using Opc.Ua;
using Opc.Ua.Server;
using ZB.MOM.WW.OtOpcUa.OpcUaServer.Compatibility.Aggregates;
using BaselineAggregateCalculator = ZB.MOM.WW.OtOpcUa.OpcUaServer.Compatibility.Aggregates.AggregateCalculator;
using BaselineStatusAggregateCalculator = ZB.MOM.WW.OtOpcUa.OpcUaServer.Compatibility.Aggregates.StatusAggregateCalculator;
using Shouldly;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

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

/// <summary>
///     Drives the application's versioned 1.5.378.182 Part 13 compatibility calculators — the same factories
///     the upgraded server registers for live aggregates in-process over a sample set, so our processed reads can be compared with the
///     reference implementation bucket by bucket (#677). The calculators run under the server's default
///     <see cref="AggregateConfiguration"/> (TreatUncertainAsBad = false, PercentDataBad = PercentDataGood = 100,
///     UseSlopedExtrapolation = false), sloped interpolation, source timestamps.
/// </summary>
/// <remarks>
///     <para>Shared (source-linked) by <c>Sql.Common.Tests</c> and both SQL backends' integration suites.</para>
///     <para>
///         <b>PercentGood is the one aggregate not taken as-is (#796).</b> The 1.5.378.182 baseline changed
///         <c>StatusAggregateCalculator.ComputeDurationGoodBad</c> (1.5.378.106 and earlier counted Good regions only):
///         with TreatUncertainAsBad = false it counts Uncertain regions as <b>Good</b> time (as Bad when true). Part 13
///         keeps Uncertain out of both (§5.4.3.31 DurationGood counts Good regions; §5.4.3.33 PercentGood =
///         DurationGood ÷ interval; Mantis 0006166, closed "no change required": an all-Uncertain interval is
///         PercentGood 0 <i>and</i> PercentBad 0), and so does ours. <see cref="Run"/> therefore answers PercentGood
///         through <see cref="Part13PercentGoodCalculator"/>: the SAME baseline calculator, region machinery (simple
///         bounds, end-of-data 1 ms region, status and Partial bits) and server-default configuration, counting only
///         Good regions — exactly what the pre-.182 oracle computed. PercentBad still counts Bad regions only (unchanged
///         by .182) and is compared as-is. <see cref="RunSdkAsIs"/> runs the baseline untouched, for the test that pins
///         the divergence.
///     </para>
///     <para>
///         Not <c>100 − PercentBad</c> under TreatUncertainAsBad = true: that flag also changes the region machinery
///         (<c>IsGood</c> drives the end-of-data 1 ms rule and the simple bounds), so after an Uncertain last sample the
///         region runs to the interval end instead of 1 ms and the total differs from the one PercentBad is computed
///         over. Pinned by <c>SdkAggregateParityTests</c>.
///     </para>
/// </remarks>
public static class SdkAggregateOracle
{
    private static readonly ITelemetryContext Telemetry = DefaultTelemetry.Create(_ => { });
    /// <summary>One processed value: value (double / int / null), full status code, timestamp.</summary>
    public readonly record struct Result(object? Value, uint StatusCode, DateTime Timestamp);

    /// <summary>The server-default aggregate configuration (what <c>AggregateManager.GetDefaultConfiguration</c> returns).</summary>
    public static AggregateConfiguration DefaultConfiguration => new()
    {
        TreatUncertainAsBad = false,
        PercentDataBad = 100,
        PercentDataGood = 100,
        UseSlopedExtrapolation = false,
        UseServerCapabilitiesDefaults = false,
    };

    /// <summary>
    ///     Runs the Part 13 oracle for <paramref name="aggregate"/> over <paramref name="samples"/>: the baseline calculator,
    ///     except PercentGood, which counts Good regions only (see the remarks, #796).
    /// </summary>
    /// <param name="aggregate">The aggregate.</param>
    /// <param name="start">Request start (later than <paramref name="end"/> for a reverse read).</param>
    /// <param name="end">Request end.</param>
    /// <param name="interval">Processing interval.</param>
    /// <param name="samples">Every stored sample of the tag, any order (sorted here).</param>
    /// <returns>The oracle's processed values, in the order it returns them.</returns>
    public static IReadOnlyList<Result> Run(HistoryAggregateType aggregate, DateTime start, DateTime end, TimeSpan interval,
        IEnumerable<(DateTime Time, HistorianValue Value, uint Status)> samples) =>
        aggregate == HistoryAggregateType.PercentGood
            ? RunCore(new LegacyCalculatorAdapter(new Part13PercentGoodCalculator(ObjectIds.AggregateFunction_PercentGood,
                    start, end, interval.TotalMilliseconds, false, DefaultConfiguration, Telemetry)), start, end, samples)
            : RunSdkAsIs(aggregate, start, end, interval, samples);

    /// <summary>
    ///     Runs the baseline (1.5.378.182) calculator for <paramref name="aggregate"/> exactly as it computes it, under
    ///     <see cref="DefaultConfiguration"/> — including its PercentGood rule (Uncertain counted as Good) that
    ///     <see cref="Run"/> deliberately does not use (#796).
    /// </summary>
    /// <param name="aggregate">The aggregate.</param>
    /// <param name="start">Request start (later than <paramref name="end"/> for a reverse read).</param>
    /// <param name="end">Request end.</param>
    /// <param name="interval">Processing interval.</param>
    /// <param name="samples">Every stored sample of the tag, any order (sorted here).</param>
    /// <param name="configuration">The configuration (default <see cref="DefaultConfiguration"/>).</param>
    /// <returns>The calculator's processed values, in the order it returns them.</returns>
    public static IReadOnlyList<Result> RunSdkAsIs(HistoryAggregateType aggregate, DateTime start, DateTime end,
        TimeSpan interval, IEnumerable<(DateTime Time, HistorianValue Value, uint Status)> samples,
        AggregateConfiguration? configuration = null) =>
        RunCore(CompatibilityAggregateFactory.Create(AggregateId(aggregate), start, end, interval.TotalMilliseconds, false,
            configuration ?? DefaultConfiguration, Telemetry), start, end, samples);

    private static IReadOnlyList<Result> RunCore(IAggregateCalculator calc, DateTime start, DateTime end,
        IEnumerable<(DateTime Time, HistorianValue Value, uint Status)> samples)
    {

        // The SDK expects values in the direction of the read: ascending forward, descending reverse.
        var ordered = samples.OrderBy(s => s.Time).ToList();
        if (end < start) ordered.Reverse();
        foreach (var s in ordered) calc.QueueRawValue(ToDataValue(s.Time, s.Value, s.Status));

        var results = new List<Result>();
        for (var guard = 0; guard < 100_000; guard++)
        {
            if (!calc.TryGetProcessedValue(true, out var dv)) break;
            results.Add(new Result(dv.WrappedValue.AsBoxedObject(Variant.BoxingBehavior.Legacy), dv.StatusCode.Code, (DateTime)dv.SourceTimestamp));
        }
        return results;
    }

    /// <summary>
    ///     Asserts our snapshots equal the SDK's: same count, same timestamps, same status code bits (severity + sub-code)
    ///     and Partial bit (and optionally the Calculated / Interpolated bits), same value (doubles to 1e-9; ints exactly;
    ///     null on a Bad status). A failure lists every differing interval side by side.
    /// </summary>
    /// <param name="ours">Our processed values.</param>
    /// <param name="sdk">The SDK's.</param>
    /// <param name="label">Context for failure messages.</param>
    /// <param name="compareCalculatedInterpolatedBits">Also compare the Calculated / Interpolated aggregate bits.</param>
    /// <param name="compareCodeBits">Compare the severity + sub-code (false only for a documented status divergence).</param>
    /// <param name="compareValues">Compare the values (false only for a documented value divergence).</param>
    /// <param name="compareTimestamps">Compare the timestamps (false only for a documented timestamp divergence).</param>
    /// <param name="comparePartialBit">Compare the Partial bit (false only for a documented divergence).</param>
    public static void ShouldMatch(IReadOnlyList<DataValueSnapshot> ours, IReadOnlyList<Result> sdk, string label,
        bool compareCalculatedInterpolatedBits = true, bool compareCodeBits = true, bool compareValues = true,
        bool compareTimestamps = true, bool comparePartialBit = true)
    {
        var problems = new List<string>();
        if (ours.Count != sdk.Count) problems.Add($"interval count: ours {ours.Count}, sdk {sdk.Count}");
        for (var i = 0; i < Math.Min(ours.Count, sdk.Count); i++)
        {
            var o = ours[i];
            var s = sdk[i];
            var bitMask = (comparePartialBit ? 0x4u : 0u) | (compareCodeBits ? 0xFFFF0000u : 0u)
                          | (compareCalculatedInterpolatedBits ? 0x3u : 0u);
            var same = (!compareTimestamps || o.SourceTimestampUtc == s.Timestamp)
                       && (o.StatusCode & bitMask) == (s.StatusCode & bitMask);
            if (!compareValues || (!compareCodeBits && StatusCode.IsBad(s.StatusCode)))
            {
                // Values not compared (or the SDK answered Bad under a status this comparison does not check).
            }
            else if (same && !StatusCode.IsBad(s.StatusCode))
            {
                same = s.Value switch
                {
                    null => o.Value is null,
                    int n => o.Value is not null && Convert.ToInt32(o.Value) == n,
                    _ => o.Value is not null && Math.Abs(Convert.ToDouble(o.Value) - Convert.ToDouble(s.Value)) <= 1e-9,
                };
            }
            else if (same && compareCodeBits) same = o.Value is null;
            if (!same)
                problems.Add($"[{i}] ours {o.SourceTimestampUtc:HH:mm:ss.fffffff} {o.Value ?? "null"} 0x{o.StatusCode:X8}" +
                             $" | sdk {s.Timestamp:HH:mm:ss.fffffff} {s.Value ?? "null"} 0x{s.StatusCode:X8}");
        }
        problems.ShouldBeEmpty($"{label} differs from the SDK:\n" + string.Join("\n", problems));
    }

    /// <summary>
    ///     The baseline <see cref="BaselineStatusAggregateCalculator"/> with PercentGood counting <b>Good</b> regions only — Part 13
    ///     §5.4.3.31/§5.4.3.33, and the 1.5.378.106 rule. Everything else (bounds, regions, Partial, status) is the
    ///     baseline's own code, run under the same configuration as PercentBad.
    /// </summary>
    private sealed class Part13PercentGoodCalculator(NodeId aggregateId, DateTime startTime, DateTime endTime,
        double processingInterval, bool stepped, AggregateConfiguration configuration, ITelemetryContext telemetry)
        : BaselineStatusAggregateCalculator(aggregateId, startTime, endTime, processingInterval, stepped, configuration, telemetry)
    {
        protected override LegacyDataValue ComputeValue(TimeSlice slice)
        {
            var values = GetValuesWithSimpleBounds(slice);
            if (values == null || values.Count == 0) return GetNoDataValue(slice);

            var regions = GetRegionsInValueSet(values, false, true);
            double good = 0, total = 0;
            foreach (var region in regions)
            {
                total += region.Duration;
                if (StatusCode.IsGood(region.StatusCode)) good += region.Duration;
            }

            var value = new LegacyDataValue
            {
                WrappedValue = ZB.MOM.WW.OtOpcUa.OpcUaServer.SdkValueBoundary.FromClr(good / total * 100),
                SourceTimestamp = GetTimestamp(slice),
                ServerTimestamp = GetTimestamp(slice),
            };
            value.StatusCode = value.StatusCode.WithAggregateBits(AggregateBits.Calculated);
            return value;
        }
    }

    /// <summary>The <see cref="CompatibilityAggregateFactory"/> adapter, for a calculator built here.</summary>
    private sealed class LegacyCalculatorAdapter(BaselineAggregateCalculator calculator) : IAggregateCalculator
    {
        public NodeId AggregateId => calculator.AggregateId;
        public bool QueueRawValue(DataValue value) => calculator.QueueRawValue(LegacyDataValue.FromSdk(value));
        public bool HasEndTimePassed(DateTimeUtc currentTime) => calculator.HasEndTimePassed((DateTime)currentTime);
        public bool TryGetProcessedValue(bool returnPartial, out DataValue value)
        {
            var processed = calculator.GetProcessedValue(returnPartial);
            value = processed is null ? default : processed.ToSdk();
            return processed is not null;
        }
    }

    private static DataValue ToDataValue(DateTime t, HistorianValue v, uint status) => new(
        v.Kind switch
        {
            HistorianValueKind.Empty => Variant.Null,
            HistorianValueKind.Int64 => Variant.From(v.Integer),
            HistorianValueKind.Boolean => Variant.From(v.Number != 0),
            HistorianValueKind.String => v.Text is { } text ? Variant.From(text) : Variant.Null,
            _ => Variant.From(v.Number),
        },
        status, t, t);

    private static NodeId AggregateId(HistoryAggregateType a) => a switch
    {
        HistoryAggregateType.Average => ObjectIds.AggregateFunction_Average,
        HistoryAggregateType.Minimum => ObjectIds.AggregateFunction_Minimum,
        HistoryAggregateType.Maximum => ObjectIds.AggregateFunction_Maximum,
        HistoryAggregateType.Range => ObjectIds.AggregateFunction_Range,
        HistoryAggregateType.MinimumActualTime => ObjectIds.AggregateFunction_MinimumActualTime,
        HistoryAggregateType.MaximumActualTime => ObjectIds.AggregateFunction_MaximumActualTime,
        HistoryAggregateType.Count => ObjectIds.AggregateFunction_Count,
        HistoryAggregateType.PercentGood => ObjectIds.AggregateFunction_PercentGood,
        HistoryAggregateType.PercentBad => ObjectIds.AggregateFunction_PercentBad,
        HistoryAggregateType.Start => ObjectIds.AggregateFunction_Start,
        HistoryAggregateType.End => ObjectIds.AggregateFunction_End,
        HistoryAggregateType.Delta => ObjectIds.AggregateFunction_Delta,
        HistoryAggregateType.TimeAverage => ObjectIds.AggregateFunction_TimeAverage,
        HistoryAggregateType.TimeAverage2 => ObjectIds.AggregateFunction_TimeAverage2,
        HistoryAggregateType.Total => ObjectIds.AggregateFunction_Total,
        HistoryAggregateType.Total2 => ObjectIds.AggregateFunction_Total2,
        HistoryAggregateType.Interpolative => ObjectIds.AggregateFunction_Interpolative,
        _ => throw new ArgumentOutOfRangeException(nameof(a), a, "no SDK aggregate id mapped"),
    };
}