// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT License.
// See the LICENSE file in the project root for more information. 

using System;
using System.Reactive.Concurrency;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using System.Reactive.Subjects;
using System.Threading;
using Microsoft.Reactive.Testing;
using Microsoft.VisualStudio.TestTools.UnitTesting;

using Assert = Xunit.Assert;

namespace ReactiveTests.Tests
{
    [TestClass]
    public class RunAsyncTest : ReactiveTest
    {
        [TestMethod]
        public void RunAsync_ArgumentChecking()
        {
            var ct = CancellationToken.None;

            ReactiveAssert.Throws<ArgumentNullException>(() => Observable.RunAsync(default(IObservable<int>), ct));
            ReactiveAssert.Throws<ArgumentNullException>(() => Observable.RunAsync<int>(default, ct));
        }

        [TestMethod]
        public void RunAsync_Simple()
        {
            SynchronizationContext.SetSynchronizationContext(null);

            var scheduler = new TestScheduler();

            var xs = scheduler.CreateHotObservable(
                OnNext(220, 42),
                OnCompleted<int>(250)
            );

            var awaiter = default(AsyncSubject<int>);
            var result = default(int);
            var t = long.MaxValue;

            scheduler.ScheduleAbsolute(100, () => awaiter = xs.RunAsync(CancellationToken.None));
            scheduler.ScheduleAbsolute(200, () => awaiter.OnCompleted(() => { t = scheduler.Clock; result = awaiter.GetResult(); }));

            scheduler.Start();

            Assert.Equal(250, t);
            Assert.Equal(42, result);

            xs.Subscriptions.AssertEqual(
                Subscribe(100)
            );
        }

        [TestMethod]
        public void RunAsync_Cancelled()
        {
            SynchronizationContext.SetSynchronizationContext(null);

            var cts = new CancellationTokenSource();
            cts.Cancel();

            var scheduler = new TestScheduler();

            var xs = scheduler.CreateHotObservable(
                OnNext(220, 42),
                OnCompleted<int>(250)
            );

            var awaiter = default(AsyncSubject<int>);
            var result = default(int);
            var t = long.MaxValue;

            scheduler.ScheduleAbsolute(100, () => awaiter = xs.RunAsync(cts.Token));
            scheduler.ScheduleAbsolute(200, () => awaiter.OnCompleted(() =>
            {
                t = scheduler.Clock;

                ReactiveAssert.Throws<OperationCanceledException>(() =>
                {
                    result = awaiter.GetResult();
                });
            }));

            scheduler.Start();

            Assert.Equal(200, t);

            xs.Subscriptions.AssertEqual(
            );
        }

        [TestMethod]
        public void RunAsync_Cancel()
        {
            SynchronizationContext.SetSynchronizationContext(null);

            var cts = new CancellationTokenSource();

            var scheduler = new TestScheduler();

            var xs = scheduler.CreateHotObservable(
                OnNext(220, 42),
                OnCompleted<int>(250)
            );

            var awaiter = default(AsyncSubject<int>);
            var result = default(int);
            var t = long.MaxValue;

            scheduler.ScheduleAbsolute(100, () => awaiter = xs.RunAsync(cts.Token));
            scheduler.ScheduleAbsolute(200, () => awaiter.OnCompleted(() =>
            {
                t = scheduler.Clock;

                ReactiveAssert.Throws<OperationCanceledException>(() =>
                {
                    result = awaiter.GetResult();
                });
            }));
            scheduler.ScheduleAbsolute(210, () => cts.Cancel());

            scheduler.Start();

            Assert.Equal(210, t);

            xs.Subscriptions.AssertEqual(
                Subscribe(100, 210)
            );
        }

        [TestMethod]
        public void RunAsync_Connectable()
        {
            SynchronizationContext.SetSynchronizationContext(null);

            var scheduler = new TestScheduler();

            var s = default(long);

            var xs = Observable.Create<int>(observer =>
            {
                s = scheduler.Clock;

                return StableCompositeDisposable.Create(
                    scheduler.ScheduleAbsolute(250, () => { observer.OnNext(42); }),
                    scheduler.ScheduleAbsolute(260, () => { observer.OnCompleted(); })
                );
            });

            var ys = xs.Publish();

            var awaiter = default(AsyncSubject<int>);
            var result = default(int);
            var t = long.MaxValue;

            scheduler.ScheduleAbsolute(100, () => awaiter = ys.RunAsync(CancellationToken.None));
            scheduler.ScheduleAbsolute(200, () => awaiter.OnCompleted(() => { t = scheduler.Clock; result = awaiter.GetResult(); }));

            scheduler.Start();

            Assert.Equal(100, s);
            Assert.Equal(260, t);
            Assert.Equal(42, result);
        }

        [TestMethod]
        public void RunAsync_Connectable_Cancelled()
        {
            SynchronizationContext.SetSynchronizationContext(null);

            var cts = new CancellationTokenSource();
            cts.Cancel();

            var scheduler = new TestScheduler();

            var s = default(long?);

            var xs = Observable.Create<int>(observer =>
            {
                s = scheduler.Clock;

                return StableCompositeDisposable.Create(
                    scheduler.ScheduleAbsolute(250, () => { observer.OnNext(42); }),
                    scheduler.ScheduleAbsolute(260, () => { observer.OnCompleted(); })
                );
            });

            var ys = xs.Publish();

            var awaiter = default(AsyncSubject<int>);
            var result = default(int);
            var t = long.MaxValue;

            scheduler.ScheduleAbsolute(100, () => awaiter = ys.RunAsync(cts.Token));
            scheduler.ScheduleAbsolute(200, () => awaiter.OnCompleted(() =>
            {
                t = scheduler.Clock;

                ReactiveAssert.Throws<OperationCanceledException>(() =>
                {
                    result = awaiter.GetResult();
                });
            }));

            scheduler.Start();

            Assert.False(s.HasValue);
            Assert.Equal(200, t);
        }

        [TestMethod]
        public void RunAsync_Connectable_Cancel()
        {
            SynchronizationContext.SetSynchronizationContext(null);

            var cts = new CancellationTokenSource();

            var scheduler = new TestScheduler();

            var s = default(long);
            var d = default(long);

            var xs = Observable.Create<int>(observer =>
            {
                s = scheduler.Clock;

                return StableCompositeDisposable.Create(
                    scheduler.ScheduleAbsolute(250, () => { observer.OnNext(42); }),
                    scheduler.ScheduleAbsolute(260, () => { observer.OnCompleted(); }),
                    Disposable.Create(() => { d = scheduler.Clock; })
                );
            });

            var ys = xs.Publish();

            var awaiter = default(AsyncSubject<int>);
            var result = default(int);
            var t = long.MaxValue;

            scheduler.ScheduleAbsolute(100, () => awaiter = ys.RunAsync(cts.Token));
            scheduler.ScheduleAbsolute(200, () => awaiter.OnCompleted(() =>
            {
                t = scheduler.Clock;

                ReactiveAssert.Throws<OperationCanceledException>(() =>
                {
                    result = awaiter.GetResult();
                });
            }));
            scheduler.ScheduleAbsolute(210, () => cts.Cancel());

            scheduler.Start();

            Assert.Equal(100, s);
            Assert.Equal(210, d);
            Assert.Equal(210, t);
        }
    }
}