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using NUnit.Framework;
using Opc.Ua.Tests;

namespace Opc.Ua.Core.Tests.Stack.State
{
    /// <summary>
    /// Tests for the handwritten MultiStateValueDiscreteState write validation which
    /// rejects numeric writes that do not match an EnumValues entry and refreshes the
    /// ValueAsText property on a successful scalar write.
    /// </summary>
    [TestFixture]
    [Category("NodeState")]
    [SetCulture("en-us")]
    [SetUICulture("en-us")]
    [Parallelizable]
    public class MultiStateValueDiscreteStateTests
    {
        // Deliberately sparse / non-zero-based to exercise the EnumValues lookup.
        private static readonly (long Value, string Name)[] s_states =
            [(1, "one"), (2, "two"), (4, "four"), (8, "eight")];

        private SystemContext m_context;

        [OneTimeSetUp]
        public void OneTimeSetUp()
        {
            ITelemetryContext telemetry = NUnitTelemetryContext.Create();
            var messageContext = ServiceMessageContext.CreateEmpty(telemetry);
            m_context = new SystemContext(telemetry)
            {
                NamespaceUris = messageContext.NamespaceUris,
                ServerUris = messageContext.ServerUris,
                EncodeableFactory = messageContext.Factory,
                TypeTable = new TypeTable(messageContext.NamespaceUris)
            };
        }

        [Test]
        public void WriteMatchingSparseValueSucceeds()
        {
            MultiStateValueDiscreteState node = CreateNode(s_states);

            ServiceResult result = WriteValue(node, Variant.From((uint)4));

            Assert.That(ServiceResult.IsGood(result), Is.True);
            Assert.That(node.WrappedValue.TryGetValue(out uint written), Is.True);
            Assert.That(written, Is.EqualTo(4u));
        }

        [Test]
        public void WriteMatchingValueUpdatesValueAsText()
        {
            MultiStateValueDiscreteState node = CreateNode(s_states);

            ServiceResult result = WriteValue(node, Variant.From((uint)8));

            Assert.That(ServiceResult.IsGood(result), Is.True);
            Assert.That(node.ValueAsText, Is.Not.Null);
            Assert.That(node.ValueAsText.WrappedValue.TryGetValue(out LocalizedText text), Is.True);
            Assert.That(text.Text, Is.EqualTo("eight"));
        }

        [Test]
        public void WriteValueBetweenGapsReturnsBadOutOfRange()
        {
            MultiStateValueDiscreteState node = CreateNode(s_states);

            ServiceResult result = WriteValue(node, Variant.From((uint)3));

            Assert.That(result.StatusCode.Code, Is.EqualTo(StatusCodes.BadOutOfRange));
        }

        [Test]
        public void WriteValueBetweenGapsLeavesValueAsTextUnchanged()
        {
            MultiStateValueDiscreteState node = CreateNode(s_states);

            _ = WriteValue(node, Variant.From((uint)3));

            Assert.That(node.ValueAsText, Is.Not.Null);
            Assert.That(node.ValueAsText.WrappedValue.TryGetValue(out LocalizedText text), Is.True);
            Assert.That(text.Text, Is.EqualTo("initial"));
        }

        [Test]
        public void WriteWithEmptyEnumValuesRejectsEveryValue()
        {
            MultiStateValueDiscreteState node = CreateNode([]);

            ServiceResult result = WriteValue(node, Variant.From((uint)1));

            Assert.That(result.StatusCode.Code, Is.EqualTo(StatusCodes.BadOutOfRange));
        }

        [Test]
        public void WriteWithoutEnumValuesChildFallsThroughToBase()
        {
            MultiStateValueDiscreteState node = CreateNode(null!);

            ServiceResult result = WriteValue(node, Variant.From((uint)99));

            Assert.That(ServiceResult.IsGood(result), Is.True);
            Assert.That(node.WrappedValue.TryGetValue(out uint written), Is.True);
            Assert.That(written, Is.EqualTo(99u));
        }

        [Test]
        public void WriteMatchingButNotWritableReturnsBadNotWritable()
        {
            MultiStateValueDiscreteState node = CreateNode(s_states);
            node.AccessLevel = AccessLevels.CurrentRead;
            node.UserAccessLevel = AccessLevels.CurrentRead;

            ServiceResult result = WriteValue(node, Variant.From((uint)4));

            Assert.That(result.StatusCode.Code, Is.EqualTo(StatusCodes.BadNotWritable));
        }

        private MultiStateValueDiscreteState CreateNode((long Value, string Name)[] states)
        {
            var node = new MultiStateValueDiscreteState(null)
            {
                NodeId = new NodeId(1000),
                BrowseName = new QualifiedName("States"),
                DataType = DataTypeIds.UInt32,
                ValueRank = ValueRanks.Scalar,
                AccessLevel = AccessLevels.CurrentReadOrWrite,
                UserAccessLevel = AccessLevels.CurrentReadOrWrite,
                Value = Variant.From((uint)0)
            };

            if (states != null)
            {
                var values = new EnumValueType[states.Length];
                for (int ii = 0; ii < states.Length; ii++)
                {
                    LocalizedText text = LocalizedText.From(states[ii].Name);
                    values[ii] = new EnumValueType
                    {
                        Value = states[ii].Value,
                        DisplayName = text,
                        Description = text
                    };
                }

                node.EnumValues = PropertyState<ArrayOf<EnumValueType>>
                    .With<StructureBuilder<EnumValueType>>(node, values.ToArrayOf());
                node.EnumValues.NodeId = new NodeId(1001);
                node.EnumValues.BrowseName = new QualifiedName(BrowseNames.EnumValues);
                node.EnumValues.DataType = DataTypeIds.EnumValueType;
                node.EnumValues.ValueRank = ValueRanks.OneDimension;
            }

            node.ValueAsText = PropertyState<LocalizedText>.With<VariantBuilder>(
                node, LocalizedText.From("initial"));
            node.ValueAsText.NodeId = new NodeId(1002);
            node.ValueAsText.BrowseName = new QualifiedName(BrowseNames.ValueAsText);
            node.ValueAsText.DataType = DataTypeIds.LocalizedText;
            node.ValueAsText.ValueRank = ValueRanks.Scalar;

            return node;
        }

        private ServiceResult WriteValue(MultiStateValueDiscreteState node, Variant value)
        {
            return node.WriteAttribute(
                m_context,
                Attributes.Value,
                NumericRange.Null,
                new DataValue(value));
        }
    }
}