using System;
using System.Collections.Generic;

namespace StellaOps.Scanner.Reachability.Ordering;

/// <summary>
/// Canonical (deterministically ordered) graph representation.
/// </summary>
public sealed class CanonicalGraph
{
    /// <summary>
    /// Ordering strategy used.
    /// </summary>
    public required GraphOrderingStrategy Strategy { get; init; }

    /// <summary>
    /// Deterministically ordered nodes.
    /// </summary>
    public required IReadOnlyList<CanonicalNode> Nodes { get; init; }

    /// <summary>
    /// Deterministically ordered edges.
    /// </summary>
    public required IReadOnlyList<CanonicalEdge> Edges { get; init; }

    /// <summary>
    /// Content hash of canonical representation.
    /// </summary>
    public required string ContentHash { get; init; }

    /// <summary>
    /// Anchor nodes (entry points), if present.
    /// </summary>
    public IReadOnlyList<string>? AnchorNodes { get; init; }

    /// <summary>
    /// Optional timestamp for diagnostics; excluded from <see cref="ContentHash"/>.
    /// </summary>
    public DateTimeOffset? ComputedAt { get; init; }
}

public sealed class CanonicalNode
{
    /// <summary>
    /// Position in ordered list (0-indexed).
    /// </summary>
    public required int Index { get; init; }

    /// <summary>
    /// Node identifier.
    /// </summary>
    public required string Id { get; init; }

    /// <summary>
    /// Node type (e.g. method, function).
    /// </summary>
    public required string NodeType { get; init; }

    /// <summary>
    /// Node label for UI display (optional).
    /// </summary>
    public string? Label { get; init; }
}

public sealed class CanonicalEdge
{
    public required int SourceIndex { get; init; }
    public required int TargetIndex { get; init; }
    public required string EdgeType { get; init; }
}