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 * Copyright (c) 2005-2026 The OPC Foundation, Inc. All rights reserved.
 *
 * OPC Foundation MIT License 1.00
 *
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 * obtaining a copy of this software and associated documentation
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 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
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 * OTHER DEALINGS IN THE SOFTWARE.
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 * The complete license agreement can be found here:
 * http://opcfoundation.org/License/MIT/1.00/
 * ======================================================================*/

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using Microsoft.Extensions.Logging;
using NUnit.Framework;
using Opc.Ua.SourceGeneration;
using Opc.Ua.SourceGeneration.Dependency;
using Opc.Ua.Tests;

namespace Opc.Ua.Schema.Model.Tests
{
    /// <summary>
    /// A NodeSet2 Variable or VariableType without a Value element has a
    /// null Value (OPC 10000-6 F.5). The generator used to initialize such
    /// a node with the default value of its DataType ((int)0, (double)0),
    /// so a server built from the NodeSet reported a value the model never
    /// declared.
    /// </summary>
    [TestFixture]
    [Category("ModelDesign")]
    [SetCulture("en-us")]
    [SetUICulture("en-us")]
    public class NodeSetValueAbsentTests
    {
        private const string NullValue = "baseState.WrappedValue = global::Opc.Ua.Variant.Null;";

        [TestCase("CreatePump1_RevisionCounter", "(int)0")]
        [TestCase("CreatePump1_RatedFlow", "(double)0")]
        [TestCase("CreatePumpType_RatedFlow", "(double)0")]
        public void VariableWithoutValueIsNull(string method, string dataTypeDefault)
        {
            string body = ExtractMethodBody(GenerateDeviceSetPump(), method);

            Assert.Multiple(() =>
            {
                Assert.That(body, Does.Contain(NullValue));
                Assert.That(body, Does.Not.Contain(dataTypeDefault));
            });
        }

        [Test]
        public void VariableWithValueKeepsIt()
        {
            string body = ExtractMethodBody(GenerateDeviceSetPump(), "CreatePump1_SerialNumber");

            Assert.That(
                body,
                Does.Contain("baseState.WrappedValue = global::Opc.Ua.Variant.From(\"SN-0001\");"));
        }

        [Test]
        public void VariableTypeWithoutValueIsNull()
        {
            string body = ExtractMethodBody(GenerateDeviceSetPump(), "CreateFlowVariableType");

            Assert.Multiple(() =>
            {
                Assert.That(body, Does.Contain(NullValue));
                Assert.That(body, Does.Not.Contain("(double)0"));
            });
        }

        [Test]
        public void InstanceOfVariableTypeWithoutValueIsNull()
        {
            string body = ExtractMethodBody(GenerateDeviceSetPump(), "CreateInstanceOfFlowVariableType");

            Assert.Multiple(() =>
            {
                Assert.That(body, Does.Contain(NullValue));
                Assert.That(body, Does.Not.Contain("(double)0"));
            });
        }

        [Test]
        public void SubtypeWithoutValueDoesNotInheritTheValueOfItsSupertype()
        {
            string generated = GenerateDeviceSetPump();
            string supertype = ExtractMethodBody(generated, "CreateInstanceOfRatedFlowVariableType");
            string subtype = ExtractMethodBody(generated, "CreateInstanceOfUnratedFlowVariableType");

            Assert.Multiple(() =>
            {
                Assert.That(supertype, Does.Contain("42.5"), "the supertype keeps its declared Value");
                Assert.That(subtype, Does.Contain(NullValue));
                Assert.That(subtype, Does.Not.Contain("42.5"));
                Assert.That(subtype, Does.Not.Contain("(double)0"));
            });
        }

        [TestCase("CreateUnsetRatedFlow")]
        [TestCase("CreateRatedFlowMeter_UnsetFlow")]
        [TestCase("CreateRatedFlowMeter1_RatedFlow")]
        public void VariableWithoutValueDoesNotInheritTheValueOfItsVariableType(string method)
        {
            string body = ExtractMethodBody(GenerateDeviceSetPump(), method);

            Assert.Multiple(() =>
            {
                Assert.That(body, Does.Contain(NullValue));
                Assert.That(body, Does.Not.Contain("42.5"));
                Assert.That(body, Does.Not.Contain("12.5"));
                Assert.That(body, Does.Not.Contain("(double)0"));
            });
        }

        [Test]
        public void VariableWithValueOverridesTheValueOfItsVariableType()
        {
            string body = ExtractMethodBody(GenerateDeviceSetPump(), "CreateRatedFlowMeter_SetFlow");

            Assert.Multiple(() =>
            {
                Assert.That(body, Does.Contain("7.25"));
                Assert.That(body, Does.Not.Contain("42.5"));
            });
        }

        [Test]
        public void DependencyPayloadCarriesTheAbsentValue()
        {
            var dependency = new ModelDependencyV1 { ModelUri = "http://test.org/UA/ValueAbsent/" };
            dependency.Nodes.Add(new DependencyNode
            {
                SymbolicName = "PumpType",
                SymbolicNamespace = "http://test.org/UA/ValueAbsent/",
                ClassName = "PumpType",
                Kind = DependencyNodeKind.ObjectType,
                Children =
                [
                    new DependencyChild
                    {
                        BrowseName = "RatedFlow",
                        SymbolicName = "RatedFlow",
                        InstanceKind = 3,
                        NodeSetValueIsNull = true
                    },
                    new DependencyChild
                    {
                        BrowseName = "SerialNumber",
                        SymbolicName = "SerialNumber",
                        InstanceKind = 3,
                        DefaultValueXml = "<String xmlns=\"http://opcfoundation.org/UA/2008/02/Types.xsd\">SN</String>"
                    }
                ]
            });

            ModelDependencyV1? decoded = ModelDependencyV1.FromBase64Payload(dependency.ToBase64Payload());

            Assert.That(decoded, Is.Not.Null);
            IReadOnlyList<DependencyChild> children = decoded!.Nodes.Single().Children;
            Assert.Multiple(() =>
            {
                Assert.That(children[0].NodeSetValueIsNull, Is.True);
                Assert.That(children[1].NodeSetValueIsNull, Is.False);
                Assert.That(children[1].DefaultValueXml, Does.Contain("SN"));
            });
        }

        private static string GenerateDeviceSetPump()
        {
            ITelemetryContext telemetry = NUnitTelemetryContext.Create(logLevel: LogLevel.Error);
            using var fileSystem = new VirtualFileSystem();
            string resources = Path.Combine(Directory.GetCurrentDirectory(), "Resources");
            const string flowTypePath = "memory://FlowVariableType.NodeSet2.xml";
            fileSystem.Add(flowTypePath, Encoding.UTF8.GetBytes(FlowVariableTypeNodeSet));
            var nodesets = new NodesetFileCollection(
                [
                    (Path.Combine(resources, "Opc.Ua.Di.NodeSet2.xml"), new NodesetFileOptions()),
                    (Path.Combine(resources, "DeviceSetPump.NodeSet2.xml"), new NodesetFileOptions()),
                    (flowTypePath, new NodesetFileOptions())
                ],
                [],
                fileSystem,
                telemetry);
            nodesets.GenerateCode(
                fileSystem,
                string.Empty,
                telemetry,
                new GeneratorOptions { OmitFluentApi = true });
            return string.Join(
                Environment.NewLine,
                fileSystem.CreatedFiles
                    .Where(c => Path.GetExtension(c) == ".cs")
                    .Select(c => Encoding.UTF8.GetString(fileSystem.Get(c))));
        }

        private static string ExtractMethodBody(string code, string methodName)
        {
            Match match = Regex.Match(code, @"\s" + Regex.Escape(methodName) + @"\(\s*this\s");
            Assert.That(match.Success, Is.True, $"Method {methodName} was not generated.");
            int end = code.IndexOf("return state;", match.Index, StringComparison.Ordinal);
            Assert.That(end, Is.GreaterThan(match.Index));
            return code[match.Index..end];
        }

        private const string FlowVariableTypeNodeSet = """
            <?xml version="1.0" encoding="utf-8"?>
            <UANodeSet xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                xmlns:xsd="http://www.w3.org/2001/XMLSchema"
                xmlns="http://opcfoundation.org/UA/2011/03/UANodeSet.xsd">
                <NamespaceUris>
                    <Uri>http://test.org/UA/FlowVariableType/</Uri>
                </NamespaceUris>
                <Models>
                    <Model ModelUri="http://test.org/UA/FlowVariableType/" PublicationDate="2026-10-01T00:00:00Z" Version="1.0.0" />
                </Models>
                <Aliases>
                    <Alias Alias="Double">i=11</Alias>
                    <Alias Alias="HasSubtype">i=45</Alias>
                    <Alias Alias="HasTypeDefinition">i=40</Alias>
                    <Alias Alias="Organizes">i=35</Alias>
                    <Alias Alias="HasComponent">i=47</Alias>
                    <Alias Alias="HasModellingRule">i=37</Alias>
                </Aliases>
                <UAVariableType NodeId="ns=1;i=2000" BrowseName="1:FlowVariableType" DataType="Double">
                    <DisplayName>FlowVariableType</DisplayName>
                    <References>
                        <Reference ReferenceType="HasSubtype" IsForward="false">i=63</Reference>
                    </References>
                </UAVariableType>
                <UAVariableType NodeId="ns=1;i=2001" BrowseName="1:RatedFlowVariableType" DataType="Double">
                    <DisplayName>RatedFlowVariableType</DisplayName>
                    <References>
                        <Reference ReferenceType="HasSubtype" IsForward="false">i=63</Reference>
                    </References>
                    <Value>
                        <Double xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">42.5</Double>
                    </Value>
                </UAVariableType>
                <UAVariableType NodeId="ns=1;i=2002" BrowseName="1:UnratedFlowVariableType" DataType="Double">
                    <DisplayName>UnratedFlowVariableType</DisplayName>
                    <References>
                        <Reference ReferenceType="HasSubtype" IsForward="false">ns=1;i=2001</Reference>
                    </References>
                </UAVariableType>
                <UAVariable NodeId="ns=1;i=5000" BrowseName="1:UnsetRatedFlow" DataType="Double">
                    <DisplayName>UnsetRatedFlow</DisplayName>
                    <References>
                        <Reference ReferenceType="HasTypeDefinition">ns=1;i=2001</Reference>
                        <Reference ReferenceType="Organizes" IsForward="false">i=85</Reference>
                    </References>
                </UAVariable>
                <UAObject NodeId="ns=1;i=5001" BrowseName="1:RatedFlowMeter">
                    <DisplayName>RatedFlowMeter</DisplayName>
                    <References>
                        <Reference ReferenceType="HasTypeDefinition">i=58</Reference>
                        <Reference ReferenceType="Organizes" IsForward="false">i=85</Reference>
                        <Reference ReferenceType="HasComponent">ns=1;i=5002</Reference>
                        <Reference ReferenceType="HasComponent">ns=1;i=5003</Reference>
                    </References>
                </UAObject>
                <UAVariable NodeId="ns=1;i=5002" BrowseName="1:UnsetFlow" ParentNodeId="ns=1;i=5001" DataType="Double">
                    <DisplayName>UnsetFlow</DisplayName>
                    <References>
                        <Reference ReferenceType="HasTypeDefinition">ns=1;i=2001</Reference>
                    </References>
                </UAVariable>
                <UAVariable NodeId="ns=1;i=5003" BrowseName="1:SetFlow" ParentNodeId="ns=1;i=5001" DataType="Double">
                    <DisplayName>SetFlow</DisplayName>
                    <References>
                        <Reference ReferenceType="HasTypeDefinition">ns=1;i=2001</Reference>
                    </References>
                    <Value>
                        <Double xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">7.25</Double>
                    </Value>
                </UAVariable>
                <UAObjectType NodeId="ns=1;i=1001" BrowseName="1:RatedFlowMeterType">
                    <DisplayName>RatedFlowMeterType</DisplayName>
                    <References>
                        <Reference ReferenceType="HasSubtype" IsForward="false">i=58</Reference>
                        <Reference ReferenceType="HasComponent">ns=1;i=6000</Reference>
                    </References>
                </UAObjectType>
                <UAVariable NodeId="ns=1;i=6000" BrowseName="1:RatedFlow" ParentNodeId="ns=1;i=1001" DataType="Double">
                    <DisplayName>RatedFlow</DisplayName>
                    <References>
                        <Reference ReferenceType="HasTypeDefinition">ns=1;i=2001</Reference>
                        <Reference ReferenceType="HasModellingRule">i=78</Reference>
                    </References>
                    <Value>
                        <Double xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">12.5</Double>
                    </Value>
                </UAVariable>
                <UAObject NodeId="ns=1;i=5004" BrowseName="1:RatedFlowMeter1">
                    <DisplayName>RatedFlowMeter1</DisplayName>
                    <References>
                        <Reference ReferenceType="HasTypeDefinition">ns=1;i=1001</Reference>
                        <Reference ReferenceType="Organizes" IsForward="false">i=85</Reference>
                        <Reference ReferenceType="HasComponent">ns=1;i=5005</Reference>
                    </References>
                </UAObject>
                <UAVariable NodeId="ns=1;i=5005" BrowseName="1:RatedFlow" ParentNodeId="ns=1;i=5004" DataType="Double">
                    <DisplayName>RatedFlow</DisplayName>
                    <References>
                        <Reference ReferenceType="HasTypeDefinition">ns=1;i=2001</Reference>
                    </References>
                </UAVariable>
            </UANodeSet>
            """;
    }
}