Minestom/src/main/java/fr/themode/minestom/Viewable.java

package fr.themode.minestom;

import fr.themode.minestom.entity.Player;
import fr.themode.minestom.net.PacketWriterUtils;
import fr.themode.minestom.net.packet.server.ServerPacket;

import java.util.Set;

public interface Viewable {

    void addViewer(Player player);

    void removeViewer(Player player);

    Set<Player> getViewers();

    default boolean isViewer(Player player) {
        return getViewers().contains(player);
    }

    default void sendPacketToViewers(ServerPacket packet) {
        if (getViewers().isEmpty())
            return;

        PacketWriterUtils.writeCallbackPacket(packet, buffer -> {
            int size = getViewers().size();
            if (size == 0)
                return;
            buffer.getData().retain(size).markReaderIndex();
            for (Player viewer : getViewers()) {
                viewer.getPlayerConnection().writeUnencodedPacket(buffer);
                buffer.getData().resetReaderIndex();
            }
        });
    }

    default void sendPacketsToViewers(ServerPacket... packets) {
        if (getViewers().isEmpty())
            return;

        for (ServerPacket packet : packets) {
            PacketWriterUtils.writeCallbackPacket(packet, buffer -> {
                int size = getViewers().size();
                if (size == 0)
                    return;
                buffer.getData().retain(size).markReaderIndex();
                for (Player viewer : getViewers()) {
                    viewer.getPlayerConnection().writeUnencodedPacket(buffer);
                    buffer.getData().resetReaderIndex();
                }
            });
        }
    }

    default void sendPacketToViewersAndSelf(ServerPacket packet) {
        if (this instanceof Player) {
            UNSAFE_sendPacketToViewersAndSelf(packet);
        } else {
            sendPacketToViewers(packet);
        }
    }

    private void UNSAFE_sendPacketToViewersAndSelf(ServerPacket packet) {
        PacketWriterUtils.writeCallbackPacket(packet, buffer -> {
            int size = getViewers().size();
            buffer.getData().retain(size + 1).markReaderIndex();
            ((Player) this).getPlayerConnection().writeUnencodedPacket(buffer);
            buffer.getData().resetReaderIndex();
            if (size != 0) {
                for (Player viewer : getViewers()) {
                    buffer.getData().resetReaderIndex();
                    viewer.getPlayerConnection().writeUnencodedPacket(buffer);
                }
            }
        });
    }

}