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

namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Conformance;

/// <summary>
///     AtTime rules (spec §4, as amended after the T10 review): exact, linear, stepped, no-prior, and the two
///     Bad-neighbour cases — inside an outage (Bad previous) ⇒ null with the outage's own Bad code; before an
///     outage (usable previous, Bad next) ⇒ previous value held, Uncertain. Never bridges.
/// </summary>
public abstract class AtTimeConformance : ConformanceBase
{
    private static readonly CancellationToken Ct = CancellationToken.None;

    // Hand-computed status literals: Interpolated = InfoType DataValue 0x400 | Interpolated 0x2.
    private const uint GoodInterpolated = 0x00000402u;
    private const uint UncertainInterpolated = 0x40A40402u; // UncertainDataSubNormal | 0x402
    private const uint BadNoData = 0x809B0000u;

    [Fact]
    public async Task Interpolated_bits_are_the_SDK_AggregateBits_Interpolated()
    {
        var code = new Opc.Ua.StatusCode(GoodInterpolated);
        code.AggregateBits.ShouldBe(Opc.Ua.AggregateBits.Interpolated);
        Opc.Ua.StatusCode.IsGood(code).ShouldBeTrue();
        new Opc.Ua.StatusCode(UncertainInterpolated).CodeBits.ShouldBe(Opc.Ua.StatusCodes.UncertainDataSubNormal);
        await Task.CompletedTask;
    }

    [Fact]
    public async Task Exact_hit_returns_the_stored_value_and_status()
    {
        await ConformanceData.SeedAAsync(B);
        var s = (await B.CreateDataSource().ReadAtTimeAsync("A", [At(10), At(20)], Ct)).Samples;
        s[0].Value.ShouldBe(20d);
        s[0].StatusCode.ShouldBe(0u);
        s[0].SourceTimestampUtc.ShouldBe(At(10));          // the requested time itself, never rounded (M3)
        s[0].ServerTimestampUtc.ShouldBe(B.Round(At(11))); // the stored ServerTimeUtc
        s[1].Value.ShouldBe(30d);                 // a stored Bad sample comes back as stored
        s[1].StatusCode.ShouldBe(0x80000000u);
    }

    [Fact]
    public async Task Between_two_good_doubles_is_linearly_interpolated_good()
    {
        await ConformanceData.SeedAAsync(B);
        var s = (await B.CreateDataSource().ReadAtTimeAsync("A", [At(5), At(2.5), At(32.5)], Ct)).Samples;
        s[0].Value.ShouldBe(15d);          // 10 + (20-10) * 5/10
        s[1].Value.ShouldBe(12.5d);        // 10 + 10 * 2.5/10
        s[2].Value.ShouldBe(42.5d);        // 40 + 10 * 2.5/10
        s.ShouldAllBe(x => x.StatusCode == GoodInterpolated);
        s[0].SourceTimestampUtc.ShouldBe(At(5)); // stamped at the requested (sub-µs) time itself, never rounded (M3)
    }

    [Fact]
    public async Task No_previous_sample_is_BadNoData()
    {
        await ConformanceData.SeedAAsync(B);
        var before = At(0).AddTicks(-B.ResolutionTicks);
        var s = (await B.CreateDataSource().ReadAtTimeAsync("A", [before], Ct)).Samples.Single();
        s.Value.ShouldBeNull();
        s.StatusCode.ShouldBe(BadNoData);
        s.SourceTimestampUtc.ShouldBe(before);
    }

    [Fact]
    public async Task A_bad_next_neighbour_holds_the_previous_value_uncertain()
    {
        await ConformanceData.SeedAAsync(B);
        var s = (await B.CreateDataSource().ReadAtTimeAsync("A", [At(15)], Ct)).Samples.Single();
        s.Value.ShouldBe(20d); // NOT 25 (interpolating toward the Bad 30)
        s.StatusCode.ShouldBe(UncertainInterpolated);
    }

    [Fact]
    public async Task A_bad_previous_neighbour_is_inside_an_outage_and_keeps_its_bad_code()
    {
        await ConformanceData.SeedAAsync(B);
        var s = (await B.CreateDataSource().ReadAtTimeAsync("A", [At(25)], Ct)).Samples.Single();
        s.Value.ShouldBeNull();              // NOT 35 (30→40) and NOT 30 (a Bad value)
        s.StatusCode.ShouldBe(0x80000000u);  // the previous sample's Bad code — never upgraded to Uncertain
        s.SourceTimestampUtc.ShouldBe(At(25));
    }

    [Fact]
    public async Task Interpolation_never_bridges_an_outage_marker()
    {
        await B.SeedAsync("M",
            (At(0), HistorianValue.FromDouble(10), Good),
            (At(5), HistorianValue.Empty, BadNoCommunication),
            (At(10), HistorianValue.FromDouble(30), Good));
        var s = (await B.CreateDataSource().ReadAtTimeAsync("M", [At(2.5), At(7.5), At(5)], Ct)).Samples;
        s[0].Value.ShouldBe(10d);   // bridging 10→30 would give 15
        s[0].StatusCode.ShouldBe(UncertainInterpolated);
        s[1].Value.ShouldBeNull();  // bridging would give 25
        s[1].StatusCode.ShouldBe(0x80310000u); // inside the outage: BadNoCommunication, as the marker says
        s[2].Value.ShouldBeNull();  // exact hit on the marker: as stored
        s[2].StatusCode.ShouldBe(0x80310000u);
    }

    [Fact]
    public async Task After_the_last_sample_the_value_is_stepped()
    {
        await ConformanceData.SeedAAsync(B);
        var s = (await B.CreateDataSource().ReadAtTimeAsync("A", [At(45)], Ct)).Samples.Single();
        s.Value.ShouldBe(50d);
        s.StatusCode.ShouldBe(GoodInterpolated);
    }

    [Fact]
    public async Task A_time_after_now_stepped_from_the_last_sample_is_uncertain()
    {
        await ConformanceData.SeedAAsync(B); // last sample +40 = 50, Good
        var src = B.CreateDataSource(new ConformanceClock(new DateTimeOffset(At(42))));
        var s = (await src.ReadAtTimeAsync("A", [At(41), At(45)], Ct)).Samples;
        s[0].Value.ShouldBe(50d);
        s[0].StatusCode.ShouldBe(GoodInterpolated);       // after the last sample but not after now: held Good
        s[1].Value.ShouldBe(50d);
        s[1].StatusCode.ShouldBe(UncertainInterpolated);  // after now: the value is not known to still hold
    }

    [Fact]
    public async Task An_uncertain_neighbour_makes_the_interpolation_uncertain()
    {
        await B.SeedAsync("U",
            (At(0), HistorianValue.FromDouble(10), Uncertain),
            (At(10), HistorianValue.FromDouble(20), Good));
        var s = (await B.CreateDataSource().ReadAtTimeAsync("U", [At(5)], Ct)).Samples.Single();
        s.Value.ShouldBe(15d);
        s.StatusCode.ShouldBe(UncertainInterpolated);
    }

    [Fact]
    public async Task Int64_is_interpolated_and_rounded_keeping_its_type()
    {
        await B.SeedAsync("I",
            (At(0), HistorianValue.FromInt64(10), Good),
            (At(10), HistorianValue.FromInt64(15), Good));
        var s = (await B.CreateDataSource().ReadAtTimeAsync("I", [At(5), At(2)], Ct)).Samples;
        s[0].Value.ShouldBe(13L); // 12.5 ⇒ 13 (away from zero)
        s[1].Value.ShouldBe(11L); // 11.0
        s[0].StatusCode.ShouldBe(GoodInterpolated);
    }

    [Fact]
    public async Task Boolean_string_and_datetime_are_stepped_from_the_previous_sample()
    {
        var d0 = new DateTime(2020, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddTicks(3 * B.ResolutionTicks);
        await B.SeedAsync("B",
            (At(0), HistorianValue.FromBoolean(true), Good),
            (At(10), HistorianValue.FromBoolean(false), Good));
        await B.SeedAsync("S",
            (At(0), HistorianValue.FromString("alpha"), Uncertain),
            (At(10), HistorianValue.FromString("beta"), Good));
        await B.SeedAsync("D",
            (At(0), HistorianValue.FromDateTime(d0), Good),
            (At(10), HistorianValue.FromDateTime(d0.AddDays(1)), Good));
        var src = B.CreateDataSource();
        var b = (await src.ReadAtTimeAsync("B", [At(9)], Ct)).Samples.Single();
        b.Value.ShouldBe(true);
        b.StatusCode.ShouldBe(GoodInterpolated);
        var s = (await src.ReadAtTimeAsync("S", [At(5)], Ct)).Samples.Single();
        s.Value.ShouldBe("alpha");
        s.StatusCode.ShouldBe(0x40000402u); // the previous sample's code (Uncertain) + Interpolated
        (await src.ReadAtTimeAsync("D", [At(5)], Ct)).Samples.Single().Value.ShouldBe(d0);
    }

    [Fact]
    public async Task Result_matches_request_length_and_order_including_duplicates()
    {
        await ConformanceData.SeedAAsync(B);
        var s = (await B.CreateDataSource().ReadAtTimeAsync("A", [At(5), At(-1), At(5), At(10)], Ct)).Samples;
        s.Count.ShouldBe(4);
        s.Select(x => x.Value).ShouldBe([15d, null, 15d, 20d]);
        s.Select(x => x.SourceTimestampUtc).ShouldBe([At(5), At(-1), At(5), At(10)]);
    }

    [Fact]
    public async Task Empty_request_and_unknown_tag()
    {
        var src = B.CreateDataSource();
        (await src.ReadAtTimeAsync("A", [], Ct)).Samples.ShouldBeEmpty();
        var s = (await src.ReadAtTimeAsync("nope", [At(1), At(2)], Ct)).Samples;
        s.Count.ShouldBe(2);
        s.ShouldAllBe(x => x.StatusCode == BadNoData && x.Value == null);
    }
}