Implement a connect callback - see #760

api/src/main/java/net/md_5/bungee/api/connection/ProxiedPlayer.java

@@ -1,5 +1,6 @@
 package net.md_5.bungee.api.connection;
 
+import net.md_5.bungee.api.Callback;
 import net.md_5.bungee.api.CommandSender;
 import net.md_5.bungee.api.config.ServerInfo;
 import net.md_5.bungee.api.tab.TabListHandler;
@@ -35,6 +36,18 @@ public interface ProxiedPlayer extends Connection, CommandSender
      */
     void connect(ServerInfo target);
 
+    /**
+     * Connects / transfers this user to the specified connection, gracefully
+     * closing the current one. Depending on the implementation, this method
+     * might return before the user has been connected.
+     *
+     * @param target the new server to connect to
+     * @param callback the method called when the connection is complete, or
+     * when an exception is encountered. The boolean parameter denotes success
+     * or failure.
+     */
+    void connect(ServerInfo target, Callback<Boolean> callback);
+
     /**
      * Gets the server this player is connected to.
      *

proxy/src/main/java/net/md_5/bungee/UserConnection.java

@@ -19,6 +19,7 @@ import lombok.Getter;
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 import lombok.Setter;
+import net.md_5.bungee.api.Callback;
 import net.md_5.bungee.api.ProxyServer;
 import net.md_5.bungee.api.chat.BaseComponent;
 import net.md_5.bungee.api.chat.TextComponent;
@@ -162,7 +163,13 @@ public final class UserConnection implements ProxiedPlayer
     @Override
     public void connect(ServerInfo target)
     {
-        connect( target, false );
+        connect( target, null );
+    }
+
+    @Override
+    public void connect(ServerInfo target, Callback<Boolean> callback)
+    {
+        connect( target, callback, false );
     }
 
     void sendDimensionSwitch()
@@ -178,7 +185,7 @@ public final class UserConnection implements ProxiedPlayer
         connect( target );
     }
 
-    public void connect(ServerInfo info, final boolean retry)
+    public void connect(ServerInfo info, final Callback<Boolean> callback, final boolean retry)
     {
         Preconditions.checkNotNull( info, "info" );
 
@@ -219,6 +226,8 @@ public final class UserConnection implements ProxiedPlayer
             @Override
             public void operationComplete(ChannelFuture future) throws Exception
             {
+                callback.done( future.isSuccess(), future.cause() );
+
                 if ( !future.isSuccess() )
                 {
                     future.channel().close();
@@ -228,7 +237,7 @@ public final class UserConnection implements ProxiedPlayer
                     if ( retry && target != def && ( getServer() == null || def != getServer().getInfo() ) )
                     {
                         sendMessage( bungee.getTranslation( "fallback_lobby" ) );
-                        connect( def, false );
+                        connect( def, null, false );
                     } else
                     {
                         if ( dimensionChange )
@@ -274,7 +283,7 @@ public final class UserConnection implements ProxiedPlayer
         disconnect0( reason );
     }
 
-    public synchronized void disconnect0(BaseComponent ...reason)
+    public synchronized void disconnect0(BaseComponent... reason)
     {
         if ( ch.getHandle().isActive() )
         {

proxy/src/main/java/net/md_5/bungee/connection/InitialHandler.java

@@ -383,7 +383,7 @@ public class InitialHandler extends PacketHandler implements PendingConnection
                             {
                                 server = AbstractReconnectHandler.getForcedHost( InitialHandler.this );
                             }
-                            userCon.connect( server, true );
+                            userCon.connect( server, null, true );
 
                             thisState = State.FINISHED;
                         }
@@ -399,7 +399,7 @@ public class InitialHandler extends PacketHandler implements PendingConnection
     @Override
     public synchronized void disconnect(String reason)
     {
-        if (!ch.isClosed())
+        if ( !ch.isClosed() )
         {
             unsafe().sendPacket( new Kick( ComponentSerializer.toString( TextComponent.fromLegacyText( reason ) ) ) );
             ch.close();
@@ -419,7 +419,10 @@ public class InitialHandler extends PacketHandler implements PendingConnection
     @Override
     public void disconnect(BaseComponent reason)
     {
-        disconnect( new BaseComponent[]{reason} );
+        disconnect( new BaseComponent[]
+        {
+            reason
+        } );
     }
 
     @Override