using System.Diagnostics;
using System.Threading.Tasks;
using Shouldly;
using Xunit;
using ZB.MOM.WW.LmxOpcUa.Host.Domain;

namespace ZB.MOM.WW.LmxOpcUa.Tests.Helpers
{
    /// <summary>
    /// Verifies the reusable OPC UA server fixture used by integration and wiring tests.
    /// </summary>
    public class OpcUaServerFixtureTests
    {
        /// <summary>
        /// Confirms that the standard fake-backed fixture starts the bridge and tears it down cleanly.
        /// </summary>
        [Fact]
        public async Task WithFakes_StartsAndStops()
        {
            var fixture = OpcUaServerFixture.WithFakes();
            await fixture.InitializeAsync();

            fixture.Service.ShouldNotBeNull();
            fixture.Service.MxClient.ShouldNotBeNull();
            fixture.Service.MxClient!.State.ShouldBe(ConnectionState.Connected);
            fixture.Service.GalaxyStatsInstance.ShouldNotBeNull();
            fixture.Service.GalaxyStatsInstance!.GalaxyName.ShouldBe("TestGalaxy");
            fixture.OpcUaPort.ShouldBeGreaterThan(16000);
            fixture.EndpointUrl.ShouldContain(fixture.OpcUaPort.ToString());

            await fixture.DisposeAsync();
        }

        /// <summary>
        /// Confirms that the fake-client fixture bypasses COM wiring and uses the provided fake runtime client.
        /// </summary>
        [Fact]
        public async Task WithFakeMxAccessClient_SkipsCom()
        {
            var mxClient = new FakeMxAccessClient();
            var fixture = OpcUaServerFixture.WithFakeMxAccessClient(mxClient);
            await fixture.InitializeAsync();

            fixture.Service.MxClient.ShouldBe(mxClient);
            mxClient.State.ShouldBe(ConnectionState.Connected);

            await fixture.DisposeAsync();
        }

        /// <summary>
        /// Confirms that separate fixture instances automatically allocate unique OPC UA ports.
        /// </summary>
        [Fact]
        public async Task MultipleFixtures_GetUniquePortsAutomatically()
        {
            var fixture1 = OpcUaServerFixture.WithFakeMxAccessClient();
            var fixture2 = OpcUaServerFixture.WithFakeMxAccessClient();

            fixture1.OpcUaPort.ShouldNotBe(fixture2.OpcUaPort);

            // Both can start without port conflicts
            await fixture1.InitializeAsync();
            await fixture2.InitializeAsync();

            fixture1.Service.ShouldNotBeNull();
            fixture2.Service.ShouldNotBeNull();

            await fixture1.DisposeAsync();
            await fixture2.DisposeAsync();
        }

        /// <summary>
        /// Confirms that fixture shutdown completes quickly enough for the integration test suite.
        /// </summary>
        [Fact]
        public async Task Shutdown_CompletesWithin30Seconds()
        {
            var fixture = OpcUaServerFixture.WithFakes();
            await fixture.InitializeAsync();

            var sw = Stopwatch.StartNew();
            await fixture.DisposeAsync();
            sw.Stop();

            sw.Elapsed.TotalSeconds.ShouldBeLessThan(30);
        }

        /// <summary>
        /// Confirms that runtime callbacks arriving after shutdown are ignored cleanly.
        /// </summary>
        [Fact]
        public async Task Stop_UnhooksNodeManagerFromMxAccessCallbacks()
        {
            var mxClient = new FakeMxAccessClient();
            var fixture = OpcUaServerFixture.WithFakeMxAccessClient(mxClient);
            await fixture.InitializeAsync();

            await fixture.DisposeAsync();

            Should.NotThrow(() => mxClient.SimulateDataChange("TestMachine_001.MachineID", Vtq.Good(42)));
        }

        /// <summary>
        /// Confirms that the fake-backed fixture builds the seeded address space and Galaxy statistics.
        /// </summary>
        [Fact]
        public async Task WithFakes_BuildsAddressSpace()
        {
            var fixture = OpcUaServerFixture.WithFakes();
            await fixture.InitializeAsync();

            fixture.Service.GalaxyStatsInstance!.ObjectCount.ShouldBe(5);
            fixture.Service.GalaxyStatsInstance.AttributeCount.ShouldBe(6);
            fixture.Service.GalaxyStatsInstance.DbConnected.ShouldBe(true);

            await fixture.DisposeAsync();
        }
    }
}