using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.IntegrationTests;

/// <summary>
///     End-to-end smoke for the model-change watch (PR-10). Boots a real session against
///     opc-plc, asserts the driver wires up the model-change subscription without
///     destabilising the rest of the capability surface, and asserts a synthetic event
///     injection still runs the debounced re-import path under live conditions.
/// </summary>
/// <remarks>
///     opc-plc doesn't currently expose a stable HTTP control endpoint for forcing a
///     <c>GeneralModelChangeEventType</c> from outside the simulator. The native
///     <c>OpcPlc.AddSlowNode</c> method is invocable via OPC UA <c>Call</c> and does
///     trigger the event, but it requires elevated permissions on the simulator's
///     security model that the default <c>--aa</c> deployment doesn't grant. So this
///     smoke uses the driver's <c>InjectModelChangeForTest</c> seam — the same code
///     path a real upstream notification takes — and asserts the debounced re-import
///     ran end-to-end against the live session.
/// </remarks>
[Collection(OpcPlcCollection.Name)]
[Trait("Category", "Integration")]
[Trait("Simulator", "opc-plc")]
public sealed class OpcUaClientModelChangeSmokeTests(OpcPlcFixture sim)
{
    [Fact]
    public async Task Driver_initializes_with_model_change_watch_enabled_against_live_simulator()
    {
        if (sim.SkipReason is not null) Assert.Skip(sim.SkipReason);

        // Default options have WatchModelChanges=true; a successful Initialize against
        // opc-plc proves the EventFilter + WhereClause + monitored-item create path is
        // accepted by an independent OPC UA stack.
        var options = OpcPlcProfile.BuildOptions(sim.EndpointUrl);
        await using var drv = new OpcUaClientDriver(options, "opcua-modelchange-init");
        await drv.InitializeAsync("{}", TestContext.Current.CancellationToken);

        // Driver should be Healthy after init even though we created an extra
        // subscription on top of any pre-existing ones.
        drv.GetHealth().State.ShouldBe(DriverState.Healthy);

        // Reads still work — i.e. the model-change subscription didn't starve the
        // session of publish slots or otherwise destabilise the data path.
        var snaps = await drv.ReadAsync([OpcPlcProfile.StepUp], TestContext.Current.CancellationToken);
        snaps.Count.ShouldBe(1);
        snaps[0].StatusCode.ShouldBe(0u);
    }

    [Fact]
    public async Task Driver_reimports_on_model_change_event()
    {
        if (sim.SkipReason is not null) Assert.Skip(sim.SkipReason);

        var debounce = TimeSpan.FromMilliseconds(500);
        var baseOpts = OpcPlcProfile.BuildOptions(sim.EndpointUrl);
        var options = new OpcUaClientDriverOptions
        {
            EndpointUrl = baseOpts.EndpointUrl,
            SecurityPolicy = baseOpts.SecurityPolicy,
            SecurityMode = baseOpts.SecurityMode,
            AuthType = baseOpts.AuthType,
            AutoAcceptCertificates = baseOpts.AutoAcceptCertificates,
            Timeout = baseOpts.Timeout,
            SessionTimeout = baseOpts.SessionTimeout,
            ModelChangeDebounce = debounce,
        };

        await using var drv = new OpcUaClientDriver(options, "opcua-modelchange-reimport");
        await drv.InitializeAsync("{}", TestContext.Current.CancellationToken);

        // Use the test seam so we don't depend on opc-plc's HTTP control endpoint;
        // the production wiring takes the same OnModelChangeNotification path.
        var fires = 0;
        drv.ModelChangeReimportHookForTest = _ =>
        {
            Interlocked.Increment(ref fires);
            return Task.CompletedTask;
        };

        // Burst of 5 events within the debounce window → exactly one re-import.
        for (var i = 0; i < 5; i++)
        {
            drv.InjectModelChangeForTest();
            await Task.Delay(50, TestContext.Current.CancellationToken);
        }
        await Task.Delay(debounce + TimeSpan.FromMilliseconds(500), TestContext.Current.CancellationToken);

        fires.ShouldBe(1, "burst within debounce window must coalesce to one re-import");
    }

    [Fact]
    public async Task Driver_initializes_with_model_change_watch_disabled()
    {
        if (sim.SkipReason is not null) Assert.Skip(sim.SkipReason);

        // Operators who don't want the brief browse-gap on topology change can flip
        // WatchModelChanges off — Initialize must still succeed end-to-end.
        var baseOpts = OpcPlcProfile.BuildOptions(sim.EndpointUrl);
        var options = new OpcUaClientDriverOptions
        {
            EndpointUrl = baseOpts.EndpointUrl,
            SecurityPolicy = baseOpts.SecurityPolicy,
            SecurityMode = baseOpts.SecurityMode,
            AuthType = baseOpts.AuthType,
            AutoAcceptCertificates = baseOpts.AutoAcceptCertificates,
            Timeout = baseOpts.Timeout,
            SessionTimeout = baseOpts.SessionTimeout,
            WatchModelChanges = false,
        };

        await using var drv = new OpcUaClientDriver(options, "opcua-modelchange-disabled");
        await drv.InitializeAsync("{}", TestContext.Current.CancellationToken);

        drv.GetHealth().State.ShouldBe(DriverState.Healthy);
    }
}