Tab

Tab.java

/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 3
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */

package packagename;

import net.md_5.bungee.api.chat.BaseComponent;
import net.md_5.bungee.chat.ComponentSerializer;
import org.bukkit.Bukkit;
import org.bukkit.entity.Player;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Tab
{

    private static Constructor<?> headerFooterConstructor;
    private static Method sendPacket;
    private static Method getHandle;
    private static Method serialize;
    private static Field playerConnection;
    private static Field headerField;
    private static Field footerField;

    private Object packet;

    static
    {
        String version = Bukkit.getServer().getClass().getPackage().getName().split( "\\." )[ 3 ];
        String nms = "net.minecraft.server." + version + ".";
        try
        {
            Class<?> entityPlayerClass = Class.forName( nms + "EntityPlayer" );
            Class<?> listHeaderFooterClass = Class.forName( nms + "PacketPlayOutPlayerListHeaderFooter" );
            getHandle = Class.forName( "org.bukkit.craftbukkit." + version + ".entity.CraftPlayer" )
                    .getMethod( "getHandle" );
            playerConnection = entityPlayerClass.getField( "playerConnection" );
            serialize = Class.forName( nms + "IChatBaseComponent$ChatSerializer" ).getMethod( "a", String.class );
            sendPacket =  Class.forName( nms + "PlayerConnection" ).getMethod( "sendPacket",
                    Class.forName( "net.minecraft.server." + version + ".Packet" ) );
            headerField = listHeaderFooterClass.getDeclaredField( "a" );
            headerField.setAccessible( true );
            footerField = listHeaderFooterClass.getDeclaredField( "b" );
            footerField.setAccessible( true );
            headerFooterConstructor = listHeaderFooterClass.getConstructor();
        } catch ( ClassNotFoundException | NoSuchMethodException
                | NoSuchFieldException e )
        {
            e.printStackTrace();
        }
    }

    public Tab(BaseComponent[] header, BaseComponent[] footer)
    {
        try
        {
            packet = headerFooterConstructor.newInstance();
            setHeader( header );
            setFooter( footer );
        } catch ( InstantiationException | IllegalAccessException | InvocationTargetException e )
        {
            e.printStackTrace();
        }
    }

    public void setHeader(BaseComponent[] header)
    {
        try
        {
            headerField.set( packet, serialize.invoke( null, ComponentSerializer.toString( header ) ) );
        } catch ( IllegalAccessException | InvocationTargetException e )
        {
            e.printStackTrace();
        }
    }

    public void setFooter(BaseComponent[] footer)
    {
        try
        {
            footerField.set( packet, serialize.invoke( null, ComponentSerializer.toString( footer ) ) );
        } catch ( IllegalAccessException | InvocationTargetException e )
        {
            e.printStackTrace();
        }
    }

    public void setHeaderFooter(Player player)
    {
        try
        {
            Object handle = getHandle.invoke( player );
            Object connection = playerConnection.get( handle );
            sendPacket.invoke( connection, packet );
        } catch ( IllegalAccessException
                | InvocationTargetException e )
        {
            e.printStackTrace();
        }
    }
}