lmxopcua/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/BucketPlanTests.cs

using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using static ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests.Fixture;

namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests;

public sealed class BucketPlanTests
{
    [Fact]
    public void BucketPlan_rejects_more_than_100k_buckets()
    {
        var ex = Should.Throw<ArgumentOutOfRangeException>(() =>
            BucketPlan.Create(DateTime.UnixEpoch, DateTime.UnixEpoch.AddSeconds(100_001), TimeSpan.FromSeconds(1)));
        ex.ParamName.ShouldBe("interval");
    }

    [Fact]
    public void Exactly_100k_one_tick_buckets_are_allowed()
    {
        var p = BucketPlan.Create(At(0), At(0).AddTicks(100_000), TimeSpan.FromTicks(1));
        p.BucketCount.ShouldBe(100_000);
        p.IntervalTicks.ShouldBe(1);
    }

    [Fact]
    public void A_partial_last_interval_is_its_own_bucket()
    {
        var p = BucketPlan.Create(At(0), At(50), TimeSpan.FromSeconds(20));
        p.BucketCount.ShouldBe(3);
        p.BucketTimestamp(2).ShouldBe(At(40));
        p.BucketTimestamp(2).Kind.ShouldBe(DateTimeKind.Utc);
        p.IsTruncated(2).ShouldBeTrue();
        p.IsTruncated(1).ShouldBeFalse();
    }

    [Fact]
    public void Zero_or_oversized_interval_is_one_bucket_and_an_empty_window_none()
    {
        BucketPlan.Create(At(0), At(80), TimeSpan.Zero).BucketCount.ShouldBe(1);
        var wide = BucketPlan.Create(At(0), At(80), TimeSpan.FromDays(1));
        wide.BucketCount.ShouldBe(1);
        wide.IntervalTicks.ShouldBe(80 * TimeSpan.TicksPerSecond);
        BucketPlan.Create(At(0), At(0), TimeSpan.FromSeconds(1)).BucketCount.ShouldBe(0);
    }

    [Fact]
    public void A_reverse_window_is_anchored_at_its_later_time_and_stamped_with_later_edges()
    {
        // #677 (Part 13 / SDK CreateSlice + GetTimestamp): At(80) → At(0), 20 s ⇒ (60,80], (40,60], (20,40], (0,20],
        // each stamped with its later edge, latest first.
        var p = BucketPlan.Create(At(80), At(0), TimeSpan.FromSeconds(20));
        p.Reversed.ShouldBeTrue();
        p.StartUtc.ShouldBe(At(0));
        p.EndUtc.ShouldBe(At(80));
        var s = p.Assemble(new Dictionary<long, DataValueSnapshot>(), t => new DataValueSnapshot(null, 0, t, t));
        s.Select(x => x.SourceTimestampUtc).ShouldBe([At(80), At(60), At(40), At(20)]);
    }

    [Fact]
    public void A_reverse_window_puts_the_partial_interval_at_its_earliest_end()
    {
        // At(50) → At(0), 20 s: (30,50], (10,30], (0,10] — the truncated bucket is the EARLIEST (the old layout truncated
        // the latest: [0,20), [20,40), [40,50)).
        var p = BucketPlan.Create(At(50), At(0), TimeSpan.FromSeconds(20));
        p.BucketCount.ShouldBe(3);
        p.LowerTicks(0).ShouldBe(At(0).Ticks);
        p.UpperTicks(0).ShouldBe(At(10).Ticks);
        p.IsTruncated(0).ShouldBeTrue();
        p.LowerTicks(2).ShouldBe(At(30).Ticks);
        p.UpperTicks(2).ShouldBe(At(50).Ticks);
        p.IsTruncated(2).ShouldBeFalse();
        var s = p.Assemble(new Dictionary<long, DataValueSnapshot>(), t => new DataValueSnapshot(null, 0, t, t));
        s.Select(x => x.SourceTimestampUtc).ShouldBe([At(50), At(30), At(10)]);
    }

    [Fact]
    public void Forward_buckets_are_start_inclusive_and_reverse_buckets_later_edge_inclusive()
    {
        var fwd = BucketPlan.Create(At(0), At(50), TimeSpan.FromSeconds(20));
        fwd.IndexOf(At(0)).ShouldBe(0);
        fwd.IndexOf(At(20)).ShouldBe(1);
        fwd.IndexOf(At(20).AddTicks(-1)).ShouldBe(0);
        fwd.IndexOf(At(49.9999999)).ShouldBe(2);
        fwd.IndexOf(At(50)).ShouldBeNull();
        fwd.IndexOf(At(0).AddTicks(-1)).ShouldBeNull();

        // (0,10] (10,30] (30,50]: the later time is in the window, the earlier one is not (as a reverse raw read).
        var rev = BucketPlan.Create(At(50), At(0), TimeSpan.FromSeconds(20));
        rev.IndexOf(At(50)).ShouldBe(2);
        rev.IndexOf(At(30)).ShouldBe(1);
        rev.IndexOf(At(30).AddTicks(1)).ShouldBe(2);
        rev.IndexOf(At(10)).ShouldBe(0);
        rev.IndexOf(At(10).AddTicks(1)).ShouldBe(1);
        rev.IndexOf(At(0).AddTicks(1)).ShouldBe(0);
        rev.IndexOf(At(0)).ShouldBeNull();
        rev.IndexOf(At(50).AddTicks(1)).ShouldBeNull();
    }

    [Fact]
    public void The_backend_bucket_formula_matches_IndexOf_in_both_directions()
    {
        // b = (t − start + adjust) / interval and b = (unixTicks(t) − base) / interval — what the SQL computes.
        foreach (var p in new[]
                 {
                     BucketPlan.Create(At(0), At(50), TimeSpan.FromSeconds(20)),
                     BucketPlan.Create(At(50), At(0), TimeSpan.FromSeconds(20)),
                     BucketPlan.Create(At(60), At(0), TimeSpan.FromSeconds(20)),
                     BucketPlan.Create(At(0).AddTicks(70), At(0), TimeSpan.FromTicks(3)),
                 })
        {
            for (var t = p.StartUtc.Ticks - 2; t <= p.EndUtc.Ticks + 2; t += Math.Max(1, (p.EndUtc.Ticks - p.StartUtc.Ticks) / 997))
            {
                var at = new DateTime(t, DateTimeKind.Utc);
                if (p.IndexOf(at) is not { } idx) continue;
                ((t - p.StartUtc.Ticks + p.BucketIndexAdjustTicks) / p.IntervalTicks).ShouldBe(idx);
                (((at - DateTime.UnixEpoch).Ticks - p.BucketBaseUnixTicks) / p.IntervalTicks).ShouldBe(idx);
                p.LowerTicks(idx).ShouldBeLessThanOrEqualTo(t);
                p.UpperTicks(idx).ShouldBeGreaterThanOrEqualTo(t);
            }
        }
    }

    [Fact]
    public void Data_starts_inside_only_strictly_between_the_bucket_edges()
    {
        var p = BucketPlan.Create(At(0), At(40), TimeSpan.FromSeconds(20));
        p.DataStartsInside(0, At(5)).ShouldBeTrue();
        p.DataStartsInside(1, At(5)).ShouldBeFalse();
        p.DataStartsInside(1, At(20)).ShouldBeFalse(); // on the edge: data covers the whole interval
        p.DataStartsInside(0, null).ShouldBeFalse();
        p.DataStartsInside(0, At(-5)).ShouldBeFalse();
    }

    [Fact]
    public void The_earliest_sample_is_needed_only_for_forward_reads_of_aggregates_other_than_Average()
    {
        // Review F2: backends skip the earliest-sample query when its answer cannot change a result.
        var fwd = BucketPlan.Create(At(0), At(40), TimeSpan.FromSeconds(10));
        var rev = BucketPlan.Create(At(40), At(0), TimeSpan.FromSeconds(10));
        AggregateEvaluator.NeedsEarliestSample(HistoryAggregateType.Count, fwd).ShouldBeTrue();
        AggregateEvaluator.NeedsEarliestSample(HistoryAggregateType.Average, fwd).ShouldBeFalse();
        AggregateEvaluator.NeedsEarliestSample(HistoryAggregateType.Count, rev).ShouldBeFalse();
        AggregateEvaluator.NeedsEarliestSample(HistoryAggregateType.Count, BucketPlan.Create(At(0), At(0), TimeSpan.Zero))
            .ShouldBeFalse();
    }

    [Fact]
    public void Assemble_fills_missing_buckets_with_the_empty_factory()
    {
        var p = BucketPlan.Create(At(0), At(60), TimeSpan.FromSeconds(20));
        var hit = new DataValueSnapshot(7d, 0, At(20), At(20));
        var s = p.Assemble(new Dictionary<long, DataValueSnapshot> { [1] = hit }, t => new DataValueSnapshot(null, 1u, t, t));
        s.Select(x => x.Value).ShouldBe([null, (object?)7d, null]);
        s[0].SourceTimestampUtc.ShouldBe(At(0));
        s[2].SourceTimestampUtc.ShouldBe(At(40));
    }

    [Fact]
    public void BucketBaseUnixTicks_is_the_start_forward()
        => BucketPlan.Create(DateTime.UnixEpoch.AddTicks(1234567), DateTime.UnixEpoch.AddSeconds(10), TimeSpan.FromSeconds(1))
            .BucketBaseUnixTicks.ShouldBe(1234567L);

    [Fact]
    public void StartUnixTicks_is_ticks_since_the_unix_epoch()
        => BucketPlan.Create(DateTime.UnixEpoch.AddTicks(1234567), DateTime.UnixEpoch.AddSeconds(10), TimeSpan.Zero)
            .StartUnixTicks.ShouldBe(1234567L);
}