namespace Sand.ChunkPrototype;

internal sealed class ChunkActivityTracker
{
    private readonly List<ChunkCoord> _activeChunks = new();
    private readonly List<ChunkCoord> _sleepingChunks = new();

    public (IReadOnlyList<ChunkCoord> ActiveChunks, int SleepingChunks) Build(IReadOnlyDictionary<ChunkCoord, ChunkCellPage> pages)
    {
        _activeChunks.Clear();
        _sleepingChunks.Clear();
        foreach (var (coord, page) in pages)
        {
            if (page.IsActive || page.HasFieldActivity || page.PendingActiveSteps > 0)
            {
                _activeChunks.Add(coord);
            }
            else
            {
                _sleepingChunks.Add(coord);
            }
        }

        _activeChunks.Sort(static (left, right) =>
        {
            var yCompare = right.Y.CompareTo(left.Y);
            return yCompare != 0 ? yCompare : left.X.CompareTo(right.X);
        });
        return (_activeChunks, _sleepingChunks.Count);
    }
}