NPCLib/api/src/main/java/net/jitse/npclib/listeners/ChunkListener.java

/*
 * Copyright (c) 2018 Jitse Boonstra
 */

package net.jitse.npclib.listeners;

import net.jitse.npclib.NPCLib;
import net.jitse.npclib.internal.NPCManager;
import net.jitse.npclib.internal.SimpleNPC;
import org.bukkit.Bukkit;
import org.bukkit.Chunk;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.world.ChunkLoadEvent;
import org.bukkit.event.world.ChunkUnloadEvent;

import java.util.UUID;

/**
 * @author Jitse Boonstras
 */
public class ChunkListener implements Listener {

    private final NPCLib instance;

    public ChunkListener(NPCLib instance) {
        this.instance = instance;
    }

    @EventHandler
    public void onChunkUnload(ChunkUnloadEvent event) {
        Chunk chunk = event.getChunk();

        for (SimpleNPC npc : NPCManager.getAllNPCs()) {
            Chunk npcChunk = npc.getLocation().getChunk();

            if (chunk.equals(npcChunk)) {
                // Unloaded chunk with NPC in it. Hiding it from all players currently shown to.

                for (UUID uuid : npc.getShown()) {
                    // Safety check so it doesn't send packets if the NPC has already
                    // been automatically despawned by the system.
                    if (npc.getAutoHidden().contains(uuid)) {
                        continue;
                    }

                    npc.hide(Bukkit.getPlayer(uuid), true, true);
                }
            }
        }
    }

    @EventHandler
    public void onChunkLoad(ChunkLoadEvent event) {
        Chunk chunk = event.getChunk();

        for (SimpleNPC npc : NPCManager.getAllNPCs()) {
            Chunk npcChunk = npc.getLocation().getChunk();

            if (chunk.equals(npcChunk)) {
                // Loaded chunk with NPC in it. Showing it to the players again.

                for (UUID uuid : npc.getShown()) {
                    // Make sure not to respawn a not-hidden NPC.
                    if (!npc.getAutoHidden().contains(uuid)) {
                        continue;
                    }

                    Player player = Bukkit.getPlayer(uuid);

                    if (!npcChunk.getWorld().equals(player.getWorld())) {
                        continue; // Player and NPC are not in the same world.
                    }

                    double hideDistance = instance.getAutoHideDistance();
                    double distanceSquared = player.getLocation().distanceSquared(npc.getLocation());
                    boolean inRange = distanceSquared <= (hideDistance * hideDistance) || distanceSquared <= (Bukkit.getViewDistance() << 4);

                    // Show the NPC (if in range).
                    if (inRange) {
                        npc.show(player, true);
                    }
                }
            }
        }
    }
}