package net.minecraft.util;

import com.mojang.logging.LogUtils;
import java.util.concurrent.CancellationException;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
import java.util.concurrent.Executor;
import java.util.function.Consumer;
import org.slf4j.Logger;

public class FutureChain implements TaskChainer, AutoCloseable {
	private static final Logger LOGGER = LogUtils.getLogger();
	private CompletableFuture<?> head = CompletableFuture.completedFuture(null);
	private final Executor executor;
	private volatile boolean closed;

	public FutureChain(final Executor executor) {
		this.executor = executor;
	}

	@Override
	public <T> void append(final CompletableFuture<T> preparation, final Consumer<T> chainedTask) {
		this.head = this.head.thenCombine(preparation, (ignored, value) -> value).thenAcceptAsync(value -> {
			if (!this.closed) {
				chainedTask.accept(value);
			}
		}, this.executor).exceptionally(t -> {
			if (t instanceof CompletionException c) {
				t = c.getCause();
			}

			if (t instanceof CancellationException c) {
				throw c;
			} else {
				LOGGER.error("Chain link failed, continuing to next one", t);
				return null;
			}
		});
	}

	public void close() {
		this.closed = true;
	}
}