package net.minecraft.network.chat;

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

public class MessageSignatureCache {
	public static final int NOT_FOUND = -1;
	private static final int DEFAULT_CAPACITY = 128;
	private final MessageSignature[] entries;

	public MessageSignatureCache(final int capacity) {
		this.entries = new MessageSignature[capacity];
	}

	public static MessageSignatureCache createDefault() {
		return new MessageSignatureCache(128);
	}

	public int pack(final MessageSignature signature) {
		for (int i = 0; i < this.entries.length; i++) {
			if (signature.equals(this.entries[i])) {
				return i;
			}
		}

		return -1;
	}

	@Nullable
	public MessageSignature unpack(final int id) {
		return this.entries[id];
	}

	public void push(final SignedMessageBody body, @Nullable final MessageSignature signature) {
		List<MessageSignature> lastSeen = body.lastSeen().entries();
		ArrayDeque<MessageSignature> queue = new ArrayDeque(lastSeen.size() + 1);
		queue.addAll(lastSeen);
		if (signature != null) {
			queue.add(signature);
		}

		this.push(queue);
	}

	@VisibleForTesting
	void push(final List<MessageSignature> entries) {
		this.push(new ArrayDeque(entries));
	}

	private void push(final ArrayDeque<MessageSignature> queue) {
		Set<MessageSignature> newEntries = new ObjectOpenHashSet<>(queue);

		for (int i = 0; !queue.isEmpty() && i < this.entries.length; i++) {
			MessageSignature entry = this.entries[i];
			this.entries[i] = (MessageSignature)queue.removeLast();
			if (entry != null && !newEntries.contains(entry)) {
				queue.addFirst(entry);
			}
		}
	}
}