Hologram.java

package io.github.ninjaservices.factions.util.hologram;

import lombok.AccessLevel;
import lombok.Getter;
import net.minecraft.server.v1_8_R3.*;
import org.bukkit.Bukkit;
import org.bukkit.Location;
import org.bukkit.craftbukkit.v1_8_R3.CraftWorld;
import org.bukkit.craftbukkit.v1_8_R3.entity.CraftPlayer;
import org.bukkit.entity.Player;

import javax.annotation.Nullable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Set;

@Getter
public class Hologram {
	
	private static final int DEFAULT_RANGE = 128;
	
	private String hologramId;
	private Location originLocation;
	
	@Getter(AccessLevel.NONE)
	private List<EntityArmorStand> lines;
	private Set<String> viewers;
	
	private long expireTime;
	
	public Hologram(Location originLocation) {
		this.hologramId = Long.toHexString(System.nanoTime());
		this.originLocation = originLocation;
		this.lines = new ArrayList<>();
		this.expireTime = System.currentTimeMillis() + (1_500);
	}
	
	public void expireIn(double seconds){
		this.expireTime = (long) (System.currentTimeMillis() + (seconds + 1000L));
	}
	
	public boolean isExpired(){
		return System.currentTimeMillis() >= expireTime;
	}
	
	public String getLine(int index) {
		EntityArmorStand stand = this.getStand(index);
		if (stand == null) {
			return null;
		}
		
		return stand.getCustomName();
	}
	
	public void addLine(String line) {
		int distanceMultiplier = lines.size();
		spawn(originLocation.clone().subtract(0, -0.2 * distanceMultiplier, 0) , line);
	}
	
	public void setLine(int index, String text) {
		EntityArmorStand stand = this.getStand(index);
		if (stand == null) {
			return;
		}
		
		stand.setCustomName(text);
		sendPacketToViewers(new PacketPlayOutEntityMetadata(stand.getId(), stand.getDataWatcher(), false));
	}
	
	
	public void teleport(Location location) {
		this.originLocation = location;
		
		double y = 0;
		for (int i = 0, linesSize = lines.size(); i < linesSize; i++) {
			EntityArmorStand line = lines.get(i);
			line.locX = location.getX();
			line.locY = location.getY() - y;
			line.locZ = location.getZ();
			
			y += 0.2;
			
			sendPacketToViewers(new PacketPlayOutEntityTeleport(line));
		}
	}
	
	public void destroy() {
		for (EntityArmorStand line : lines) {
			sendPacketToViewers(new PacketPlayOutEntityDestroy(line.getId()));
		}
	}
	
	EntityArmorStand spawn(Location location , String text) {
		WorldServer handle = ((CraftWorld) location.getWorld()).getHandle();
		
		EntityArmorStand entityArmorStand = new EntityArmorStand(handle);
		
		entityArmorStand.setCustomName(text);
		entityArmorStand.setCustomNameVisible(true);
		entityArmorStand.setInvisible(true);
		entityArmorStand.setSmall(true);
		
		entityArmorStand.locX = location.getX();
		entityArmorStand.locY = location.getY();
		entityArmorStand.locZ = location.getZ();
		
		sendPacketToViewers(new PacketPlayOutSpawnEntityLiving(entityArmorStand));
		
		lines.add(entityArmorStand);
		
		return entityArmorStand;
	}
	
	
	private void sendPacketToViewers(Packet<?> packet) {
		Collection<? extends Player> onlinePlayers = Bukkit.getOnlinePlayers();
		
		for (Player player : onlinePlayers) {
			if(distance(originLocation,player.getLocation()) <= DEFAULT_RANGE){
				sendPacket(player, packet);
			}
		}
	}
	
	private void sendPacket(Player player, Packet<?> packet) {
		((CraftPlayer) player).getHandle()
			.playerConnection
			.sendPacket(packet);
	}
	
	@Nullable
	EntityArmorStand getStand(int index) {
		try {
			return lines.get(index);
		} catch (Exception e) {
			return null;
		}
	}
	
	public double distance(Location a, Location b){
		return Math.sqrt(
			square(a.getX() - b.getX())
			+ square(a.getY() - b.getY())
			+ square(a.getZ() - b.getZ())
		);
	}
	
	private double square(double x){
		return x * x;
	}
}