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 * obtaining a copy of this software and associated documentation
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// CA2000: test code; many disposables are ownership-transferred to test fixtures or short-lived,
// making CA2000 noisy without a real leak risk. Disabled file-level for the suite.
#pragma warning disable CA2000
using System.Threading;
using NUnit.Framework;

namespace Opc.Ua.Core.Tests.Stack.Server
{
    [TestFixture]
    [Category("Server")]
    [SetCulture("en-us")]
    [SetUICulture("en-us")]
    [Parallelizable]
    public class RequestLifetimeTests
    {
        [Test]
        public void Constructor_Default_CreatesInstance()
        {
            using var lifetime = new RequestLifetime();

            Assert.That(lifetime.CancellationToken.IsCancellationRequested, Is.False);
            Assert.That(lifetime.StatusCode, Is.EqualTo(StatusCodes.Good));
        }

        [Test]
        public void Constructor_WithExternalToken_CreatesLinkedTokenSource()
        {
            using var cts = new CancellationTokenSource();
            using var lifetime = new RequestLifetime(cts.Token);

            Assert.That(lifetime.CancellationToken.IsCancellationRequested, Is.False);

            cts.Cancel();

            Assert.That(lifetime.CancellationToken.IsCancellationRequested, Is.True);
            Assert.That(lifetime.StatusCode, Is.EqualTo(StatusCodes.Good));
        }

        [Test]
        public void TryCancel_WhenNotCancelled_ReturnsTrue_SetsStatusCode_CancelsToken()
        {
            using var lifetime = new RequestLifetime();

            bool result = lifetime.TryCancel(StatusCodes.BadTimeout);

            Assert.That(result, Is.True);
            Assert.That(lifetime.CancellationToken.IsCancellationRequested, Is.True);
            Assert.That(lifetime.StatusCode, Is.EqualTo(StatusCodes.BadTimeout));
        }

        [Test]
        public void TryCancel_WhenAlreadyCancelled_ReturnsFalse_LeavesStatusCode()
        {
            using var lifetime = new RequestLifetime();

            bool firstResult = lifetime.TryCancel(StatusCodes.BadTimeout);
            bool secondResult = lifetime.TryCancel(StatusCodes.BadUnexpectedError);

            Assert.That(firstResult, Is.True);
            Assert.That(secondResult, Is.False);
            Assert.That(lifetime.StatusCode, Is.EqualTo(StatusCodes.BadTimeout));
            Assert.That(lifetime.CancellationToken.IsCancellationRequested, Is.True);
        }

        [Test]
        public void TryCancelConcurrentCallersFirstStatusWins()
        {
            // a client Cancel, a Session close and the request timeout race to cancel the same
            // request; exactly one of them may claim it, and its status must be the one reported.
            for (int iteration = 0; iteration < 2000; iteration++)
            {
                using var lifetime = new RequestLifetime();
                using var barrier = new Barrier(2);
                bool timeoutWon = false;
                bool cancelWon = false;

                var timeout = new Thread(() =>
                {
                    barrier.SignalAndWait();
                    timeoutWon = lifetime.TryCancel(StatusCodes.BadTimeout);
                });
                var cancel = new Thread(() =>
                {
                    barrier.SignalAndWait();
                    cancelWon = lifetime.TryCancel(StatusCodes.BadRequestCancelledByClient);
                });
                timeout.Start();
                cancel.Start();
                timeout.Join();
                cancel.Join();

                Assert.That(timeoutWon ^ cancelWon, Is.True, $"Iteration {iteration}: exactly one caller must win.");
                Assert.That(
                    lifetime.StatusCode,
                    Is.EqualTo(timeoutWon ? StatusCodes.BadTimeout : StatusCodes.BadRequestCancelledByClient),
                    $"Iteration {iteration}: the winner's status must be reported.");
            }
        }

        [Test]
        public void TryCancel_AfterDispose_ReturnsFalse()
        {
            var lifetime = new RequestLifetime();
            lifetime.Dispose();

            bool result = lifetime.TryCancel(StatusCodes.BadTimeout);

            Assert.That(result, Is.False);
            Assert.That(lifetime.CancellationToken.IsCancellationRequested, Is.False);
        }

        [Test]
        public void MarkCompleted_DisposesToken_CannotCancel()
        {
            var lifetime = new RequestLifetime();
            lifetime.MarkCompleted();

            bool result = lifetime.TryCancel(StatusCodes.BadTimeout);

            Assert.That(result, Is.False);

            Assert.That(lifetime.CancellationToken.IsCancellationRequested, Is.False);
        }

        [Test]
        public void None_Property_ReturnsCompletedInstance()
        {
            RequestLifetime lifetime = RequestLifetime.None;

            Assert.That(lifetime.StatusCode, Is.EqualTo(StatusCodes.Good));

            bool result = lifetime.TryCancel(StatusCodes.BadTimeout);

            Assert.That(result, Is.False);

            Assert.That(lifetime.CancellationToken.IsCancellationRequested, Is.False);
        }
    }
}