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 * OPC Foundation MIT License 1.00
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using System.Threading.Tasks;
using Moq;
using NUnit.Framework;
using Opc.Ua.Tests;

namespace Opc.Ua.Server.Tests
{
    [TestFixture]
    public class RequestManagerTests
    {
        private Mock<IServerInternal> m_mockServer;
        private RequestManager m_requestManager;

        [SetUp]
        public void SetUp()
        {
            m_mockServer = new Mock<IServerInternal>();
            m_mockServer.Setup(s => s.Telemetry).Returns(NUnitTelemetryContext.Create());
            m_requestManager = new RequestManager(m_mockServer.Object);
        }

        [TearDown]
        public void TearDown()
        {
            m_requestManager?.Dispose();
        }

        [Test]
        public void ConstructorThrowsArgumentNullExceptionWhenServerNull()
        {
            Assert.That(() => new RequestManager(null), Throws.ArgumentNullException);
        }

        [Test]
        public void RequestReceivedThrowsArgumentNullExceptionWhenContextNull()
        {
            Assert.That(() => m_requestManager.RequestReceived(null), Throws.ArgumentNullException);
        }

        [Test]
        public void RequestCompletedThrowsArgumentNullExceptionWhenContextNull()
        {
            Assert.That(() => m_requestManager.RequestCompleted(null), Throws.ArgumentNullException);
        }

        [Test]
        public void CancelRequestsCancelsMatchingRequestsAndFiresEvent()
        {
            // Arrange
            var mockSession = new Mock<ISession>();
            mockSession.Setup(s => s.Id).Returns(new NodeId(1));

            var requestHeader = new RequestHeader { RequestHandle = 42, TimeoutHint = 0 };
            using var requestLifetime = new RequestLifetime();
            var context = new OperationContext(
                requestHeader,
                null,
                RequestType.Read,
                requestLifetime,
                mockSession.Object);

            m_requestManager.RequestReceived(context);

            bool eventFired = false;
            uint cancelledRequestId = 0;
            m_requestManager.RequestCancelled += (sender, reqId, status) =>
            {
                eventFired = true;
                cancelledRequestId = reqId;
            };

            // Act
            m_requestManager.CancelRequests(42, out uint cancelCount);

            // Assert
            Assert.That(cancelCount, Is.EqualTo(1));
            Assert.That(eventFired, Is.True);
            Assert.That(cancelledRequestId, Is.EqualTo(context.RequestId));
            Assert.That(requestLifetime.CancellationToken.IsCancellationRequested, Is.True);
        }

        [Test]
        public void CancelRequestsShouldCancelActivateSessionRequestWithoutSession()
        {
            const uint requestHandle = 1234;
            using var requestLifetime = new RequestLifetime();
            var context = new OperationContext(
                new RequestHeader { RequestHandle = requestHandle },
                null,
                RequestType.ActivateSession,
                requestLifetime);

            m_requestManager.RequestReceived(context);

            uint cancelCount = 0;
            Assert.DoesNotThrow(
                () => m_requestManager.CancelRequests(requestHandle, out cancelCount));

            Assert.That(cancelCount, Is.EqualTo(1));
            Assert.That(
                context.OperationStatus.Code,
                Is.EqualTo(StatusCodes.BadRequestCancelledByRequest));
        }

        [Test]
        public void RequestCompletedRemovesRequestAndCompletesLifetime()
        {
            // Arrange
            var mockSession = new Mock<ISession>();
            mockSession.Setup(s => s.Id).Returns(new NodeId(1));

            var requestHeader = new RequestHeader { RequestHandle = 42, TimeoutHint = 0 };
            using var requestLifetime = new RequestLifetime();
            var context = new OperationContext(
                requestHeader,
                null,
                RequestType.Read,
                requestLifetime,
                mockSession.Object);

            m_requestManager.RequestReceived(context);

            // Act
            m_requestManager.RequestCompleted(context);

            // Assert
            // To ensure it is removed, cancelling it will yield 0 count
            m_requestManager.CancelRequests(42, out uint cancelCount);
            Assert.That(cancelCount, Is.Zero);
            // Assert that lifetime is completed (disposed), which means TryCancel returns false
            Assert.That(requestLifetime.TryCancel(StatusCodes.BadTimeout), Is.False);
        }

        [Test]
        public async Task TimerCancelsExpiredRequestsAndFiresEventAsync()
        {
            // Arrange
            var mockSession = new Mock<ISession>();
            mockSession.Setup(s => s.Id).Returns(new NodeId(1));

            // TimeoutHint is small to ensure it expires quickly
            var requestHeader = new RequestHeader { RequestHandle = 43, TimeoutHint = 100 };
            using var requestLifetime = new RequestLifetime();
            var context = new OperationContext(
                requestHeader,
                null,
                RequestType.Read,
                requestLifetime,
                mockSession.Object);

            bool eventFired = false;
            m_requestManager.RequestCancelled += (sender, reqId, status) =>
            {
                if (reqId == context.RequestId && status == StatusCodes.BadTimeout)
                {
                    eventFired = true;
                }
            };

            m_requestManager.RequestReceived(context);

            // Act
            // Wait for timer to expire since TimeoutHint = 100ms. Note the original timer runs every 1000ms.
            // We need to wait a bit more than 1000ms.
            await Task.Delay(1200).ConfigureAwait(false);

            // Assert
            Assert.That(eventFired, Is.True);
            Assert.That(requestLifetime.CancellationToken.IsCancellationRequested, Is.True);
        }

        [Test]
        public void DisposeCancelsPendingRequests()
        {
            // Arrange
            var mockSession = new Mock<ISession>();
            mockSession.Setup(s => s.Id).Returns(new NodeId(1));

            var requestHeader = new RequestHeader { RequestHandle = 44, TimeoutHint = 0 };
            using var requestLifetime = new RequestLifetime();
            var context = new OperationContext(
                requestHeader,
                null,
                RequestType.Read,
                requestLifetime,
                mockSession.Object);

            m_requestManager.RequestReceived(context);

            // Act
            m_requestManager.Dispose();

            // Assert
            Assert.That(requestLifetime.CancellationToken.IsCancellationRequested, Is.True);
        }
    }
}