package net.minecraft.advancements;

import com.google.common.annotations.VisibleForTesting;
import it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet;
import java.util.Set;
import org.jspecify.annotations.Nullable;

public class AdvancementNode {
	private final AdvancementHolder holder;
	@Nullable
	private final AdvancementNode parent;
	private final Set<AdvancementNode> children = new ReferenceOpenHashSet<>();

	@VisibleForTesting
	public AdvancementNode(final AdvancementHolder holder, @Nullable final AdvancementNode parent) {
		this.holder = holder;
		this.parent = parent;
	}

	public Advancement advancement() {
		return this.holder.value();
	}

	public AdvancementHolder holder() {
		return this.holder;
	}

	@Nullable
	public AdvancementNode parent() {
		return this.parent;
	}

	public AdvancementNode root() {
		return getRoot(this);
	}

	public static AdvancementNode getRoot(final AdvancementNode advancement) {
		AdvancementNode root = advancement;

		while (true) {
			AdvancementNode parent = root.parent();
			if (parent == null) {
				return root;
			}

			root = parent;
		}
	}

	public Iterable<AdvancementNode> children() {
		return this.children;
	}

	@VisibleForTesting
	public void addChild(final AdvancementNode child) {
		this.children.add(child);
	}

	public boolean equals(final Object obj) {
		return this == obj ? true : obj instanceof AdvancementNode that && this.holder.equals(that.holder);
	}

	public int hashCode() {
		return this.holder.hashCode();
	}

	public String toString() {
		return this.holder.id().toString();
	}
}