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

namespace ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Tests;

/// <summary>
///     PR 2.3 — proactive Symbol-Version invalidation listener. Verifies the contract
///     mirrored on <see cref="FakeTwinCATClient"/>: <c>ConnectAsync</c> registers a
///     listener, <see cref="FakeTwinCATClient.FireSymbolVersionChange"/> wipes the
///     handle cache + bumps the diagnostic counter, the next read recreates the
///     handle, and <c>Dispose</c> unregisters cleanly.
/// </summary>
/// <remarks>
///     The fake's state machine is a high-fidelity mirror of <c>AdsTwinCATClient</c>'s
///     <c>RegisterSymbolVersionChangedAsync</c> / <c>OnAdsSymbolVersionChanged</c>
///     wiring; the production class is exercised end-to-end on a real PLC by the
///     integration-tier <see cref="ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.IntegrationTests"/>
///     online-change scenario, which is gated on the operator triggering an actual
///     activate-config from XAE.
/// </remarks>
[Trait("Category", "Unit")]
public sealed class TwinCATSymbolVersionTests
{
    private const string DevA = "ads://5.23.91.23.1.1:851";

    [Fact]
    public async Task ConnectAsync_registers_symbol_version_listener()
    {
        var fake = new FakeTwinCATClient();
        fake.SymbolVersionRegistered.ShouldBeFalse("listener should not be armed before connect");

        await fake.ConnectAsync(new TwinCATAmsAddress("5.23.91.23.1.1", 851), TimeSpan.FromSeconds(5),
            TestContext.Current.CancellationToken);

        fake.SymbolVersionRegistered.ShouldBeTrue();
        fake.SymbolVersionRegistrationCount.ShouldBe(1);
    }

    [Fact]
    public async Task FireSymbolVersionChange_clears_handle_cache()
    {
        var fake = new FakeTwinCATClient { Values = { ["MAIN.A"] = 1, ["MAIN.B"] = 2, ["MAIN.C"] = 3 } };
        await fake.ConnectAsync(new TwinCATAmsAddress("5.23.91.23.1.1", 851), TimeSpan.FromSeconds(5),
            TestContext.Current.CancellationToken);
        await fake.ReadValueAsync("MAIN.A", TwinCATDataType.DInt, null, null, TestContext.Current.CancellationToken);
        await fake.ReadValueAsync("MAIN.B", TwinCATDataType.DInt, null, null, TestContext.Current.CancellationToken);
        await fake.ReadValueAsync("MAIN.C", TwinCATDataType.DInt, null, null, TestContext.Current.CancellationToken);
        fake.HandleCacheCount.ShouldBe(3);

        fake.FireSymbolVersionChange();

        fake.HandleCacheCount.ShouldBe(0);
        // Each cached handle gets a delete record (mirror of AdsTwinCATClient's
        // best-effort DeleteVariableHandleAsync fan-out on cache-wipe).
        fake.HandleDeleteInvocations.Count.ShouldBe(3);
    }

    [Fact]
    public async Task After_bump_next_read_recreates_handle()
    {
        var fake = new FakeTwinCATClient { Values = { ["MAIN.X"] = 42 } };
        await fake.ConnectAsync(new TwinCATAmsAddress("5.23.91.23.1.1", 851), TimeSpan.FromSeconds(5),
            TestContext.Current.CancellationToken);
        await fake.ReadValueAsync("MAIN.X", TwinCATDataType.DInt, null, null, TestContext.Current.CancellationToken);
        fake.HandleCreateInvocations.Count.ShouldBe(1);

        fake.FireSymbolVersionChange();

        // Cache is cold — next read pays the CreateVariableHandle cost again.
        await fake.ReadValueAsync("MAIN.X", TwinCATDataType.DInt, null, null, TestContext.Current.CancellationToken);
        fake.HandleCreateInvocations.Count.ShouldBe(2);
        fake.HandleCacheCount.ShouldBe(1);
    }

    [Fact]
    public async Task SymbolVersionBumps_counter_increments_per_bump()
    {
        var fake = new FakeTwinCATClient();
        await fake.ConnectAsync(new TwinCATAmsAddress("5.23.91.23.1.1", 851), TimeSpan.FromSeconds(5),
            TestContext.Current.CancellationToken);
        fake.SymbolVersionBumps.ShouldBe(0);

        fake.FireSymbolVersionChange();
        fake.SymbolVersionBumps.ShouldBe(1);

        fake.FireSymbolVersionChange();
        fake.FireSymbolVersionChange();
        fake.SymbolVersionBumps.ShouldBe(3);
    }

    [Fact]
    public async Task Dispose_unregisters_listener()
    {
        var fake = new FakeTwinCATClient();
        await fake.ConnectAsync(new TwinCATAmsAddress("5.23.91.23.1.1", 851), TimeSpan.FromSeconds(5),
            TestContext.Current.CancellationToken);
        fake.SymbolVersionRegistered.ShouldBeTrue();

        fake.Dispose();

        fake.SymbolVersionRegistered.ShouldBeFalse();
        fake.SymbolVersionUnregistrationCount.ShouldBe(1);
    }

    [Fact]
    public async Task Reconnect_re_registers_listener()
    {
        // Production marks the listener as needing re-registration on every (re)connect
        // because the device-side notification subscription is per-AMS-session — same
        // lifecycle as the handle cache itself.
        var fake = new FakeTwinCATClient();
        await fake.ConnectAsync(new TwinCATAmsAddress("5.23.91.23.1.1", 851), TimeSpan.FromSeconds(5),
            TestContext.Current.CancellationToken);
        fake.SymbolVersionRegistrationCount.ShouldBe(1);

        fake.SimulateReconnect();

        fake.SymbolVersionRegistered.ShouldBeTrue();
        fake.SymbolVersionRegistrationCount.ShouldBe(2);
        fake.SymbolVersionUnregistrationCount.ShouldBe(1);
    }

    [Fact]
    public async Task Bump_through_driver_invalidates_handle_cache_for_subsequent_per_tag_reads()
    {
        // Drive the bump from outside the driver and verify the per-tag (handle-cached)
        // path resumes with a fresh handle on the next read. Whole-array reads route
        // through the per-tag path, so they're the cleanest way to assert the contract
        // through the public driver surface.
        var factory = new FakeTwinCATClientFactory();
        var captured = new FakeTwinCATClient
        {
            Values = { ["MAIN.Recipe"] = new int[] { 1, 2, 3, 4 } },
        };
        factory.Customise = () => captured;
        var drv = new TwinCATDriver(new TwinCATDriverOptions
        {
            Devices = [new TwinCATDeviceOptions(DevA)],
            Tags =
            [
                new TwinCATTagDefinition("Recipe", DevA, "MAIN.Recipe", TwinCATDataType.DInt,
                    ArrayDimensions: [4]),
            ],
            Probe = new TwinCATProbeOptions { Enabled = false },
        }, "drv-symver", factory);
        await drv.InitializeAsync("{}", TestContext.Current.CancellationToken);

        await drv.ReadAsync(["Recipe"], TestContext.Current.CancellationToken);
        captured.HandleCreateInvocations.Count.ShouldBe(1);

        // Simulate the PLC publishing a Symbol-Version-changed event mid-flight.
        captured.FireSymbolVersionChange();
        captured.SymbolVersionBumps.ShouldBe(1);
        captured.HandleCacheCount.ShouldBe(0);

        // Next read recreates the handle from cold.
        await drv.ReadAsync(["Recipe"], TestContext.Current.CancellationToken);
        captured.HandleCreateInvocations.Count.ShouldBe(2);
    }
}