using FluentAssertions;
using Marathon.Domain.AnomalyDetection;
using Marathon.Domain.Entities;
using Marathon.Domain.Enums;
using Marathon.Domain.ValueObjects;

namespace Marathon.Domain.Tests.AnomalyDetection;

public sealed class SuspensionFreezeDetectorTests
{
    private static readonly TimeSpan MoscowOffset = TimeSpan.FromHours(3);
    private static readonly DateTimeOffset BaseTime = new(2026, 5, 10, 18, 0, 0, MoscowOffset);
    private static readonly EventId Event = new("26000002");

    // suspension gap 60s, freeze threshold 0.05, min 3 snapshots.
    private static SuspensionFreezeDetector CreateSut() => new(60, 0.05m, 3);

    private static OddsSnapshot Live(int seconds, decimal r1, decimal r2) =>
        new(Event, BaseTime.AddSeconds(seconds), OddsSource.Live,
            new List<Bet>
            {
                new(MatchScope.Instance, BetType.Win, Side.Side1, null, new OddsRate(r1)),
                new(MatchScope.Instance, BetType.Win, Side.Side2, null, new OddsRate(r2)),
            });

    [Fact]
    public void Should_FlagFreeze_When_SuspensionResumesUnchanged()
    {
        // 90s gap between the 2nd and 3rd snapshot; line resumes identical.
        var snapshots = new[]
        {
            Live(0,   1.5m, 3.0m),
            Live(30,  1.5m, 3.0m),
            Live(120, 1.5m, 3.0m), // 90s gap, unchanged
            Live(150, 1.5m, 3.0m),
        };

        var result = CreateSut().Detect(Event, snapshots);

        result.Should().ContainSingle();
        result[0].Kind.Should().Be(AnomalyKind.SuspensionFreeze);
        result[0].Score.Should().Be(1.0m, "an unchanged line is a complete freeze");
    }

    [Fact]
    public void Should_NotFlag_When_FlipAcrossSuspension()
    {
        // Favourite changes across the gap — that is the SuspensionFlip detector's job.
        var snapshots = new[]
        {
            Live(0,   1.3m, 4.0m),
            Live(30,  1.3m, 4.0m),
            Live(120, 4.0m, 1.3m), // 90s gap, flipped
            Live(150, 4.0m, 1.3m),
        };

        CreateSut().Detect(Event, snapshots).Should().BeEmpty();
    }

    [Fact]
    public void Should_NotFlag_When_NoSuspensionGap()
    {
        // Continuous 30s steps — no gap exceeds the 60s suspension threshold.
        var snapshots = new[]
        {
            Live(0,  1.5m, 3.0m),
            Live(30, 1.5m, 3.0m),
            Live(60, 1.5m, 3.0m),
        };

        CreateSut().Detect(Event, snapshots).Should().BeEmpty();
    }

    [Fact]
    public void Should_ReturnEmpty_When_FewerThanMinSnapshots()
    {
        var snapshots = new[] { Live(0, 1.5m, 3.0m), Live(120, 1.5m, 3.0m) };

        CreateSut().Detect(Event, snapshots).Should().BeEmpty();
    }

    [Fact]
    public void Should_EmitParseableEvidence_For_DetectedFreeze()
    {
        var snapshots = new[]
        {
            Live(0,   1.5m, 3.0m),
            Live(30,  1.5m, 3.0m),
            Live(120, 1.5m, 3.0m),
        };

        var anomaly = CreateSut().Detect(Event, snapshots).First();

        AnomalyEvidenceParser.TryParse(anomaly.EvidenceJson, out var data).Should().BeTrue();
        data.PreSuspension.Favourite.Should().Be(data.PostSuspension.Favourite, "the favourite is unchanged in a freeze");
    }

    [Fact]
    public void Should_Throw_When_FreezeThresholdOutOfRange()
    {
        var act = () => new SuspensionFreezeDetector(60, 0m, 3);
        act.Should().Throw<ArgumentOutOfRangeException>();
    }
}