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

namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.ParityTests;

/// <summary>
///     PR 5.4 — Write-by-classification parity. Each driver routes writes by the
///     attribute's <see cref="SecurityClassification"/>: <c>FreeAccess</c> /
///     <c>Operate</c> use plain <c>Write</c>; <c>Tune</c> / <c>Configure</c> /
///     <c>VerifiedWrite</c> use <c>WriteSecured</c>. Both backends must surface the
///     same StatusCode for the same write request — successful for FreeAccess /
///     Operate (assuming the dev Galaxy has at least one writable attribute) and
///     failure for Configure when no auth principal is supplied.
/// </summary>
[Trait("Category", "ParityE2E")]
[Collection(nameof(ParityCollection))]
public sealed class WriteByClassificationParityTests
{
    private readonly ParityHarness _h;
    public WriteByClassificationParityTests(ParityHarness h) => _h = h;

    [Fact]
    public async Task FreeAccess_or_Operate_write_returns_same_StatusCode_on_both_backends()
    {
        _h.RequireBoth();

        var b = new RecordingAddressSpaceBuilder();
        await ((ITagDiscovery)_h.LegacyDriver!).DiscoverAsync(b, CancellationToken.None);

        var target = b.Variables.FirstOrDefault(v =>
            v.AttributeInfo.SecurityClass is SecurityClassification.FreeAccess or SecurityClassification.Operate
            && v.AttributeInfo.DriverDataType is DriverDataType.Float32 or DriverDataType.Float64 or DriverDataType.Int32);
        if (target is null) Assert.Skip("no FreeAccess/Operate numeric writable attribute on dev Galaxy");

        var request = new[] { new WriteRequest(target.AttributeInfo.FullName, 0.0) };
        var results = await _h.RunOnAvailableAsync(
            (driver, ct) => ((IWritable)driver).WriteAsync(request, ct),
            CancellationToken.None);

        var legacyCode = results[ParityHarness.Backend.LegacyHost][0].StatusCode;
        var mxgwCode = results[ParityHarness.Backend.MxGateway][0].StatusCode;
        AssertStatusClassMatches(legacyCode, mxgwCode, target.AttributeInfo.FullName);
    }

    [Fact]
    public async Task Configure_class_write_routes_through_secured_path_on_both_backends()
    {
        _h.RequireBoth();

        var b = new RecordingAddressSpaceBuilder();
        await ((ITagDiscovery)_h.LegacyDriver!).DiscoverAsync(b, CancellationToken.None);

        var target = b.Variables.FirstOrDefault(v =>
            v.AttributeInfo.SecurityClass is SecurityClassification.Configure or SecurityClassification.Tune);
        if (target is null) Assert.Skip("no Configure/Tune attribute on dev Galaxy");

        var request = new[] { new WriteRequest(target.AttributeInfo.FullName, 0.0) };
        var results = await _h.RunOnAvailableAsync(
            (driver, ct) => ((IWritable)driver).WriteAsync(request, ct),
            CancellationToken.None);

        // Both backends route through the secured-write path. The exact StatusCode
        // depends on whether the running test identity has write permission on the
        // dev Galaxy — what matters here is that they agree on the status *class*
        // (Good vs Bad vs Uncertain), not which exact code they produce.
        var legacyCode = results[ParityHarness.Backend.LegacyHost][0].StatusCode;
        var mxgwCode = results[ParityHarness.Backend.MxGateway][0].StatusCode;
        AssertStatusClassMatches(legacyCode, mxgwCode, target.AttributeInfo.FullName);
    }

    /// <summary>
    ///     Pin the parity invariant that *matters*: both backends classify the same
    ///     write outcome as Good / Uncertain / Bad. The exact OPC UA code can diverge
    ///     because legacy <c>MxAccessGalaxyBackend</c> flat-maps every failure to
    ///     <c>BadInternalError</c> while the new <c>GatewayGalaxyDataWriter</c> uses
    ///     <c>MxStatusProxy.RawDetectedBy</c> to distinguish gateway-layer faults
    ///     (<c>BadCommunicationError</c>) from MxAccess HRESULT faults — see
    ///     <c>docs/v2/Galaxy.ParityMatrix.md</c> "Accepted deltas". Tighter mapping
    ///     parity isn't worth investing in: legacy retires in PR 7.2.
    /// </summary>
    private static void AssertStatusClassMatches(uint legacyCode, uint mxgwCode, string tag)
    {
        IsBadStatus(legacyCode).ShouldBe(IsBadStatus(mxgwCode),
            $"status-class (Bad) parity for '{tag}': legacy=0x{legacyCode:X8}, mxgw=0x{mxgwCode:X8}");
        IsGoodStatus(legacyCode).ShouldBe(IsGoodStatus(mxgwCode),
            $"status-class (Good) parity for '{tag}': legacy=0x{legacyCode:X8}, mxgw=0x{mxgwCode:X8}");
    }

    private static bool IsBadStatus(uint code) => (code & 0xC0000000u) == 0x80000000u;
    private static bool IsGoodStatus(uint code) => (code & 0xC0000000u) == 0x00000000u;
}