
+     */
+    public void setUsername(String username) {
+        Check.notNull(username, "The player username cannot be null");
+        this.username = username;
+    }
+
+    /**
+     * Get the player uuid
+     *
+     * @return the player uuid
+     */
+    public UUID getPlayerUuid() {
+        return playerUuid;
+    }
+
+    /**
+     * Change the player uuid
+     *
+     * @param playerUuid the new player uuid
+     */
+    public void setPlayerUuid(UUID playerUuid) {
+        Check.notNull(playerUuid, "The player uuid cannot be null");
+        this.playerUuid = playerUuid;
+    }
+}