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using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using Moq;
using NUnit.Framework;
using Opc.Ua.Schema;
using Opc.Ua.Tests;

namespace Opc.Ua.Server.Tests
{
    /// <summary>
    /// Tests for building and registering dynamic stand-in encodeables for the
    /// runtime-loaded custom DataTypes of a server address space.
    /// </summary>
    [TestFixture]
    [Category("ComplexTypes")]
    [Parallelizable]
    public class ServerComplexTypeSystemTests
    {
        private const string TestNamespaceUri = "http://test.org/UA/ComplexTypes/";

        private static readonly int[] s_decoyValue = [42];

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

            m_namespaceUris = new NamespaceTable();
            m_namespaceUris.GetIndexOrAppend(Types.Namespaces.OpcUa);
            m_ns = m_namespaceUris.GetIndexOrAppend(TestNamespaceUri);

            m_typeTree = new TypeTable(m_namespaceUris);
            m_factory = EncodeableFactory.Create();
            m_nodesById = [];

            m_structTypeId = new NodeId(6001, m_ns);
            m_structEncodingId = new NodeId(7001, m_ns);
            m_enumTypeId = new NodeId(6002, m_ns);

            BuildAddressSpace();

            m_mockNodeManager = new Mock<IMasterNodeManager>();
            m_mockNodeManager
                .Setup(m => m.FindNodeInAddressSpaceAsync(
                    It.IsAny<NodeId>(),
                    It.IsAny<CancellationToken>()))
                .Returns<NodeId, CancellationToken>((id, _) =>
                    new ValueTask<NodeState>(
                        m_nodesById.TryGetValue(id, out NodeState node) ? node : null));

            m_mockServer = new Mock<IServerInternal>();
            m_mockServer.Setup(s => s.NamespaceUris).Returns(m_namespaceUris);
            m_mockServer.Setup(s => s.TypeTree).Returns(m_typeTree);
            m_mockServer.Setup(s => s.Factory).Returns(m_factory);
            m_mockServer.Setup(s => s.NodeManager).Returns(m_mockNodeManager.Object);
            m_mockServer.Setup(s => s.Telemetry).Returns(m_telemetry);
            m_mockServer.Setup(s => s.DefaultSystemContext)
                .Returns(new ServerSystemContext(m_mockServer.Object));
        }

        [Test]
        public async Task LoadComplexTypesBuildsStandInsForRuntimeStructAndEnum()
        {
            var options = new ServerComplexTypeOptions { ThrowOnError = true };

            await m_mockServer.Object
                .LoadComplexTypesAsync(m_telemetry, options)
                .ConfigureAwait(false);

            Assert.Multiple(() =>
            {
                Assert.That(
                    m_factory.TryGetEncodeableType(
                        NodeId.ToExpandedNodeId(m_structTypeId, m_namespaceUris),
                        out IEncodeableType structType),
                    Is.True,
                    "the runtime structure type should be registered in the factory");
                Assert.That(structType, Is.Not.Null);

                Assert.That(
                    m_factory.TryGetEncodeableType(
                        NodeId.ToExpandedNodeId(m_structEncodingId, m_namespaceUris),
                        out _),
                    Is.True,
                    "the binary encoding id should resolve to the structure stand-in");

                Assert.That(
                    m_factory.TryGetEnumeratedType(
                        NodeId.ToExpandedNodeId(m_enumTypeId, m_namespaceUris),
                        out IEnumeratedType enumType),
                    Is.True,
                    "the runtime enumeration type should be registered in the factory");
                Assert.That(enumType, Is.Not.Null);
            });
        }

        [Test]
        public async Task LoadComplexTypesSkipsAlreadyKnownTypes()
        {
            var options = new ServerComplexTypeOptions { ThrowOnError = true };

            // first pass builds the stand-ins into the factory
            await m_mockServer.Object
                .LoadComplexTypesAsync(m_telemetry, options)
                .ConfigureAwait(false);
            int knownAfterFirstPass = m_factory.KnownTypeIds.Count();

            // second pass must skip everything that is already known to the factory
            await m_mockServer.Object
                .LoadComplexTypesAsync(m_telemetry, options)
                .ConfigureAwait(false);

            Assert.That(
                m_factory.KnownTypeIds.Count(),
                Is.EqualTo(knownAfterFirstPass),
                "types already present in the factory must not be rebuilt");
        }

        [Test]
        public async Task LoadComplexTypesReturnsFactoryBackedResolver()
        {
            var options = new ServerComplexTypeOptions { ThrowOnError = true };

            // a schema-only type that has no encodeable in the factory, supplied
            // through the optional registry, must still resolve via the composite
            var registry = new DataTypeDefinitionRegistry();
            var schemaOnlyId = new NodeId(6009, m_ns);
            registry.Add(new UaTypeDescription(
                new ExpandedNodeId(schemaOnlyId),
                new QualifiedName("SchemaOnly", m_ns),
                new StructureDefinition
                {
                    BaseDataType = DataTypeIds.Structure,
                    StructureType = StructureType.Structure,
                    Fields = []
                },
                TestNamespaceUri));

            IDataTypeDefinitionResolver resolver = await m_mockServer.Object
                .LoadComplexTypesAsync(m_telemetry, options, registry)
                .ConfigureAwait(false);

            Assert.Multiple(() =>
            {
                // the primed factory is the source for the runtime stand-ins
                Assert.That(
                    resolver.TryResolve(
                        NodeId.ToExpandedNodeId(m_structTypeId, m_namespaceUris),
                        out UaTypeDescription structDescription),
                    Is.True);
                Assert.That(structDescription.Definition, Is.InstanceOf<StructureDefinition>());
                Assert.That(structDescription.NamespaceUri, Is.EqualTo(TestNamespaceUri));

                Assert.That(
                    resolver.TryResolve(
                        NodeId.ToExpandedNodeId(m_enumTypeId, m_namespaceUris),
                        out UaTypeDescription enumDescription),
                    Is.True);
                Assert.That(enumDescription.Definition, Is.InstanceOf<EnumDefinition>());

                // the composite falls through to the registry for schema-only types
                Assert.That(
                    resolver.TryResolve(
                        new ExpandedNodeId(schemaOnlyId),
                        out UaTypeDescription schemaOnlyDescription),
                    Is.True);
                Assert.That(schemaOnlyDescription.Name, Is.EqualTo("SchemaOnly"));
            });
        }

        [Test]
        public void AddComplexTypeSystemRegistersOptionsAndResolver()
        {
            var services = new ServiceCollection();
            services
                .AddOpcUa()
                .AddServer(options => options.ApplicationName = "TestComplexTypeServer")
                .AddComplexTypeSystem(options => options.OnlyEnumTypes = true);

            using ServiceProvider provider = services.BuildServiceProvider();

            ServerComplexTypeOptions registeredOptions =
                provider.GetService<ServerComplexTypeOptions>();
            Assert.That(registeredOptions, Is.Not.Null);
            Assert.That(registeredOptions.OnlyEnumTypes, Is.True);
            Assert.That(provider.GetService<IDataTypeDefinitionResolver>(), Is.Not.Null);
        }

        [Test]
        public async Task GetEnumTypeArrayIgnoresUnrelatedPropertyAndSelectsEnumStrings()
        {
            // DataType with a decoy HasProperty listed BEFORE the real EnumStrings
            // property. The old "first non-null" logic would have returned the
            // decoy; the resolver must match by BrowseName instead.
            var enumWithProps = new NodeId(6003, m_ns);
            var decoyPropId = new NodeId(7101, m_ns);
            var enumStringsPropId = new NodeId(7102, m_ns);

            var dataTypeNode = new DataTypeState
            {
                NodeId = enumWithProps,
                BrowseName = new QualifiedName("EnumWithProps", m_ns),
                SuperTypeId = DataTypeIds.Enumeration,
                IsAbstract = false
            };
            dataTypeNode.AddReference(
                ReferenceTypeIds.HasProperty, false, new ExpandedNodeId(decoyPropId));
            dataTypeNode.AddReference(
                ReferenceTypeIds.HasProperty, false, new ExpandedNodeId(enumStringsPropId));
            m_nodesById[enumWithProps] = dataTypeNode;

            m_nodesById[decoyPropId] = new BaseDataVariableState(null)
            {
                NodeId = decoyPropId,
                BrowseName = new QualifiedName("SomethingElse", m_ns),
                Value = new Variant(s_decoyValue)
            };
            m_nodesById[enumStringsPropId] = new BaseDataVariableState(null)
            {
                NodeId = enumStringsPropId,
                BrowseName = new QualifiedName(BrowseNames.EnumStrings),
                Value = new Variant(new LocalizedText[]
                {
                    new("Red"),
                    new("Green")
                })
            };

            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);

            Variant result = await resolver
                .GetEnumTypeArrayAsync(NodeId.ToExpandedNodeId(enumWithProps, m_namespaceUris))
                .ConfigureAwait(false);

            Assert.That(
                result.TryGetValue(out ArrayOf<LocalizedText> texts),
                Is.True,
                "the EnumStrings property must be selected and the decoy ignored");
            Assert.That(texts.Count, Is.EqualTo(2));
        }

        [Test]
        public async Task GetEnumTypeArrayPrefersEnumValuesOverEnumStrings()
        {
            // Both EnumStrings (listed first) and EnumValues are present; the
            // richer EnumValues must win regardless of reference order.
            var enumWithProps = new NodeId(6004, m_ns);
            var enumStringsPropId = new NodeId(7201, m_ns);
            var enumValuesPropId = new NodeId(7202, m_ns);

            var dataTypeNode = new DataTypeState
            {
                NodeId = enumWithProps,
                BrowseName = new QualifiedName("EnumWithBoth", m_ns),
                SuperTypeId = DataTypeIds.Enumeration,
                IsAbstract = false
            };
            dataTypeNode.AddReference(
                ReferenceTypeIds.HasProperty, false, new ExpandedNodeId(enumStringsPropId));
            dataTypeNode.AddReference(
                ReferenceTypeIds.HasProperty, false, new ExpandedNodeId(enumValuesPropId));
            m_nodesById[enumWithProps] = dataTypeNode;

            m_nodesById[enumStringsPropId] = new BaseDataVariableState(null)
            {
                NodeId = enumStringsPropId,
                BrowseName = new QualifiedName(BrowseNames.EnumStrings),
                Value = new Variant(new LocalizedText[] { new("Red") })
            };
            m_nodesById[enumValuesPropId] = new BaseDataVariableState(null)
            {
                NodeId = enumValuesPropId,
                BrowseName = new QualifiedName("EnumValues"),
                Value = new Variant(new ExtensionObject[]
                {
                    new(new EnumValueType
                    {
                        Value = 0,
                        DisplayName = new LocalizedText("Red")
                    })
                })
            };

            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);

            Variant result = await resolver
                .GetEnumTypeArrayAsync(NodeId.ToExpandedNodeId(enumWithProps, m_namespaceUris))
                .ConfigureAwait(false);

            Assert.That(
                result.TryGetValue(out ArrayOf<ExtensionObject> enumValues),
                Is.True,
                "EnumValues must be preferred over EnumStrings");
            Assert.That(enumValues.Count, Is.EqualTo(1));
        }

        [Test]
        public async Task LoadDataTypeSystemReturnsEmpty()
        {
            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);

            IReadOnlyDictionary<NodeId, DataDictionary> result =
                await resolver.LoadDataTypeSystem().ConfigureAwait(false);

            Assert.That(result, Is.Empty);
        }

        [Test]
        public async Task BrowseTypeIdsForDictionaryComponentReturnsDefault()
        {
            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);

            (ExpandedNodeId typeId, ExpandedNodeId encodingId, DataTypeNode dataTypeNode) = await resolver
                .BrowseTypeIdsForDictionaryComponentAsync(
                    NodeId.ToExpandedNodeId(m_structTypeId, m_namespaceUris))
                .ConfigureAwait(false);

            Assert.Multiple(() =>
            {
                Assert.That(typeId.IsNull, Is.True);
                Assert.That(encodingId.IsNull, Is.True);
                Assert.That(dataTypeNode, Is.Null);
            });
        }

        [Test]
        public async Task FindSuperTypeReturnsSuperType()
        {
            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);

            NodeId superType = await resolver
                .FindSuperTypeAsync(m_structTypeId)
                .ConfigureAwait(false);

            Assert.That(superType, Is.EqualTo(DataTypeIds.Structure));
        }

        [Test]
        public async Task FindReturnsDataTypeNodeForDataTypeAndNullOtherwise()
        {
            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);

            INode dataTypeNode = await resolver
                .FindAsync(NodeId.ToExpandedNodeId(m_structTypeId, m_namespaceUris))
                .ConfigureAwait(false);
            // the encoding node is a BaseObjectState, not a DataType
            INode encodingNode = await resolver
                .FindAsync(NodeId.ToExpandedNodeId(m_structEncodingId, m_namespaceUris))
                .ConfigureAwait(false);

            Assert.Multiple(() =>
            {
                Assert.That(dataTypeNode, Is.InstanceOf<DataTypeNode>());
                Assert.That(
                    ExpandedNodeId.ToNodeId(dataTypeNode.NodeId, m_namespaceUris),
                    Is.EqualTo(m_structTypeId));
                Assert.That(encodingNode, Is.Null);
            });
        }

        [Test]
        public async Task BrowseForEncodingsReturnsBinaryEncodingId()
        {
            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);
            string[] supported = [BrowseNames.DefaultBinary];

            (ArrayOf<NodeId> encodings, ExpandedNodeId binaryEncodingId, ExpandedNodeId xmlEncodingId) = await resolver
                .BrowseForEncodingsAsync(
                    NodeId.ToExpandedNodeId(m_structTypeId, m_namespaceUris),
                    supported)
                .ConfigureAwait(false);

            Assert.Multiple(() =>
            {
                Assert.That(
                    ExpandedNodeId.ToNodeId(binaryEncodingId, m_namespaceUris),
                    Is.EqualTo(m_structEncodingId));
                Assert.That(xmlEncodingId.IsNull, Is.True);
                Assert.That(encodings.Count, Is.EqualTo(1));
            });
        }

        [Test]
        public async Task BrowseForEncodingsArrayOverloadAggregatesEncodings()
        {
            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);
            string[] supported = [BrowseNames.DefaultBinary];
            ArrayOf<ExpandedNodeId> ids =
                [NodeId.ToExpandedNodeId(m_structTypeId, m_namespaceUris)];

            ArrayOf<NodeId> encodings = await resolver
                .BrowseForEncodingsAsync(ids, supported)
                .ConfigureAwait(false);

            Assert.That(encodings.Count, Is.EqualTo(1));
        }

        [Test]
        public async Task LoadDataTypesReturnsCustomSubtypesAndSkipsUaTypes()
        {
            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);

            ArrayOf<INode> result = await resolver
                .LoadDataTypesAsync(NodeId.ToExpandedNodeId(DataTypeIds.Structure, m_namespaceUris))
                .ConfigureAwait(false);

            bool hasCustomStruct = false;
            for (int i = 0; i < result.Count; i++)
            {
                if (ExpandedNodeId.ToNodeId(result[i].NodeId, m_namespaceUris) == m_structTypeId)
                {
                    hasCustomStruct = true;
                }
            }
            Assert.That(hasCustomStruct, Is.True);
        }

        [Test]
        public async Task LoadDataTypesAddsRootNodeWhenRequested()
        {
            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);

            ArrayOf<INode> result = await resolver
                .LoadDataTypesAsync(
                    NodeId.ToExpandedNodeId(m_structTypeId, m_namespaceUris),
                    addRootNode: true)
                .ConfigureAwait(false);

            bool hasRoot = false;
            for (int i = 0; i < result.Count; i++)
            {
                if (ExpandedNodeId.ToNodeId(result[i].NodeId, m_namespaceUris) == m_structTypeId)
                {
                    hasRoot = true;
                }
            }
            Assert.That(hasRoot, Is.True);
        }

        [Test]
        public void LoadDataTypesThrowsWhenRootNodeCannotBeResolvedAsDataType()
        {
            var resolver = new AddressSpaceComplexTypeResolver(m_mockServer.Object);
            var unknownId =
                NodeId.ToExpandedNodeId(new NodeId(9999, m_ns), m_namespaceUris);
            // an existing node that is not a DataType surfaces the same way
            var nonDataType =
                NodeId.ToExpandedNodeId(m_structEncodingId, m_namespaceUris);

            ServiceResultException missing = Assert.ThrowsAsync<ServiceResultException>(
                async () => await resolver
                    .LoadDataTypesAsync(unknownId, addRootNode: true)
                    .ConfigureAwait(false));
            ServiceResultException wrongClass = Assert.ThrowsAsync<ServiceResultException>(
                async () => await resolver
                    .LoadDataTypesAsync(nonDataType, addRootNode: true)
                    .ConfigureAwait(false));

            Assert.Multiple(() =>
            {
                Assert.That(missing.StatusCode.Code, Is.EqualTo(StatusCodes.BadNodeIdUnknown.Code));
                Assert.That(
                    wrongClass.StatusCode.Code,
                    Is.EqualTo(StatusCodes.BadNodeIdUnknown.Code));
            });
        }

        private void BuildAddressSpace()
        {
            m_typeTree.AddSubtype(DataTypeIds.BaseDataType, NodeId.Null);
            m_typeTree.AddSubtype(DataTypeIds.Structure, DataTypeIds.BaseDataType);
            m_typeTree.AddSubtype(DataTypeIds.Enumeration, DataTypeIds.BaseDataType);
            m_typeTree.AddSubtype(m_structTypeId, DataTypeIds.Structure);
            m_typeTree.AddSubtype(m_enumTypeId, DataTypeIds.Enumeration);

            // Abstract base DataTypes are findable but carry no definition so the
            // schema walk skips them cleanly (without falling back to a read).
            AddAbstractBaseType(DataTypeIds.BaseDataType, "BaseDataType");
            AddAbstractBaseType(DataTypeIds.Structure, "Structure");
            AddAbstractBaseType(DataTypeIds.Enumeration, "Enumeration");

            var structureDefinition = new StructureDefinition
            {
                BaseDataType = DataTypeIds.Structure,
                StructureType = StructureType.Structure,
                Fields =
                [
                    new StructureField
                    {
                        Name = "Number",
                        DataType = DataTypeIds.Int32,
                        ValueRank = ValueRanks.Scalar
                    },
                    new StructureField
                    {
                        Name = "Text",
                        DataType = DataTypeIds.String,
                        ValueRank = ValueRanks.Scalar
                    }
                ]
            };
            var structureNode = new DataTypeState
            {
                NodeId = m_structTypeId,
                BrowseName = new QualifiedName("TestStructure", m_ns),
                SuperTypeId = DataTypeIds.Structure,
                IsAbstract = false,
                DataTypeDefinition = new ExtensionObject(structureDefinition)
            };
            structureNode.AddReference(
                ReferenceTypeIds.HasEncoding,
                false,
                new ExpandedNodeId(m_structEncodingId));
            m_nodesById[m_structTypeId] = structureNode;

            m_nodesById[m_structEncodingId] = new BaseObjectState(null)
            {
                NodeId = m_structEncodingId,
                BrowseName = new QualifiedName(BrowseNames.DefaultBinary)
            };

            var enumDefinition = new EnumDefinition
            {
                Fields =
                [
                    new EnumField { Name = "Red", Value = 0 },
                    new EnumField { Name = "Green", Value = 1 },
                    new EnumField { Name = "Blue", Value = 2 }
                ]
            };
            m_nodesById[m_enumTypeId] = new DataTypeState
            {
                NodeId = m_enumTypeId,
                BrowseName = new QualifiedName("TestEnum", m_ns),
                SuperTypeId = DataTypeIds.Enumeration,
                IsAbstract = false,
                DataTypeDefinition = new ExtensionObject(enumDefinition)
            };
        }

        private void AddAbstractBaseType(NodeId nodeId, string name)
        {
            m_nodesById[nodeId] = new DataTypeState
            {
                NodeId = nodeId,
                BrowseName = new QualifiedName(name),
                IsAbstract = true
            };
        }

        private ITelemetryContext m_telemetry;
        private NamespaceTable m_namespaceUris;
        private ushort m_ns;
        private TypeTable m_typeTree;
        private IEncodeableFactory m_factory;
        private Dictionary<NodeId, NodeState> m_nodesById;
        private Mock<IMasterNodeManager> m_mockNodeManager;
        private Mock<IServerInternal> m_mockServer;
        private NodeId m_structTypeId;
        private NodeId m_structEncodingId;
        private NodeId m_enumTypeId;
    }
}