namespace RobotNet10.GlobalPathPlanner.Model;

/// <summary>
/// Represents a node in the KD-Tree structure.
/// Immutable to prevent structural corruption.
/// </summary>
/// <remarks>
/// Initializes a new KD-Tree node.
/// </remarks>
public class KDTreeNode(GlobalNode node, int axis, KDTreeNode? left = null, KDTreeNode? right = null)
{
    /// <summary>
    /// The spatial node stored at this tree node.
    /// </summary>
    public GlobalNode Node { get; } = node ?? throw new ArgumentNullException(nameof(node));

    /// <summary>
    /// Left child (contains points with smaller values along the split axis).
    /// </summary>
    public KDTreeNode? Left { get; } = left;

    /// <summary>
    /// Right child (contains points with larger values along the split axis).
    /// </summary>
    public KDTreeNode? Right { get; } = right;

    /// <summary>
    /// The axis used for splitting: 0 for X, 1 for Y.
    /// </summary>
    public int Axis { get; } = axis;
}