minecraft-kajetans-mod/src/main/java/me/km/networking/PlayerDisplay.java

package me.km.networking;

import io.netty.buffer.ByteBuf;
import java.nio.charset.StandardCharsets;
import net.minecraft.client.Minecraft;
import net.minecraftforge.fml.common.network.simpleimpl.IMessage;
import net.minecraftforge.fml.common.network.simpleimpl.IMessageHandler;
import net.minecraftforge.fml.common.network.simpleimpl.MessageContext;

public class PlayerDisplay implements IMessage
{
    // 1 - add - index, text
    // 2 - remove - index
    // 3 - clear
    private byte action;
    private byte index;
    private String text;
    
    public PlayerDisplay() 
    {
        action = -1;
        index = -1;
        text = "";
    }
    
    public PlayerDisplay(byte action, byte index, String text) 
    {
        this.action = action;
        this.index = index;
        if(text.length() > 32)
        {
            this.text = text.substring(0, 32);
        }
        else
        {
            this.text = text;
        }
    }
    
    @Override
    public void fromBytes(ByteBuf buf) 
    {
        action = buf.readByte();
        index = buf.readByte();
        int length = buf.readInt();
        text = buf.readBytes(length).toString(StandardCharsets.UTF_8);
    }

    @Override
    public void toBytes(ByteBuf buf) 
    {
        buf.writeByte(action);
        buf.writeByte(index);
        byte[] b = text.getBytes(StandardCharsets.UTF_8);
        buf.writeInt(b.length);
        buf.writeBytes(b);
    }

    public static class Handler implements IMessageHandler<PlayerDisplay, IMessage>
    {
        @Override
        public IMessage onMessage(PlayerDisplay message, MessageContext ctx) 
        {
            Minecraft mc = net.minecraft.client.Minecraft.getMinecraft();
            mc.addScheduledTask(() -> 
            {
                switch(message.action)
                {
                    case 1:
                        PlayerDisplayGui.INSTANCE.add(message.index, message.text);
                        break;
                    case 2:
                        PlayerDisplayGui.INSTANCE.remove(message.index);
                        break;
                    case 3: 
                        PlayerDisplayGui.INSTANCE.clear();
                        break;
                }
            });
            return null;
        }
    }
}