using System;
using System.Threading;
using System.Threading.Tasks;
using Shouldly;
using Volo.Abp.Testing;
using Xunit;

namespace Volo.Abp.Threading
{
    public class NullCancellationTokenProvider_Tests : AbpIntegratedTest<AbpThreadingTestModule>
    {
        private readonly ICancellationTokenProvider _cancellationTokenProvider;

        public NullCancellationTokenProvider_Tests()
        {
            _cancellationTokenProvider = NullCancellationTokenProvider.Instance;
        }

        [Fact]
        public void Should_Return_None_Token()
        {
            _cancellationTokenProvider.Token.ShouldBe(CancellationToken.None);
        }

        [Fact]
        public void Should_Return_Specific_Token()
        {
            var cts = new CancellationTokenSource();

            using (_cancellationTokenProvider.Use(cts.Token))
            {
                var newCancellationTokenProvider = NullCancellationTokenProvider.Instance;

                newCancellationTokenProvider.Token.ShouldBe(cts.Token);
            }

            _cancellationTokenProvider.Token.ShouldBe(CancellationToken.None);
        }

        [Fact]
        public void Should_Cancel_After_100_Milliseconds()
        {
            var cts = new CancellationTokenSource();
            cts.CancelAfter(TimeSpan.FromMilliseconds(100));

            using (_cancellationTokenProvider.Use(cts.Token))
            {
                var newCancellationTokenProvider = NullCancellationTokenProvider.Instance;
                Should.Throw<OperationCanceledException>(() => LongTask(1000, newCancellationTokenProvider.Token));
            }
        }

        private void LongTask(int loopCounter, CancellationToken cancellationToken = default)
        {
            for (var i = 0; i < loopCounter; i++)
            {
                cancellationToken.ThrowIfCancellationRequested();

                Thread.Sleep(10);
            }
        }
    }
}