//
//  ========================================================================
//  Copyright (c) 1995-2020 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.util.concurrent.CancellationException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

import org.hamcrest.Matchers;
import org.junit.jupiter.api.Test;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

public class FutureCallbackTest
{
    @Test
    public void testNotDone()
    {
        FutureCallback fcb = new FutureCallback();
        assertFalse(fcb.isDone());
        assertFalse(fcb.isCancelled());
    }

    @Test
    public void testGetNotDone() throws Exception
    {
        FutureCallback fcb = new FutureCallback();

        long start = TimeUnit.NANOSECONDS.toMillis(System.nanoTime());
        assertThrows(TimeoutException.class, () -> fcb.get(500, TimeUnit.MILLISECONDS));
        assertThat(TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start, Matchers.greaterThan(50L));
    }

    @Test
    public void testDone() throws Exception
    {
        FutureCallback fcb = new FutureCallback();
        fcb.succeeded();
        assertTrue(fcb.isDone());
        assertFalse(fcb.isCancelled());

        long start = TimeUnit.NANOSECONDS.toMillis(System.nanoTime());
        assertEquals(null, fcb.get());
        assertThat(TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start, Matchers.lessThan(500L));
    }

    @Test
    public void testGetDone() throws Exception
    {
        final FutureCallback fcb = new FutureCallback();
        final CountDownLatch latch = new CountDownLatch(1);

        new Thread(() ->
        {
            latch.countDown();
            try
            {
                TimeUnit.MILLISECONDS.sleep(100);
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
            fcb.succeeded();
        }).start();

        latch.await();
        long start = TimeUnit.NANOSECONDS.toMillis(System.nanoTime());
        assertEquals(null, fcb.get(10000, TimeUnit.MILLISECONDS));
        assertThat(TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start, Matchers.greaterThan(10L));
        assertThat(TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start, Matchers.lessThan(1000L));

        assertTrue(fcb.isDone());
        assertFalse(fcb.isCancelled());
    }

    @Test
    public void testFailed() throws Exception
    {
        FutureCallback fcb = new FutureCallback();
        Exception ex = new Exception("FAILED");
        fcb.failed(ex);
        assertTrue(fcb.isDone());
        assertFalse(fcb.isCancelled());

        long start = TimeUnit.NANOSECONDS.toMillis(System.nanoTime());
        ExecutionException e = assertThrows(ExecutionException.class, () -> fcb.get());
        assertEquals(ex, e.getCause());

        assertThat(TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start, Matchers.lessThan(100L));
    }

    @Test
    public void testGetFailed() throws Exception
    {
        final FutureCallback fcb = new FutureCallback();
        final Exception ex = new Exception("FAILED");
        final CountDownLatch latch = new CountDownLatch(1);

        new Thread(() ->
        {
            latch.countDown();
            try
            {
                TimeUnit.MILLISECONDS.sleep(100);
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
            fcb.failed(ex);
        }).start();

        latch.await();
        long start = TimeUnit.NANOSECONDS.toMillis(System.nanoTime());
        ExecutionException e = assertThrows(ExecutionException.class, () -> fcb.get(10000, TimeUnit.MILLISECONDS));
        assertEquals(ex, e.getCause());
        assertThat(TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start, Matchers.greaterThan(10L));
        assertThat(TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start, Matchers.lessThan(5000L));

        assertTrue(fcb.isDone());
        assertFalse(fcb.isCancelled());
    }

    @Test
    public void testCancelled() throws Exception
    {
        FutureCallback fcb = new FutureCallback();
        fcb.cancel(true);
        assertTrue(fcb.isDone());
        assertTrue(fcb.isCancelled());

        long start = TimeUnit.NANOSECONDS.toMillis(System.nanoTime());
        CancellationException e = assertThrows(CancellationException.class, () -> fcb.get());
        assertThat(e.getCause(), Matchers.instanceOf(CancellationException.class));
        assertThat(TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start, Matchers.lessThan(100L));
    }

    @Test
    public void testGetCancelled() throws Exception
    {
        final FutureCallback fcb = new FutureCallback();
        final CountDownLatch latch = new CountDownLatch(1);

        new Thread(() ->
        {
            latch.countDown();
            try
            {
                TimeUnit.MILLISECONDS.sleep(100);
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
            fcb.cancel(true);
        }).start();

        latch.await();
        long start = TimeUnit.NANOSECONDS.toMillis(System.nanoTime());
        CancellationException e = assertThrows(CancellationException.class,() -> fcb.get(10000, TimeUnit.MILLISECONDS));
        assertThat(e.getCause(), Matchers.instanceOf(CancellationException.class));

        assertThat(TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start, Matchers.greaterThan(10L));
        assertThat(TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start, Matchers.lessThan(1000L));

        assertTrue(fcb.isDone());
        assertTrue(fcb.isCancelled());
    }
}
