using System.Net;
using System.Net.Sockets;
using Microsoft.Extensions.Logging.Abstractions;
using Opc.Ua;
using Opc.Ua.Client;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;

namespace ZB.MOM.WW.OtOpcUa.OpcUaServer.IntegrationTests;

/// <summary>
///     v3 Batch 4 (B4-WP5) — the over-the-wire proof of the dual-namespace address space. Boots the real
///     <see cref="OtOpcUaSdkServer"/> (exactly as <c>SubscriptionSurvivalTests</c> / the multi-notifier
///     alarm test do), materialises a raw device folder + a raw tag Variable (<c>ns=Raw, s=&lt;RawPath&gt;</c>)
///     and an equipment folder + a UNS reference Variable (<c>ns=UNS, s=&lt;Area/Line/Equip/Eff&gt;</c>) through
///     the PRODUCTION <see cref="SdkAddressSpaceSink"/>, wires the <c>Organizes</c> UNS→Raw edge, then drives a
///     real OPC UA client to assert:
///     <list type="number">
///       <item>BOTH namespace URIs (<see cref="V3NodeIds.RawNamespaceUri"/> +
///         <see cref="V3NodeIds.UnsNamespaceUri"/>) are registered + distinct (they replaced the single
///         <c>.../ns</c>).</item>
///       <item>Both subtrees browse + read: the raw Variable at its RawPath NodeId and the UNS Variable at its
///         equipment-path NodeId.</item>
///       <item>The UNS Variable <c>Organizes</c>-references its backing raw node.</item>
///       <item>Single-source fan-out parity: one driver publish (modelled as a
///         <see cref="SdkAddressSpaceSink.WriteValue"/> to each NodeId with identical value/quality/timestamp)
///         is read back IDENTICALLY on both NodeIds.</item>
///       <item>HistoryRead via EITHER NodeId returns <c>GoodNoData</c> under the shared historian tagname (the
///         <c>NullHistorianDataSource</c> default — the offline parity path).</item>
///       <item>The <c>WriteOperate</c> gate is symmetric across both NodeIds: an anonymous client write is
///         rejected identically on the raw and the UNS NodeId (fail-closed at the role gate — the POSITIVE
///         realm-qualified routing path is unit-covered in <c>DriverHostActorWriteRoutingTests</c> /
///         <c>NodeManagerWriteRevertTests</c>, which drive a role-carrying identity the node manager
///         directly).</item>
///     </list>
///     Heavy in-process server+client integration — runs in the serial integration pass, and is fully
///     offline-safe (no Docker / SQL / gateway; the historian read defaults to the Null source).
/// </summary>
public sealed class DualNamespaceAddressSpaceTests
{
    private const string ServerUri = "urn:OtOpcUa.DualNamespaceAddressSpace";

    // Raw device tree (ns=Raw): Folder → tag Variable, both keyed by RawPath.
    private const string RawDeviceFolder = "Plant/Modbus/dev1";
    private const string RawTagPath = "Plant/Modbus/dev1/Speed";
    // UNS equipment tree (ns=UNS): equipment Folder → reference Variable keyed by the equipment path.
    private const string EquipFolder = "filling/line1/station1";
    private const string UnsVarPath = "filling/line1/station1/Speed";
    // Both NodeIds register the SAME historian tagname (the raw tag's RawPath).
    private const string HistorianTagname = RawTagPath;

    [Fact]
    public async Task Both_namespaces_registered_and_both_subtrees_browse_read_and_organize()
    {
        var pkiRoot = Path.Combine(Path.GetTempPath(), $"otopcua-dualns-browse-{Guid.NewGuid():N}");
        var port = AllocateFreePort();
        var ct = TestContext.Current.CancellationToken;
        try
        {
            var (server, host) = await BootServerAsync(port, pkiRoot + "-srv", ServerUri, ct);
            await using var _ = host;

            var sink = new SdkAddressSpaceSink(server.NodeManager!);
            MaterialiseDualTree(sink);
            // One driver publish per NodeId (the fan-out the DriverHostActor performs) — identical payload.
            var ts = DateTime.UtcNow;
            sink.WriteValue(RawTagPath, 42.5f, OpcUaQuality.Good, ts, AddressSpaceRealm.Raw);
            sink.WriteValue(UnsVarPath, 42.5f, OpcUaQuality.Good, ts, AddressSpaceRealm.Uns);

            using var session = await OpenSessionAsync($"opc.tcp://127.0.0.1:{port}/OtOpcUa", ct);

            // (1) both namespaces registered + distinct.
            var rawNs = (ushort)session.NamespaceUris.GetIndex(V3NodeIds.RawNamespaceUri);
            var unsNs = (ushort)session.NamespaceUris.GetIndex(V3NodeIds.UnsNamespaceUri);
            rawNs.ShouldBeGreaterThan((ushort)0, "the Raw namespace must be registered");
            unsNs.ShouldBeGreaterThan((ushort)0, "the UNS namespace must be registered");
            rawNs.ShouldNotBe(unsNs, "the two namespaces must have distinct indices");

            var rawNodeId = new NodeId(RawTagPath, rawNs);
            var unsNodeId = new NodeId(UnsVarPath, unsNs);

            // (2) both subtrees browse + read.
            var rawValue = await session.ReadValueAsync(rawNodeId, ct);
            var unsValue = await session.ReadValueAsync(unsNodeId, ct);
            StatusCode.IsGood(rawValue.StatusCode).ShouldBeTrue("raw node reads Good");
            StatusCode.IsGood(unsValue.StatusCode).ShouldBeTrue("uns node reads Good");
            Convert.ToSingle(rawValue.Value).ShouldBe(42.5f);
            Convert.ToSingle(unsValue.Value).ShouldBe(42.5f);

            // (3) the UNS Variable Organizes-references its backing raw node.
            var (_, refs) = await BrowseForwardAsync(session, unsNodeId, ReferenceTypeIds.Organizes);
            var organizesRaw = refs.Any(r =>
                r.ReferenceTypeId == ReferenceTypeIds.Organizes &&
                r.NodeId.NamespaceIndex == rawNs &&
                r.NodeId.ToString().Contains(RawTagPath, StringComparison.Ordinal));
            organizesRaw.ShouldBeTrue(
                $"the UNS variable ({UnsVarPath}) must Organizes-reference its raw node ({RawTagPath}); " +
                $"forward Organizes refs = [{string.Join(", ", refs.Select(r => r.NodeId))}]");
        }
        finally
        {
            SafeDelete(pkiRoot + "-srv");
        }
    }

    [Fact]
    public async Task Single_source_fans_to_both_nodeids_with_identical_value_quality_and_timestamp()
    {
        var pkiRoot = Path.Combine(Path.GetTempPath(), $"otopcua-dualns-fanout-{Guid.NewGuid():N}");
        var port = AllocateFreePort();
        var ct = TestContext.Current.CancellationToken;
        try
        {
            var (server, host) = await BootServerAsync(port, pkiRoot + "-srv", ServerUri + ".Fanout", ct);
            await using var _ = host;

            var sink = new SdkAddressSpaceSink(server.NodeManager!);
            MaterialiseDualTree(sink);

            using var session = await OpenSessionAsync($"opc.tcp://127.0.0.1:{port}/OtOpcUa", ct);
            var rawNs = (ushort)session.NamespaceUris.GetIndex(V3NodeIds.RawNamespaceUri);
            var unsNs = (ushort)session.NamespaceUris.GetIndex(V3NodeIds.UnsNamespaceUri);

            // The single source (one RawPath) fans to the raw NodeId AND every referencing UNS NodeId with
            // identical value/quality/timestamp — the fan-out drift invariant.
            var ts = new DateTime(2026, 7, 16, 8, 30, 0, DateTimeKind.Utc);
            sink.WriteValue(RawTagPath, 123.75f, OpcUaQuality.Good, ts, AddressSpaceRealm.Raw);
            sink.WriteValue(UnsVarPath, 123.75f, OpcUaQuality.Good, ts, AddressSpaceRealm.Uns);

            var rawValue = await session.ReadValueAsync(new NodeId(RawTagPath, rawNs), ct);
            var unsValue = await session.ReadValueAsync(new NodeId(UnsVarPath, unsNs), ct);

            Convert.ToSingle(unsValue.Value).ShouldBe(Convert.ToSingle(rawValue.Value));
            unsValue.StatusCode.ShouldBe(rawValue.StatusCode);
            unsValue.SourceTimestamp.ShouldBe(rawValue.SourceTimestamp);
            unsValue.SourceTimestamp.ShouldBe(ts);
        }
        finally
        {
            SafeDelete(pkiRoot + "-srv");
        }
    }

    [Fact]
    public async Task HistoryRead_via_either_nodeid_returns_GoodNoData_under_the_shared_tagname()
    {
        var pkiRoot = Path.Combine(Path.GetTempPath(), $"otopcua-dualns-hist-{Guid.NewGuid():N}");
        var port = AllocateFreePort();
        var ct = TestContext.Current.CancellationToken;
        try
        {
            var (server, host) = await BootServerAsync(port, pkiRoot + "-srv", ServerUri + ".History", ct);
            await using var _ = host;

            var sink = new SdkAddressSpaceSink(server.NodeManager!);
            MaterialiseDualTree(sink); // both variables historized under the SAME tagname (HistorianTagname)

            using var session = await OpenSessionAsync($"opc.tcp://127.0.0.1:{port}/OtOpcUa", ct);
            var rawNs = (ushort)session.NamespaceUris.GetIndex(V3NodeIds.RawNamespaceUri);
            var unsNs = (ushort)session.NamespaceUris.GetIndex(V3NodeIds.UnsNamespaceUri);

            var rawStatus = await HistoryReadRawStatusAsync(session, new NodeId(RawTagPath, rawNs), ct);
            var unsStatus = await HistoryReadRawStatusAsync(session, new NodeId(UnsVarPath, unsNs), ct);

            // NullHistorianDataSource default: a historized node's HistoryRead surfaces GoodNoData (never an
            // error) — identical for the raw and the UNS NodeId under the one registered historian tagname.
            rawStatus.ShouldBe((StatusCode)StatusCodes.GoodNoData, "raw NodeId HistoryRead");
            unsStatus.ShouldBe((StatusCode)StatusCodes.GoodNoData, "uns NodeId HistoryRead");
        }
        finally
        {
            SafeDelete(pkiRoot + "-srv");
        }
    }

    [Fact]
    public async Task WriteOperate_gate_is_symmetric_across_both_nodeids()
    {
        var pkiRoot = Path.Combine(Path.GetTempPath(), $"otopcua-dualns-write-{Guid.NewGuid():N}");
        var port = AllocateFreePort();
        var ct = TestContext.Current.CancellationToken;
        try
        {
            var (server, host) = await BootServerAsync(port, pkiRoot + "-srv", ServerUri + ".Write", ct);
            await using var _ = host;

            var sink = new SdkAddressSpaceSink(server.NodeManager!);
            MaterialiseDualTree(sink); // both variables writable

            using var session = await OpenSessionAsync($"opc.tcp://127.0.0.1:{port}/OtOpcUa", ct);
            var rawNs = (ushort)session.NamespaceUris.GetIndex(V3NodeIds.RawNamespaceUri);
            var unsNs = (ushort)session.NamespaceUris.GetIndex(V3NodeIds.UnsNamespaceUri);

            var rawWrite = await WriteValueStatusAsync(session, new NodeId(RawTagPath, rawNs), 7.0f, ct);
            var unsWrite = await WriteValueStatusAsync(session, new NodeId(UnsVarPath, unsNs), 7.0f, ct);

            // The anonymous session carries no WriteOperate role, so the node manager's fail-closed write gate
            // rejects BOTH writes identically — the gate applies uniformly to the raw and the UNS NodeId (a
            // UNS write is neither more nor less privileged than the raw write it fans from).
            rawWrite.ShouldBe((StatusCode)StatusCodes.BadUserAccessDenied, "raw NodeId write (no WriteOperate role)");
            unsWrite.ShouldBe(rawWrite, "uns NodeId write rejected identically to the raw NodeId");
        }
        finally
        {
            SafeDelete(pkiRoot + "-srv");
        }
    }

    /// <summary>Materialise the raw device folder + raw tag Variable, the equipment folder + UNS reference
    /// Variable (both historized under the SAME tagname, both writable), and the Organizes UNS→Raw edge.</summary>
    private static void MaterialiseDualTree(SdkAddressSpaceSink sink)
    {
        sink.EnsureFolder(RawDeviceFolder, parentNodeId: null, displayName: "dev1", realm: AddressSpaceRealm.Raw);
        sink.EnsureVariable(RawTagPath, RawDeviceFolder, "Speed", "Float", writable: true,
            realm: AddressSpaceRealm.Raw, historianTagname: HistorianTagname);

        sink.EnsureFolder(EquipFolder, parentNodeId: null, displayName: "station1", realm: AddressSpaceRealm.Uns);
        sink.EnsureVariable(UnsVarPath, EquipFolder, "Speed", "Float", writable: true,
            realm: AddressSpaceRealm.Uns, historianTagname: HistorianTagname);

        // Organizes UNS→Raw: the UNS variable references its backing raw node (the fan-out source).
        sink.AddReference(UnsVarPath, AddressSpaceRealm.Uns, RawTagPath, AddressSpaceRealm.Raw, "Organizes");
    }

    private static async Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)>
        BrowseForwardAsync(ISession session, NodeId node, NodeId referenceType)
    {
        // Match the SDK overload the codebase uses (DefaultSessionAdapter.BrowseAsync) — no trailing ct.
        var (_, cp, refs) = await session.BrowseAsync(
            null, null, node, 0u, BrowseDirection.Forward, referenceType,
            includeSubtypes: true, nodeClassMask: 0u);
        return (cp, refs ?? new ReferenceDescriptionCollection());
    }

    private static async Task<StatusCode> HistoryReadRawStatusAsync(ISession session, NodeId node, CancellationToken ct)
    {
        var details = new ReadRawModifiedDetails
        {
            StartTime = DateTime.UtcNow.AddHours(-1),
            EndTime = DateTime.UtcNow,
            NumValuesPerNode = 10,
            IsReadModified = false,
            ReturnBounds = false,
        };
        var nodesToRead = new HistoryReadValueIdCollection { new HistoryReadValueId { NodeId = node } };
        var response = await session.HistoryReadAsync(
            null, new ExtensionObject(details), TimestampsToReturn.Source, false, nodesToRead, ct);
        response.Results.ShouldNotBeNull();
        response.Results.Count.ShouldBe(1);
        return response.Results[0].StatusCode;
    }

    private static async Task<StatusCode> WriteValueStatusAsync(ISession session, NodeId node, object value, CancellationToken ct)
    {
        var writeCollection = new WriteValueCollection
        {
            new WriteValue { NodeId = node, AttributeId = Attributes.Value, Value = new DataValue(new Variant(value)) },
        };
        var response = await session.WriteAsync(null, writeCollection, ct);
        response.Results.ShouldNotBeNull();
        response.Results.Count.ShouldBe(1);
        return response.Results[0];
    }

    private static async Task<(OtOpcUaSdkServer Server, OpcUaApplicationHost Host)> BootServerAsync(
        int port, string pkiRoot, string appUri, CancellationToken ct)
    {
        var options = new OpcUaApplicationHostOptions
        {
            ApplicationName = appUri,
            ApplicationUri = appUri,
            OpcUaPort = port,
            PublicHostname = "127.0.0.1",
            PkiStoreRoot = pkiRoot,
            EnabledSecurityProfiles = new List<OpcUaSecurityProfile> { OpcUaSecurityProfile.None },
            AutoAcceptUntrustedClientCertificates = true,
        };
        var server = new OtOpcUaSdkServer();
        var host = new OpcUaApplicationHost(options, NullLogger<OpcUaApplicationHost>.Instance);
        await host.StartAsync(server, ct);
        return (server, host);
    }

    private static async Task<ISession> OpenSessionAsync(string endpointUrl, CancellationToken ct)
    {
        var appConfig = new ApplicationConfiguration
        {
            ApplicationName = "OtOpcUa.DualNamespaceClient",
            ApplicationUri = $"urn:OtOpcUa.DualNamespaceClient.{Guid.NewGuid():N}",
            ApplicationType = ApplicationType.Client,
            SecurityConfiguration = TestClientSecurity.Build(TestClientSecurity.AllocatePkiRoot()),
            ClientConfiguration = new ClientConfiguration { DefaultSessionTimeout = 60_000 },
        };
        await appConfig.ValidateAsync(ApplicationType.Client, ct);
        appConfig.CertificateValidator.CertificateValidation += (_, e) => e.Accept = true;

        var endpoint = await CoreClientUtils.SelectEndpointAsync(
            appConfig, endpointUrl, false, DefaultTelemetry.Create(_ => { }), ct);
        var endpointConfiguration = EndpointConfiguration.Create(appConfig);
        var configuredEndpoint = new ConfiguredEndpoint(null, endpoint, endpointConfiguration);

        return await new DefaultSessionFactory(DefaultTelemetry.Create(_ => { })).CreateAsync(
            appConfig, configuredEndpoint, updateBeforeConnect: false, checkDomain: false,
            sessionName: "DualNamespaceAddressSpaceTests", sessionTimeout: 60_000,
            identity: new UserIdentity(new AnonymousIdentityToken()), preferredLocales: null, ct: ct);
    }

    private static int AllocateFreePort()
    {
        var listener = new TcpListener(IPAddress.Loopback, 0);
        listener.Start();
        var port = ((IPEndPoint)listener.LocalEndpoint).Port;
        listener.Stop();
        return port;
    }

    private static void SafeDelete(string dir)
    {
        if (Directory.Exists(dir))
        {
            try { Directory.Delete(dir, recursive: true); }
            catch { /* best-effort */ }
        }
    }
}