package net.minecraft.network.chat;

import it.unimi.dsi.fastutil.objects.ObjectArrayList;
import it.unimi.dsi.fastutil.objects.ObjectList;
import java.util.Optional;
import org.jetbrains.annotations.Nullable;

public class LastSeenMessagesValidator {
	private final int lastSeenCount;
	private final ObjectList<LastSeenTrackedEntry> trackedMessages = new ObjectArrayList<>();
	@Nullable
	private MessageSignature lastPendingMessage;

	public LastSeenMessagesValidator(int lastSeenCount) {
		this.lastSeenCount = lastSeenCount;

		for (int i = 0; i < lastSeenCount; i++) {
			this.trackedMessages.add(null);
		}
	}

	public void addPending(MessageSignature signature) {
		if (!signature.equals(this.lastPendingMessage)) {
			this.trackedMessages.add(new LastSeenTrackedEntry(signature, true));
			this.lastPendingMessage = signature;
		}
	}

	public int trackedMessagesCount() {
		return this.trackedMessages.size();
	}

	public boolean applyOffset(int offset) {
		int i = this.trackedMessages.size() - this.lastSeenCount;
		if (offset >= 0 && offset <= i) {
			this.trackedMessages.removeElements(0, offset);
			return true;
		} else {
			return false;
		}
	}

	public Optional<LastSeenMessages> applyUpdate(LastSeenMessages.Update lastSeenUpdater) {
		if (!this.applyOffset(lastSeenUpdater.offset())) {
			return Optional.empty();
		} else {
			ObjectList<MessageSignature> objectList = new ObjectArrayList<>(lastSeenUpdater.acknowledged().cardinality());
			if (lastSeenUpdater.acknowledged().length() > this.lastSeenCount) {
				return Optional.empty();
			} else {
				for (int i = 0; i < this.lastSeenCount; i++) {
					boolean bl = lastSeenUpdater.acknowledged().get(i);
					LastSeenTrackedEntry lastSeenTrackedEntry = (LastSeenTrackedEntry)this.trackedMessages.get(i);
					if (bl) {
						if (lastSeenTrackedEntry == null) {
							return Optional.empty();
						}

						this.trackedMessages.set(i, lastSeenTrackedEntry.acknowledge());
						objectList.add(lastSeenTrackedEntry.signature());
					} else {
						if (lastSeenTrackedEntry != null && !lastSeenTrackedEntry.pending()) {
							return Optional.empty();
						}

						this.trackedMessages.set(i, null);
					}
				}

				return Optional.of(new LastSeenMessages(objectList));
			}
		}
	}
}