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// 
// ========================================================================
// Copyright (c) 1995-2022 Mort Bay Consulting Pty Ltd and others.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// 
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
// 
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// 
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
// 
package org.eclipse.jetty.util;

import java.io.IOException;
import java.util.concurrent.CancellationException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicBoolean;

// @deprecated The Eclipse Jetty and Apache Felix Http Jetty packages are no longer supported.
@Deprecated(since = "2021-05-27")
public class FuturePromise implements Future, Promise {

    private static Throwable COMPLETED = new ConstantThrowable();

    private final AtomicBoolean _done = new AtomicBoolean(false);

    private final CountDownLatch _latch = new CountDownLatch(1);

    private Throwable _cause;

    private C _result;

    public FuturePromise() {
    }

    public FuturePromise(C result) {
        _cause = COMPLETED;
        _result = result;
        _done.set(true);
        _latch.countDown();
    }

    public FuturePromise(C ctx, Throwable failed) {
        _result = ctx;
        _cause = failed;
        _done.set(true);
        _latch.countDown();
    }

    @Override
    public void succeeded(C result) {
        if (_done.compareAndSet(false, true)) {
            _result = result;
            _cause = COMPLETED;
            _latch.countDown();
        }
    }

    @Override
    public void failed(Throwable cause) {
        if (_done.compareAndSet(false, true)) {
            _cause = cause;
            _latch.countDown();
        }
    }

    @Override
    public boolean cancel(boolean mayInterruptIfRunning) {
        if (_done.compareAndSet(false, true)) {
            _result = null;
            _cause = new CancellationException();
            _latch.countDown();
            return true;
        }
        return false;
    }

    @Override
    public boolean isCancelled() {
        if (_done.get()) {
            try {
                _latch.await();
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
            return _cause instanceof CancellationException;
        }
        return false;
    }

    @Override
    public boolean isDone() {
        return _done.get() && _latch.getCount() == 0;
    }

    @Override
    public C get() throws InterruptedException, ExecutionException {
        _latch.await();
        if (_cause == COMPLETED)
            return _result;
        if (_cause instanceof CancellationException)
            throw (CancellationException) new CancellationException().initCause(_cause);
        throw new ExecutionException(_cause);
    }

    @Override
    public C get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
        if (!_latch.await(timeout, unit))
            throw new TimeoutException();
        if (_cause == COMPLETED)
            return _result;
        if (_cause instanceof TimeoutException)
            throw (TimeoutException) _cause;
        if (_cause instanceof CancellationException)
            throw (CancellationException) new CancellationException().initCause(_cause);
        throw new ExecutionException(_cause);
    }

    public static void rethrow(ExecutionException e) throws IOException {
        Throwable cause = e.getCause();
        if (cause instanceof IOException)
            throw (IOException) cause;
        if (cause instanceof Error)
            throw (Error) cause;
        if (cause instanceof RuntimeException)
            throw (RuntimeException) cause;
        throw new RuntimeException(cause);
    }

    @Override
    public String toString() {
        return String.format("FutureCallback@%x{%b,%b,%s}", hashCode(), _done.get(), _cause == COMPLETED, _result);
    }
}