Hologram.java

package com.mrpowergamerbr.sparklycore.utils.hologram;

import java.lang.ref.WeakReference;
import java.lang.reflect.Field;
import java.util.Arrays;
import java.util.List;

import org.bukkit.Bukkit;
import org.bukkit.Location;
import org.bukkit.entity.Entity;
import org.bukkit.entity.EntityType;
import org.bukkit.entity.Player;

import com.comphenix.protocol.wrappers.WrappedDataWatcher;
import com.comphenix.protocol.wrappers.WrappedWatchableObject;
import com.mrpowergamerbr.packetwrapper.AbstractPacket;
import com.mrpowergamerbr.packetwrapper.WrapperPlayServerAttachEntity;
import com.mrpowergamerbr.packetwrapper.WrapperPlayServerEntityDestroy;
import com.mrpowergamerbr.packetwrapper.WrapperPlayServerEntityMetadata;
import com.mrpowergamerbr.packetwrapper.WrapperPlayServerEntityTeleport;
import com.mrpowergamerbr.packetwrapper.WrapperPlayServerSpawnEntityLiving;

import lombok.*;
import me.mrpowergamerbr.sparklycore.utils.collections.WeakArrayList;

/**
 * Class to spawn holograms in 1.8
 * @author Leonardo
 *
 */
public class Hologram {
    int horseId = 0; // Also used as the Armor Stand ID
    String line;
    @Getter
    Location location;
    @Getter
    @Setter
    WeakArrayList<Player> viewers = new WeakArrayList<Player>();
    @Getter
    @Setter
    ViewHandler vh;
    static WrappedDataWatcher wdw = null; // This is static because we don't need to regenerate this every time

    static {
        wdw.setObject(0, (byte) 0x20); // Invisible
        wdw.setObject(3, (byte) 1); // Always show nametag
        int bitmask = 0x02; // No gravity
        bitmask = bitmask | 0x16; // Zero Bounding Box (Marker)
        wdw.setObject(10, (byte) bitmask); // Set our metadatas
    }

    public Hologram(Location location, String line) {
        this.location = location;
        this.line = line;
        horseId = getId();
    }

    public void setViewHandler(ViewHandler vh) {
        this.vh = vh;
    }

    private static int getId() {
        try {
            Field field = Class.forName(
                    "net.minecraft.server." + Bukkit.getServer().getClass().getName().split("\\.")[3] + ".Entity")
                    .getDeclaredField("entityCount");
            field.setAccessible(true);
            int id = field.getInt(null);
            field.set(null, id + 1);
            return id;
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return -1;
    }

    public void setLine(String line) {
        this.line = line;

        for (WeakReference<Player> p : viewers.getItems()) {
            if (p.get() != null) {
                List<AbstractPacket> packets = null;

                packets = generateMetadataPackets18(p.get());

                for (AbstractPacket packet : packets) {
                    packet.sendPacket(p.get());
                }
            }
        }
    }

    public String getLineForPlayer(Player p) {
        if (vh != null) {
            return vh.onView(this, p, line);
        }
        return line;
    }

    private List<AbstractPacket> generateMetadataPackets18(Player p) {
        WrapperPlayServerEntityMetadata metadata = new WrapperPlayServerEntityMetadata();
        metadata.setEntityID(horseId);
        WrappedWatchableObject wwo = new WrappedWatchableObject(2, getLineForPlayer(p));
        metadata.setMetadata(Arrays.asList(wwo));

        return Arrays.asList(metadata);
    }

    public void addEveryoneAsViewer() {
        for (Player p : Bukkit.getOnlinePlayers()) {
            addViewer(p);
        }
    }

    public void removeEveryoneFromViewers() {
        for (WeakReference<Player> p : getViewers().getItems()) {
            if (p.get() != null) {
                despawnForPlayer(p.get());
                viewers.remove(p.get());
            }
        }
    }

    public void addViewer(Player p) {
        viewers.add(p);

        spawnForPlayer(p);
    }

    public void removeViewer(Player p) {
        viewers.remove(p);

        despawnForPlayer(p);
    }

    public void spawnForAll() {
        if (line == null) {
            throw new RuntimeException("Line is null!");
        }

        for (WeakReference<Player> p : viewers.getItems()) {
            if (p.get() != null) {
                spawnForPlayer(p.get());
            }
        }
    }

    public void spawnForPlayer(Player p) {
        if (!p.getLocation().getWorld().equals(location.getWorld())) {
            return;
        }
        List<AbstractPacket> packets = null;

        packets = generateSpawnPackets18(p);

        for (AbstractPacket packet : packets) {
            packet.sendPacket(p);
        }
    }

    private List<AbstractPacket> generateSpawnPackets18(Player p) {
        // Because Armor Stand is a living entity...
        WrapperPlayServerSpawnEntityLiving armorStand = new WrapperPlayServerSpawnEntityLiving();

        armorStand.setEntityID(horseId);
        armorStand.setX(location.getX());
        armorStand.setY(location.getY() + 1.52);
        armorStand.setZ(location.getZ());
        armorStand.setType(EntityType.ARMOR_STAND); // Armor Stand ID

        WrappedDataWatcher wdw = Hologram.wdw.deepClone();
        wdw.setObject(2, getLineForPlayer(p));

        armorStand.setMetadata(wdw);

        List<AbstractPacket> packets = Arrays.asList(armorStand);
        return packets;
    }

    public void despawnForPlayer(Player p) {
        WrapperPlayServerEntityDestroy remove = new WrapperPlayServerEntityDestroy();

        remove.setEntityIds(new int[] { horseId });

        remove.sendPacket(p);
    }

    public void despawnForAll() {
        WrapperPlayServerEntityDestroy remove = new WrapperPlayServerEntityDestroy();

        remove.setEntityIds(new int[] { horseId });

        for (WeakReference<Player> p : viewers.getItems()) {
            if (p.get() != null) {
                remove.sendPacket(p.get());
            }
        }
    }

    public void teleport(Location l) {
        this.location = l;

        // Optimizing teleport: Create only one packet and then send to everyone
        WrapperPlayServerEntityTeleport teleport = new WrapperPlayServerEntityTeleport();
        teleport.setEntityID(horseId);
        teleport.setX(l.getX());
        teleport.setY(l.getY());
        teleport.setZ(l.getZ());

        for (WeakReference<Player> p : viewers.getItems()) {
            if (p.get() != null) {
                teleport.sendPacket(p.get());
            }
        }
    }

    public void teleport(Player p, Location l) {
        this.location = l;

        // Not so optimized: Do not use for (Player p : Bukkit.getOnlinePlayers()) { teleport(p, l); } for this! Use teleport(l);
        WrapperPlayServerEntityTeleport teleport = new WrapperPlayServerEntityTeleport();
        teleport.setEntityID(horseId);
        teleport.setX(l.getX());
        teleport.setY(l.getY());
        teleport.setZ(l.getZ());

        teleport.sendPacket(p);
    }

    public void teleport(List<Player> players, Location l) {
        this.location = l;

        // Optimizing teleport: Create only one packet and then send to everyone
        WrapperPlayServerEntityTeleport teleport = new WrapperPlayServerEntityTeleport();
        teleport.setEntityID(horseId);
        teleport.setX(l.getX());
        teleport.setY(l.getY());
        teleport.setZ(l.getZ());

        for (Player p : players) {
            teleport.sendPacket(p);
        }
    }

    public Hologram addLineBelow(String line) {
        Hologram hologram = new Hologram(getLocation().clone().add(0, -0.285, 0), line);
        return hologram;
    }

    public Hologram addLineAbove(String line) {
        Hologram hologram = new Hologram(getLocation().clone().add(0, 0.285, 0), line);
        return hologram;
    }

    public void attachTo(Entity entity) {
        WrapperPlayServerAttachEntity wpsae = new WrapperPlayServerAttachEntity();
        wpsae.setVehicleId(entity.getEntityId());
        wpsae.setEntityID(horseId);

        for (WeakReference<Player> p : getViewers().getItems()) {
            if (p.get() != null) {
                wpsae.sendPacket(p.get());
            }
        }
    }

    public void unattach() {
        WrapperPlayServerAttachEntity wpsae = new WrapperPlayServerAttachEntity();
        wpsae.setVehicleId(-1);
        wpsae.setEntityID(horseId);

        for (WeakReference<Player> p : getViewers().getItems()) {
            if (p.get() != null) {
                wpsae.sendPacket(p.get());
            }
        }
    }
}

class ViewHandler {
    public String onView(Hologram hologram, Player player, String string) {
        return string;
    }
}