using System.Threading;
using System.Threading.Tasks;
using Xunit;
using ZB.MOM.WW.LmxOpcUa.Host;
using ZB.MOM.WW.LmxOpcUa.Host.Configuration;

namespace ZB.MOM.WW.LmxOpcUa.Tests.Helpers
{
    /// <summary>
    /// xUnit fixture that manages an OpcUaService lifecycle with automatic port allocation.
    /// Guarantees no port conflicts between parallel tests.
    ///
    /// Usage (per-test):
    ///   var fixture = OpcUaServerFixture.WithFakes();
    ///   await fixture.InitializeAsync();
    ///   try { ... } finally { await fixture.DisposeAsync(); }
    ///
    /// Usage (skip COM entirely):
    ///   var fixture = OpcUaServerFixture.WithFakeMxAccessClient();
    /// </summary>
    internal class OpcUaServerFixture : IAsyncLifetime
    {
        private static int _nextPort = 16000;

        /// <summary>
        /// Gets the started service instance managed by the fixture.
        /// </summary>
        public OpcUaService Service { get; private set; } = null!;

        /// <summary>
        /// Gets the OPC UA port assigned to this fixture instance.
        /// </summary>
        public int OpcUaPort { get; }

        /// <summary>
        /// Gets the OPC UA endpoint URL exposed by the fixture.
        /// </summary>
        public string EndpointUrl => $"opc.tcp://localhost:{OpcUaPort}/LmxOpcUa";

        /// <summary>
        /// The fake Galaxy repository injected into the service. Mutate Hierarchy/Attributes
        /// then call Service.TriggerRebuild() to simulate a Galaxy redeployment.
        /// </summary>
        public FakeGalaxyRepository? GalaxyRepository { get; }

        /// <summary>
        /// The fake MxAccess client injected into the service (when using WithFakeMxAccessClient).
        /// </summary>
        public FakeMxAccessClient? MxAccessClient { get; }

        /// <summary>
        /// The fake MxProxy injected into the service (when using WithFakes).
        /// </summary>
        public FakeMxProxy? MxProxy { get; }

        private readonly OpcUaServiceBuilder _builder;
        private bool _started;

        /// <summary>
        /// Initializes a fixture around a prepared service builder and optional fake dependencies.
        /// </summary>
        /// <param name="builder">The builder used to construct the service under test.</param>
        /// <param name="repo">The optional fake Galaxy repository exposed to tests.</param>
        /// <param name="mxClient">The optional fake MXAccess client exposed to tests.</param>
        /// <param name="mxProxy">The optional fake MXAccess proxy exposed to tests.</param>
        private OpcUaServerFixture(OpcUaServiceBuilder builder,
            FakeGalaxyRepository? repo = null,
            FakeMxAccessClient? mxClient = null,
            FakeMxProxy? mxProxy = null)
        {
            OpcUaPort = Interlocked.Increment(ref _nextPort);
            _builder = builder;
            _builder.WithOpcUaPort(OpcUaPort);
            _builder.DisableDashboard();
            GalaxyRepository = repo;
            MxAccessClient = mxClient;
            MxProxy = mxProxy;
        }

        /// <summary>
        /// Creates fixture with FakeMxProxy + FakeGalaxyRepository (standard test data).
        /// The STA thread and COM interop run against FakeMxProxy.
        /// </summary>
        /// <param name="proxy">An optional fake proxy to inject; otherwise a default fake is created.</param>
        /// <param name="repo">An optional fake repository to inject; otherwise standard test data is used.</param>
        /// <returns>A fixture configured to exercise the COM-style runtime path.</returns>
        public static OpcUaServerFixture WithFakes(
            FakeMxProxy? proxy = null,
            FakeGalaxyRepository? repo = null)
        {
            var p = proxy ?? new FakeMxProxy();
            var r = repo ?? new FakeGalaxyRepository
            {
                Hierarchy = TestData.CreateStandardHierarchy(),
                Attributes = TestData.CreateStandardAttributes()
            };

            var builder = new OpcUaServiceBuilder()
                .WithMxProxy(p)
                .WithGalaxyRepository(r)
                .WithGalaxyName("TestGalaxy");

            return new OpcUaServerFixture(builder, repo: r, mxProxy: p);
        }

        /// <summary>
        /// Creates fixture using FakeMxAccessClient directly — skips STA thread + COM entirely.
        /// Fastest option for tests that don't need real COM interop.
        /// </summary>
        /// <param name="mxClient">An optional fake MXAccess client to inject; otherwise a default fake is created.</param>
        /// <param name="repo">An optional fake repository to inject; otherwise standard test data is used.</param>
        /// <param name="security">An optional security profile configuration for the test server.</param>
        /// <param name="redundancy">An optional redundancy configuration for the test server.</param>
        /// <param name="applicationUri">An optional explicit application URI for the test server.</param>
        /// <param name="serverName">An optional server name override for the test server.</param>
        /// <returns>A fixture configured to exercise the direct fake-client path.</returns>
        public static OpcUaServerFixture WithFakeMxAccessClient(
            FakeMxAccessClient? mxClient = null,
            FakeGalaxyRepository? repo = null,
            SecurityProfileConfiguration? security = null,
            RedundancyConfiguration? redundancy = null,
            string? applicationUri = null,
            string? serverName = null)
        {
            var client = mxClient ?? new FakeMxAccessClient();
            var r = repo ?? new FakeGalaxyRepository
            {
                Hierarchy = TestData.CreateStandardHierarchy(),
                Attributes = TestData.CreateStandardAttributes()
            };

            var builder = new OpcUaServiceBuilder()
                .WithMxAccessClient(client)
                .WithGalaxyRepository(r)
                .WithGalaxyName("TestGalaxy");

            if (security != null)
                builder.WithSecurity(security);
            if (redundancy != null)
                builder.WithRedundancy(redundancy);
            if (applicationUri != null)
                builder.WithApplicationUri(applicationUri);
            if (serverName != null)
                builder.WithGalaxyName(serverName);

            return new OpcUaServerFixture(builder, repo: r, mxClient: client);
        }

        /// <summary>
        /// Builds and starts the OPC UA service for the current fixture.
        /// </summary>
        public Task InitializeAsync()
        {
            Service = _builder.Build();
            Service.Start();
            _started = true;
            return Task.CompletedTask;
        }

        /// <summary>
        /// Stops the OPC UA service when the fixture had previously been started.
        /// </summary>
        public Task DisposeAsync()
        {
            if (_started)
            {
                try { Service.Stop(); }
                catch { /* swallow cleanup errors */ }
            }
            return Task.CompletedTask;
        }
    }
}