namespace StellaOps.AuditPack.Services;

public sealed partial class VerdictReplayPredicate
{
    private static DivergenceCategory MapDriftTypeToCategory(DriftType driftType)
    {
        return driftType switch
        {
            DriftType.Decision => DivergenceCategory.Decision,
            DriftType.VerdictDigest => DivergenceCategory.VerdictHash,
            DriftType.VerdictField => DivergenceCategory.VerdictField,
            DriftType.InputDigest => DivergenceCategory.Input,
            _ => DivergenceCategory.Other
        };
    }

    private static string GenerateDivergenceSummary(List<DivergenceItem> divergences)
    {
        if (divergences.Count == 0)
        {
            return "Replay matched original verdict exactly.";
        }

        var hasDecisionChange = divergences.Any(d => d.Category == DivergenceCategory.Decision);
        var hasVerdictChange = divergences.Any(d => d.Category == DivergenceCategory.VerdictHash);
        var hasInputChange = divergences.Any(d => d.Category == DivergenceCategory.Input);

        if (hasDecisionChange)
        {
            return "Replay produced a different policy decision.";
        }

        if (hasVerdictChange)
        {
            return "Replay verdict differs in content but decision is the same.";
        }

        if (hasInputChange)
        {
            return "Input digests differ but verdict is unchanged.";
        }

        return $"Replay detected {divergences.Count} divergence(s).";
    }
}