namespace RuleEngine.Core;

/// <summary>
/// Per-game wildcard configuration — replaces the old static HashSet approach.
/// Each MahjongGameState owns its own registry so different game variants
/// don't leak wildcard state between tests or concurrent games.
/// </summary>
public class WildcardRegistry
{
    private readonly HashSet<int> _wildcards = new();

    /// <summary>Base wildcard encoding range (50-59) for extra tiles added to deck.</summary>
    public const int WildcardBase = 50;

    /// <summary>Non-extra wildcard tiles — normal tiles (e.g. 红中=35) that ALSO act as wildcards.</summary>
    public IReadOnlySet<int> ConfiguredWildcards => _wildcards;

    public void Clear() => _wildcards.Clear();

    public void Add(int tile) => _wildcards.Add(tile);

    public void AddRange(IEnumerable<int> tiles)
    {
        foreach (var t in tiles) _wildcards.Add(t);
    }

    /// <summary>Is this tile a wildcard? Checks encoding range AND configured set.</summary>
    public bool IsWildcard(int tile) =>
        (tile >= WildcardBase && tile <= WildcardBase + 9) || _wildcards.Contains(tile);

    /// <summary>Count how many tiles in a list are wildcards.</summary>
    public int CountWildcards(IReadOnlyList<int> tiles) =>
        tiles.Count(t => IsWildcard(t));

    /// <summary>Parse wildcard tile names from DSL into encodings.</summary>
    public static int? NameToEncoding(string name) => name switch
    {
        "红中" => 35,
        "发财" => 36,
        "白板" => 37,
        _ => null
    };

    public WildcardRegistry Clone()
    {
        var r = new WildcardRegistry();
        r.AddRange(_wildcards);
        return r;
    }
}