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 * OPC Foundation MIT License 1.00
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using System;
using System.Threading.Tasks;
using NUnit.Framework;
using Opc.Ua.Redundancy.Server;
using Opc.Ua.Server.TestFramework;

namespace Opc.Ua.Server.Tests
{
    [TestFixture]
    [Category("ServiceLevel")]
    public sealed class ServerServiceLevelOwnershipTests
    {
        [SetUp]
        public async Task StartServerAsync()
        {
            m_fixture = new ServerFixture<StandardServer>(telemetry => new StandardServer(telemetry))
            {
                SecurityNone = true
            };
            await m_fixture.LoadConfigurationAsync().ConfigureAwait(false);
            m_fixture.Config.ServerConfiguration!.MaxSessionCount = 1;
            m_server = await m_fixture.StartAsync().ConfigureAwait(false);
            EndpointDescription endpoint = m_server.GetEndpoints().Find(
                description => description.SecurityPolicyUri == SecurityPolicies.None);
            m_channel = new SecureChannelContext("service-level", endpoint, RequestEncoding.Binary);
        }

        [TearDown]
        public async Task StopServerAsync()
        {
            await m_fixture.StopAsync().ConfigureAwait(false);
        }

        [TestCase((byte)210)]
        [TestCase((byte)255)]
        public async Task ProviderOwnedHealthyLevelSurvivesSessionChurnAsync(byte initialLevel)
        {
            var provider = new MutableProvider(initialLevel);
            var startup = new ServiceLevelStartupTask(provider);
            await startup.OnServerStartedAsync(m_server.CurrentInstance).ConfigureAwait(false);
            Assert.That(m_server.CurrentInstance.ServerObject.ServiceLevel!.Value, Is.EqualTo(initialLevel));

            CreateSessionResponse created = await CreateSessionAsync().ConfigureAwait(false);
            Assert.That(m_server.CurrentInstance.ServerObject.ServiceLevel.Value, Is.EqualTo(initialLevel));
            provider.SetLevel(235);
            Assert.That(m_server.CurrentInstance.ServerObject.ServiceLevel.Value, Is.EqualTo((byte)235));

            await CloseSessionAsync(created).ConfigureAwait(false);
            Assert.That(m_server.CurrentInstance.ServerObject.ServiceLevel.Value, Is.EqualTo((byte)235));
        }

        [Test]
        public async Task ASecondProviderCannotTakeServiceLevelOwnershipAsync()
        {
            var first = new MutableProvider(210);
            var second = new MutableProvider(240);
            await new ServiceLevelStartupTask(first).OnServerStartedAsync(m_server.CurrentInstance)
                .ConfigureAwait(false);

            Assert.ThrowsAsync<InvalidOperationException>(async () =>
                await new ServiceLevelStartupTask(second).OnServerStartedAsync(m_server.CurrentInstance)
                    .ConfigureAwait(false));
            second.SetLevel(255);
            Assert.That(m_server.CurrentInstance.ServerObject.ServiceLevel!.Value, Is.EqualTo((byte)210));
            first.SetLevel(215);
            Assert.That(m_server.CurrentInstance.ServerObject.ServiceLevel.Value, Is.EqualTo((byte)215));
        }

        [Test]
        public async Task UnownedServiceLevelStillTracksSessionHeadroomAsync()
        {
            Assert.That(m_server.CurrentInstance.ServerObject.ServiceLevel!.Value, Is.EqualTo((byte)255));
            CreateSessionResponse created = await CreateSessionAsync().ConfigureAwait(false);
            Assert.That(m_server.CurrentInstance.ServerObject.ServiceLevel.Value, Is.EqualTo((byte)200));
            await CloseSessionAsync(created).ConfigureAwait(false);
            Assert.That(m_server.CurrentInstance.ServerObject.ServiceLevel.Value, Is.EqualTo((byte)255));
        }

        /// <summary>
        /// The Server.Auditing write handler converted the Variant with
        /// Convert.ToBoolean(object), which throws for a Variant.
        /// </summary>
        [Test]
        public void AuditingWriteHandlerTakesTheBooleanValue()
        {
            IServerInternal server = m_server.CurrentInstance;
            PropertyState<bool> auditing = server.ServerObject.Auditing!;
            bool initial = server.Auditing;

            Variant value = !initial;
            ServiceResult result = auditing.OnSimpleWriteValue!(
                server.DefaultSystemContext, auditing, ref value);
            Assert.That(ServiceResult.IsGood(result), Is.True);
            Assert.That(server.Auditing, Is.EqualTo(!initial));

            Variant mismatch = "true";
            result = auditing.OnSimpleWriteValue!(
                server.DefaultSystemContext, auditing, ref mismatch);
            Assert.That(result.StatusCode, Is.EqualTo(StatusCodes.BadTypeMismatch));
            Assert.That(server.Auditing, Is.EqualTo(!initial));
        }

        private ValueTask<CreateSessionResponse> CreateSessionAsync()
        {
            return m_server.CreateSessionAsync(
                m_channel, new RequestHeader(), null, null, null, "service-level",
                default, default, 60000, 0, RequestLifetime.None);
        }

        private ValueTask<CloseSessionResponse> CloseSessionAsync(CreateSessionResponse session)
        {
            return m_server.CloseSessionAsync(
                m_channel, new RequestHeader { AuthenticationToken = session.AuthenticationToken },
                true, RequestLifetime.None);
        }

        private ServerFixture<StandardServer> m_fixture;
        private StandardServer m_server;
        private SecureChannelContext m_channel;

        private sealed class MutableProvider(byte level) : IServiceLevelProvider
        {
            public event Action<byte>? ServiceLevelChanged;

            public byte GetServiceLevel()
            {
                return m_level;
            }

            public void SetLevel(byte value)
            {
                m_level = value;
                ServiceLevelChanged?.Invoke(value);
            }

            private byte m_level = level;
        }
    }
}