using Microsoft.Extensions.Logging.Abstractions;
using Opc.Ua;
using Opc.Ua.Client;
using Opc.Ua.Configuration;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.Hosting;
using ZB.MOM.WW.OtOpcUa.Server.OpcUa;
using ZB.MOM.WW.OtOpcUa.Server.Security;

namespace ZB.MOM.WW.OtOpcUa.Server.Tests;

/// <summary>
///     Closes LMX follow-up #6 — proves that two <see cref="IDriver"/> instances registered
///     on the same <see cref="DriverHost"/> land in isolated namespaces and their reads
///     route to the correct driver. The existing <see cref="OpcUaServerIntegrationTests"/>
///     only exercises a single-driver topology; this sibling fixture registers two.
/// </summary>
/// <remarks>
///     Each driver gets its own namespace URI of the form <c>urn:OtOpcUa:{DriverInstanceId}</c>
///     (per <c>DriverNodeManager</c>'s base-class <c>namespaceUris</c> argument). A client
///     that browses one namespace must see only that driver's subtree, and a read against a
///     variable in one namespace must return that driver's value, not the other's — this is
///     what stops a cross-driver routing regression from going unnoticed when the v1
///     single-driver code path gets new knobs.
/// </remarks>
[Trait("Category", "Integration")]
public sealed class MultipleDriverInstancesIntegrationTests : IAsyncLifetime
{
    private static readonly int Port = 48500 + Random.Shared.Next(0, 99);
    private readonly string _endpoint = $"opc.tcp://localhost:{Port}/OtOpcUaMultiDriverTest";
    private readonly string _pkiRoot = Path.Combine(Path.GetTempPath(), $"otopcua-multi-{Guid.NewGuid():N}");

    private DriverHost _driverHost = null!;
    private OpcUaApplicationHost _server = null!;

    public async ValueTask InitializeAsync()
    {
        _driverHost = new DriverHost();
        await _driverHost.RegisterAsync(new StubDriver("alpha", folderName: "AlphaFolder", readValue: 42),
            "{}", CancellationToken.None);
        await _driverHost.RegisterAsync(new StubDriver("beta", folderName: "BetaFolder", readValue: 99),
            "{}", CancellationToken.None);

        var options = new OpcUaServerOptions
        {
            EndpointUrl = _endpoint,
            ApplicationName = "OtOpcUaMultiDriverTest",
            ApplicationUri = "urn:OtOpcUa:Server:MultiDriverTest",
            PkiStoreRoot = _pkiRoot,
            AutoAcceptUntrustedClientCertificates = true, HealthEndpointsEnabled = false,
        };

        _server = new OpcUaApplicationHost(options, _driverHost, new DenyAllUserAuthenticator(),
            NullLoggerFactory.Instance, NullLogger<OpcUaApplicationHost>.Instance);
        await _server.StartAsync(CancellationToken.None);
    }

    public async ValueTask DisposeAsync()
    {
        await _server.DisposeAsync();
        await _driverHost.DisposeAsync();
        try { Directory.Delete(_pkiRoot, recursive: true); } catch { /* best-effort */ }
    }

    [Fact]
    public async Task Both_drivers_register_under_their_own_urn_namespace()
    {
        using var session = await OpenSessionAsync();

        var alphaNs = session.NamespaceUris.GetIndex("urn:OtOpcUa:alpha");
        var betaNs = session.NamespaceUris.GetIndex("urn:OtOpcUa:beta");

        alphaNs.ShouldBeGreaterThanOrEqualTo(0, "DriverNodeManager for 'alpha' must register its namespace URI");
        betaNs.ShouldBeGreaterThanOrEqualTo(0, "DriverNodeManager for 'beta' must register its namespace URI");
        alphaNs.ShouldNotBe(betaNs, "each driver owns its own namespace");
    }

    [Fact]
    public async Task Each_driver_subtree_exposes_only_its_own_folder()
    {
        using var session = await OpenSessionAsync();

        var alphaNs = (ushort)session.NamespaceUris.GetIndex("urn:OtOpcUa:alpha");
        var betaNs = (ushort)session.NamespaceUris.GetIndex("urn:OtOpcUa:beta");

        var alphaRoot = new NodeId("alpha", alphaNs);
        session.Browse(null, null, alphaRoot, 0, BrowseDirection.Forward, ReferenceTypeIds.HierarchicalReferences,
            true, (uint)NodeClass.Object | (uint)NodeClass.Variable, out _, out var alphaRefs);
        alphaRefs.ShouldContain(r => r.BrowseName.Name == "AlphaFolder",
            "alpha's subtree must contain alpha's folder");
        alphaRefs.ShouldNotContain(r => r.BrowseName.Name == "BetaFolder",
            "alpha's subtree must NOT see beta's folder — cross-driver leak would hide subscription-routing bugs");

        var betaRoot = new NodeId("beta", betaNs);
        session.Browse(null, null, betaRoot, 0, BrowseDirection.Forward, ReferenceTypeIds.HierarchicalReferences,
            true, (uint)NodeClass.Object | (uint)NodeClass.Variable, out _, out var betaRefs);
        betaRefs.ShouldContain(r => r.BrowseName.Name == "BetaFolder");
        betaRefs.ShouldNotContain(r => r.BrowseName.Name == "AlphaFolder");
    }

    [Fact]
    public async Task Reads_route_to_the_correct_driver_by_namespace()
    {
        using var session = await OpenSessionAsync();

        var alphaNs = (ushort)session.NamespaceUris.GetIndex("urn:OtOpcUa:alpha");
        var betaNs = (ushort)session.NamespaceUris.GetIndex("urn:OtOpcUa:beta");

        var alphaValue = session.ReadValue(new NodeId("AlphaFolder.Var1", alphaNs));
        var betaValue = session.ReadValue(new NodeId("BetaFolder.Var1", betaNs));

        alphaValue.Value.ShouldBe(42, "alpha driver's ReadAsync returns 42 — a misroute would surface as 99");
        betaValue.Value.ShouldBe(99, "beta driver's ReadAsync returns 99 — a misroute would surface as 42");
    }

    private async Task<ISession> OpenSessionAsync()
    {
        var cfg = new ApplicationConfiguration
        {
            ApplicationName = "OtOpcUaMultiDriverTestClient",
            ApplicationUri = "urn:OtOpcUa:MultiDriverTestClient",
            ApplicationType = ApplicationType.Client,
            SecurityConfiguration = new SecurityConfiguration
            {
                ApplicationCertificate = new CertificateIdentifier
                {
                    StoreType = CertificateStoreType.Directory,
                    StorePath = Path.Combine(_pkiRoot, "client-own"),
                    SubjectName = "CN=OtOpcUaMultiDriverTestClient",
                },
                TrustedIssuerCertificates = new CertificateTrustList { StoreType = CertificateStoreType.Directory, StorePath = Path.Combine(_pkiRoot, "client-issuers") },
                TrustedPeerCertificates = new CertificateTrustList { StoreType = CertificateStoreType.Directory, StorePath = Path.Combine(_pkiRoot, "client-trusted") },
                RejectedCertificateStore = new CertificateTrustList { StoreType = CertificateStoreType.Directory, StorePath = Path.Combine(_pkiRoot, "client-rejected") },
                AutoAcceptUntrustedCertificates = true,
                AddAppCertToTrustedStore = true,
            },
            TransportConfigurations = new TransportConfigurationCollection(),
            TransportQuotas = new TransportQuotas { OperationTimeout = 15000 },
            ClientConfiguration = new ClientConfiguration { DefaultSessionTimeout = 60000 },
        };
        await cfg.Validate(ApplicationType.Client);
        cfg.CertificateValidator.CertificateValidation += (_, e) => e.Accept = true;

        var instance = new ApplicationInstance { ApplicationConfiguration = cfg, ApplicationType = ApplicationType.Client };
        await instance.CheckApplicationInstanceCertificate(true, CertificateFactory.DefaultKeySize);

        var selected = CoreClientUtils.SelectEndpoint(cfg, _endpoint, useSecurity: false);
        var endpointConfig = EndpointConfiguration.Create(cfg);
        var configuredEndpoint = new ConfiguredEndpoint(null, selected, endpointConfig);

        return await Session.Create(cfg, configuredEndpoint, false, "OtOpcUaMultiDriverTestClientSession", 60000,
            new UserIdentity(new AnonymousIdentityToken()), null);
    }

    /// <summary>
    ///     Driver stub that returns a caller-specified folder + variable + read value so two
    ///     instances in the same server can be told apart at the assertion layer.
    /// </summary>
    private sealed class StubDriver(string driverInstanceId, string folderName, int readValue)
        : IDriver, ITagDiscovery, IReadable
    {
        public string DriverInstanceId => driverInstanceId;
        public string DriverType => "Stub";

        public Task InitializeAsync(string driverConfigJson, CancellationToken ct) => Task.CompletedTask;
        public Task ReinitializeAsync(string driverConfigJson, CancellationToken ct) => Task.CompletedTask;
        public Task ShutdownAsync(CancellationToken ct) => Task.CompletedTask;
        public DriverHealth GetHealth() => new(DriverState.Healthy, DateTime.UtcNow, null);
        public long GetMemoryFootprint() => 0;
        public Task FlushOptionalCachesAsync(CancellationToken ct) => Task.CompletedTask;

        public Task DiscoverAsync(IAddressSpaceBuilder builder, CancellationToken ct)
        {
            var folder = builder.Folder(folderName, folderName);
            folder.Variable("Var1", "Var1", new DriverAttributeInfo(
                $"{folderName}.Var1", DriverDataType.Int32, false, null, SecurityClassification.FreeAccess, false, IsAlarm: false));
            return Task.CompletedTask;
        }

        public Task<IReadOnlyList<DataValueSnapshot>> ReadAsync(
            IReadOnlyList<string> fullReferences, CancellationToken cancellationToken)
        {
            var now = DateTime.UtcNow;
            IReadOnlyList<DataValueSnapshot> result =
                fullReferences.Select(_ => new DataValueSnapshot(readValue, 0u, now, now)).ToArray();
            return Task.FromResult(result);
        }
    }
}