#pragma once
#include "vde/spatial/spatial_index.h"
#include <vector>

namespace vde::spatial {
using core::AABB3D;
using core::Point3D;
using core::Vector3D;
using core::Ray3Dd;
using core::Triangle3D;

template <typename T>
class KDTree : public SpatialIndex<T> {
public:
    void build(const std::vector<T>& items) override;
    void insert(const T& item) override;
    bool remove(const T& item) override;
    std::vector<T> query_range(const AABB3D& range) const override;
    std::vector<T> query_knn(const Point3D& point, size_t k) const override;
    std::vector<T> query_ray(const Ray3Dd& ray) const override;
    void clear() override;
    size_t size() const override { return items_.size(); }

private:
    struct Node {
        AABB3D bounds;
        int item_idx = -1;   // -1 for internal node; index into items_ for leaf
        int split_axis = 0;
        int left = -1;
        int right = -1;
    };

    std::vector<T> items_;
    std::vector<Node> nodes_;
    int root_ = -1;

    /// Return a representative 3D position for the item (used for spatial ordering)
    static Point3D get_position(const T& item);

    /// Return an axis-aligned bounding box for the item
    static AABB3D get_aabb(const T& item);

    /// Test whether the item intersects a ray
    static bool ray_hits_item(const T& item, const Ray3Dd& ray);

    int build_recursive(int start, int end);
    void query_range_recursive(int node_idx, const AABB3D& range,
                               std::vector<T>& result) const;
    void query_ray_recursive(int node_idx, const Ray3Dd& ray,
                             std::vector<T>& result) const;
};

}  // namespace vde::spatial