ScadaBridge/tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/Adapters/OpcUaNodeReferenceTests.cs

using Opc.Ua;
using ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Adapters;

namespace ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests.Adapters;

/// <summary>
/// Stored bindings hard-code a namespace <i>index</i>, which is only
/// meaningful against one server's namespace table. These tests pin the durable
/// <c>nsu=&lt;uri&gt;</c> form and the back-compat of the existing <c>ns=</c> form.
/// </summary>
public class OpcUaNodeReferenceTests
{
    // Mirrors an OtOpcUa v3 server: 0=UA (spec), 1=ApplicationUri, 2=raw, 3=uns.
    private const string RawUri = "https://zb.com/otopcua/raw";
    private const string UnsUri = "https://zb.com/otopcua/uns";

    private static NamespaceTable V3Table()
    {
        var t = new NamespaceTable();                 // index 0 = http://opcfoundation.org/UA/
        t.Append("urn:localhost:OtOpcUa");            // 1
        t.Append(RawUri);                             // 2
        t.Append(UnsUri);                             // 3
        return t;
    }

    // The v2 server: a single custom namespace, which also landed at index 2.
    private static NamespaceTable V2Table()
    {
        var t = new NamespaceTable();
        t.Append("urn:localhost:OtOpcUa");            // 1
        t.Append("https://zb.com/otopcua/ns");        // 2
        return t;
    }

    /// <summary>Verifies that the legacy namespace index form still resolves.</summary>
    [Fact]
    public void Resolve_IndexForm_StillWorks()
    {
        // Back-compat: every binding in the field today is this shape.
        var nodeId = OpcUaNodeReference.Resolve("ns=2;s=pymodbus/plc/HR200", V3Table());

        Assert.Equal(2, nodeId.NamespaceIndex);
        Assert.Equal("pymodbus/plc/HR200", nodeId.Identifier);
    }

    /// <summary>Verifies that the namespace URI form resolves to the server's live namespace index.</summary>
    [Fact]
    public void Resolve_UriForm_MapsToLiveIndex()
    {
        var nodeId = OpcUaNodeReference.Resolve($"nsu={RawUri};s=pymodbus/plc/HR200", V3Table());

        Assert.Equal(2, nodeId.NamespaceIndex);
        Assert.Equal("pymodbus/plc/HR200", nodeId.Identifier);
    }

    /// <summary>Verifies that the namespace URI form tracks the index across servers with different namespace tables.</summary>
    [Fact]
    public void Resolve_UriForm_TracksIndexAcrossServers()
    {
        // The point of the durable form: same reference, a server that orders its
        // namespaces differently, still the right namespace.
        var reordered = new NamespaceTable();
        reordered.Append("urn:localhost:OtOpcUa");   // 1
        reordered.Append("urn:something:else");      // 2  <- pushed raw along
        reordered.Append(RawUri);                    // 3

        var v3 = OpcUaNodeReference.Resolve($"nsu={RawUri};s=Tag", V3Table());
        var moved = OpcUaNodeReference.Resolve($"nsu={RawUri};s=Tag", reordered);

        Assert.Equal(2, v3.NamespaceIndex);
        Assert.Equal(3, moved.NamespaceIndex);       // followed the URI, not the index
    }

    /// <summary>Verifies that the index form silently binds to a different namespace after a server upgrade.</summary>
    [Fact]
    public void Resolve_IndexForm_SilentlyBindsToTheWrongNamespace_AcrossServerUpgrade()
    {
        // This is the namespace-index hazard, pinned as a characterisation test rather than a wish:
        // v2's sole custom namespace and v3's raw namespace BOTH sit at index 2, so a
        // v2-era ns=2 binding resolves happily against v3 while meaning something else
        // entirely. Nothing in the index form can detect that — which is the whole
        // argument for re-authoring bindings in the nsu= form.
        const string v2Binding = "ns=2;s=Line1/Pump/Speed";

        var againstV2 = OpcUaNodeReference.Resolve(v2Binding, V2Table());
        var againstV3 = OpcUaNodeReference.Resolve(v2Binding, V3Table());

        Assert.Equal(againstV2.NamespaceIndex, againstV3.NamespaceIndex);
        Assert.Equal("https://zb.com/otopcua/ns", V2Table().GetString(againstV2.NamespaceIndex));
        Assert.Equal(RawUri, V3Table().GetString(againstV3.NamespaceIndex));   // different namespace, no error

        // The durable form fails loudly instead.
        var ex = Assert.Throws<ArgumentException>(
            () => OpcUaNodeReference.Resolve($"nsu=https://zb.com/otopcua/ns;s=Line1/Pump/Speed", V3Table()));
        Assert.Contains("does not publish", ex.Message);
    }

    /// <summary>Verifies that resolving an unknown namespace URI throws.</summary>
    [Fact]
    public void Resolve_UnknownNamespaceUri_Throws()
    {
        var ex = Assert.Throws<ArgumentException>(
            () => OpcUaNodeReference.Resolve("nsu=https://example.invalid/nope;s=Tag", V3Table()));

        Assert.Contains("NamespaceArray", ex.Message);
    }

    /// <summary>Verifies that resolving a reference to another server throws.</summary>
    [Fact]
    public void Resolve_ForeignServerReference_Throws()
    {
        var ex = Assert.Throws<ArgumentException>(
            () => OpcUaNodeReference.Resolve($"svr=1;nsu={RawUri};s=Tag", V3Table()));

        Assert.Contains("another server", ex.Message);
    }

    /// <summary>Verifies that an unparseable reference throws.</summary>
    /// <param name="reference">The malformed node reference.</param>
    [Theory]
    [InlineData("")]
    [InlineData("   ;;; not a node id")]
    public void Resolve_Unparseable_Throws(string reference)
    {
        Assert.ThrowsAny<ArgumentException>(() => OpcUaNodeReference.Resolve(reference, V3Table()));
    }

    /// <summary>Verifies that a server namespace is converted to the durable URI form.</summary>
    [Fact]
    public void ToDurable_ServerNamespace_EmitsUriForm()
    {
        var browsed = new ExpandedNodeId("pymodbus/plc/HR200", 2, null, 0);

        var durable = OpcUaNodeReference.ToDurable(browsed, V3Table());

        Assert.Equal($"nsu={RawUri};s=pymodbus/plc/HR200", durable);
    }

    /// <summary>Verifies that the standard namespace stays in the short form.</summary>
    [Fact]
    public void ToDurable_StandardNamespace_StaysShort()
    {
        // ns=0 is spec-fixed; qualifying it would be noise.
        var durable = OpcUaNodeReference.ToDurable(new ExpandedNodeId(85u, 0), V3Table());

        Assert.Equal("i=85", durable);
    }

    /// <summary>Verifies that a durable reference round-trips through resolve.</summary>
    [Fact]
    public void ToDurable_RoundTripsThroughResolve()
    {
        // The bug this closes: browse emitted ExpandedNodeId.ToString(), which for a
        // URI-carrying reference produced a string NodeId.Parse could not read back.
        var table = V3Table();
        var browsed = new ExpandedNodeId("Area/Line/Equip/Speed", 0, UnsUri, 0);

        var durable = OpcUaNodeReference.ToDurable(browsed, table);
        var resolved = OpcUaNodeReference.Resolve(durable, table);

        Assert.Equal(3, resolved.NamespaceIndex);
        Assert.Equal("Area/Line/Equip/Speed", resolved.Identifier);
    }

    /// <summary>Verifies that a URI missing from the namespace table falls back instead of throwing.</summary>
    [Fact]
    public void ToDurable_UriNotInTable_FallsBackRatherThanThrowing()
    {
        // Browsing is a discovery path — a namespace we cannot name should degrade to
        // the raw string, not abort the browse.
        var browsed = new ExpandedNodeId("Tag", 0, "https://example.invalid/nope", 0);

        var durable = OpcUaNodeReference.ToDurable(browsed, V3Table());

        Assert.Contains("Tag", durable);
    }
}