package net.minecraft.world.level.entity;

import it.unimi.dsi.fastutil.ints.Int2ObjectLinkedOpenHashMap;
import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
import it.unimi.dsi.fastutil.ints.Int2ObjectMap.Entry;
import it.unimi.dsi.fastutil.ints.Int2ObjectMaps;
import it.unimi.dsi.fastutil.objects.ObjectIterator;
import java.util.function.Consumer;
import javax.annotation.Nullable;
import net.minecraft.world.entity.Entity;

public class EntityTickList {

    private Int2ObjectMap<Entity> active = new Int2ObjectLinkedOpenHashMap();
    private Int2ObjectMap<Entity> passive = new Int2ObjectLinkedOpenHashMap();
    @Nullable
    private Int2ObjectMap<Entity> iterated;

    public EntityTickList() {}

    private void a() {
        if (this.iterated == this.active) {
            this.passive.clear();
            ObjectIterator objectiterator = Int2ObjectMaps.fastIterable(this.active).iterator();

            while (objectiterator.hasNext()) {
                Entry<Entity> entry = (Entry) objectiterator.next();

                this.passive.put(entry.getIntKey(), (Entity) entry.getValue());
            }

            Int2ObjectMap<Entity> int2objectmap = this.active;

            this.active = this.passive;
            this.passive = int2objectmap;
        }

    }

    public void a(Entity entity) {
        this.a();
        this.active.put(entity.getId(), entity);
    }

    public void b(Entity entity) {
        this.a();
        this.active.remove(entity.getId());
    }

    public boolean c(Entity entity) {
        return this.active.containsKey(entity.getId());
    }

    public void a(Consumer<Entity> consumer) {
        if (this.iterated != null) {
            throw new UnsupportedOperationException("Only one concurrent iteration supported");
        } else {
            this.iterated = this.active;

            try {
                ObjectIterator objectiterator = this.active.values().iterator();

                while (objectiterator.hasNext()) {
                    Entity entity = (Entity) objectiterator.next();

                    consumer.accept(entity);
                }
            } finally {
                this.iterated = null;
            }

        }
    }
}