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

namespace Opc.Ua.Client.Tests
{
    /// <summary>
    /// Deterministic unit tests for <see cref="ChannelManagerSessionFactory"/> that exercise
    /// its constructor guards, diagnostics delegation, argument validation and the
    /// channel-only reconnect participant without opening a real session or touching the network.
    /// </summary>
    [TestFixture]
    [Category("Client")]
    [Category("ChannelManagerSessionFactory")]
    [SetCulture("en-us")]
    [SetUICulture("en-us")]
    public sealed class ChannelManagerSessionFactoryTests
    {
        private ITelemetryContext m_telemetry;

        [SetUp]
        public void SetUp()
        {
            m_telemetry = NUnitTelemetryContext.Create();
        }

        [Test]
        public void ConstructorWithNullManagerThrowsArgumentNullException()
        {
            ArgumentNullException ex = Assert.Throws<ArgumentNullException>(() =>
                new ChannelManagerSessionFactory(null!, m_telemetry));

            Assert.That(ex.ParamName, Is.EqualTo("manager"));
        }

        [Test]
        public void ConstructorWithNullTelemetryThrowsArgumentNullException()
        {
            var manager = new Mock<IClientChannelManager>();

            ArgumentNullException ex = Assert.Throws<ArgumentNullException>(() =>
                new ChannelManagerSessionFactory(manager.Object, null!));

            Assert.That(ex.ParamName, Is.EqualTo("telemetry"));
        }

        [Test]
        public void ConstructorStoresTelemetry()
        {
            var manager = new Mock<IClientChannelManager>();

            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry);

            Assert.That(factory.Telemetry, Is.SameAs(m_telemetry));
        }

        [Test]
        public void WithSubscriptionEngineReturnsAConfiguredCopyAndLeavesTheOriginal()
        {
            var manager = new Mock<IClientChannelManager>();
            var registry = new Mock<ISecurityPolicyRegistry>().Object;
            var original = new ChannelManagerSessionFactory(
                manager.Object,
                m_telemetry,
                DiagnosticsMasks.All,
                securityPolicies: registry);
            ISubscriptionEngineFactory engine = new Mock<ISubscriptionEngineFactory>().Object;

            ISessionFactory copy = original.WithSubscriptionEngine(engine);

            Assert.That(copy, Is.TypeOf<ChannelManagerSessionFactory>());
            Assert.That(copy, Is.Not.SameAs(original));
            Assert.That(copy.SubscriptionEngineFactory, Is.SameAs(engine));
            Assert.That(copy.ReturnDiagnostics, Is.EqualTo(DiagnosticsMasks.All));
            Assert.That(copy.Telemetry, Is.SameAs(m_telemetry));
            Assert.That(((ChannelManagerSessionFactory)copy).SecurityPolicyRegistry, Is.SameAs(registry));
            Assert.That(original.SubscriptionEngineFactory, Is.Null);
        }

        [Test]
        public void ReturnDiagnosticsDefaultsToNone()
        {
            var manager = new Mock<IClientChannelManager>();

            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry);

            Assert.That(factory.ReturnDiagnostics, Is.EqualTo(DiagnosticsMasks.None));
        }

        [Test]
        public void ConstructorAppliesReturnDiagnostics()
        {
            var manager = new Mock<IClientChannelManager>();

            var factory = new ChannelManagerSessionFactory(
                manager.Object,
                m_telemetry,
                DiagnosticsMasks.All);

            Assert.That(factory.ReturnDiagnostics, Is.EqualTo(DiagnosticsMasks.All));
        }

        [Test]
        public void ReturnDiagnosticsSetterUpdatesValue()
        {
            var manager = new Mock<IClientChannelManager>();

            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry)
            {
                ReturnDiagnostics = DiagnosticsMasks.ServiceSymbolicId
            };

            Assert.That(factory.ReturnDiagnostics, Is.EqualTo(DiagnosticsMasks.ServiceSymbolicId));

            factory.ReturnDiagnostics = DiagnosticsMasks.All;

            Assert.That(factory.ReturnDiagnostics, Is.EqualTo(DiagnosticsMasks.All));
        }

        [Test]
        public void ConstructorAcceptsTimeProvider()
        {
            var manager = new Mock<IClientChannelManager>();

            var factory = new ChannelManagerSessionFactory(
                manager.Object,
                m_telemetry,
                DiagnosticsMasks.SymbolicId,
                TimeProvider.System);

            Assert.That(factory.Telemetry, Is.SameAs(m_telemetry));
            Assert.That(factory.ReturnDiagnostics, Is.EqualTo(DiagnosticsMasks.SymbolicId));
        }

        [Test]
        public async Task CreateChannelAsyncReturnsChannelFromManagerAsync()
        {
            var channel = new Mock<IManagedTransportChannel>();
            var manager = new Mock<IClientChannelManager>();
            manager
                .Setup(m => m.GetAsync(
                    It.IsAny<ConfiguredEndpoint>(),
                    It.IsAny<Func<IManagedTransportChannel, IReconnectParticipant>>(),
                    It.IsAny<ITransportWaitingConnection>(),
                    It.IsAny<CancellationToken>()))
                .Returns(() => new ValueTask<IManagedTransportChannel>(channel.Object));

            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry);
            ConfiguredEndpoint endpoint = CreateEndpoint();

            ITransportChannel result = await factory.CreateChannelAsync(
                CreateConfiguration(),
                null,
                endpoint,
                updateBeforeConnect: false,
                checkDomain: false,
                CancellationToken.None).ConfigureAwait(false);

            Assert.That(result, Is.SameAs(channel.Object));
            Assert.That(endpoint.UpdateBeforeConnect, Is.False);
            Assert.That(endpoint.Configuration, Is.Not.Null);
            manager.Verify(
                m => m.GetAsync(
                    endpoint,
                    It.IsAny<Func<IManagedTransportChannel, IReconnectParticipant>>(),
                    It.IsAny<ITransportWaitingConnection>(),
                    It.IsAny<CancellationToken>()),
                Times.Once);
        }

        [Test]
        public async Task CreateChannelAsyncWithConnectionKeepsUpdateBeforeConnectAsync()
        {
            var channel = new Mock<IManagedTransportChannel>();
            var connection = new Mock<ITransportWaitingConnection>();
            var manager = new Mock<IClientChannelManager>();
            manager
                .Setup(m => m.GetAsync(
                    It.IsAny<ConfiguredEndpoint>(),
                    It.IsAny<Func<IManagedTransportChannel, IReconnectParticipant>>(),
                    It.IsAny<ITransportWaitingConnection>(),
                    It.IsAny<CancellationToken>()))
                .Returns(() => new ValueTask<IManagedTransportChannel>(channel.Object));

            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry);
            ConfiguredEndpoint endpoint = CreateEndpoint();

            ITransportChannel result = await factory.CreateChannelAsync(
                CreateConfiguration(),
                connection.Object,
                endpoint,
                updateBeforeConnect: true,
                checkDomain: false,
                CancellationToken.None).ConfigureAwait(false);

            Assert.That(result, Is.SameAs(channel.Object));
            Assert.That(endpoint.UpdateBeforeConnect, Is.True);
        }

        [Test]
        public void CreateChannelAsyncWithNullConfigurationThrowsArgumentNullException()
        {
            var manager = new Mock<IClientChannelManager>();
            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry);
            ConfiguredEndpoint endpoint = CreateEndpoint();

            ArgumentNullException ex = Assert.ThrowsAsync<ArgumentNullException>(async () =>
                await factory.CreateChannelAsync(
                    null!,
                    null,
                    endpoint,
                    updateBeforeConnect: false,
                    checkDomain: false,
                    CancellationToken.None).ConfigureAwait(false));

            Assert.That(ex.ParamName, Is.EqualTo("configuration"));
        }

        [Test]
        public void CreateChannelAsyncWithNullEndpointThrowsArgumentNullException()
        {
            var manager = new Mock<IClientChannelManager>();
            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry);

            ArgumentNullException ex = Assert.ThrowsAsync<ArgumentNullException>(async () =>
                await factory.CreateChannelAsync(
                    CreateConfiguration(),
                    null,
                    null!,
                    updateBeforeConnect: false,
                    checkDomain: false,
                    CancellationToken.None).ConfigureAwait(false));

            Assert.That(ex.ParamName, Is.EqualTo("endpoint"));
        }

        [Test]
        public void CreateAsyncReverseConnectWithNullEndpointThrowsArgumentNullException()
        {
            var manager = new Mock<IClientChannelManager>();
            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry);

            ArgumentNullException ex = Assert.ThrowsAsync<ArgumentNullException>(async () =>
                await factory.CreateAsync(
                    CreateConfiguration(),
                    (ReverseConnectManager)null!,
                    null!,
                    updateBeforeConnect: false,
                    checkDomain: false,
                    "TestSession",
                    30000u,
                    null,
                    default,
                    CancellationToken.None).ConfigureAwait(false));

            Assert.That(ex.ParamName, Is.EqualTo("endpoint"));
        }

        [Test]
        public void CreateAsyncReverseConnectWithNullManagerDelegatesToPlainPath()
        {
            var manager = new Mock<IClientChannelManager>();
            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry);

            ArgumentNullException ex = Assert.ThrowsAsync<ArgumentNullException>(async () =>
                await factory.CreateAsync(
                    null!,
                    (ReverseConnectManager)null!,
                    CreateEndpoint(),
                    updateBeforeConnect: false,
                    checkDomain: false,
                    "TestSession",
                    30000u,
                    null,
                    default,
                    CancellationToken.None).ConfigureAwait(false));

            Assert.That(ex.ParamName, Is.EqualTo("configuration"));
        }

        [Test]
        public void RecreateAsyncWithNullTemplateDelegatesToInnerFactory()
        {
            var manager = new Mock<IClientChannelManager>();
            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry);

            ArgumentException ex = Assert.ThrowsAsync<ArgumentException>(async () =>
                await factory.RecreateAsync(null!, CancellationToken.None).ConfigureAwait(false));

            Assert.That(ex.ParamName, Is.EqualTo("sessionTemplate"));
        }

        [Test]
        public async Task CreateChannelAsyncBindsChannelOnlyReconnectParticipantAsync()
        {
            var channel = new Mock<IManagedTransportChannel>();
            var manager = new Mock<IClientChannelManager>();
            IReconnectParticipant? capturedParticipant = null;
            manager
                .Setup(m => m.GetAsync(
                    It.IsAny<ConfiguredEndpoint>(),
                    It.IsAny<Func<IManagedTransportChannel, IReconnectParticipant>>(),
                    It.IsAny<ITransportWaitingConnection>(),
                    It.IsAny<CancellationToken>()))
                .Returns((
                    ConfiguredEndpoint endpoint,
                    Func<IManagedTransportChannel, IReconnectParticipant> participantFactory,
                    ITransportWaitingConnection connection,
                    CancellationToken ct) =>
                {
                    capturedParticipant = participantFactory(channel.Object);
                    return new ValueTask<IManagedTransportChannel>(channel.Object);
                });

            var factory = new ChannelManagerSessionFactory(manager.Object, m_telemetry);
            ConfiguredEndpoint configuredEndpoint = CreateEndpoint();

            await factory.CreateChannelAsync(
                CreateConfiguration(),
                null,
                configuredEndpoint,
                updateBeforeConnect: false,
                checkDomain: false,
                CancellationToken.None).ConfigureAwait(false);

            Assert.That(capturedParticipant, Is.Not.Null);
            Assert.That(capturedParticipant.Id, Does.StartWith("ChannelManagerSessionFactory-"));
            Assert.That(capturedParticipant.Endpoint, Is.SameAs(configuredEndpoint));

            ParticipantReconnectResult reconnectResult = await capturedParticipant
                .OnReconnectAsync(channel.Object, 0, CancellationToken.None)
                .ConfigureAwait(false);

            Assert.That(reconnectResult, Is.EqualTo(ParticipantReconnectResult.Reactivated));
        }

        private static ConfiguredEndpoint CreateEndpoint()
        {
            return new ConfiguredEndpoint(null!, new EndpointDescription
            {
                EndpointUrl = "opc.tcp://localhost:4840",
                SecurityMode = MessageSecurityMode.None,
                SecurityPolicyUri = SecurityPolicies.None
            });
        }

        private ApplicationConfiguration CreateConfiguration()
        {
            return new ApplicationConfiguration(m_telemetry)
            {
                ClientConfiguration = new ClientConfiguration()
            };
        }
    }
}