using System.Collections.Immutable;

namespace StellaOps.Scanner.ChangeTrace.Builder;

/// <summary>
/// Options for change trace building.
/// </summary>
public sealed record ChangeTraceBuilderOptions
{
    /// <summary>
    /// Include package-level diffing. Default: true.
    /// </summary>
    public bool IncludePackageDiff { get; init; } = true;

    /// <summary>
    /// Include symbol-level diffing. Default: true.
    /// </summary>
    public bool IncludeSymbolDiff { get; init; } = true;

    /// <summary>
    /// Include byte-level diffing. Default: false.
    /// </summary>
    public bool IncludeByteDiff { get; init; } = false;

    /// <summary>
    /// Minimum confidence threshold for symbol matches.
    /// Default: 0.75.
    /// </summary>
    public double MinSymbolConfidence { get; init; } = 0.75;

    /// <summary>
    /// Rolling hash window size for byte diffing.
    /// Default: 2048 bytes.
    /// </summary>
    public int ByteDiffWindowSize { get; init; } = 2048;

    /// <summary>
    /// Maximum binary size for byte-level analysis (bytes).
    /// Default: 10MB.
    /// </summary>
    public long MaxBinarySize { get; init; } = 10 * 1024 * 1024;

    /// <summary>
    /// Lattice policies to apply during trust delta computation.
    /// Default: ["lattice:default@v3"].
    /// </summary>
    public ImmutableArray<string> Policies { get; init; } = ["lattice:default@v3"];

    /// <summary>
    /// Gets the diff methods enabled based on options.
    /// </summary>
    public ImmutableArray<string> GetDiffMethods()
    {
        var methods = ImmutableArray.CreateBuilder<string>();
        if (IncludePackageDiff) methods.Add("pkg");
        if (IncludeSymbolDiff) methods.Add("symbol");
        if (IncludeByteDiff) methods.Add("byte");
        return methods.ToImmutable();
    }

    /// <summary>
    /// Default options instance.
    /// </summary>
    public static ChangeTraceBuilderOptions Default { get; } = new();
}